Garmin GPS 45/40/38 Frequently Asked Questions ============================================== [start of part 1 of 3] From - Mon Sep 02 07:14:32 1996 Newsgroups: sci.geo.satellite-nav From: klah@eskimo.com (Lane A. Holdcroft) Subject: Garmin GPS 45/40/38 FAQ V1.082 part 1 of 3 [start of part 1 of 3] Garmin GPS 45/40/38 Frequently Asked Questions ============================================== V 1.082 Aug 30, 1996 Compiled by Lane A. Holdcroft Garmin 45/40/38 FAQ Copyright 1995, 1996 by Lane A. Holdcroft. Original contributors retain their copyright for all of their contributions. I am still reviewing the many suggestions and postings that I have received for inclusion in future versions. This document is not in any way endorsed by Garmin International. I am not affiliated with Garmin or any of their retailers. This FAQ is targeted primarily at the GPS 45, GPS 40, and GPS 38. The GPS 50, 65, and 75 have many internal similarities (and some software compatibility) to the GPS 45/40/38. There is also a table at the end of the FAQ with most Garmin products listed. The GPS 38 (released late Feb 1996), is very similar to the GPS 40. However, it has improved software, no external antenna connector, no beeper, no video tape, and a lower price. See the new section "GPS 38 reports". The GPS 45XL is a GPS 45 with the GPS 38 software enhancements released in mid July 1996. The GPS 90 and the recently introduced 89 are very similar to the GPS 45 but have very different software and more non-volatile memory for their aero navigation database. The GPS 89 has a much smaller navigation database. 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 new 12 channel mobile mount GPS unit. It is the first 12 channel unit not intended for remote use (it includes a display). It has a case similar to the GPS 120. It started shipping in the Spring of 1996. The GPSMAP 175 is Garmin's new 12 channel handheld just announced in July 1996. It should also be very popular with hikers due to its excellent reception in trees. It is due to ship in late September 1996. | The GPS 195 is the aviation model of the GPSMAP 175. TABLE OF CONTENTS: ================== 0.00 ABOUT THIS FAQ: -General FAQ info? -Attribution? -FAQ revision history? -Future features? -Suggestions for improvement? 1.00 GENERAL FEATURES: -What are some key features of the Garmin GPS 45/40/38? -What are the disadvantages of the GPS 45/40/38? -Comparison chart for the GPS 38/40/45/45XL/89/90 family? | -What are the differences between the GPS 45 and GPS 40? -What is the accuracy of the GPS 45/40/38/90/89? -What is the Garmin GBR 21 Differential Beacon Receiver? -Are there any other differential receivers available? -How can I improve the accuracy of a GPS unit with averaging? -How accurate is velocity measurement on the GPS 45/40/38/90/89? | -How accurate is the clock on the GPS 45/40/38/90/89? -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 can't I get my first fix? | 2.00 SPECIFICATIONS/REPORTS: -GPS 45/40 specifications? -GPS 45/40 reports/description? -GPS 45 XL? -GPS 38 reports? -GPS 90 press release/specs? -GPS 89 info? | -GPS 120 description? | -GPS 130 description? | -GPS 135 description? | -GPSMAP 175 description? | -GPS 20/25/30/31/35 (remote only models)? -GPS 30/31 description? 3.00 FIRMWARE (INTERNAL SOFTWARE): -90 knot speed limit? -GPS 45/40 firmware versions? -GPS 38/45XL firmware versions? | -What are the undocumented modes for the GPS 45/40/38/90/89? -What are some undocumented modes for the GPS 75? | -Why is internal temperature available? -VMG error? | -What are the GPS 45/40 data NMEA 0183 V2.0 sentences | 4.00 BATTERY/POWER: -How is power selected between the internal batteries and the external supply? -What voltages do the fuel gauge correspond to? -Current consumption of a GPS 45 at different external supply input voltages? -How does BatterySave mode work? -Rechargeable 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? 5.00 SERIAL/POWER INTERFACE: -External serial/power connector alternatives? -How do I interface the GPS 45/40/38 to an IBM-PC compatible computer? -How do I interface the GPS 45/40/38 to a Macintosh? 6.00 APPLICATION SOFTWARE: -What Macintosh software is available for Garmin GPS units? -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 ftp/www sites? -Digital maps with lat/lon? 7.00 ANTENNAS: -What is the GPS 40/38 internal antenna? -How is the GPS 45/90/89 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 loss for different coaxial cables? -What is the GPS 40 antenna connector? 8.00 MISCELLANEOUS: -GPS mounting options? -Waterproofness? -Cases? -Garmin 45/40/38 wish list? -Can I use my GPS unit in a plane? -Performance in trees? -Internal electrical hardware? -Why is the firmware not in a socket? -Can I receive GPS signals through my house? -For how long will a particular track interval interval collect data? 9.00 GARMIN PRODUCTS: -Garmin GPS models? -Garmin accessories? -Where can I purchase a unit? ---------------------------------------------------------------------- QUESTIONS AND ANSWERS: ====================== 0.00 ABOUT THIS FAQ: --------------- -General FAQ info? The Usenet newsgroup "sci.geo.satellite-nav" has a high proportion of questions dealing with the very popular Garmin GPS 45, GPS 40, and GPS 38. I hope this will answer most of them. Because of the large number of questions that are still posted to the newsgroup that have been answered in this FAQ, I usually post this every several weeks to the newsgroup "sci.geo.satellite-nav". 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 GPS 45/40/38 because of their low prices. However, there is a lot of discussion about Garmin units. This FAQ is based on my experience with my GPS 45 and others' postings to the GPS newsgroup since the GPS 45 was first introduced about March 1994. 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 a new NMEA FAQ. They are both available on his ftp site which is the best single site on the web for low cost GPS's. I also send the latest version of this Garmin 45/40/38 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. -Attribution? Garmin 45/40/38 FAQ Copyright 1995, 1996 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). If I felt clarification within another person's quoted material would be beneficial, my comments are contained within the brackets "[" and "]". -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 ftp/www sites considerably Expanded Garmin DGPS info Split application software to 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 (8.00, 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 declination Added section on remote only units Added first 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 PLEASE DESTROY ALL PREVIOUS VERSIONS, ESPECIALLY BEFORE VERSION V1.06 because they had at least several errors. The "|" character is used to mark paragraphs or a line for significant changes in content from the previous version of the FAQ. -Future features? UTM advantages. -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 firmware version of your GPS 45/40/38. 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. Please send CONSTRUCTIVE suggestions to Lane A. Holdcroft (klah@eskimo.com) 1.00 GENERAL FEATURES: ----------------- -What are some key features of the Garmin GPS 45/40/38? Garmin GPS 45/40/38 specific: Relatively inexpensive (list < $500 US, discounted < $200 US for GPS 38). | 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. Water resistant. 64 x 100 pixel graphical display. Over 100 mapping datums used around the world. -What are the disadvantages of the GPS 45/40/38? 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 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 and external power and/or data cables are between about $20 and $50. 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 new GPS 38 uses a wider font to be more readable. If you have good corrected vision, it should not be a problem up close. If not, then the GPS 45/40 may not be a good choice for you. Presumably, the 45XL has the wider font of the GPS 38. 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. See "Performance in trees" section for details. -Comparison chart for the GPS 38/40/45/45XL/89/90 family? | Note that all of the following units have the same case and the circuit boards are identical but they have different parts installed: GPS 38 40 45 45XL 89 90 Use Marine Marine Marine Marine Aero Aero Antenna Intern Intern Extern Extern Extern Extern Ext Ant Conn. None MCX BNC BNC BNC BNC Max Ext V 8VDC 8VDC 40VDC 40VDC 40VDC 40VDC Beeper No Yes Yes Yes Yes Yes Video Tape No Yes No No No No Newer firmware Yes No No Yes - - Speed limit(kt) 90 90 90 90 999 999 Extra Nav Info No No No No Some All Yoke mount No No No No No Yes Ant. ext. cable No No No No Yes Yes ~Retail $ $300 $425 $500 $500 $600? $800? ~Discount $ $200 $270 $280 $300 $450 $650 (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. Some antenna case seals break after extensive handling (I speak from experience). 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, however the GPS 45 is apparently slightly more sensitive for satellites that are directly overhead. 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 and 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 would be potentially damaging. Therefore, the mobile power cigarette adapter is $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 includes a video tape on its operation. 4) The GPS 40/38 has a dark gray case, whereas the GPS 45 has a white front case and a black rear case. 5) The GPS 40 is less expensive than the 45 (and the 38 is least expensive). -What is the accuracy of the GPS 45/40/38/90/89? 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 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 meters Differential accuracy (regardless of Selective Availability) | Vertical accuracy (altitude): Approximately 1.5 to 2 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 errors in altitude due to SA are especially obvious when you are on the ocean! -What is the Garmin GBR 21 Differential Beacon Receiver? The US and Canadian governments are setting up Differential GPS (DGPS) stations to transmit correction signals. They are usually broadcast on existing marine beacon frequencies around 300 KHz. They are already operational in many areas along the coasts. In addition to compensating for errors in the position, these correction signals also undo the deliberate degradation of the accuracy (SA) by the U.S. Department of Defense. Look at the US Coast Guard's web site (under "ftp/www sites" in this FAQ) for locations and status of their differential stations. When connected to your Garmin GPS, the GBR 21 will increase its accuracy to under 10 meters when within receiving range of Differential Beacon stations on the coasts. This also makes your speed indications accurate to about 1/10 knot, which is great for sailboat racers. Works with DGPS-ready GPS 40, 45, 50, 65, 75, and GPSMAP 210/220 models. Coupler measures 1.6"D x 4.8"H and requires a 4' whip antenna. 30' RG-58 coax included. Receiver box measures 5.2"x3.6"x1.5". Draws 130 mA. One year parts and labor includes water damage. List $799 [West Marine Catalog] -Are there any other differential receivers available? Some other manufacturers' differential units that pick up the Coast Guard broadcasts can be used with a Garmin GPS unit but they can not automatically tune the frequency of the differential receiver as Garmin's can. I don't know how much of an advantage this is. There are probably some other differences also. I would appreciate a detailed review by an user of this option. There are services that transmit correction signals on FM broadcast band subcarriers which are not limited to the coasts but you must buy their differential receivers for several hundred dollars and pay a monthly charge. DCI (http://www.dgps.com) and Accupoint are most often mentioned. There are also companies that transmit correction signals via satellite and again you must buy their differential receiver and pay a monthly charge. -How can I improve the accuracy of a GPS unit with averaging? Because the Garmin 45/40/38/90/89 units do not save the individual satellites used and their timing information for each fix, you can not accurately postprocess the data. 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. 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 elsewhere in the FAQ), 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. This 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 separated by 15 minutes or longer, the error of the mean drops as the square root of n. (Robert S. Lawrence lawrence@alumni.cs.colorado.edu) Of course you can take readings more often over a shorter period of time but you just won't achieve as great accuracy. | 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. It is felt by some in the newsgroup that that the maximum accuracy with extensive averaging is about +/- 10 meters while other feel that accuracy within a couple of meters is achievable. -How accurate is velocity measurement on the GPS 45/40/38/90/89? | 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 to monitor the phase of the military frequency. Therefore, virtually all handhelds that are less than $1500 are not very accurate for velocity without DGPS. Probably to prevent the wanderings of SA, the Garmin 45/40 (V2.41 at least) will display "0.0" (without the DGPS option at least) if the speed is less than: 1.0 knots 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)! | -How accurate is the clock on the GPS 45/40/38/90/89? First of all, there is a clock IC in the unit to keep the approximate time. To get accurate time, you must be locked on several satellites. Internally the GPS unit knows 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 extremely accurate time much better than 1 uS, there are some GPS boards that have a very precise timing output. Garmin also has a less precise timing output on a few of their boards to about 1 uS. | -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 not trivial to find a person at sea with strong winds and 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 the grid should be placed on it. The earth is not a true sphere, but an ellipsoid. The datum describes the radius and eccentricity as well as the offset of the grid. The Garmin units have over 100 mapping datums used throughout the world! The key thing 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 the most accurate simple datum. Most maps in the US will likely eventually be WGS84. Most CD-ROM maps use WGS-84. NAD83 is almost identical. NAD27 CONUS Used by most current U.S. Forest Service and USGS maps. The CON reportedly represents Continental 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 and/or lookup table 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. | -Why can't I get my first fix? | The first fix occurs if the GPS unit has moved more than about 150 miles (which is usually the case when you first receive a new GPS unit). This is a very common problem which I should have addressed before but I didn't since it is mentioned in the manual. It is useful for technical reasons for the GPS unit to know approximately where to expect the satellites (ie. 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 a while (more than a couple of weeks), then the exact satellite orbital info may not be up to date. It can take a while for that data to be downloaded. Here is a very conservative approach to getting an initial fix: 1) Find a location with a VERY clear view of the sky not blocked by buildings, trees, etc. 2) Put the unit in Operation Normal, not BatterySave mode (just in case). 3) Preset your approximate location to really speed up the process. (I have heard that the new GPS 38 and GPS 45XL have added a quick start feature to the firmware to figure out your approximate location which provides some of this information). Of course the GPS can figure out where it is on its own, it just takes a lot longer. 4) 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). 5) Allow lots of time for your unit to acquire a location. 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. 6) If you still don't have a fix after several hours and you really had a clear view of the sky, then your GPS receiver may be broken. In general when you are having trouble getting a fast fix (not the initial fix that we are discussing here), turning the unit off and then back on can really speed things up (as is mentioned in the manual). I use this trick all of the time. Also, it seems to take a lot longer to get a fix when you are moving fast as in a car or fast boat. 2.00 SPECIFICATIONS/REPORTS: ----------------------- -GPS 45/40 specifications? Here are the specs out of the manual: Physical Case: Waterproof, dry nitrogen-filled Size: 6.15"H x 2"W x 1.23"D (15.6 x 5.1 x [3.12] cm) Weight: 10 ounces [0.284 kg] 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* *subject to accuracy degradation to 100m [95% of the time] under the DOD imposed Selective Availability Program (note: I average 150') Velocity Accuracy 0.1 knot RMS steady state [w/o SA, several knots error w/ SA] Dynamics: Performs to specs to 3g's Power Input: 4 AA batteries or 5-40 vDC Usage: .75 watts Battery life: 10 hours (normal mode) w/alk. batt. Up to 20 hours in battery saver mode Kai Schumann Schumann_Kai@Lilly.com ---------------------------------------------------------------------- -GPS 45/40 reports/description? Here are 2 good reviews that were posted to the newsgroup. One is from a 45 owner, the other from a 40 owner. Keep in mind that other than the antenna and input voltage range, both units are IDENTICAL 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: gscott@netcom.com (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 (5-40 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. 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 GCA, GLL, GSA, GSV, RMB, RMC, RTE, WPL; Proprietary sentences PGRME (estimated error), PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control). 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 - gscott@netcom.com -or- gavin@denkart.com ---------------------------------------------------------------------- >From: swest@as.arizona.edu (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 swest@as.arizona.edu (Steve West) ---------------------------------------------------------------------- -GPS 45 XL? The GPS 45 XL is simply a GPS 45 with the improved GPS 38 firmware. This has been anticipated by most of us since the introduction of the GPS 38. The GPS 45 XL was announced by Garmin about July 1, 1996 and is shipping in mid July 1996. To see what additional software features were added, see the GPS 38 section below. Because the GPS 45 XL has more features than the existing GPS 45, the GPS 45 is currently being substantially discounted and will be phased out. -GPS 38 description? Also see the comparison chart at the beginning of the FAQ. The GPS 38 was released late Feb 1996. Here is a brief comparison between a GPS 38 and a GPS 40: GPS 38 Advantages: Better software About $60 cheaper Things the GPS 38 does NOT include that the 40 does: External antenna connector Internal beeper Video Tape If I didn't need the external antenna connector, I would definitely buy the GPS 38 over the GPS 40 (but then again, I want the 45's antenna and antenna connector). [Lane Holdcroft] Here is some info from Garmin's press release: The GPS 38 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. They will sell for about $200 US discounted. 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, which, to my eyes anyway, is slightly easier to read in the dark with the backlight. [The GPS 38 display is blue instead of black.] We have checked out both MacGPS 0.4b8 and MacGPS Pro 1.4.3 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] Another poster's 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" [LCD] type display AM/PM Time display 9 oz. weight guestimated street price of $189 What the Garmin 40 has that the Garmin 38 does not: Antenna connector Map Datums: 103 "FTN" [LCD] type display Internal Alarm beeper Carrying Case User Video 10 oz. weight street price of $269 (soon to be lower, my guess: $249). 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 ddm@onramp.net (Donn Mumma) Some dealers have just received units at the end of February 1996. See the Garmin dealers at the end of this document for contact info. [end of part 1 of 3]