Unofficial Garmin GPS FAQ (formerly Garmin GPS 45/40/38 FAQ) ============================================================ V 1.101 Mar 29, 1997 V 1.101.a Feb 19,2008 (1.101.a is 1.101 with email address removed --tim) Compiled by Lane A. Holdcroft Garmin GPS FAQ Copyright 1995, 1996, 1997 by Lane A. Holdcroft. Original contributors retain their copyright for all of their contributions. This document is not in any way endorsed by Garmin International. I am not affiliated with Garmin or any of their retailers. This Garmin GPS FAQ is targeted primarily at the GPS 45/45XL, 40, 38, II, and 12XL but also has lots of information on the GPS 89, 90, 120, and 175. Most of this FAQ applies to other Garmin units as well. This does not have any significant information about Garmin's professional surveying equipment or permanently mounted aircraft GPS's. | Garmin finally has their website up and working! It is: http://www.garmin.com | If you want to print this out and have the columns line up, use a non-proportionally spaced font such as "Courier". Also note that this document is huge! | The GPS 12XL was just released in January 1997. It is like the GPS 40 but has 12 channels for better performance in marginal conditions such as trees and it does NOT have the 90 knot speed limit. As of March 1997, it is still difficult to obtain due to limited supply and large demand. There are numerous user reports in the section "GPS 12XL". | The GPS II is sort of like a differently shaped GPS 45XL which includes map zoom buttons. It was released in November 1996. | The GPS 38 (released Feb 1996), is very similar to the GPS 40. However, the 38 has improved software, no external antenna connector, no beeper, no video tape, and a lower price. See the new section "GPS 38". The GPS 40 is being discontinued but is still available. It was the predecessor to the GPS 38. However the 40 had an external antenna connector. | The GPS 45 was Garmin's first really small handheld GPS. It is probably the most popular GPS sold to date, but will likely be surpassed by the cheaper GPS 38. | The GPS 45XL (released July 1996) is a GPS 45 (April 1994) with the GPS 38 software enhancements. Almost all references to the GPS 45 in this FAQ also apply to the GPS 45XL except some of the software specifics. | The older GPS 50, 65, and 75 have many internal similarities (and some software compatibility) to the GPS 45/40/38. The GPS 89 and 90 are very similar to the GPS 45 but have different software and additional non-volatile memory for their aero navigation database. Among other things, the GPS 89 has a much less detailed navigation database than the GPS 90. The GPS 120 (released late 1995) has almost identical software to the GPS 45 but a mobile mount, external antenna and a much larger display. The GPS 130 is Garmin's 12 channel mobile mount GPS unit with a map. It has a case similar to the GPS 120. It started shipping in the Spring of 1996. The GPSMAP 175 is Garmin's large 12 channel handheld announced in July 1996. It is large for a handheld but has a nice built-in map of the world and can take detailed map cartridges. It started shipping in September 1996. | The GPS 195 is the aviation model of the GPSMAP 175. CAUTION: It seems like it should go without saying, but a GPS unit does NOT replace common sense! If there is any possibility of getting lost, you should have a MAP AND COMPASS and KNOW HOW TO USE THEM! An electronic instrument is not failproof. Also, GPS units do not work without good batteries. | ====================================================================== TABLE OF CONTENTS: ----------------- 1.00 ABOUT THIS FAQ: -General FAQ info? -FAQ revision history? -Suggestions for improvement? 2.00 GARMIN PRODUCTS: | -Garmin GPS models? -Garmin accessories? 3.00 GENERAL GARMIN QUESTIONS: -What are some key features of the Garmin GPS 45/40/38/II? -What are the disadvantages of the GPS 45/40/38/II? -Comparison of the GPS 38/40/45/45XL/II/89/90/12XL? | -What are the differences between the GPS 45 and GPS 40? -What are the differences between the GPS 45XL and GPS II? | -What is the accuracy of the Garmin GPS units? -How does the GPS 12XL averaging feature work? | -Performance in trees? | 4.00 GENERAL USE QUESTIONS: -Why can't I get an initial fix? -How can I improve the accuracy of a GPS unit with averaging? -Can I post-process data from the GPS? | -How accurate is velocity measurement? -How accurate is the clock? -What is the MOB function? -What is a waypoint? -Which map datum do I use? -How does the GPS calculate the local magnetic variation? -Why do I get the message "Need 2D Altitude"? | -How do I calculate the distance between 2 locations? | -When will Selective Availability (SA) be turned off? | -What will be the effect of the GPS rollover in the year 1999? | 5.00 SPECIFICATIONS/REPORTS: -GPS 45XL/45/40/38 specifications? -GPS 45/40? -GPS 45XL? -GPS 38? -GPS II? -GPS 12XL? | -GPS 89 (aero)? -GPS 90 (aero)? -GPS 120? -GPS 130? -GPS 135? -GPSMAP 175? -GPS 20/25/30/31/35 (remote only models)? -GPS 30/31 description? 6.00 DIFFERENTIAL GPS (DGPS): -What is Differential GPS? -Garmin's GBR 21 Differential Beacon Receiver and alternatives? -Garmin's GBR 21 Differential Beacon Receiver unit report? | 7.00 FIRMWARE (INTERNAL SOFTWARE): -90 knot speed limit? -GPS 45/40 firmware versions? -What are the undocumented modes for the GPS 45/40/38/90/89/120/II/12XL? -What are some undocumented modes for the GPS 75? -Why is internal temperature available? -VMG error? -Garmin NMEA 0183 data sentences? | 8.00 BATTERY/POWER: -How is power selected between the internal batteries and the external supply? -What voltages do the GPS 45 fuel gauge correspond to? -Current consumption of a GPS 45 at different external supply input voltages? -How does BatterySave mode work? -GPS 38 batteries too tight? | -Batteries? -Other battery/external power options? -How long is memory conserved without batteries? -Does the serial I/O consume much more power when it is enabled? -What is the minimum external supply voltage for the GPS 45/45XL? | -What is the external voltage range for the GPS 12XL | 9.00 SERIAL/POWER INTERFACE: -External serial/power connector alternatives? -How do I interface the GPS 45/40/38/II/12XL to an IBM-PC compatible computer? -Can I use one cable for both power and data at the same time? | -Can I power my GPS from the serial port on my laptop or PC? | -How do I interface the GPS 45/40/38/II/12XL to a Macintosh? 10.00 APPLICATION SOFTWARE: -What Macintosh software is available? -What other (non-PC, non-Mac) GPS software for Garmins is available? | -What MS-DOS/Win software is available specifically for Garmin GPS units? -What MS-DOS/Win software is available that communicates using NMEA 183 format? -Other MS-DOS software? -GPS www/ftp sites? | -Digital maps with lat/lon? 11.00 ANTENNAS: -What is the GPS 40/38/12XL internal antenna? -How is the GPS 45/90/89/II antenna internally constructed? -How well does the internal antenna work inside a car? -What are the remote antenna options? -GPS 45 antenna extension cables? -Can I make my own external antenna? -What is the Trimble OEM antenna? | -What is the loss for different coaxial cables? -What is the GPS 40/12XL antenna connector? 12.00 MISCELLANEOUS: -GPS mounting options? -Waterproofness? -Cases? -Garmin 45/40/38 wish list? -Can I use my GPS unit in a plane? -Internal electrical hardware? -Why is the GPS 45/40/38/90/89 firmware not in a socket? -Can I receive GPS signals through my house? -For how long will a particular track interval collect data? -Where can I purchase a unit? ====================================================================== QUESTIONS AND ANSWERS: ---------------------- 1.00 ABOUT THIS FAQ: --------------- -General FAQ info? Unofficial Garmin FAQ Copyright 1995, 1996, 1997 by Lane A. Holdcroft. Original contributors retain their copyright for all of their contributions. You may copy this in its entirety, but not for monetary benefit. If a portion of this document is quoted, please give the original author credit. Thanks to the many people who have contributed to this document! I tried to give credit to the original author at the end of each contribution. If an answer does not have an attribution, I usually answered it based on my recollection of the consensus of previous postings and/or my personal experience (or the contributor did not want credit). Sometimes I delete some quoted material for brevity, grammar, or accuracy. If I felt clarification within another person's quoted material would be beneficial, my comments should always be contained within the brackets "[" and "]". The Usenet newsgroup "sci.geo.satellite-nav" has a high proportion of questions dealing with the very popular Garmin GPS units. This should answer most of them. The newsgroup was originally intended to be oriented more towards professionals in the GPS business rather than recreational users that are more inclined to use the low cost Garmin GPS's. However, there is a lot of discussion about Garmin units. This FAQ is based on my experience with my Garmin GPS units and others' postings to the GPS newsgroup since the GPS 45 was first introduced about March 1994. I have had a GPS 45, 38, and 12XL. I have a particular interest in the electrical aspects of these units. | The latest version of this FAQ and some links to other sites can be found at my www or ftp sites (or Peter's site in the next section): http://www.eskimo.com/~klah/index.html or ftp://ftp.eskimo.com/u/k/klah/index.html or ftp to "ftp.eskimo.com", cd to "/u/k/klah" For more general information not specific to the Garmin units, read the general GPS FAQ maintained by Peter Bennett. He also has an excellent NMEA FAQ. They are both available on his ftp site which is the best single site on the web for information and software on low cost GPS's. I also send the latest version of this Garmin FAQ there. ftp://sundae.triumf.ca/pub/peter/index.html http:://vancouver-webpages.com/peter/index.html ftp://ftp-i2.informatik.rwth-aachen.de/pub/arnd/GPS/peter/index.html A fair amount of the information posted about the Garmin units in the GPS newsgroup is incorrect. I have spent a lot of time trying to make this document error free, but there is no guarantee to the accuracy of this information! Minor errors have been found in the past. When the term "GPS receiver" or "GPS unit" is used in this FAQ, this is meant to refer to the handheld unit that uses the Global Positioning System. Technically, the "receiver" is the radio portion of the handheld device only and the term "GPS" refers to the complete navigation system and not the unit itself. ---------------------------------------------------------------------- -FAQ revision history? Ver Date Major changes --- ---- ------------- 1.00 Aug 4, 1995 Initial release 1.01 Aug 7, 1995 Minor corrections 1.02 Aug 20, 1995 Added detailed speed limit info Added GPS 90 info Added more detailed list of specs Added Garmin accessory list 1.03 Aug 22, 1995 Minor corrections 1.04 Aug 29, 1995 Added Garmin 45/40 wish list Added section head numbers Added GPS 45 external current consumption Added FAQ revision history 1.05 Sep 18, 1995 Added info about "Diag mode" Added info about Accuracy Added info about Garmin differential receivers Added "|" indicating major changes in line or paragraph Reordered several sections Split out application software into its own heading Many minor corrections 1.06 Oct 10, 1995 Added section on coax cable losses Added section on CD-ROM map programs Added section on houses blocking signals Added GPS 40 mode from a GPS 45 Added GPS 30 info Expanded www/ftp sites considerably Expanded Garmin DGPS info Split application software into Garmin & NMEA 183 Split out intro into a separate section Minor corrections 1.07 April 23, 1996 Added sections on GPS 38 & 120 Added info on BatterySave mode Added info on memory backup Added Eagle Accunav info (Performance in trees) Added other PC software section Added more info on Macintosh software Added improving the accuracy section Expanded Garmin GPS models section Reduced the Garmin software price Updated Garmin's address and phone numbers Updated several E-mail addresses 1.08 July 22, 1996 Added sections on GPS 45XL, 89, 130, 175 Added section on velocity & magnetic variation Added section on remote only units Added initial fix info Added undocumented GPS 75 modes Added VMG error info Added NMEA 183 info 1.081 Aug 8, 1996 Fixed variation/declination nomenclature 1.082 Aug 30, 1996 Corrected serial port statement Fixed Eagle/Lowrance UTM info Updated APRS files location 1.10 Mar 25 1997 Added sections on GPS II, 12XL, 89, 175 Added report on GPS 21 Differential receiver Added info on GPS week rollover in 1999 Added info about the Trimble OEM antenna Added info on GPS 38 tight batteries Added info about when SA will end Added info on 45 external power minimum voltage Added Delorme Tripmate reference Added Auto Locate mode power up option Added --- to separate questions Added === to separate sections Updated serial port maximum voltage information Moved Garmin products to front Deleted old GPS 45 NMEA info Replaced Eagle/Trimble Info w/ GPS 12XL Moved DGPS to separate section 1.101 Mar 29 1997 Fixed index and section header inconsistencies Fixed some grammar errors PLEASE DELETE ALL PREVIOUS VERSIONS! | The "|" character is used to mark paragraphs or a line for significant changes in content from the previous version of the FAQ. ---------------------------------------------------------------------- -Suggestions for improvement? You can help improve this document by sending E-mail to me about errors or suggestions for improvement. It would be very useful if you could give your sources of information. Also, please include the version of the FAQ and the model number and firmware version of your GPS unit. There is often conflicting information and your detailed references are valuable for resolving those discrepancies. I receive lots of feedback but it takes time to process and verify all of the information. Because of the large volume of E-mail I receive, I can not always answer individual questions not pertaining to the FAQ. However, I do consider all suggestions. I read the newsgroup very regularly but occasionally I do miss something Garmin related. I am still reviewing the many suggestions and postings that I have received for inclusion in future versions. Please send CONSTRUCTIVE suggestions to Lane A. Holdcroft ====================================================================== 2.00 GARMIN PRODUCTS: ---------------- -Garmin GPS models? There could be some mistakes! List prices change often. Discounted prices can be variable and they only apply to some dealers in the US. OUTDOOR/MARINE PRODUCTS INTRO $US $US MODEL USE DATE SPEED LIMIT DISC LIST ----- --- ---- ----------- ----- ----- GPS II marine, hiking, cycling 11/96 90 knots $220 $309 | GPS 12XL 12 channel hiking handheld 01/97 999 knots $260 $386 | GPS 38 marine, hiking handheld 1996 90 knots $150 $300 GPS 40 marine, hiking handheld 09/94 90 knots $200 $425 GPS 45 marine, hiking handheld 04/94 90 knots $250 $495 GPS 45XL marine, hiking handheld 07/96 90 knots $290 $495 GPS 50 marine, old, replaced by GPS 75 <1992 90 knots NA NA GPS 65 marine mount, works like GPS 75 1992 90 knots $400 $665 GPS 75 marine, hiking handheld 1992? 90 knots $380 $825 GPS 80 military GPS 40 w/ 5-40V input 1995 999 knots? $650 $900 GPS 85 military GPS 75 999 knots? $700 $900 | GPS 120 marine mount 45 w/ big display 1995 90 knots $320 $463 GPSMAP 130 12 ch marine mount w/ map ~04/96 90 knots $700 $1082 GPSMAP 135 12 ch w/map&sonar(no transd) 1996 90 knots $1190 GPSCOM 170 12 ch marine GPS w/ VHF radio 1996 ? knots $1082 GPSMAP 175 12 ch mar/hik map handheld 1996 ?? knots $700 $1082 GPS100MRN marine handheld/portable 90 knots $1850 GBR21 DGPS beacon receiver n/a $500 $799 MAP 205 chartplotter, no GPS n/a $770 $1249 GPSMAP 210 chartplotter, B&W 90 knots $1000 $1655 GPSMAP 220 chartplotter, color 90 knots $1650 $2730 Notice that all of Garmin's marine units (except the GPS 12XL) have an artificially low speed limit. This speed limit did not start with the Garmin 45 as some have suggested. AVIATION PRODUCTS $US MODEL USE SPEED LIMIT LIST GPS 55 aviation (discontinued) 1992 ? knots NA GPS 89 aviation, cheaper GPS 90 07/96 999 knots $450 $499 GPS 90 aviation, similar to GPS 45 04/95 999 knots $650 $699 GPS 95 aviation (discontinued?) ? ~999 knots? NA GPS 95XL aviation (aero ver of GPS 75) ? ~999 knots? $1495 GPS 100 STD handheld/portable 999 $1795 GPS 100 PRT handheld/portable w/ dbase 999 $2095 GPS 100 AVD handheld/portable w/ mnt rack 999 $2495 GPS 150 panel mount, VFR 999 $2995 GPS 155 panel mount, IFR, n-p approach 999 $4995 GPS 165 DZUS rail mount version of GPS 155 999 $6495 GPS 190 GPS w/ VHF transceiver 1996 ? $1399 GPS 195 aviation version of GPS 130 1996 ? $1299 GNC 250 panel mount GPS/COMM 999 $3250 OEM/BOARDS/SENSORS [These units do not have displays. They are for remote use only.] $US MODEL USE SPEED LIMIT LIST GPS 20 MultiTrac8 sensor board (eval kit), 999 kts $499 $150 in quantity w/o antenna, $240 in quantity w/antenna GPS 25 PhaseTrac12 (eval kit), 12 channel sensor board (eval kit), 999 kts $599 $225 in quantity w/o antenna, $315 in quantity w/antenna [this has a parallel receiver] GPS 30 Integrated antenna/sensor board 999 $340 $499 (eval kit), $240 in quantity GPS 31 Marine mount version of GPS 30 999 $355 GPS 35 12 channel version of GPS 30 999 $599 (eval kit), $315 in quantity GIS/SURVEY PRODUCTS $US MODEL USE SPEED LIMIT LIST GPS SRVY II portable w/ datalogging capabl. 999 $2995 ---------------------------------------------------------------------- -Garmin accessories? Here is a list of most Garmin accessories: List prices as of Feb 1995: [THESE PRICES ARE OLD AND SOME OPTIONS HAVE BEEN DISCONTINUED. however, this is the most complete list of accessories I have seen] [NOTE: All GPS 40 options except for antennas work on GPS 38] | GPS40 part number Item description list price GA27 Low Profile [patch] remote ant w/8ft $160.00 [RG-174] cable MCX connector & magnetic & suction mount 010-10061-00 Trunk lip mount GA 26/27 18.95 010-10062-00 Flange mount GA 26/27 18.95 011-00152-00 Suction cup mount GA 26/27 18.95 011-00153-00 Magnetic antenna mount GA 26/27 25.00 320-00048-00 8 ft extension cable GA 27 40.00 4015 GPS 40 carry case 35.00 4040 GPS 40/45 Cross load cable(unit to unit) 50.00 [320-0040-00] 4041 GPS 40/45 PC Interface cable [DE-9 conn] 30.00 4042 GPS40 data cable 25.00 4050 GPS 40 cigarette lighter adapter 50.00 4514 GPS 40/45 PC Software and cable kit 150.00 4518 GPS 40/45 mounting bracket 45.00 GPS 45 GA 26 low profile [patch] remote ant w/magnetic & suction cup with 8 ft [RG-142?] cable 160.00 BNC conn 320-0049-00 8 ft extension cable for GA 26 40.00 GA 28 [Mast mount] remote marine [quad-helix] ant w/30 ft [RG-58] cable and BNC connector 160.00 010-10067-00 GA 28 flange mount kit 22.00 1011 Marine/RV remote ant w/30 ft cable BNC 160.00 [discontinued?] 1013 30 ft low-loss ant ext cable w/connectors 115.00 1028 Magnetic mount ant with 10 ft cable 160.00 [discontinued?] 4522 GPS 45 handheld/portable ant 100.00 GPS 45-000 GPS 45 w/ Portable? antenna 495.00 [GPS 45-100 GPS 45 w/ GA28 antenna] [GPS 45-200 GPS 45 w/ GA26 antenna] 5519 Remote antenna mount: suction cup/screw mount w/ 6ft cable BNC 40.00 4040 GPS 40/45 Crossload cable (unit to unit) 50.00 4041 GPS 40/45 PC interface cable 30.00 4514 GPS 40/45 PCX5 Software and cable kit [now 100.00] [010-10054-00] 4515 GPS 45 carrying case 35.00 4518 GPS 45 mounting bracket 45.00 [010-10048-00] 4520 GPS 45 power/data cable 30.00 [010-10082-00] 4550 GPS 45 cigarette lighter adapter 25.00 [010-10085-00] Disclaimer: These prices may not be current list check around and see if deals exist Sid ( a buyer not a dealer, stockholder and have no vested interest in Garmin) ====================================================================== 3.00 GENERAL GARMIN QUESTIONS: ------------------------- -What are some key features of the Garmin GPS 45/40/38/II? Relatively inexpensive (list < $500 US, discounted < $150 US for GPS 38). Very easy to use. | Very feature rich. Battery life is over 10 hours w/ 4 AA alkaline batteries. Very compact size. Serial port allowing transfer of data to/from a PC/Mac. Neat 768 point track log feature which can be graphically displayed. Ability to download the above track log data to a PC/Mac. Easy to use due to a simple menu system. Some water resistance. | 64 x 100 pixel graphical display. Over 100 mapping datums used around the world. ---------------------------------------------------------------------- -What are the disadvantages of the GPS 45/40/38/II? 1) There is a firmware speed limit of 90 knots / 104 MPH. See "90 knot speed limit" question elsewhere in the FAQ for more details. The GPS 90/89/12XL do NOT have this limitation. 2) The list prices on some options are more expensive than some competitors. For example, a replacement 45 antenna is $100 list. However, some dealers offer substantial discounts. 3) Because of the GPS 45/40/38/90/89's compact size, there is not sufficient space for number buttons. It has a 4 position rocking button to enter numbers and labels like the high score on a video game. This is not as fast as using a keypad. 4) The display size is small. This is a very compact GPS unit. The character size is also very small on the GPS 45/40. However the the newer units use a slightly wider font to be more readable. If you have good corrected vision, it should not be a problem up close. | 5) The GPS 45/40/38 (like all other single channel sequential receiver GPS units) are not able to track as well under heavy tree cover as parallel receiver designs. However, this limitation can be overcome with an amplified external antenna. See "Performance in trees" section for details. | ---------------------------------------------------------------------- -Comparison of the GPS 38/40/45/45XL/II/89/90/12XL? | You can understand the Garmin product family a lot better if you realize that they have a few basic design features. | Garmin basically makes 2 GPS engines: | MultiTrac8: 1 parallel channel that sequences through 8 satellites 12 channel: True 12 channel parallel design Garmin basically makes 2 input power circuits: | 10-40V input, 12-14V is most ideal (GPS 45/II/12XL/90/89) 5-8V input, 8V is most ideal (GPS 40/38) Garmin basically makes 2 different included antennas: | Swivel quad-helix (GPS 45/II/89/90) Internal patch antenna (GPS 40/38/12XL/175/195) Note that all of the following units (except the GPS II) have a very similar case except for the antenna and external antenna connectors. Also note that all except the 12XL use the same MultiTrac8 engine. GPS 38 40 45 45XL II 89 90 12XL Pri Use Marine Marine Marine Marine Bik/Hik Aero Aero Hiking Channels 8/1 8/1 8/1 8/1 8/1 8/1 8/1 12 Case style 40 40 45 45 Triang 45 45 40 Antenna Intern Intern Extern Extern Extern Extern Extern Intern Ext Ant Conn. None MCX BNC BNC BNC BNC BNC MCX Max Ext V 8V 8V 40V 40V 36V 40V 40V 40V Beeper No Yes Yes Yes No Yes Yes Yes Newer firmware Yes No No Yes Yes No No Yes Speed limit(kt) 90 90 90 90 90 999 999 999 Aero Nav Info No No No No No Some All No Yoke mount No No No No No No Yes No Ant. ext. cable No No No No No Yes Yes No ~Retail $ $300 $425 $500 $500 $450? $600? $800? $500 ~Discount $ $150 $200 $250 $290 $220 $450 $650 $260 [info is not guaranteed!] ---------------------------------------------------------------------- -What are the differences between the GPS 45 and GPS 40? 1) ANTENNA: The GPS 45 has an external quad-helix swivel antenna (about 3/4" x 3/4" x 3") whereas the 40/38 has compact "patch" antenna built into the main case. A GPS 40/38 looks like a GPS 45 without the swivel antenna. The GPS 45 uses a standard BNC connector for the antenna, whereas the GPS 40 has a "MCX" type connector for the optional external antenna and the GPS 38 has no external antenna connector. The GPS 45's external antenna hangs out the side of the instrument and could be broken if it were snagged or handled roughly ($100 replacement cost!). This is not a problem with the GPS 40/38. The GPS 45's BNC connector is preferable if you want to add an extension cable since BNC extensions are available from many more sources. This is an advantage because you can avoid the cost of an additional antenna if you want to temporarily mount it remotely from the GPS unit. The GPS 45's BNC connectors are more susceptible to corrosion from salt water and the 45's antenna could leak if it was not well sealed. Many weren't. The GPS 45 can be held at different viewing angles as long as the antenna is swivelled vertically whereas the GPS 40/38 must be held at a specific angle for optimum reception. There is a lot of debate about the exact differences in antenna sensitivity. I could not see a difference in side by side tests. However some people feel the GPS 45 is slightly more sensitive particularly when the unit is first turned on. | 2) The GPS 45 takes a much wider range of input voltages (up to 40 Volts). This is because the 45 has an internal switching power supply whereas the GPS 40/38 do not. The GPS 40/38 are only rated for 5 to 8 Volts for external power. Connecting the GPS 40/38 directly to a higher voltage supply could be potentially damaging. Therefore, the mobile power cigarette adapter is about $20 more expensive for the GPS 40/38 (because it must include a regulator). Also, the GPS 40/38 has an additional center pin in the center of the power/data connector to prevent the use of the GPS 45 cigarette lighter cord which would probably damage the GPS 40/38 due to overvoltage. 3) The GPS 40/38 has a dark gray case, whereas the GPS 45 has a white front case and a black rear case. 4) They are priced differently. | ---------------------------------------------------------------------- -What are the differences between the GPS 45XL and GPS II? | Here is a summary from Steve Kanavos: My Garmin GPS II just arrived today. What a nice unit. The software is no comparison to my 45XL's. Here are some differences just for the curious ones until I post a more detailed review. What's New compared to 45XL 1. Horizontal or Vertical Display 2. 3 Stage backlighting 3. Supposed longer battery life ..15 hrs normal 4. Much more solid construction. 5. 106 Datums Plus User definable! 6. Better display (at least I think so) 7. Improved Ant mounting and performance (had my 45XL side by side) 8. Two additional zoom buttons 9. User selectable displays of Max Speed, Ave Speed, Total trip time and more. 10.Easier menu navigation 11.Lower price! I will provide more detail later on. What's missing compared to the 45XL 1. No warning sounds 2. No carrying case 3. Not dry nitrogen filled or laser welded case however it is well gasketed throughout. (Unit can be opened as it is a two piece design. 4. Green versus black LCD SOME COMMON STUFF 1. Computer interfaceable 2. Uses standard BNC Antenna connection as well as provides +5 Volts to the BNC connector. 3. Power 5-36 Volts 4. The GPS II maintains the software capabilities of the 45XL as well. "Steve J. Kanavos" ---------------------------------------------------------------------- -What is the accuracy of Garmin GPS units? Note that the error tolerance displayed on the GPS does not include errors due to SA and that all position accuracy specs for the GPS are based on 95% DDRMS and ASSUME EXCELLENT SATELLITE COVERAGE. This will not be the case if you are surrounded by buildings, hills, or thick trees! Horizontal accuracy: 100 meters Official accuracy (Selective Availability ON) <50 meters Actual current accuracy (Selective Availability ON) 15 meters Theoretical accuracy (Selective Availability OFF) 5-10 meters Differential accuracy (regardless of Selective Availability) Vertical accuracy (altitude): Approximately 1.6 times worse than horizontal accuracy depending on the geometry of acquired satellites. In fact, you can get much better vertical accuracy with an altimeter (but it must be regularly adjusted to compensate for changes in barometric pressure). The variations in altitude due to SA are especially obvious when you are on the ocean! Another possible source of error on some (apparently non-Garmin) GPS units is that GPS altitude is the height above the selected mapping datum reference, not height above mean sea level. | However, apparently the Garmin units can calculate the difference between mean sea level and the datum and correct for that in the displayed altitude. This is based on my observations of the NMEA data from my GPS 45 and the NMEA FAQ. This data is available in the NMEA 183 V2.0 sentence "GGA". | ---------------------------------------------------------------------- -How does the GPS 12XL averaging feature work? | It seems to work pretty well. To activate it, you must first press the "MARK" button and select "AVERAGE" from the menu. You are supposed to be stationary. You can see the estimated error drop the longer you leave it in this mode. You can save the averaged waypoint. The error estimate does not appear to include Selective Availability. | ---------------------------------------------------------------------- -Performance in trees? GPS reception is always difficult in thick trees for all GPS receivers. The attenuation depends on the density of the canopy, and how much moisture is in and on the leaves. If the canopy is too dense, you may have to find a clearing to get a fix. I have observed that the Garmin sequencing receivers using the included antenna perform well among trees that grow in very dry climates but perform poorly among trees that grow in wet climates. | Several other people have reported that the external antennas work better than the built in antennas when they are walking through trees. This is because most external antennas are amplified and your body is not shielding the signal. If you are walking, you could mount the external antenna to your hat or to a pipe coming out of a backpack. | The GPS 45/40/38/II do not perform quite as well as some other units when surrounded by trees. It was believed that this is because the GPS 45/40/38/II has a single channel receiver that sequences between 8 satellites instead of having more continuous channels like many other units. Parallel receivers are able to track more marginal signals at once. However, they cost more and do not have the battery life of a sequencing receiver such as the GPS 45/40/38/II. The performance of my GPS 45 and a friends 12 channel GPS 35 (with a built-in antenna) were compared side by side as we drove through a heavily wooded park. (We actually compared the HDOP's and number of satellites tracked.) The GPS 45 was inferior with its built in antenna. | However, when the test was repeated and I used an amplified remote antenna on my GPS 45, the performance was very comparable with the 12 channel GPS 35! | Therefore, I now believe that additional antenna amplification for the GPS 45 is more needed than a having more parallel channels! | Garmin just started shipping the GPS 12XL which is a new 12 channel handheld instrument in a GPS 40/38 type case. It does perform better under trees than my GPS 45 but I have not done a controlled test yet. | ====================================================================== 4.00 GENERAL USE QUESTIONS: --------------------- -Why can't I get an initial fix? The "initial fix" occurs if the GPS unit has moved more than several hundred miles (which is also usually the case when you first receive a new GPS unit). This is a very common problem for new GPS users. It is useful for technical reasons for the GPS unit to know approximately where the satellites are relative to the GPS unit so that it can get a fix more quickly. Also, if the unit has not been used in quite a while (more than a couple of weeks), then the satellite orbital info will not be up to date. It takes about 12-30?? minutes to update the satellite orbital almanac (long term, less accurate) and ephemeris (short term, more accurate) data. | These tips are also useful even if you have had the unit on recently. | Here is a very conservative approach to getting a quick fix on any GPS: 1) Find a location with a VERY clear view of the sky not blocked by buildings, trees, etc. 2) Preset your approximate location to really speed up the process. The new GPS 45XL/38/II/12XL have added a quick start location feature to the firmware which asks you your approximate location. It goes into this mode if it can't find the satellites quickly. Of course the GPS can calculate where it is on its own, it just takes longer. 3) Put the unit in Operation Normal (or sky search if you don't know your location from a map), not BatterySave mode (this mode seems to be less aggressive in finding weak signals). 4) Make sure your antenna is properly angled. On a GPS 45/II, the antenna should be vertical. On a GPS 38/40/12XL, the unit should be held level, so the display faces up. 5) Go to the satellite screen and watch the signal strength bars appear. (If you have a GPS 45/40, I would use diagnostic mode so you can see the hollow vs. solid bars. This is documented in the FAQ under the FIRMWARE section). 6) Allow lots of time for your unit to acquire a fix. It could take a long time if you don't have a good view of the sky. I wouldn't totally give up on it until you have given it over an hour. If you do not have a clear view of the sky, or the satellites are not in optimum positions, or you the GPS unit needs to download the latest satellite orbit corrections, it would be helpful to have the extra time. 7) If you still don't have a fix after several hours and you REALLY had a clear view of the sky, your GPS receiver may be broken. You might try a new set of batteries just in case. In general when you are having trouble getting a fast fix (not the initial fix that we have been discussing here), turning the unit off and then back on can allow you to get a much faster fix. (This is mentioned in the manual). I use this trick all of the time and it helps substantially! Also, it seems to take longer to get a fix when you are moving fast as in a car or fast boat. ---------------------------------------------------------------------- -How can I improve the accuracy of a GPS unit with averaging? Although the official accuracy of the GPS system for non-military users is 100 meters 95% of the time, in fact when you look at the data plots (such as available from MIT in the www/ftp sites section), you can see that the accuracy is much better than 50 meters 95% of the time if you are stationary. One credible poster collected some data suggesting that when you are moving at about 60 MPH, the accuracy is closer to 70 meters (about twice the stationary error) 95% of the time with most common non-surveying GPS units. Accuracy can be improved much further by averaging. You can turn on the track log feature and select a timer interval, then leave the GPS on for a long time, and then look at the map screen and then just visually average the position. Of course this can be done more precisely by downloading the track log data and averaging it on a computer. [Lane Holdcroft] I have made some simple tests of SA errors and found that they seem to be random (and therefore, by definition, unpredictable) with a temporal autocorrelation function that drops to about 0.3 in 15 minutes. Thus, it is of very little advantage to take readings at intervals of less than 15 minutes. For readings [evenly spaced] separated by 15 minutes or longer, the error of the mean drops as the square root of n. (Robert S. Lawrence) The above conclusions were drawn from averaging days of data. If you are only averaging several hours of data (or less), then it would be beneficial to take readings much more often (such as every minute) so that you can get a significant number of data points. | The concept of averaging is based on the assumption that the errors (especially due to SA) are centered around zero. In fact the specification for SA does not require zero offset, but this is usually the case. Many people feel that accuracy within several meters is achievable. This looks very reasonable looking at the MIT plots. | ---------------------------------------------------------------------- -Can I post-process data from my GPS? | Post-processing is a way of applying differential corrections after the waypoints are saved. Because the non-surveying units do not save the individual satellites used and their timing information for each fix, you can NOT accurately post-process the data. Your accuracy will probably only be about 20 meters. Another problem is that the displayed information is averaged using a temporal filter rather than being real-time. This averaging is detrimental when you are trying to post-process the data. Yet another possible problem is that if more than 4 satellites are used in the position calculation, the weighting formula for the satellites may not be known. | ---------------------------------------------------------------------- -How accurate is velocity measurement? With the Differential GPS option, velocity accuracy should be very good, otherwise it is generally poor. Because of Selective Availability, velocity at very low speeds is almost worthless. I have seen speeds up to about 3 knots when I was stationary and had good satellite reception. This error becomes smaller (on a percentage basis) as your speed increases. To get really accurate velocity without using Differential GPS, you usually need to have a very expensive (usually surveying grade) receiver with some very sophisticated software that monitors the phase of the military frequency. Therefore, virtually all handhelds that are less than about $1500 are not very accurate for velocity without DGPS. Probably to prevent the wanderings of SA, the Garmin 45/40/38 will display "0.0" (without the DGPS option) if the speed is less than: 1.0 knot 1.2 statute miles/hr 1.8 kilometers/hr Also, compass headings do not appear to update unless you are going at least twice the above listed speeds (presumably to keep the compass headings from being meaningless at such low speeds)! When you are moving very slowly (such as hiking), obviously it would be preferable to use the "North Up" option for the map to prevent the map orientation from jumping around in circles. | ---------------------------------------------------------------------- -How accurate is the clock? First of all, there is a clock IC in the unit to keep the approximate time when the unit is not locked on satellites. To get accurate GPS time, you must be locked on satellites. Internally the GPS unit calculates the time more accurately than 1 uS, however the display and particularly the serial port are lower priority tasks and will not be updated immediately. We do not know the maximum error. When I have crudely compared the displayed time to the international time standards (received by shortwave radio), the difference usually seems to be well under one second (but there are no guarantees). To get accuracy of around 1uS, Garmin and other manufacturers make boards that have a 1uS or better precise timing output. Also, Tom Clark has designed a "Totally Accurate Clock" that is based on several models of GPS and greatly increases the time accuracy through averaging. See the www/ftp sites section for the address. | ---------------------------------------------------------------------- -What is the MOB function? The "Man Over Board" function is a common feature for marine GPS units. If a person were to fall overboard, the skipper uses this function to immediately mark the current location and the GPS goes into a "Go To" mode where it directs the skipper back to the point where the button was pressed. It is difficult to find a person at sea with large waves. ---------------------------------------------------------------------- -What is a waypoint? A waypoint is a nautical term referring to a label used to mark a specific location. For a GPS unit, a waypoint can be any location you want to mark and label in memory for future reference. ---------------------------------------------------------------------- -Which map datum do I use? A map datum is a mathematical model of the earth's shape and it specifies how a grid should be placed on it. The earth is not a true sphere, but an ellipsoid. The datum describes the radius and eccentricity of the ellipsoid as well as the offset of the grid. The Garmin units have over 100 mapping datums used throughout the world! The key point is to use the same datum setting in your GPS as is used on your map or you could easily be off by hundreds of meters. Here are the most commonly used datums in the US: WGS84 WGS-84 is considered a very accurate simple worldwide datum. Most maps in the US are moving towards WGS84. Most CD-ROM maps use WGS-84. NAD83 is almost identical to WGS-84 with differences of only a few millimeters. NAD27 CONUS Used by most current U.S. Forest Service and USGS maps. The CON represents Continental or Contiguous US. | There are many other NAD27 versions for North and Central America such as NAD27 CANADA ---------------------------------------------------------------------- -How does the GPS calculate the local magnetic variation? | The GPS unit has a formula programmed into the firmware that predicts the magnetic variation for a particular location on the earth. Apparently mariners use the term variation and landlubbers use the term declination. Of course there could be other local magnetic disturbances, so check your charts. | ---------------------------------------------------------------------- -Why do I get the message "Need 2D Altitude"? | To get a 3-Dimensional fix (horizontal, vertical, and altitude), you need 4 satellites (time is the 4th variable for those mathematically inclined). If your GPS unit can only use 3 satellites, then you may be prompted to enter the altitude (on the position screen) so that it can get a precise fix. On the rare occasions that I get that error, I make sure that I have a good view of the sky and then turn off the power and turn it back on and I usually get a 3-D fix. | ---------------------------------------------------------------------- -How do I calculate the distance between 2 locations? | I will put a couple of approximate formulas here in the future. I need to doublecheck them first! There are so many with so many different levels of complexity and accuracy. For a very accurate free PC program that does the calculations, see victorf's site in the www/ftp sites section. The files are INVERSE.ZIP and DIRECT.ZIP There is also a FAQ file at Peter Bennett's ftp site that has some info. For much more detail about the calculations, see the hang gliding FAQ. It has a very detailed section on distance calculations. ---------------------------------------------------------------------- -When will Selective Availability (SA) be turned off? | Selective Availability is the deliberate program of adding error to the GPS positions through the manipulation of the signal timing on the satellites. This is done for the US military to discourage their use on missles by enemies. The US military has special receivers that can decode the full accuracy of the available signal. Some people think that these codes could be easily cracked. Anybody that thinks that does not understand the complexity of the problem. It was developed by Cryptologists to prevent other Cryptologists from breaking it. Unfortunately, it is very secure. | It is true that SA was turned off during the Persian Gulf War and the invasion of Haiti. This was only because there was a shortage of military GPS receivers and the US defense department bought some non-defense ones. Although the enemy had the benefit of non-SA accuracy, they had very few GPS receivers compared to the number that the US could use. In 1996, the US Government issued a formal statement that SA will be in affect for at least the year 2000 and up to 2006. They will make the determination whether to extend SA after the year 2000. Of course the US government can change the postion at any time in the future. The official US Government statement is at the site http://www.navcen.uscg.mil/ | Remember, the GPS signals were only originally intended for the US military and they don't charge anyone to use them! It is the US taxpayers that are actually paying for the system. If fact the US Government is NOT degrading the signal to the full 100 meters (95% of the time) but is actually running at about 35 meters. | ---------------------------------------------------------------------- -What will be the effect of the GPS rollover in the year 1999? | For the GPS to help keep track of time, the satellites broadcast the "GPS week". GPS week zero started Jan 6, 1980 but the GPS week is limited to a maximum number of only 1024 (10 bits). Therefore at midnight between Aug 21 and Aug 22 1999 UTC, the GPS week will roll over to zero which may be interpreted as Jan 6, 1980. If the software engineers did not anticipate this, then the time would be screwed up in the GPS. Apparently MAGELLAN (NOT Garmin) issued a press release stating that some of their older units need to have a free firmware upgrade. However, Garmin has stated in writing to me that they did foresee this problem and they say that all Garmin units should be unaffected by the GPS week roll over. Also one of the founders of Garmin was quoted in a magazine as saying the same thing. | ====================================================================== 5.00 SPECIFICATIONS/REPORTS: ---------------------- -GPS 45XL/45/40/38 specifications? Here are the specs out of the manual: Physical -------- Case: Ultrasonically welded, dry nitrogen-filled | Size: 6.15"H x 2"W x 1.23"D (15.6 x 5.1 x [3.1] cm) Weight: [9 ounces, 255g] w/ batteries. Temp Range: 5 to 158 degrees F [-15 to +70 degrees C] Performance ----------- Receiver: Differential-ready MultiTrac8 Acquisition Time: Approx 20 seconds (warm) Approx 2 minutes (cold) Approx 7.5 minutes (autolocate) Update rate: 1/sec, continuous Position Accuracy 5-10 meters (16-33 ft) with DGPS correction 15 meters (49 ft) RMS* (note: I average 150') *subject to accuracy degradation to 100m [95% of the time] under the DOD imposed Selective Availability Program Velocity Accuracy 0.1 knot RMS steady state [w/o SA, several knots error w/ SA] Dynamics: Performs to specs to 3g's [Navigation Features -------------------- Waypoints: 250 alphanumeric Routes: 20 with 30 waypoints each] | Power ----- Input: 4 AA batteries or [GPS 45/12XL 10-40 VDC | GPS 40/38 5-8 VDC] | Usage: .75 watts Battery life: 10 hours (normal mode) w/alk. batt. Up to 20 hours in battery saver mode Kai Schumann ---------------------------------------------------------------------- -GPS 45/40? Here are 2 good reviews that were posted to the newsgroup. One is from a 45 (not the software enhanced 45XL) owner, the other from a 40 owner. Keep in mind that other than the antenna and input voltage range (and software enhancements), both units are very similar and most comments apply to both. | I have included their reviews pretty much in full because they do a very good job of covering the features of these units, and they both include lots of useful information which would be beneficial to someone who is contemplating buying a Garmin unit. >From: (Gavin Scott) Date: Wed, 27 Apr 1994 04:46:39 GMT Today I received a new Garmin GPS 45 Here are my initial impressions, along with a list of features and specifications for the unit. I will follow up with more comments in a week or so after I have had a real chance to play with it for a while. I have no connection with Garmin or West Marine. I purchased the GPS 45 myself, for my own use. I have owned handheld GPS receivers going back to the original Magellan Nav-1000 (which has now been upgraded repeatedly and is a NAV5000 now). I have some experience with other GPS units including a Garmin GPS100 owned by a friend. The brand new (shipping for only a week or so) Garmin GPS 45 looks to be the hottest handheld around. It is a small (literally pocket sized) 10oz package, and yet sports a large graphic LCD display. For a picture, look in the current West Marine catalog (you can get one from them at 1-800-538-0775) or most other marine equipment dealer catalogs, or call Garmin at 1-800-800-1020 and ask them to fax you a data sheet. ------- GARMIN GPS 45 --------- PHYSICAL DESCRIPTION: This sucker is small! It easily disappears into the front pockets of my Levis Dockers. The spec sheet lists the dimensions as 6.15 inches high, 2 inches wide, and 1.23 inches deep. Weight is an amazing 10 ounces (spec sheet, 4 AA batteries included), and my cheap postal scale weighs it in at 11 ounces (with batteries and case). At the top on the right side is a recessed BNC connector where the tiny built in flip-up antenna is attached. The antenna is of the same sort as the Magellan and Garmin units have used for some time, except for the size! The GPS 45 antenna measures 3 inches long by 0.775 inches square. The dimensions of the main unit given above do not include antenna, which makes the top of the unit about 3 inches wide overall. The most striking feature of the GPS 45 (after size) is the large LCD display which takes up the bottom half of the front of the unit. The display has a 'portrait' orientation, being much taller than it is wide. Above the display is a four way rocker switch surrounded by six other buttons. This layout allows the unit to be easily held in either hand with the thumb operating the buttons. The joystick like flat rubber rocker switch is used for all data entry. Alpha-numeric data is entered by cycling through the possible letters/numbers. To the left of the rocker 'cursor' button are (top to bottom) GOTO, Power/Backlight, and QUIT buttons. to the right are PAGE, MARK and ENTER. The top 1/4 of the front is blank except for a logo (picture of the earth with no text). The front part of the unit is white, and the back is black. Batteries (4 AA) are inserted into the bottom, beneath a seal opened with a quarter turn fold out doohickey. The batteries disappear into two tubes. I don't know where they have room for the electronics with all that space taken up inside by the batteries! A 4 pin (round DIN like) connector is on the back. The pins are described in the manual as Ground, Power in ([10]-40 VDC!), and DATA IN and DATA OUT. A rubber plug protects the connector when it is not in use. The whole unit is waterproof, and is actually filled with dry nitrogen and the waterproofness is covered by the one year warranty. ACCESSORIES INCLUDED: 4 AA [alkaline] batteries (installed). [A carrying case.] A reference manual (61 pages, dated February 1994). A quick reference card (which is too big to fit in the case, but printed on plastic waterproof paper). Warranty registration card. An offer to sell you a training video for $29.95 A wrist strap. The whole mess comes in a white cardboard box with pale Garmin logos on it that is about 11"x7"x3". SPECIFICATIONS: Temp range 5-158 degrees F (-15-70C). Acquisition times: 20 seconds (warm), 2 minutes (cold), 7.5 minutes (sky search). Update rate 1/second. Position accuracy 5-10M (with DGPS), 15M RMS (without SA), [100 Meter accuracy with 95% confidence (with SA on, as is the case now)] Dynamics: 3g's. Power usage .75 watts. Battery life 10 Hours normal, 20 hours battery saver mode. NMEA INTERFACE INFORMATION: NMEA 0180, 0182. [GPS 45/40 info:] 0183 version 1.5 (Approved sentences BWC, GLL, RMB, RMC, XTE, VTG, WPL; Proprietary sentences PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control)). 0183 version 2.0 (Approved sentences [GGA], GLL, GSA, GSV, RMB, RMC, RTE, WPL; Proprietary sentences PGRME (estimated error), PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control). [For the GPS 38 and 45XL, the following sentences were added: NMEA 0183 V1.5 BOD NMEA 0183 V2.0 WPL and PSLIB] | Plus Garmin's proprietary bi-directional format that allows upload/download of waypoints and other information with appropriate software. DGPS corrections are accepted from any RTCM-104 v2.0 format compatible beacon receiver, but use of Garmin's GBR 21 (discounted to $500) will allow tuning and control from the GPS 45 itself (using the proprietary NMEA data strings above). OPERATIONAL DESCRIPTION, FEATURES, PRELIMINARY EXPERIENCES: To turn it on, you press the power button down firmly. You are greeted with an animated spinning globe and in large letters "Welcome to the Garmin GPS 45" and it gives the firmware revision as "2.02". First displayed is the satellite status screen. This nifty display shows the position in the sky for each satellite, a bar graph of the signal strength of up to 8 stats at a time, a large battery power gauge bar, a backlight indicator (a very useful feature in daylight when you can't tell if the blue EL backlight is on or not), and a status message ("Acquiring" etc). Pressing the PAGE key cycles through the main displays which are as follows: POSITION PAGE: Shows a graphical compass display (like looking at a compass from eye level). Ground track and speed, Position in LAT/LON down to .001 minutes resolution, Altitude (including an accuracy +- value!), and the current time (Local time not GPS time) with 1 second resolution. MAP SCREEN This is way cool. You get a moving map display that will let you zoom from a 0.2 mile range up to 320 miles. You can also pan around, point to waypoints, create new waypoints by pointing etc. There is no provision for a map database, but the nine nearest waypoints can be displayed with their names, along with range circles, course, ground track, and other information, all configurable. You can have TRACK UP or NORTH UP as you like. CROSS TRACK (CDI) SCREEN: Shows bearing and distance to next waypoint, graphical XTE and distance to go, current time and ETE, Track and Speed, etc. MENU SCREEN: >From here you get to enter waypoints and routes and do all the setup stuff. There are about 16 screens of config data and stuff accessible. OTHER MISCELLANEOUS STUFF: Let's see, it is getting late so let me try and highlight the other unusual features. Of course all the stuff for creating routes and waypoints is there. You get 250 Alphanumeric waypoints (which you can add an annotation line of info to!), 20 reversible routes, Man Overboard mode (Press GOTO twice). I have only operated it outside enough to get an initial fix (sky search) and try out some basic stuff and the moving map. If you lose memory (almanac) data or move >300 miles you are forced to do a 7.5-15 minute sky search [unless you enter the new coordinates]. Once this is done, acquisitions are fast, multiple satellite tracking is quick, and overall the thing seems to work wonderfully. All the usual config options are there (Statute, Nautical, or Metric units, True, Auto magnetic, or Manual magnetic headings). There are 102 different map datums in the system (including some really off the wall stuff), but no option to enter your own (but yours is probably already in there). Positions can be displayed in DDDMM.MMM or DDMMSS.S format or UTM coordinates, or British, Irish, or Swiss GRID formats. CDI scale can be +-.25, 1.25 or 5 Miles or kilometers. You can choose to display CMG/VMG rather than track/speed. There is a simulator mode [which simulates strong satellite reception so you can practice operation of the unit indoors]. The differences between normal and battery saver mode are not described (other than to say that battery save mode saves 50% of the battery power and is "suitable for most applications". Velocity is allegedly limited to about [104] MPH, but there is no mention in the manual about it. Well, that's all for now. There are a number of other minor features but this should give you an idea. Overall, this is one of the niftiest gadgets I have ever seen, and definitely the best handheld GPS I have seen yet! Gavin Scott ------------------- >From: (Steve West) Subject: Garmin GPS 40 features summary Date: 14 Sep 1994 15:59:26 GMT Here is a brief review of Garmin 40 features. I'm just a novice. Also, this is just a skim of the features. The unit provides all kinds of shortcut ways to do things. I have also missed several features in this review. The unit comes with a 60 page manual. It still has references to marine stuff, but for the most part, it provides general descriptions/instructions applicable to land or water use. ... STATUS AND POSITION PAGE: This page has a polar plot of satellites that are visible over your horizon. The display is "live" so the positions of the satellites change with time. They are represented by numbers. Below the polar plot is a space for 8 signal strength bar graphs. As a satellite is acquired, the number on the polar plot is changed from inverse to normal video, and a bar graph for the satellite strength is created. The bar graphs are shuffled as new satellites are acquired, or old ones move out of view, or the "lock" was lost. 3 satellites are required for lat/long and 4 to add altitude. It also estimates the horizontal accuracy of the result [based on the geometry of the acquired satellite locations]. It usually states an accuracy between 500 ft and 49 ft. Once the unit is set up for your location, it can usually acquire 5-7 satellites within a couple minutes after turn-on. It seems pretty insensitive to orientation. If it cannot maintain a lock on at least 3 satellites, it sends you an alarm saying poor GPS coverage. POSITION PAGE: The position page shows your current lat/long/altitude. There is a moving compass segment at the top that shows your current bearing if you are moving. It estimates your velocity too, and shows you the current time. NAVIGATION PAGE: This page shows an active course deviation indicator (CDI). It allows you to choose a waypoint target, and then you simply follow the roadway to your destination--this is really cool! It estimates your velocity and arrival time and a bunch of other things. It also provides a Man Overboard function (MOB). MAP PAGE: The map page plots a map of waypoints and your current course. You can zoom and pan the map. The waypoints are indicated with a square and the name you gave them as you input them. At any time, you can simply highlight a waypoint on the map and it will tell you the required bearing and distance to get to it. It does lots of other stuff too. MENU PAGE: This page allows selection of 11 menu systems: 1. Nearest waypoint list (shows 9 nearest waypoints). 2. Waypoint list (lists all waypoints and allows you to look at them in detail) 3. Waypoint (details of single waypoint) 4. routes (allows development of up to 20 routes with 30 waypoints each along with editing, copying, pasting etc. You can also specify preferences for waypoint summaries to show DTK, ETE, ETA, etc). 5. Distance and sun calculations (allows input of 2 waypoints for distance and bearing calculation and shows sunrise/sunset times at the destination waypoint). 6. Operation menu (allows selection of unit mode, time offset, LCD display contrast, backlight time, and tone/beep control). 7. Navigation setup (set up position display format, map datum format, CDI scale, units preference, magnetic headings). 8. Track and log setup (allows the unit to automatically make a log of your positions. You can set it up for time or distance intervals for auto data taking plus a bunch of other stuff). 9. Map setup. configure the map display with polar rings, show route or not, show names or not, select preference north up or track up etc, configure track log plotting). 10. I/O setup (configure I/O and differential GPS). 11. messages menu (whenever the unit sends you an alarm for one reason or another, it details the message here). MARKING WAYPOINTS: Marking waypoints is as easy as pressing the mark button. The current lat/long/time are stored. You can give the point a name and provide your own comments and put the point in a specific route number if desired. APPENDICES [from manual]: A. Glossary of terms B. Messages possible on message page. C. Longitudinal time offsets [in hours] D. Map Datums E. Maintenance and Specs. F. Electrical wiring and interfaces. G. Installation of optional mounting bracket and I/O connector. H. Index Steve West ---------------------------------------------------------------------- -GPS 45XL? The GPS 45XL is simply a GPS 45 with the improved GPS 38 firmware. The GPS 45XL started shipping in July 1996. To see what additional software features were added, see the GPS 38 section below. Because the GPS 45XL has a few more features than the existing GPS 45, the GPS 45 has been discounted and is being phased out. ---------------------------------------------------------------------- -GPS 38? The GPS 38 was released late Feb 1996. Also see the comparison chart at the beginning of the FAQ. Here is some info from Garmin's press release: The GPS 38 [software] is similar to the GPS 40, but with the following improvements: A significantly lower price. "EZinit" for quick and easy first-time initialization. Users simply select their country, state or province for a fast, first position fix. "Backtrack" - an extension of the route feature that allows users to exactly re-trace their course based on their track log history, without having to manually create waypoints along the way. "Compass navigation" - a new page that graphically depicts a rotating compass dial. A large, directional arrow shows your bearing to your destination. "Re-designed moving map" - allows a larger presentation of information pertinent to the particular trip. "Four new grid formats" - German, Taiwan, Swedish, and Maidenhead grids. "New Fonts" for improved readability. [Each character is 4 pixels wide instead of 3.] "Re-settable trip odometer" "24 hour or 12 hour with a.m./p.m. time display" Here is some more info from Larry James: What is the size, weight, etc. of the new GARMIN GPS 38? The GPS 38 weighs 9 oz. It uses 4 AA batteries, which last up to 20 hours in battery saver mode. It uses the same "Multi-Track 8" GPS engine as the GPS 40 and GPS 45. It is physically quite similar to the GPS 40. Is the 90 [knot] speed limitation still there? Yes. What does the GPS 40 have that the GPS 38 does not? An MCX connector on the back to connect an active external antenna. What provision is there for computer connection? The GPS 38 is compatible with all the data cables, mounting brackets, DGPS receivers, and commercial software that work with the GPS 40. It is probably compatible with the net freeware also. James Associates will make sure MacGPS is compatible. You will have to check with the authors of free PC software for their policy. Here are some additional new features of the GPS 38: The satellite status page shows an empty signal-strength bar while ephemeris data is being collected for that satellite. Thus you know what satellites are actually being used in the position solution. [This is available on the GPS 40/45 by going into diagnostics mode explained elsewhere in the FAQ.] The GPS 38 is 1 oz lighter than the GPS 45 and the GPS 40. The GPS 38 uses a different type of LCD display. [The GPS 38 display is blue instead of black.] We have checked out both MacGPS and MacGPS Pro with the GPS 38, and both work fine in all modes, no update is required. The GPS 38 does not include a video (unlike the GPS 40). [Larry James, http://www.csn.net/~lwjames] -------------- Some more info: The Garmin 38 is very similar to the Garmin 40/45 with the following differences. What the Garmin 38 has that the Garmin 40 does not: Coordinated System: Maidenhead (used by HAMs with packet) Map Datums: 106 Full Screen Compass with Waypoint Pointer Instant Initialization by Country Trip Odometer Backtrack feature "STN" type [LCD] display AM/PM Time display 9 oz. weight What the Garmin 40 has that the Garmin 38 does not: Antenna connector Map Datums: 103 "FTN" type [LCD] display Internal Alarm beeper Carrying Case User Video 10 oz. weight Paul James ------------------- I got some data sheets from Garmin in the mail the other day, including the 38. Here's a summary ("same" means same as Garmin 45): * Size, weight, display size: same * Case: waterproof tested, ultrasonically welded, dry nitrogen-filled * Magenta LCD display with electroluminescent (EL) backlight * Resettable trip odometer * Coordinates: Lat/lon, UTM/UPS, plus 7 grids, including Maidenhead * Internal lithium memory backup battery * Antenna: internal * Power: 4AA or 5-8 VDC * Does not come with batteries or carrying case * Battery Life: <= 12 h (normal), <= 20 h (saver mode) * Waypoints, routes, datums: same * Operating System: same * Differential-ready (same) * Acquisition times, update rates, accuracy, interfaces: same Donn Mumma ---------------------------------------------------------------------- -GPS II? I have examined the GPS II at a marine store. I would describe it as being like a GPS 45 but with a triangular block shape. It can be used either vertically or on it side because the software can rotate the characters on the display by 90 degrees. The BNC antenna swivels. It also has zoom in and zoom out buttons which are very handy. Zooming in and out is rather awkward to use on the other units in the GPS 45 family. There are also optional mounts: 010-10122-00 GPS II handlebar mount (presumably for bicycles) 010-10111-00 other GPS II mount | ---------------- Here is a very detailed review by Daniel Butler: I recently bought a Garmin GPS II from West Marine (special order from warehouse), and these are my inital impressions. Since I've only had a GPS 38, that's all I have to compare it to. Other than not having an external antenna and different voltage tolerances, the 38 is nearly identical to the 45XL. The GPS II unit has software version 2.02. The 38's is 3.03. Physical: The II is slightly shorter and bigger around than the 38, mostly because of the external antenna, which connects via the standard BNC connector. The battery compartment of the II has a smaller lid with small rubber gaskets that seem to seal better than the 38's awkward lid. The II has more room for the batteries than the 38--batteries that get stuck in the 38 don't in the II. The II has a triangular shaped back, so that when you hold it in front of you in portrait mode, the antenna cannot be made to point straight up like the 45's. There are six screws that hold the back on and sandwich a rubber gasket between the back and the front. The documentation makes no mention of waterproofness or water resistance, and looking closely at the gasket, I suspect that there's not enough screws to maintain the seal's integrity all around the perimeter. A resourceful enough individual, however, could probably get creative enough with silicone to ensure a seal if waterproofness is that important. The rubber cover for the computer/power interface is much easier to open. The II comes with a lanyard and a strip of hook-and-loop fastener for mounting the unit to your dash. But, if you stick the fastener on the II, it will no longer sit flat on a table (it rocks), and the angle it sits on the dash makes it difficult to read. The plastic over the display of the II is inset a little bit more than on the 38, making it less likely to get scratched. The buttons on the II are bigger and spaced better, and the rocker switch has little bumps on it, making it easier to feel in the dark. There is also an inset screw hole on the back side for mounting it to something--probably one of those overpriced accessories Garmin wants to sell you. Display Quality: The II's display is identical to the 38's in the light, the same green color with blue text and graphics. The nighttime display is very different. The 38 is lit by a bright blue or turquoise backlighting (bright, but hard to read), whereas the II has three levels of yellowish-green backlighting (dimmest, dimmer, and dim). In total darkness the II is actually easier to read--it doesn't kill your night vision either, and I imagine the II's lighting has much less battery drain. (The 38 is like a flashlight at night, actually). The II's display is hard to see near dusk on the dashboard in any stage of lighting. Little-known Features: Holding ENTER when turning the unit on still initiates the test page, as does ZOOM OUT and pressing the rocker switch UP, to the RIGHT, or diagonally UP/RIGHT while in portrait mode. While in test mode you can test if buttons are working, or press ENTER to see some interesting pattern tests. Turn the unit off to get out of the test. Holding MARK down while turning the unit on will do a hard reset, after which the GPS II knows nothing and must search the sky for satellites to refind itself and relearn the date. Only the very patient want to do this, because it takes quite a while to find and then autolocate. All waypoints, routes, and track info are deleted. Holding PAGE while turning on does, I guess, a soft reset, which the time is remembered, but the position is not--and you must do either an autolocate or quick locate. The GPS 38 didn't have this feature, but I can't imagine why I would ever use it. By pressing the four cardinal directions on the rocker switch immediately after turning on, you can enter a debug mode, just as with the 38, with the same D-menu (diagnostics) and extra numbers on a couple of screens. I get the greatest success with the UP-DOWN-LEFT-RIGHT sequence. You can't get the spinning logo on the moving map page anymore by holding the OFF key for a bit. In fact the cool spinning logo is gone and replaced with a new, rising earth with disappearing horizontal lines. Kind of primitive animation, actually. Some things are better left unchanged. New Features: o Switch between portrait or landscape mode by holding down PAGE. o ZOOM IN or OUT keys that work on the moving map page. You can pan any direction, including diagonally, with the rocker switch--no need to change from ZOOM to PAN modes like on the 38. Very nice. o TRACK OPTIONS and MAP OPTIONS are available from the moving map page by pressing ENTER, instead of having to go to the menu page. o On the satellite status page, the contrast can be adjusted with the rocker switch. o Waypoints names have a bigger font on the waypoints list. I don't like it as much, though. o On the compass page, you have two user-selectable fields in which you can display either total time in travel, average speed, maximum speed, altitude, trip odometer, or elapsed time. When you reset one, it resets the others. Very cool, especially since total time in travel and average speed only counts the time you're actually moving. Great for knowing how fast you walk while hiking or while paddling on a river. o On the goto waypoint page, you have one slot available for viewing one of ETE, ETA, CTS, XTK, VMG, or TRN, which all have meanings, but I don't have the documentation here right now. o It only takes two seconds to turn off instead of three. It's the little things... Performance: From what I can tell about setting it side by side with the 38 and leaving it on for quite a while, the II doesn't use as much battery power as the 38. Not much less, but there seems to be a noticeable difference. The difference is probably be more significant if you use the light regularly. The reception in my 38 is very good, even under canopy one a fix is obtained, but I have never gotten it to pick up inside the house. I did manage to get a 3D fix with the II. Quite amazing. Sitting in the windowsill facing west, I could track five satellites. Outside on a clear day away from obstructions, both pick up quite well, but the signal bars on the II are probably 10-20% longer than those on the 38, on average, and the EPE is usually less. In more marginal conditions, like on my dash driving around town, the II could had a fix with 6-7 satellites, while the 38 had never even gotten a 2D lock--and they were turned on at the same time. When turned off and turned on again in clear view of the sky, it is a little quicker acquiring the birds (by a couple of seconds) than the 38. This is probably a result of the better antenna. Compatibility The GPS II works with Street Atlas 4.0, Map 'n Go 2.0, Waypoints+, Garlink, and WinGPS 3.92 just fine, as far as I can tell. I hope this information helps anybody that's thinking about buying one of these units. Daniel Butler --------- Here is yet another detailed GPS II review by Paul Menconi: Experience with the Garmin GPS II GPS hand-held receiver Garmin has recently expanded its line of hand-held GPS receivers. Of particular interest to me is the GPS II. Last year I borrowed a 45 (the "45 classic") for three months, including a week of bare-boat chartering in the Virgin Islands, and was quite impressed with its capabilities and ease of use. The II seemed to fit my needs better, but before buying one I was concerned that I wasn't giving up any of the capabilities of the 45. The 45 has been replaced by the 45XL, which looks identical but has some added functions. After some consideration I finally bought the GPS II. I herewith offer a modest comparison of the new GPS II and old 45. Hopefully this will be useful to others in making the decision of which hand-held GPS best suits them. It appears from the specifications that the new Garmin 45XL and GPS II are identical internally. The obvious external differences are driven by different intended uses. It's clear the 45XL is still Garmin's premiere small handheld, intended for marine use. The GPS II has an identical display and controls layout, but at around $US250 is $40 or so cheaper than the 45XL. While the 45XL retains the nitrogen filled, welded plastic case, the II is held together by screws, with a thick rubber gasket between the case halves. Construction aside, the main difference between the 45 and the II is the shape of the case. While the 45 is rectangular in cross section, the II is more of a rounded triangle. This shape, and a slight relocation of the external antenna, allows the unit to be set lengthwise on a table (or dashboard), with the screen tilted at a convenient reading angle. Of course, the 45 could be propped up on its side, but the display would be sideways. Holding in the Page key on the GPS II, though, rotates the display image 90 degrees, so that everything is right side up. The GPS II has the same buttons as the 45, arranged in the same fashion, and performing the same functions. At the far end of the case, though, top or right, depending on orientation, are two extra buttons. These are the zoom buttons, In and Out. The zoom function has been moved from the track display graphic screen to these dedicated buttons. This method is more convenient and certainly less confusing than the way it was done on the 45. It is one, and I think the only, added feature the 45XL does not share. The five screens of the 45 are retained, and are accessed in the same order. However, there are some changes. The differences are listed here: Satellite Status Page: The battery level indicator does not go away when connected to an external source. The satellite signal strength bars are hollow when the receiver has found the satellite and is collecting data. The bars turn solid only when the indicated satellite is being used. Screen contrast may also be adjusted from here by pressing the "rocker keypad." If a position fix is not found within some period of time, or if the unit has traveled more than 500 since its last fix, it enters the "EZinit" mode. This mode is used when the unit is really confused about where it is. The user is offered three choices: select from a country list (which offers an approximation of the current lat and long); do an autolocate, in which the unit spends some 15 minutes reading all the satellite info in order to fix its position; or an "ignore EZinit" mode that continues acquiring. EZinit is an interesting addition, but not really necessary. The original 45 had the autolocate feature, which allows the unit to find its location after being seriously displaced. The first fix can be greatly speeded up by manually entering the approximate lat and long, which in effect is what the "EZinit" feature does, although it requires scrolling through a long (very long -- at last we can figure out where Bosnia-Herzegovina is) list of countries and states. Position Page: Same as in the "45 classic," with the addition of two user-configurable fields. One of these takes the place of the old "Alt" field, and the other is squeezed in above it. The first of these fields can be set to any of the following parameters: TRIP: trip odometer; distance traveled since reset (a much-requested feature, with resolution to 0.1 miles for the first 99.9 miles and 1 mile to 999 miles. I don't know what happens after that.) AVSPD: Average speed since reset (Resets with Trip and/or Ttime) MXSPD: maximum speed traveled since reset TTIME: trip time; total cumulative time during which a ground speed was maintained (An interesting feature, although I can't imagine it being widely demanded. Resets with Trip and/or Avspd) ELPSD: elapsed time; total cumulative time since reset All of these parameters are easily resettable. The other field may be set to: ALT: altitude above sea level TTIME ELPSD TRIP Of particular interest is the TRIP function. This actually does measure the total distance traveled, not just the straight-line distance between points. Trip time, TTIME, is a timer that runs only when the ground speed is about one or two mph. Presumably it is used, with the TRIP distance, to calculate the average speed. Map Page: This is the graphic track display. Numbers in the corners display bearing and distance to the next waypoint (upper left and right corners, respectively), and the current track and speed (lower left and right corners). The main change in this screen is that the map and track setups are done from this page, not from the set-up page. I think this was done partially because there is not enough room on the set-up page for the whole list of items to be set up when in the horizontal display mode. By moving the track and map set-ups to the map page, there is enough room on the set up page for what's left. The result, though, makes sense. It's much easier to change the settings without having to change screens. Compass Page: The "45 classic" had the "highway" page, a graphic giving steering guidance to a destination. This display is retained in the GPS II and the 45XL, and is augmented by another display that is simpler, easier to understand, and that makes more sense for use on roads and highways. The display consists of a circular "compass" with the cardinal points, N, E, S, and W, displayed on the outside. The compass rotates so that the direction of travel is always at the top. Inside is a thick arrow indicating the direction to the next destination, again with the current direction of travel at the top. While the highway display is excellent for steering a boat, driving on a road or hiking on a trail offers far less freedom in direction of travel. This new display is well suited for use where the terra is more firma. Both the "compass" and "highway" displays show the bearing and distance to the destination waypoint in the upper corners and the current direction and speed in the lower. The characters for these readouts are larger and more easily readable than in the previous model. At the top center is listed the name of the destination waypoint. At the bottom center is another user-definable field. Options available are: ETE (default): estimated time enroute ETA: estimated time of arrival CTS: course to steer XTK: cross track error VMG: velocity made good TRN: turn; the amount of correction in degrees needed to travel directly to the destination Changing from the "highway" display to the "compass" display is simply done by pressing the Enter key twice. Setup Page: Essentially the same as the 45, except that the track and map setup entries have been moved to the map page. Waypoint Page: No changes here, except a larger font is used for the waypoint names. They are noticeably easier to read. So let's see, what else? The II comes with virtually no accessories. It does not include a case. It does include a strip of Velcro that can be stuck to the bottom of the unit. (I put the "hooks" part on my GPS II, which then stuck like crazy to my fuzzy dash cover.) Like the original 45, it comes with a thin wrist strap that makes me think of a g-string (both in its appearance and in the protection it offers). The strap ties to a wire loop on the battery door. The manual is thorough, although it won't stand up to heavy use, in contrast to the 45's spiral-bound booklet. The antenna of the GPS II comes off just like the 45's, leaving behind a standard BNC connector. The same power and data cable fit both the II and the 45. I was able to download data from the 45 using a Garmin data cable connected to my PC's serial port. I haven't yet had a chance to try that with the II, but will eventually, and don't anticipate any problems. The manual for the II states that the unit will drive three NMEA devices using NMEA 183 ver 2.0. Literature for the 45XL claims NMEA 180, 182, and 183. This may be a significant difference if you plan on using the unit to drive an autopilot or other NMEA devices. The display on the 45XL is noticeably clearer and darker than that on the II. Both displays are clear and readable, but the 45 display might work better under marginal conditions. And, Garmin is finally including a notice in their literature about the 90 MPH speed limitation on their non-aviation GPS receivers. All in all, I like the GPS II and its new software features. Like I said, I'd get the 45XL for primarily marine use, but it is obvious that the II is intended for use in vehicles. The salesman where I got mine told me that Garmin will be selling a bicycle bracket that clips into recesses molded in the case, allowing the unit to be mounted on the handlebars (or a boat's stern railing, perhaps). The owner's manual admonishes the new user to fasten the unit securely so it won't fly about the vehicle, and to pay attention to the road while driving. This last is no joke: if you think cellular phone use while driving is dangerous, wait until you're behind someone on the freeway driving with his knees to keep both hands free for punching buttons on his GPS. I've found that my GPS fits well on the little shelf in front of the speedometer in my car. It even gets reasonable satellite reception there. For the last few weeks I've been driving around trying out the various displays (but always with one hand on the wheel!). I've concluded that the usefulness of GPS on the highway is limited to places you've already been recently. Once you've got some waypoints set in and a route estabished it's great for predicting time of arrival. It's rather pointless, however, to expect it to lead you directly to your destination, since you're confined to the road. I think the next step is to interface the GPS with map software on a laptop.... Paul Menconi ---------------------------------------------------------------------- -GPS 12XL? | This is the very long awaited compact true 12 channel unit and it does NOT have the 90 knot speed limit! It also apparently has flash memory so that the firmware could be uploaded from the serial port. I was able to buy a returned GPS 12XL (on an impulse) from West Marine and have had a great time playing around with it. My first impressions are that it is more sensitive under trees and the user interface is very much like the 45XL/38/II. I haven't had an opportunity to do a side by side comparison with a 45 or 38 yet. The position averaging feature is rather convenient. I really miss the BNC swivel antenna of the GPS 45XL for use on the dash of my car. The external antenna connector (MCX) is obscure but is used by a couple of other Garmin models. I hope they come out with a BNC swivel antenna version sometime. If you are not put off by the lack of a BNC swivel antenna, this is the small handheld model to get for hiking in thick trees. Due to some reservations I had heard about the battery life, I put in a brand new set of alkaline batteries and they lasted 12 hours, 25 minutes. (Lane Holdcroft) | ----------------- Larry James posted the following about the GPS 12XL: Most of you have been waiting and wondering and hoping. The wait is over. Garmin announces the new GPS 12XL Professional Navigator for challenging environments: PhaseTrak12 parallel channel receiver for fast position fixes in tough conditions, including tree canopy and urban obstructions. GPS 40 style and size case with built-in antenna now meets stringent military 810(e) environmental specifications. 500 waypoints, 20 reversible routes, over 1000 track log points. Proximity waypoint alarms with beeper. TracBack and the other GPS 45XL features, plus position averaging and user-programmable datum. The great battery life Garmin handhelds are known for (up to 12 hours using 4 AA Alkaline batteries). Larry James, James Associates, http://www.csn.net/~lwjames ------------------- Here are some more detailed specs that were received by Lee from a FAX from Garmin: NAVIGATION FEATURES Waypoints: 500, Nearest 9 (automatic) 9 proximity Routes: 20 reversible with up to 30 points each, plus MOB and "TracBack" modes TracBack: Automatic track log navigation Map Datums: 107 including 1 User definable Datum Coordinates: Lat/lon, UTM/UPS, plus 7 grids, including Maindenhead and user UTM. PERFORMANCE Receiver: PhaseTrac12 receiver(12 parallel channels) continuously tracks up to 12 satellites to compute and update position Acquisition Times: Warm: approx 15 sec, Cold: Approx 45 sec, Autolocate: Approx 5 min Update Rate: 1/sec continuous Accuracy: Position: 15 meters (49 feet) RMS (subject degradation to 100 meter due to SA) Velocity: Performs to 999 kts, .1 knot RMS steady state Dynamics: 6 Gs Interfaces NMEA 180, 182, 183 and RTCM 104 DGPS corrections Antenna: Internal Patch (External antenna optional) PHYSICAL Size: 2.1"W x 5.8"H x 1.2"D (5.3x14.7x3.1 cm) Weight: 9.5 oz(269g)w/batteries Display: 2.2"H x 1.5"W (5.6x3.8 cm) high contrast LCD with electro luminescent backlighting, Case Ultrasonically welded Temp Range 5 to 158 Deg F (-15 to 70 C) Memory Backup: Internal rechargeable lithium battery POWER Source: 4AA batteries or 10-40vDC Battery Life: Up to 12 hrs. ACCESSORIES Standard: GPS 12XL Receiver, 4 AA Batteries, User's Manual, Quick Reference Guide, Carrying Case, Wrist Strap. Optional: Mounting Kit, Data Transfer Cable, Cigarette Lighter Adapter, PC Kit External Antenna There is also a note stating "Specifications are preliminary and subject to change without notice." Please excuse any typos and spelling errors Lee -------------- Here is a detailed 12XL review by Lewis Schnaper: So when I heard about the 12XL it sounded like the next best thing. FWTH, here are my notes on a couple of day's use of the new unit. January 17, 1997 I got a 12XL yesterday at Northern Lights Avionics in Anchorage for $265. My first and strongest impression is that the receiver is incredibly sensitive and quick. I've got a 38, and have only been able to get a fix in the house by putting it by a window and waiting, and often no fix results. The 12XL gets four or eight satellites in the middle of the house, and I've gotten a fix from power-on in as little as 14 seconds, while the 38, in a similar position is getting one satellite, at most. Strangely, the signal strength indicators some times go up when the unit is held vertically. Physical: the case is almost identical with the 38, but for a slightly different angle to the antenna. One 38 feature that is missing is a molded in attachment at the top for the lanyard. Instead, you're left hooking the lanyard to the bail that opens the battery compartment. Display: this is a slightly different screen than the 38. The text appears to be the same pixel size, but the 12XL is dark gray on light gray, rather than the dark blue on olive of the 38. In light I'd say the 38 is a little easier to read, while in the dark with the backlight, the 12XL is more visible. Screens: On the satellite status page the only difference is that the bars are smaller because it shows 12 satellites versus 8 on the 38. On the position page, the aircraft type compass reads compass points (N-NW-NNW) rather than the 38's mix of N-345-330-NW. I don't see a way to alter this in the setup. In the 38 on this page you could change the trip length, altitude, and enter a position. I figured that this was for initialization, but never confirmed that. On the 12XL, you can only change the trip length. The map and steering pages look identical. The arrangement of the setup menu is different, but many of the elements are the same. Some differences are the ability to set 9 proximity waypoints and a distance from each, and the unit will then warn you when you are within the specified radius. There is also a user-definable grid and datum. The unit does have an audible beeper, which can be set to messages only or messages and keystrokes. My preference would be to have the message screen come up automatically, but on the 12XL you still have to hit page. One interesting new function is that when you mark an waypoint you can hit an average key then watch as the FOM "Figure of Merit" decreases. This seems to happen pretty quickly--like 10 seconds, and seems to start at around 100'+ and go down to around 60'. I'm not sure what's happening here, but assume that this is the confidence radius for the position. You can still get into the test mode by holding Enter when you power up. [To get into the diagnostic mode, you must press all 4 arrow keys and hold them a little longer than you would on the 45 or 38.] Also, the globe rotation animation is gone, as is the trick for adjusting the world's spin speed and direction. The content manual is similar to the 38, not very technical and a number of features are not well explained. The wire comb binding is a little too small for the number of pages, and I'd guess that pages will start to fall out with much use. The unit comes with a little nylon case, which looks like it was cut to fit a bigger unit or, more likely, one with an external antenna. I'm going to take both units out on snowshoes this afternoon and see how they work outside, but based on first impressions the 12XL is going to offer a significant performance improvement for hiking use. If the battery life turns out to be shorter than a full day, the 38 may still be preferable for boating, if no external power is used. January 19, 1997 I did a five mile snowshoe with the unit yesterday in an area with about a third of the sky covered by a high ridge. I left the unit on for the whole walk, and as far as I could tell it tracked continuously, despite the limited sky and the fact that it was in the breast pocket of my jacket and sometimes the antenna was faced in towards my chest. I was impressed with the performance. Battery life is still a concern. This was the original set of batteries, but they seemed to go long before ten hours. I did find that there was an hour or more of operation left after the "low battery power" warning went off. Another factor may have been that the temperature was down in the 20s. Lewis Schnaper | ------------ Here is another GPS 12XL review by Philip Blair: Well I've had a chance to play a bit with my 12XL and so far I'm still well impressed but to be honest I would probably be just as happy had I bought a 38. The drain on the battery also seems to depend greatly on how many satellites are being tracked. On the other hand I have been well impressed by the ability of the unit to hold on to satellites, now there is no way you see a bird through a mountain but it has managed to have 7 up in my bedroom. In view of the metal blinds and the like this amazed me. I did a few tests by turning the unit off and walking a few hundred yards, then turning the unit back on. It had a fix in about 15 seconds, as claimed by Garmin, and I don't think that I can complain about that. The software works very well for me, now this is my first GPS and I will still be navigating with a map and compass for most of the time, the GPS is just a safety aid. However I have entered a few waypoints, made up a route and followed the moving map and it works. In fact it works so well that I would be concerned that some users would be tempted to leave the map at home and just follow the GPS. The "TracBack" function allows the user to sally forth while the 12XL takes care of deciding where the waypoints should go. You can then use this "robotic" list of waypoints to guide you back. Now for me this is a function which will rarely be used but I would imagine that it would be very attractive for some users. I've tried it and it works, it seems to use 1024 waypoints as it goes along and it then rationalises these down to 30 waypoints to make up an active route. Probably best to use this for fairly simple routes I suppose, just in case it rationalises out that detour around the cliff top :-) For some people the speed limit thing was a big deal and the manual says that there isn't one, quote: "performs to 999kts, 6g dynamics.". Now I haven't tested this but it is unlikely that Garmin are making it up. The only big down point is that there is a fortune to be made by someone who can produce a shock proof, waterproof case which will go on a belt or rucksack strap. If the unit could be operated while in this case then all the better. There seem to be thousands of companies out there willing to sell you expensive portable gear but very few of them are willing to help you not break it. Bottom line: If I had to do it again I'd still buy a 12XL but most 38 owners shouldn't lose any sleep. Philip Blair ---------------------------------------------------------------------- -GPS 89 (aero)? The GPS 89 is a GPS 90 with a much less complete jeppeson database (only has airport and VOR locations) and fewer accessories. It does not include the yoke mount but it does include an antenna extension. | Here is an extensive review from Derek Ruddock: Here are my initial impressions of the Garmin 89 GPS system. I bought the Garmin for use when I fly sailplanes. The unit has an international Jeppesen database of airports and VOR's, but without the useless (for me) data such as fuel availability and runway layouts found in the more expensive GPS90. For this review, I will follow the layout of Gavin Scotts review of the Garmin GPS40 posted on 27 Apr 1994. I bought my unit on 22 July 1996, from Eastern Electronics and paid $449 USD. Shipping and insurance via FedEx to Sydney cost an additional $50 USD (Ouch!). PHYSICAL DESCRIPTION: The spec sheet lists the dimensions as 15.6 * 5.1 *1.23 cm (6.15 * 2 * 1.23 inches). Weight is 269 grams (9.5 ounces) with 4 AA batteries included) At the top on the right side is a recessed BNC connector where the tiny (7cm * 2cm * 2cm approx) antenna is attached. The dimensions of the main unit given above do not include antenna, which makes the top of the unit about 7cm (3 inches wide) overall. At the top of the unit is a four way rocker switch surrounded by six other buttons. This layout allows the unit to be easily held in either hand with the thumb operating the buttons. The joystick like flat rubber rocker switch is used for all data entry. Alpha-numeric data is entered by cycling through the possible letters/numbers. To the left of the rocker 'cursor' button are (top to bottom) GOTO NRST: sets direct course to a selected waypoint, or by pressing twice displays the nine closest locations. Power/Backlight QUIT returnd to previous page or clears & restores previous value To the right are PAGE: cycles through the available pages WPT: displays Jeppesen Airport & VOR's plus up to 250 User waypoints ENTER: confirms data entry. The top 1/4 of the front is blank except for an embossed logo). Beneath the switches is the large LCD display which takes up the bottom half of the front of the unit. The display has a 'portrait' orientation, and is twice as high as it is wide. The unit is completely black. Batteries (4 AA alkaline) are inserted into the bottom, by rotating the thumb loop 1 quarter turn anti-clockwise. A 4 pin Garmin connector is at the base of the back of the unit. The pins are described in the manual as Ground, Power in ([10]-40V DC), and DATA IN | and DATA OUT. A rubber plug protects the connector when it is not in use. The whole unit is filled with dry nitrogen and the ultrasonically welded, and is covered by the one year warranty. ACCESSORIES INCLUDED: BNC cable with bracket and suction cap (for remote mounting of the aerial) 4 AA [alkaline] batteries (installed). Carrying case (black vinyl leathercloth with belt loop and Garmin logo in white. Reference manual (63 pages, dated April 1996). Quick reference card Warranty registration card. Wrist strap. Everything comes in a white cardboard box . SPECIFICATIONS: Temp range 5-158 degrees F (-15 to 70C). Acquisition times: 20 seconds (warm), 2 minutes (cold), 7.5 minutes (sky search). Update rate 1/second (continuous) Position accuracy 5-10M (with DGPS), 15M RMS (without SA), [100 Meter accuracy with 95% confidence (with SA on, as is the case now)] Dynamics: 3g's. Power usage .75 watts. Battery life 12 Hours normal, 20 hours battery saver mode. NMEA INTERFACE INFORMATION: NMEA 0183 Version 2.0. Approved sentences GPGGA, GPGLL, GPGSV, GPRMB, GPRMC, GPRTE, GPWPL, GPBOD Proprietary sentences PGRME (estimated error), PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control). Five I/O options are available: Garmin/Garmin using their proprietary interface, None/None, None/NMEA, RTCM/None and RTCM/NMEA. DGPS corrections are accepted from any RTCM-104 v2.0 format compatible beacon receiver, Garmin's GBR 21 being the recommended receiver. OPERATIONAL DESCRIPTION, FEATURES, PRELIMINARY EXPERIENCES: To turn it on, you press the power/backlight button and hold for 2 seconds. The welcome page displays "Welcome to the Garmin GPS 89" and it gives the firmware revision as "2.07" as the unit performs a self test. After the self test, the Jeppesen database information is displayed (in my case "Worldwide Cycle 9604 effective 28 Mar 1996 to 25 Apr 1996") (yes it has expired!.) this fades after a seconfd or two and the satellite status page is displayed. This display shows the position in the sky for each satellite, a bar graph of the signal strength of up to 8 stats at a time, a large battery power gauge bar, a backlight indicator , and a status message ("Acquiring" etc). Pressing the PAGE key cycles through the main displays which are as follows: POSITION PAGE: Shows (from top to bottom): Compass display (like looking at a compass from eye level). Track and speed Trip Distance and Altitude Position in LAT/LON down to .001 minutes resolution Time (either local time or UPS depending on preferences) to 1 second. MAP PAGE This is a moving map display. At the top of the map are three options for zoom range, pan and configuration. The autozoom feature will automatically keep your current position (signified by an aircraft icon in the lower centre of the display) and your next waypoint on the screen. This can be manually overridden. As you get closer to the waypoint, the map will automatically change scale to keep you both on the display. Depending on the (user selected) setup, the airports/VOR's/user waypoints are displayed using their ICAO prefix. The display can be tailored to suppress the display of this data if desired. Selecting a waypoint and pressing enter displays details of the waypoint. You can zoom manually 0.5 TO 600km (0.2 mile up to 320 miles). In addition it is possible to You can have TRACK UP or NORTH UP as you like. NAVIGATION PAGE Shows (from top to bottom): Bearing and Distance to next waypoint Track and Ground speed CDI scale (Course Deviation Indicator) with Relative Bearing Pointer (arrow showing the direction to the next waypoint) ETE/ETA and Crosstrack Error Time and VNAV altitude MENU SCREEN: These options lead to other configuration menus. Shows (from top to bottom): E6-B Menu (power jockey functions) Alarms/CDI User Wpt List Routes Messages Audio/Display Units/Datum Date/Time Track Log Interface OTHER MISCELLANEOUS STUFF: EZinit: to speed up initialisation, enter your approximate location (Very easy if you are at an airport, just select one from the built in database) You can input 250 Alphanumeric waypoints with (6 character name, 16 character comment) 20 reversible routes with up to 32 waypoints each. Pressing GOTO twice stores your current positions as a waypoint. Other functions: Sunrise/sunset calculation, vertical navigation , Winds aloft calculation, trip and fuel planning , proximity alarms, countdown timer, All the usual config options are there (Statute, Nautical, or Metric units, True, Auto magnetic, or Manual magnetic headings). You cannot mix units (eg I would like to measure my height and speed using nautical units, but distances using km. This is not possible.) There are dozens of map datums(data?) to choose from. Positions can be displayed in DDDMM.MMM or DDMMSS.S format or UTM coordinates, or British, Irish, or Swiss GRID formats. CDI scale can be +-.25, 1.25 or 5 Miles or kilometers. You can choose to display CMG/VMG rather than track/speed. There is a simulator mode [which simulates strong satellite reception so you can practice operation of the unit indoors]. The differences between normal and battery saver mode are not described (other than to say that battery save mode saves 50% of the battery power and is "suitable for most applications". Derek Ruddock ---------------------------------------------------------------------- -GPS 90 (aero)? The GPS 90 comes with either a US or International (UK and Europe) database. If you buy it in the US, make sure you get the database you want. John Mccurdy The Jeppesen database is updated regularly and the update cost is about $125 for one time, $312/yr for quarterly updates, and $845/yr for 28-day cycle updates. If you let it expire, then you will receive a warning message on every powerup that the database is out of date but you may continue operation. The Garmin GPS 90 looks like the GPS 45 except that it has different firmware, a dark grey case (top and bottom), and a couple of buttons are relabeled. Internally it has more battery backed up memory and may have better shielding. Of course it does not have the 90 knot speed limit and it has some other software features for aviation use such as a database of public airports and navigation aids. I found the following press release which was posted a while ago. Some additional info and specifications from a recent posting follows the press release. Start of press release: ----------------- Subject: GARMIN introduces GPS 90 Organization: GARMIN International Date: Tue, 4 Apr 1995 15:25:38 GMT Essentially, if you know the GARMIN product line, this is a 45 and a 95XL all rolled into one package. FOR IMMEDIATE RELEASE: April 9, 1995 GARMIN Introduces Powerful GPS Receiver in Small Package The GPS 90, the world's smallest handheld GPS, is packed with all the features of its larger counterparts LENEXA, Kan. GARMIN International, aviation's leading GPS manufacturer, announces the introduction of the GPS 90, the world's smallest GPS handheld receiver. At only 10 ounces, and about the size of a remote control, the GPS 90 is full-featured, with moving map graphics, a large LCD display and an extensive Jeppesen database that includes all airports, runway diagrams and available navaids and SUAs, all at the pilot's fingertips. Significantly, battery life for the GPS 90 is approximately 15 hours on only four AA batteries, greatly exceeding that of any other GPS receiver to date. The ergonomic design of the GPS 90 truly is a breed apart from other models in the marketplace. Specifically, the GPS 90 is designed to fit comfortably in the pilot's palm for single-handed operation. Or, the unit mounts nicely in a universal yoke mount, which is an included accessory with purchase. The GPS 90's unique thumbkey rockerpad offers two scrolling speeds and quick, intuitive data entry. The GPS 90 will bring many pilots into the GPS fold for the first time, said Tim Casey, GARMIN's aviation marketing manager. Its size, simplistic software operation and amazing battery life make it the one piece of equipment every pilot's bag should make room for. The GPS 90 has a unique, rockerpad cursor control and only six function keys, enabling pilots to quickly access one of five main pages that are displayed on the EL backlit LCD screen. Those five pages are: satellite status, position, moving map, navigation and menu. The satellite status page shows which satellites the receiver is tracking, the strength of their signals, and also displays the battery power via a graphic fuel gauge. The position page indicates your track, speed, latitude, longitude, altitude and time-of-day. The moving map graphically plots your course as you mark waypoints and travel waypoint to waypoint. The map is capable of 12 range scales from 1/5th to 320 miles and will also zoom and pan the area you're navigating. Pilots may also view airports, VORs, NDBs, SUAs and other user-chosen information provided by the internal Jeppesen database. The navigation page indicates your bearing, distance, track and speed to an active waypoint. A course deviation indicator tells you when you're off course. The menu page offers pilots various setup and user-preference options, an E6-B menu, sunrise/sunset calculations and route and waypoint management features. GPS 90 users may also choose to operate the unit at home in the simulator mode to plan trips, customize user options and enter or modify waypoint and route information. The unit will store 250 user-defined waypoints and up to 20 reversible routes, with 30 waypoints each. Additionally, the case for the GPS 90 is ultra-sonically welded and dry-nitrogen filled. The GPS 90, along with the entire GARMIN product line, relies upon GARMIN's proprietary MultiTrac8 receiver technology, which tracks and uses signals from up to eight satellites simultaneously. The GPS 90 comes with a carrying case, user's manual and quick reference card, wrist strap, universal yoke mount bracket, suction cup antenna mount, power-data cable and a cigarette lighter adapter. Optional accessories available for purchase include a serial data cable and PC kit. The GPS 90 is currently available and lists at $799. GARMIN International designs, manufactures and markets GPS equipment for a variety of markets, including aviation, marine, military, survey, OEM and general recreation. For more information on the GPS 90 or any of GARMIN's other GPS receivers, contact GARMIN International [see new address at end of FAQ]. [End of press release] ---------------------- Here is some info about the GPS 90 supplied by Roger Vermeir: Controls are the same, except for some key labels: 'GOTO' on the 45 is called 'GOTO NRST' on the 90 'MARK' on the 45 is called 'WPT' on the 90. Here are some specs of the 90: up to 250 user waypoints; up to 20 reversible routes (with up to 30 wpts each) acquisition: warm approx. 15 sec (I've had several in less than 8 sec, in good conditions) cold: approx. 2 min autolocate : approx. 7.5 min (but it may need up to 15 min, and if you are in a real 'Poor GPS coverage' area, it will start beeping and then auto shut-off) update rate 1/sec (cont) accuracy: position: 15 m (49 ft) RMS (100 m 2DRMS if DoD's SA is ON) velocity: 0.1 kts RMS steady state [several kts realistically because SA is ON] Dynamics: 999 kts velocity, 3 G's Interfaces: NMEA 180, 182, 183, unit-to-unit, PC, RTCM 104 v.2.0 (corrections) MAP datums : 105 size: 6.15 x 2 x 1.23 inches (15.6 x 5.1 x 3.1 cm) weight: 9 ounces (255 g) inclusive batteries display: 2.2 x 1.5 inches (5.6 x 3.8 cm) high contrast backlit LCD case: ultrasonically welded, dry nitrogen filled power: 4 AA batteries or 8...40 V DC 0.75 W max consumption Temp. range : 5 F to 158 F (-15 C to + 70 C ) Battery life: up to 15 hours (normal mode) or 20 hours (battery saver mode) Built-in rechargeable lithium battery saves almanac and waypoint data while you are changing batteries, BUT WILL ONLY SAVE DATA FOR A FEW MONTHS (according to the Garmin manual). Roger Vermeir ---------------------------------------------------------------------- -GPS 120? The GPS 120 looks like it has GPS 45/40 software but it has a mobile mount (sort of like the GPS 65), a much larger display, no battery compartment, and it includes an external antenna. It looks like it was intended to be permanently mounted in the cockpit of a boat. The only differences I can see is that the GPS 120 has a Man Over Board button and an anchor alarm option in the menu. Power input: 10-40 VDC, 2 watts The specifications are virtually identical to those of the GPS 45. The GPS 120 sells for less than $400 US discounted. ---------------------------------------------------------------------- -GPS 130? The GPS 130 was Garmin's first 12 channel GPS unit with a display! The GPS 130 looks like the GPS 120. It has a mobile mount unit with no battery compartment. It has a much higher resolution display than the GPS 120 and it also has grayscale capability. It includes a map of the world but also uses optional very detailed map cartridges. Someone measured the current and said it was about 150mA at 12 VDC (without the antenna). See the GPSMAP 175 for more information because the units are similar. | ---------------------------------------------------------------------- -GPS 135? Here is an announcement about another new unit: Garmin announces the availability of the GPSMAP 135 Sounder. It combines the PhaseTrak12 parallel channelGPS engine and an advanced sonar sounder with fish-finding capabilities. Larry James (http://www.csn.net/~lwjames) ---------------------------------------------------------------------- -GPSMAP 175? It started shipping late August 1996. It has a much higher resolution display than the GPS 45/40/38 family. Here is Larry's announcement for the newsgroup: GARMIN announces the GPSMAP 175, a big screen handheld with a 4-level gray scale LCD display and the PhaseTrac12 parallel-channel GPS engine. Takes G-chart cartridges for background maps. Larry James (http://www.csn.net/~lwjames) 250 waypoints 20 reversible routes, 30 points each > 100 map datums Well I couldn't wait, so I called Garmin Sales and Marketing to ask about this unit... Here's the info I got from Lee, GPSMAP 175 Introduced 7/10/96 Dimensions ........................ 7.6"x2.9"x2.1"[19.3x7.4x5.3cm] Weight ............................ 1.4 lbs [635g] Max power consumption ............. 1.5 Watts Display size ...................... 2.25"x3.38" [4.1" or 10.4cm diameter] Pixel count ....................... 160x240 Power needs ....................... 6 AA cells which can last up to 10 hours. Antenna ........................... Internal Patch Will accept 6-40 volts DC external power. Can accept optional active antenna. The person(Lee) I spoke with definitely referred to this receiver as a 12 channel receiver. This is all I asked about, as they were my main questions. I assume the software is much like the G38 with additional Charting capabilities. Glenn Wiltse ----------------- Here is a GPSMAP 175 review by Rick Prelinger: What follows is a nontechnical evaluation of the new Garmin GPS175. I hope it will help readers of this group with their purchase decisions. I ordered my Garmin GPSMAP 175 from West Marine, receiving it on November 29th. Availability is spotty but at that time some units had arrived in their West Coast warehouse. My unit is software v. 2.28, internal database v. 2.01. The unit resembles an expanded GPS 38, except that the orientation of the control buttons and screen is slightly different. Its dimensions are 7.5 inches high, just a shade under 3 inches wide, and 2 inches deep. Weighing something over a pound (I don't have a scale handy), it is best carried in a deep coat pocket or in some kind of cushioned case. It's heavy but you get used to the weight rapidly, and its improved acquisition time makes it easier to hold, because you won't be holding it for very long. The LCD display is perhaps the unit's most striking feature; it's a three-level grayscale display with fairly high resolution (I don't have the manual handy, either), 2.375 inches wide by 3.5 inches high. It's protected by a clear plastic shield that appears to be easily scratchable. There are ten control buttons, pretty much standard high-end Garmin buttons. The two added buttons not present on my previous unit (a GPS 45) are the "Zoom" up/down button, used for controlling map scale, and the "Menu" button, which leads to context-sensitive help menus. Pressing "Menu" once leads to the local menu, relevant to the page you are currently in; pressing it twice leads to the Main Menu, which looks a lot like the main menu on the 45 at first glance, but many of the submenus are more sophisticated. After the unit is turned on a warning screen full of text comes up. You need to press the "Enter" key to get rid of this. It's basically a disclaimer for the electronic chart, that it isn't intended to replace the use of official government paper charts. Another Garmin product liability concern, which gets old very quickly. It'd be nice to bypass this screen; maybe another user knows how to do this. The display is excellent. The only problem from my point of view is just what another writer in this group mentioned -- it isn't always visible from every angle. When I rest it between the windshield and dashboard cushion of my Honda, I find that I sometimes have to shift my head or reorient the unit in order to see the display clearly. Nevertheless, the typography and graphic design is readable. For many this may be one of the greatest consideration in favor of this unit -- it's extremely easy to read, especially in a moving car or when you glance at it while in the field. The power button controls the level of backlighting -- there are three levels (I usually stick with the second, intermediate level at night) and the timeouts are programmable via the menus. The GPSMAP 175 uses what looks like Futura Condensed for menus and text, and for small type on the maps and the CDI uses what seems to be the same typeface as the revised G45 software. Both are highly legible. For the time, position and speed screens, it uses large numerals, about .25 inches high, very highly readable from several feet away. This is another great feature as far as I am concerned, made possible by the overall size of the display. I had never before used a 12-channel unit and was of course knocked out to see 12 channel positions. In general, I have not seen more than 10 satellites in average use. Like other units, when it sees a satellite it shows hollow signal- strength bars during the acquisition process, the bars filling in solidly when a satellite is acquired. A small display to the left of the skyview shows EPE (estimated position error), DOP (dilution of precision), and battery life, in a fuel-gauge format. The skyview display can be configured either north up or track up, which gives you a great rough compass display if like me you are a signal strength freak. Being able to track many sats simultaneously means that the unit is much more sensitive and precise than the G45. It also means that satellite acquisition is much faster. Typically, it takes less than a minute to acquire 2D position and 3D position follows very shortly (these figures reflect experience in urban areas). If the unit is "hot," acquisition time is generally much less. Occasionally, the unit will sit for from 3 to 5 minutes without acquisition; I believe this is linked to low battery power or perhaps early software bugs. I haven't yet had the experience that is regular to the G45 where you have to reboot in order to "unfreeze" the unit and acquire satellites. I rarely get an EPE of 49 feet (about the best SA allows) but quite often get EPE's in the 60 or 70 foot range, in and around New York City. [EPE does not include the effects of SA]. DOPs of less than 2.0 are common; my lowest DOP is 1.2 so far. The thing to realize about this unit is that high precision is quite regular, allowing you to record good track while walking, for example. I put the GPSMAP 175 and the G45 side by side on the dashboard and found that the 175 always saw more satellites and was consistently more accurate at tracking a route (and less subject to SA error) than the G45. On the other hand, the G45 often displayed lower EPE numbers. Go figure. The second screen (I forget its name) shows track (with a moving compass band), speed over ground, course over ground, altitude (one figure only, without any indication of vertical error -- you have to assume vertical error, and many people may not know about this), and trip mileage. The trip mileage counter is easily resettable and works well, but undercounts by exactly 4 percent (when used in an automobile). Plus, if the unit is powered down, this counter will continue to increment at power up where it was left off, and will not reflect true trip mileage. The position and all displays can be shown in all the usual formats. This unit also permits Maidenhead Grid and Taiwan Grid, in addition to all the others available in the G45. The moving map is quite great. It works at range scales from .125 to 4096 miles, which are controlled by pressing the right or left sides of the "Zoom" button. This has to be seen to be believed, though I imagine that future generations of handheld units will support color LCD displays as well as contain higher-definition maps in firmware. Changing map scales is quick but occasionally slows down for "loading," and it slows down a lot when G-charts are inserted (see below). The internal database contains what amounts to an outline map of the world, but it focuses on coastal areas. Therefore, Houston is displayed, but not San Antonio, and huge areas of the United States appear without any legend other than superimposed latitude and longitude lines. The internal map also does not extend past somewhere around 68 degrees latitude, which means that no polar features appear. The manual shows what parts of the world are omitted, but most places the Western sailor might head are covered. That being said, though, there are a lot of things on this map, and of course the user can superimpose his or her own coordinates. It's a lot of fun to scroll around the map. The basic world map is valid down to the 64 nm scale; then cartography begins to become generalized and eventually disappears. G-charts fill the gap (see below). The map also makes it very easy to initialize the unit, because you can select a point in the map to tell the unit where it is. The map is configured through the menu, and it is possible to control which features appear (at least as far as G-charts are concerned). G-charts are little ROM chips that contain digitized chart information. They come in offshore and inland versions. The offshore ones are geared to the needs of mariners; the inland ones contain Interstate, US and state highways and some county roads, but offer much more detail in the vicinity of lakes, rivers and reservoirs. Garmin will send you a price list on request, but they range from $99.00 (for states and small harbors) to $149.00 (medium-level information) to $395.00 (for electronic charts that incorporate information from as many as 35 government charts). Their cartography department can also send you printouts showing the coverage and paper base maps related to specific electronic charts. The G-charts add a reasonably high level of detail to the moving map, and are good down to 1 nm in some cases, in others not so far. I have not yet taken my unit (just today equipped with a New York State East G-chart, which cost $149.00) on the road, but I expect that it would be a very nice way of tracking road progress. More on this later. G-charts cover very specific areas; I bought New York East, which stops right at the New York border. An example: although the New Jersey side of the Hudson River is contained in the G-chart and in the built-in world map, only half of the George Washington Bridge shows up on the screen -- the half on the New York state side. On the other hand, New York East contains all detail to Syracuse, plus highway information (not water information) for the western half of New York State. The CDI display is three-dimensional, much easier to use and more distinct than the G45. Its attributes are programmable as well. A few other things: you can set "proximity waypoints," which will set off an alarm when you approach them; there is a set of little graphic icons which can associate with specific waypoints on the map, such as telephone, ATM, camping place, dock, etc.; it contains the "tracback" feature found on the G38, which is way cool...you can reverse the track you have taken, and the unit will convert it into a route, defining waypoints automatically. There is a trip and fuel planning module, which I have not yet used; a set of timers, and input-output protocols as usual. The I/O connector is a 13-pin job on the rear of the unit, open and unprotected. I haven't really studied this yet. To sum up: this is a delightful "prosumer" unit that immediately replaced the G45 for me. I can't go back to a single-channel receiver. It's overpriced ($699 at present) and I imagine it will look clunky and dated within two or three years, but I am very pleased with its accuracy, sensitivity, programmability and complement of features. Recommended for those who seek the functionality of an advanced Garmin unit and who are willing to put up with something larger than a G45. WISH LIST: The "Nearest Waypoints" list still contains only 9 waypoints. Another screen of nearest waypoints would be great. "Nearest" is defined as under 116 miles; at 116 miles waypoints disappear off the screen. The unit still stores only 250 waypoints. Other small Garmin units are now holding 500. The speed limit is still somewhere around 100 statute mph. However, in simulator mode, you can jack the unit up to 621 mph! (I assume this is the upper limit of the air units, because it roughly equals 999 kph). Some kind of "battery saver" mode. Right now a set of alkaline batteries (the unit takes 6!) is specified to last 10 hours, and this is expensive! Better design for the battery pack -- it is flimsy and difficult to remove batteries, as another writer has mentioned, and I always feel as if I'm about to break mine. A G-chart showing major highways throughout the United States, or at least one for eastern U.S. and western U.S., for people like me who are drivers rather than mariners. G-charts for wilderness areas, as well. (Who controls G- chart protocol? Is it possible to be a third-party supplier of G-charts?) Some kind of simulated alphanumeric keypad to better enter letters and numbers. I'm sick of using the cursor control to cycle through an alphabet as in my Casio watch. Permission to reprint all or part of this article is granted, but only if writer is credited. Rick Prelinger ---------------------------------------------------------------------- -GPS 20/25/30/31/35 (remote only models)? These units do not have displays. They are for remote use only! Here is a quick chart to separate the remote models: Model Channels board or TracPac ----- -------- ---------------- GPS 20 1/8 board GPS GPS 25 12 board GPS GPS 30/31* 1/8 TracPac GPS 35/36* 12 TracPac *marine mount version of GPS 30 or 35 [Lane Holdcroft] Although it is not made by Garmin, I should also mention the 12 channel Delorme Tripmate for only $150 which includes some nice mapping software for your laptop computer. It also doesn't have a display or buttons. It needs to be "kick started" with a specific NMEA string before it will output data. The GPS is actually made for Delorme by Rockwell. | UNIT P/N COMES WITH GPS20-000 MultiTrac8 sensor board only GPS20-101 GPS20 with GA28 marine ant. and 15' cable GPS20-020 GPS20 with GA27 mag mount ant. and 8' cable GPS20-099 GPS20 Eval Kit* GPS25-000 PhaseTrac12 sensor board only GPS25-010 GPS25 with GA28 GPS25-020 GPS25 with GA27 GPS25-099 GPS25 Eval Kit* GPS30-000 MultiTrac8 and ant. combo GPS30-099 GPS30 Eval Kit* GPS30-100 GPS30 PC Version with DB9 connector GPS31-000 same as above, but with threaded 1" marine ant. GPS35-000 PhaseTrac12 and ant. combo GPS35-099 GPS30 Eval Kit* GPS35-100 GPS35 PC version with DB9 connector * Eval Kits come with GPS engine, antenna with cables & connector, power/data cable with connector, NMEA monitor software & documentation. All Garmin engines come complete with DGPS input capability, PPS timing output and lithium 3V battery on board Further Info PhaseTrac12: 12 parallel channel, phase tracking accuracy in the world's smallest GPS footprint. MultiTrac8: Tracks and uses up to 8 satellites for accurate, reliable GPS data at an incredibly low 1 watt power consumption. With same footprint as PhaseTrac12 and a real time clock, PPS timing and nonvolatile memory right on the board. TracPac: A sure bet on Plug and Play GPS. Combines a GPS engine and antenna in an all weather, low profile housing that's a perfect fit for vehicle and PC applications. Just connect to 10 - 32 volts DC and your data interface, pick the mounting option you need and you're off. Available with choice of PhaseTrac12 or MultiTrac8 engine. Consumes very little power and feature DGPS capability. NMEA 0183 output. PhaseTrac12 MultiTrac8 Architecture 12 parallel channels Patented MultiTrac8 Time to first fix reacquisition < 2 sec < 2 sec warm 15 sec 20 sec cold 45 sec 2 min sky search < 5 min 15 min update rate 1 sec contin