Garmin GPS 45/40/38 Frequently Asked Questions ============================================== [start of part 2 of 3] From - Mon Sep 02 07:15:39 1996 Newsgroups: sci.geo.satellite-nav From: klah@eskimo.com (Lane A. Holdcroft) Subject: Garmin GPS 45/40/38 FAQ V1.082 part 2 of 3 [start of part 2 of 3] -GPS 90 press release/specs? 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. facts@cix.compulink.co.uk (John Mccurdy) Also, the Jeppesen database is updated regularly and the update cost is $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 If you let it expire, then you will receive a warning message on every powerup that the database is out of date but you may continue operation.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 may have better shielding and more battery backed up memory. 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 (meirr@btmaa.bel.alcatel.be) -GPS 89 info? | The GPS 89 is a GPS 90 with a much less complete jeppeson database and fewer accessories. It does not include the yoke mount but it does include an antenna extension. It is available for as low as $420 when heavily discounted. | -GPS 120 description? 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 about $400 US discounted. -GPS 130 description? | 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). -GPS 135 description? | Here is an announcement about another new unit: Garmin announces the availability of the GPSMAP 135 Sounder. It combines the PhaseTrack12 parallel channelGPS engine and an advanced sonar sounder with fish-finding capabilities. Larry James (http://www.csn.net/~lwjames) -GPSMAP 175 description? | The GPSMAP 175 is Garmin's long awaited 12 channel handheld unit. This should be the answer for people that need good performance in heavy tree cover. It was just officially announced in July 1996 and should be shipping in late August. 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 PhaseTrack12 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 capabilitys. I didn't ask but also assume it has Garmin's infamous 90 knot speed limit. [Unfortunately it does have the 90 knot limit -Editor] iggy@home.merit.edu (Glenn Wiltse) -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 25 12 board GPS 30 1/8 TracPac GPS 31* 1/8 TracPac GPS 35 12 TracPac * marine mount version of GPS 30 [Lane Holdcroft] 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 nonvolotile 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 reacquistion < 2 sec < 2 sec warm 15 sec 20 sec cold 45 sec 2 min sky search < 5 min 15 min update rate 1 sec continuous 1 sec cont. Dynamics velocity 999 knots 999 knots acceleration 6 g 3 g jerk 60 m/s^3 20 m/s^3 Datums 102 predefined, 1 user defined Electrical input voltage 5.0V DC +- 5% regulated power consumption 1.1 Watts 0.8 watts (Track Pak's 10-30V DC) 1.4 watts 1.2 watts backup on board 3V lithium (10 year lifetime) sensitivity -166 dBW Timing 1pps 1pps Connectors antenna 50 ohm MCX female connector for active (5V DC @ 15ma) or passive antenna power/data single row, right angle 12 pin male Physical configuration 1 integrated board engine size 1.83"W X 2.75"L X 0.45"H weight 1.1 oz op temp -30 deg C - 80 deg C (remove Li battery for extended usage above 80 deg C) storage temp -40 deg C - 85 deg C Interfaces compatibility 2 RS-232 serial ports data rate User selectable baud rate 1200/2400(tx only)/4800/9600 format NMEA 0183 v.2.0, ASCII inputs initial position, date and time (not required), 2D/3D & earth datum command, RTCM-104 v.2.0 differential outputs position, velocity & time, receiver and satellite status, geometry and error estimates timing output timing output with +- 1 microsecond accuracy The TracPak is an integrated engine/antenna system 2.33"W X 3.80"L X 1.04"H 7.2 oz Connector 50-ohm MCX female 5V DC@15ma for active Operating Temp: -30C->85C Storage Temp: -40C->85C Data Rate 1200,2400,4800,9600 NMEA 0183 v. 2.0 The following info is for the GPS25 only! (The 20 will be real close but I have not cross checked the info) Connector: 1 - Tx2 (Not used) 2 - Rx2 RTCM input 3 - PPS 1us pulse at 1hz. Can drive a 50Ohm load 4 - Tx1 RS-232 compatible Output 5 - Rx1 RS-232 compatible Input (-25 < V <+25V) 6 - Reset supply at least 2.5 V to reset engine 7 - V_Aux External power for battery backup. 50uA. (4 < V < 33) 8 - Gnd 9 - NC 10 - 5V DC Regulated input. +5V +/-5%. 350mA maximum. Must be clean! 11 - NC 12 - NMEA NMEA compatable output (same data as on pin 4) Data Input: Almanac: $GPALM (GPS 25 only) almanac data Initalization: $PGRMI includes position, utc data and time Configuration: $PGRMC includes altitude, datum selection, baud rate Output Select: $PGRMO turns on specific output sentences. Data Input: Almanac: $GPALM (GPS 25 only) almanac data Inialization: $PGRMI includes position, utc data and time Configuration: $PGRMC includes altitude, datum selection, baud rate Output Select: $PGRMO turns on specific output sentences. Data Output: Time have leap seconds accounted for $GPALM: Almanac (GPS 25 only) $GPGGA: Position include time, position, quality, number of satellites used. Horz DOP, Alt, DGPS data age, diff station ID $GPGSA: DOP, active SVs Mode, 2D/3D, Satellites tracked, PDOP, HDOP, VDOP $GPGSV: Sats in View Sv #, elevation, azimuth, S/N $GPRMC: Basic info Time, Position, speed, course, date, magnetic variation. $GPVTG: trak, speed course, mag course, speed in knots, speed in kmh $LCGLL: Loran simulation position, time $LCVTG: Loran tracking simulation course, mag course, speed kts,speed kmh $PGRME: Error Horizontal Error, Vertical Error, Total Error $PGRMF: GPS Fix Week number, gps seconds, date, time, leap seconds, postion, speed (kmh), course, PDOP, Time DOP $PGRMT: Sensor Status Product version, test results( chksum, receiver, stored data, RTC, oscillator,data collection, board temp, board config data. $PGRMV: 3d speed east, north, up, all in m/s Map Datums: There are 104 of them (some are the same) plus one user selectable one if you have your own ideas of how round the earth is. On the $GPGGA NMEA output the message uses: latitude in ddmm.mmmm longitude in dddmm.mmmm On the $LCGLL (Loran position): latitude in ddmm.mm longitude in dddmm.mm [Garmin literature] There is a list server for a group of people buying the 12 channel remote only (no display) Garmin GPS boards at maiser@humec.ksu.edu under the name "GPS". There is also a group buy through TAPR for the MultiTrac 8 boards. TAPR is the Tucson Amateur Packet Radio group which is promoting packet use with APRS software listed in the web sites section of the FAQ. There is info at: http://www.tapr.org -GPS 30/31 description? [The GPS 31 is very similar but apparently has a marine antenna mount.] To those of you who asked what is the Garmin GPS 30: The GPS 30 looks like a PC mouse without buttons. Its dimensions are: 56.4 X 96.3 X 26.7 mm [2.23"W x 3.80"L x 1.04"H]. It has no buttons, no LCD, no battery compartment; just an eight wire cable. >From what I've read it works much like the GPS 40 without the human interface (just computer interface) It needs an external power source. It appears to have two wires for power (besides the ground): VIN - Unregulated 10-30VDC 200mA (maximum). Typical operating current is 110mA. VAUX - Optional External Backup Power Connection. This is an optional connection. Internal battery capacity is 180 mA hour. typical current requirement is 65uA @ 5VDC. If used, a 4VDC to 30 VDC power source is required. Luis Lamela (Lamela@lnec.pt) 3.00 FIRMWARE (INTERNAL SOFTWARE): ---------------------------- -90 knot speed limit? There is a firmware speed limit of 90 Knots (Nautical miles/hour), 104 statute MPH, and 167 km/h for the GPS 45/40/38/75. Most of the fields are replaced with dashes or underlines above the speed limit except for the compass and clock. There is no doubt that this is a firmware (software) imposed limit. Contrary to many reports on the internet, the limit is NOT 99 or 100 MPH and it is NOT 99 or 100 knots. Almost all other civilian GPS receivers have a maximum speed limit of about 1000 knots and a maximum altitude (of about 60000 ft) to discourage their use on InterContinental Ballistic Missiles as required by the US Department of Defense. This has created a lot of debate in the GPS newsgroup primarily because it is so poorly documented and is arbitrary. Reports indicate that it is now mentioned briefly in newer versions of the GPS 40 and 38 manuals. The problem is that most people were not forewarned. Obviously every potential customer does not have the time to read the manual before deciding to purchase the unit. I believe that potential customers should be prominently warned about the limitation in the first few pages of the manual and on the box of the instrument so that they can see the limitations before their purchase. I already knew about the limit from this newsgroup so at least I had prior knowledge. I noticed that some of the newer Garmin data sheets list the limit as "approximately 95 knots or 103 MPH" which a great improvement although they still don't have the exact number in knots correct. You would think they would know their own software imposed limits! Surprisingly, the limit is not listed on the GPSMAP 195 spec sheet but I am told it still exists. This 90 knot speed limit was apparently done to prevent these models from competing with the aviation models that are priced at several hundred dollars more. This is a common marketing technique called "market positioning" or "price positioning". An alternative way to look at it is that aviation unit purchases help to subsidize the costs of the GPS 45/40/38 models! Garmin's defense is that this was done to reduce their liability by preventing their use in aircraft. The other GPS manufacturers don't seem so concerned. The Magellan GPS 2000 is available for $200 and it doesn't have the limit! | Unfortunately, instead of the warning message "90 knot marketing speed limit exceeded", it states "Poor GPS Coverage" which is simply not true. | There are some aviation models called the Garmin GPS 90 and 89 that look like the GPS 45 except that they have different firmware, a black case, and a couple of buttons are relabeled so Garmin certainly has the capability of making them work above 90 knots. Internally they could have better shielding and the 90 at least has more battery backed up memory. Of course they do not have the 90 knot speed limit and they have some other software features for aviation use such as a database of public airports and navigation aids. See the Garmin GPS 90 and 89 section elsewhere in this FAQ. Because of the speed limit, some people have bought other manufacturers' GPS units instead. Hopefully this speed limit will be removed in a future firmware version. Thanks to John M. Lewis (70544.73@compuserve.com) for his well documented test with a laptop computer in a plane. His report is included below. The reports of 100 knot or 100 MPH limits were in error. Here is a report of the details by John Lewis: I took a GPS 45 into an aircraft, it worked OK up to and below 90.0 KTS. Above 90.0 nautical miles per hour it beeped with "Poor GPS Coverage" and did not display the track, speed, position, or altitude. The time and the "compass card" did display. The track map did not indicate the >90Kts points, nor did the track data download. Upon decreasing speed to 90.0 Kts, even if only for a second, the full display reappeared, with accurate position information. During the speed blackout, the sat status page indicated 8 satellites with nearly full signal strength bars. The GPS 45 was attached to an HP100LX palmtop for data recording. The following is an excerpt edited to pertinent RMC sentences: Garmin GPS 45 V2.32 NMEA V2 RMC sentences ID, UTC-GPS, LAT , LON , KNOTS,Track, Date $GPRMC,231109,A,3030.183,N,08819.149,W,087.2,284.8,140595,,*0E $GPRMC,231111,A,3030.203,N,08819.206,W,086.2,293.9,140595,,*02 $GPRMC,231113,A,3030.229,N,08819.257,W,089.3,300.4,140595,,*04 $GPRMC,231115,V,,,,,,,140595,,*38 $GPRMC,231117,V,,,,,,,140595,,*3A . . $GPRMC,231539,V,,,,,,,140595,,*32 $GPRMC,231541,V,,,,,,,140595,,*3D $GPRMC,231543,A,3032.451,N,08824.848,W,090.0,097.0,140595,,*06 $GPRMC,231545,V,,,,,,,140595,,*39 $GPRMC,231547,V,,,,,,,140595,,*3B . . $GPRMC,231643,V,,,,,,,140595,,*3C $GPRMC,231645,V,,,,,,,140595,,*3A $GPRMC,231648,A,3032.932,N,08824.232,W,086.7,277.8,140595,,*05 $GPRMC,231650,A,3032.915,N,08824.287,W,081.2,256.0,140595,,*0E Reconfiguring the 45 for display in Statute MPH, the display changed to dashes at speeds in excess of 104 MPH. When configured for Metric, the device becomes useless above 167 K/H. The ability to instantly relock and display correct data upon reducing speed to 90.0 Kts, as well as the ability to display correct heading via the compass card indicates a software induced blanking, not a hardware limitation. There may exist a hardware limitation at speeds in excess of 110 Kts, this test flight did not exceed 110 Kts IAS. John M Lewis <70544.73@compuserve.com> -GPS 45/40 firmware versions: These versions do not apply to any other Garmin products except the 40 & 45. The firmware is believed to be identical between the 2 products except that different model numbers are displayed on power up ("45" vs. "40"). Here are some versions and their differences that have been mentioned in the newsgroup. Most other differences are not known outside of Garmin. V2.02 4/94 Early release of GPS 45 ... V2.20 1994 ... V2.24 1994 ... V2.31 V2.32 Shipped for many months V2.40 5/95 New feature: Fuel Gauge gone when connected to external power V2.41 6/95 Some units have simulator random power down problem (minor)++ V2.42 7/95 Simulator random power down problem partially fixed V2.43 9/95 Simulator random power down problem fully fixed [V2.43 is still the current version 6/1996] The above dates are approximate within about 1 month. ++Simulator mode is a mode which simulates satellite signal acquisition, presumably when you are not outside and want to practice with the unit. You can still program the unit indoors (or wherever you are that you can't lock onto the satellites) using "normal mode" instead, however in normal mode the unit will automatically shut down after 15 minutes of not finding enough satellites (to conserve the batteries). If you want to update your firmware, you can have the unit serviced at Garmin's $149 flat rate fee for repairs. (I think the price may have gone up slightly.) It is not a trivial operation. See the section "Internal electrical hardware" for the details of what is required for the EPROM replacement. I have seen the simulator bug in V2.41 of the software. Some reports indicate that it does not affect all units with V2.41 firmware. If a unit has the bug, when you are in simulator mode after an apparently random amount of time (sometimes immediately), the unit turns itself off. You simply turn it back on or use normal mode and turn it back on every 15 minutes. This is not a serious problem. I have not heard of any serious bugs in past versions so it is very likely not worth upgrading. It is fortunate for us that Garmin is continually upgrading their firmware. Many companies don't. -GPS 38/45XL firmware versions: V3.03 2/96 Not a bad version | V3.04 4/96 (still current in June) -What are the undocumented modes for the GPS 45/40/38/90/89? Globe spin rate and direction: Go to the map display. Then press the OFF button for 1-2 seconds. The globe will still be on the screen and you can change the speed with the up/down buttons and the direction of rotation with the right/left buttons. Press any other button to return to normal mode. Test screen: Hold down ENTER while pressing on the POWER button. Invokes button test screen and displays labeled: SNR Signal to Noise Ratio? DRIFT of FREQ below FREQ apparently this is a 16 MHz internal clock TEMP degrees Celsius BATTERY voltage in hundredths of Volts EXTERNAL external power connector voltage in hundredths of Volts TIME Universal Coordinated Time without local offset Press LEFT or RIGHT arrows to adjust contrast. Press ENTER 2 times to get an all black screen, press ENTER again for cool exploding rectangles on the display. Press ENTER again to exit this mode. Hold down OFF button to exit test screen. Also turns beep on if you had it off! Full reset and memory clear: Hold down MARK while pressing on the POWER button (CLEARS MEMORY!!!). DO NOT TRY THIS UNLESS YOU ARE WILLING TO LOSE ALL SAVED INFO!!!!!!!!!! Waypoints, Track, Routes and more will all be gone. I would not do this unless my GPS unit was having serious problems (and then only as a last resort attempt to fix it before sending it in for repair)! It returns all settings to initial factory defaults. Diagnostics mode: To get into this mode, quickly after turning on the power (while the globe is still spinning), press all 4 arrows one at a time (in any order). 2 or 3 digit numbers are added to many screens. Reportedly they are the process stack depth. | The signal strength bars are initially hollow. They become solid apparently when some specific data has been downloaded from the satellite. The number in the bottom right of the satellite screen (usually something like 1.3 or 4.2), looks like an indication of the geometric degradation of [precision] (GDOP). It varies with the number and location of satellites being received, being lowest when a group of satellites scattered widely over the sky are present, and highest for a cluster of satellites, or when the received satellites are all in a straight line. It also seems to vary in step with the "accuracy" number normally displayed in the top right. Contributed by proach@cais2.cais.com (Peter Roach) The internal temperature in degrees Fahrenheit is added to the position screen to the right of the time. A "DIAG" option is added at the bottom of the menu screen. The following is displayed on the DIAG screen: Battery voltage in hundredths of volts. Elapsed time (can be zeroed by pressing ENTER). Screen can be paused by pressing MARK. Looks like there is a lot of internal software debugging info. GPS 40 mode [may only work with older firmware versions]: I just found an interesting feature of my GPS45 (v2.32). Pressing the center of the thumbwheel switch (engaging all four) upon powerup results in the welcome screen changing to "Welcome to the Garmin GPS 40", with the same software version mentioned as in the 45 announcement. [Editor was not able to duplicate w/ V2.41 firmware] Michael J. Klein (mjk@shore.net) -What are some undocumented modes for the GPS 75? | + switch on and press ENTER: display & receiver osc.-selftest + switch on and press the '0'-button: go to Auto- Locate-Mode + switch on and press CLR: completely destroy the RAM contents (clock, almanac, route, settings) Sebastian Birnbach (birnbacs@informatik.tu-muenchen.de) -Why is internal temperature available? In some electronic circuits, it is useful to measure the internal temperature so that it can be used to compensate for changes in components over temperature. As the unit warms up, this internal temperature will generally be warmer than the ambient (surrounding) temperature. The internal temperature measurement is not intended for use as a thermometer to measure the air temperature (although it would probably work well immediately after the unit is turned on before it warms up). I would speculate that the temperature is used to monitor the drift of the 16 MHz clock since apparently the frequency drift info is displayed on one of the diagnostic screens above. There are two different modes on the GPS 45/40/38 that allow you to read the internal temperature. One is in Fahrenheit, the other is in Celsius. See the previous "Diagnostics mode" and "Test screen" sections above for details. -VMG error? Garmin has apparently implemented the VMG (Velocity Made Good) differently than most other GPS manufacturers on the GPS 45 and GPS 75. It appears that it was fixed in the (newer versions at least) GPS 38 but I have seen conflicting reports which are probably due to variations in firmware versions. The 45 [and 75] VMG calculation shows you your speed along a course from your starting point to your destination. This gives you misleading (IMHO) readings. (It still gives you a positive VMG after you pass your destination and are getting further away from it.) The 38 displays a correct (IMHO) VMG from your current position to your destination and ignores your starting point. Randall P Devol (randyd@shell.portal.com) The 75 [and 45] only knows where you told it you wanted to go when. it assumes you want to go to the 'active' waypoint from the point where you were when you pressed the 'GOTO' button'. if you wish to change this starting position just press 'GOTO' again and select the desired waypoint to 'GOTO'. Now VMG will be the new speed made good to the waypoint from the current position. vic fraenckel -What are the GPS 45/40 data NMEA 0183 V2.0 sentences | Also see the NMEA FAQ on Peter Bennett's site listed elsewhere in the FAQ. FYI here is the NMEA 0183 v 2.0 actual live output of the GPS45: $GPRMC,064504,A,3410.983,N,11814.012,W,000.0,189.2,271294,013.9,E*6F $GPRMB,A,,,,,,,,,,,,V*71 $GPGGA,064504,3410.982,N,11814.012,W,1,05,2.6,315.6,M,31.5,M,,*5F $GPGSA,A,3,,04,,07,09,12,24,,,,,,4.6,2.6,3.8*30 $GPGSV,2,1,07,02,11,117,00,04,61,067,42,05,40,316,00,07,29,054,39*7E $GPGSV,2,2,07,09,56,262,45,12,82,217,43,24,59,181,44,,,,*4B $PGRME,59.3,M,72.0,M,93.3,M*1D $GPGLL,3410.982,N,11814.012,W,064505,A*31 $PGRMZ,1034,f,3*2D $PGRMM,WGS 84*06 $GPRTE,1,1,c*1B Here are what I consider useful sentences for all the data I want to log: $GPRMC,064504,A,3410.983,N,11814.012,W,000.0,189.2,271294,013.9,E*6F utc ok lat------- lon-------- knots | date-- mag var the OK is "A" not OK is "V" |____track made good $GPGGA,064504,3410.982,N,11814.012,W,1,05,2.6,315.6,M,31.5,M,,*5F utc lat------- lon--------ok#sat altitude geoidal HDOP separation the last two elements are age in seconds from last DGPS update and DGPS station ID the OK is 0 for no, 1 for GPS, and 2 for DGPS $GPGSA,A,3,,04,,07,09,12,24,,,,,,4.6,2.6,3.8*30 | || | |__VDOP Vertical Dilution of Precision | || | |______HDOP Horiz | || ||__________PDOP Position | ||_sats in view 12 max_| | |_________________________________1 no fix, 2 2D, 3 3D |___________________________________Automatic or Manual $PGRME,59.3,M,72.0,M,93.3,M*1D HPE--- VPE--- EPE--- Horiz, Vert, and Estimated Position error in meters $PGRMM,WGS 84*06 datum These repeat data but each offers some unique data as well. I intend to log from GPRMC: (NMEA) date/time lat/lon track/knots variation from GPGGA (NMEA) OK, #Sat, altitude, geoidal separation from GPGSA (NMEA) 2D/3D, PDOP, HDOP, and VDOP from PGRME (proprietary Garmin) HPE, VPE, EPE from PGRMM (proprietary Garmin) datum The others are: satellite views: $GPGSV,2,1,07,02,11,117,00,04,61,067,42,05,40,316,00,07,29,054,39*7E $GPGSV,2,2,07,09,56,262,45,12,82,217,43,24,59,181,44,,,,*4B | |_msg # | | | |_SNR 00-99dB null=not tracking |___tot # of msg's (1-3) | | |_____Satellite azimuth (true 000-360) | |________Satellite elevation (90 degrees max) |___________Satellite number $GPGLL,3410.982,N,11814.012,W,064505,A*31 lat------- lon-------- utc--- ok $PGRMZ,1034,f,3*2D (Garmin proprietary) alt ft|____2=user altitude, 3=GPS altitude $GPRTE,1,1,c*1B |__on ALL this is a checksum |___route ID and then followed by WAYPOINT IDs. |_____message number |_______total number of messages Richard L. Hess | 4.00 BATTERY/POWER: -------------- -How is power selected between the internal batteries and the external supply? This differs between the 40/38 and the 45. The 45 switches completely to the supply with the highest voltage. The 40/38 does a slower crossover from one supply to the other as the voltage of one exceeds the voltage of the other, and will draw part of its operating current from a current-limited external supply such as a solar panel, even if the current-limited supply cannot supply the total power needs of the GPS 40/38. The remaining current which the solar panel cannot supply is supplied by the internal batteries. Larry James (lwjames@csn.net) If neither is high enough, the unit will shut off to allow the memory to be maintained. -What voltages do the fuel gauge correspond to? I hooked up a GPS45 to a variable supply in the shop and found the following in testing the battery monitor display. DC supplied thru battery compartment [V2.32] Full reading ~5.65v 3/4 ~5.3v 1/2 ~5.00v 1/4 ~4.6v Empty ~4.25v low battery alarm, unit turns off Readings did not exactly repeat and there appeared to be some hysteresis, hence the tilde. Unit transitioned smoothly between external dc and internal batteries when external power was cycled (unit did not lose sat lock). davew@cruzio.com (David Wells) There are variations between units so the above info may not apply directly to your unit! For example, my unit shuts off between 3.7 and 4.0 V when powered by internal batteries. However, when externally powered, it only goes down to 6.25 V. Keep this in mind if you are using an external battery pack! | You can easily calibrate your own unit by going into diag mode or the test screen as explained under the FIRMWARE section and just compare the battery voltage with the fuel gauge at various battery levels. It is easy to see what your actual battery life is in hours and minutes by using the elapsed timer in the "Diag mode" and simply zeroing it when you change batteries. -Current consumption of a GPS 45 at different external supply input voltages? This is from a GPS 45 unit with V2.41 firmware and internal batteries removed: (There are manufacturing variations between units and this does NOT apply to a GPS 40/38) Normal Mode (as opposed to Battery Saver mode) Simulator Mode uses half as much current POWER POWER V in OFF ON ---- --- -- 6.25 V 1.0 mA unit turned itself off! 7 V 1.1 mA 144-166 mA 8 V 1.3 mA 120-138 mA 10 V 1.8 mA 80-100 mA GPS 45 only, GPS 40/38 might be damaged! 12 V 2.3 mA 68-84 mA GPS 45 only, GPS 40/38 might be damaged! 14 V 2.8 mA 62-78 mA GPS 45 only, GPS 40/38 might be damaged! 16 V 3.3 mA 62-76 mA GPS 45 only, GPS 40/38 might be damaged! 24 V 5.2 mA 64-80 mA GPS 45 only, GPS 40/38 might be damaged! 32 V 7.1 mA 64-80 mA GPS 45 only, GPS 40/38 might be damaged! >From this data, I conclude that you do not want your GPS 45 external supply to drop down below about 7 Volts. Also, there is no advantage to a supply with more than about 14 Volts as the extra voltage will just be converted to heat. Also (on the GPS 45 at least), there is a big difference between the battery input and the external power input circuitry. -How does BatterySave mode work? According to Garmin's Tech Support Department- These are a couple of the things the saver does: 1. Stops the unit from trying to re-lock if it loses the birds. 2. Cycles the receiver off and on periodically if you are motionless. (update time) Ralph Fowler (rwf@mindspring.com) Garmin technical support also claims that there is no disadvantage to Battery Saver mode but many people have observed that the ability to hold lock on satellites is poorer under weak signal conditions in Battery Saver mode. | Most people feel that the BatterySave mode offers only a modest battery life improvement in general use. If you have a strong signal, it probably does not hurt to leave it in Battery Saver mode. If you change modes, then the unit loses all satellites and must reacquire them (although it happens quickly). Also, as is mentioned in the manual, when you have trouble getting the receiver to lock on the satellites, if you turn the unit off and then on again it often performs much better. [Lane A. Holdcroft] The RF circuitry draws considerable power. In normal mode it is on continuously. In battery saver mode, after a lock is established and the necessary data downloaded from the required number of satellites, the RF circuitry is turned off for short periods, then back on. If the user's velocity vector is constant during the off period, then when it comes back on, the satellite signals will be right where the receiver expects them to be (in time). When the receiver verifies that, it can go back to sleep again for another short period, saving the batteries. If the signals are not where expected, if the velocity change is small, the receiver can quickly find them by searching either side of the expected time delay. Obviously no change in velocity can be detected while the RF circuitry is off. The conclusion is: If you are going at a nearly steady velocity under a clear sky, use battery saver mode. If you are under trees with marginal signals, or want the fastest possible response to velocity and direction change, use normal mode. Larry James (lwjames@csn.net) Here is yet another informed person's explanation: The battery saver mode cycles the receiver portion of the GPS on for one second and off for two (then repeats) to conserve power. The CPU portion of the GPS is on continuously and interpolates speed/position during the off cycle. If the GPS has a hard time keeping up with speed/heading changes (i.e. a "high dynamics" situation) then Battery Save will automatically be overridden in favor of Normal mode operation. It will revert back to Battery Save operation (again automatically) once speed/heading readings stabilize. | -Rechargeable Batteries? Renewals: Rayovac Renewal (tm) rechargeable alkaline batteries work very well in the GPS 45/40/38 units. They are only rated for about 25 recharges (compared with approximately 300-1000 recharges for NiCd batteries) but have a longer life per charge and a slower self discharge rate. Actually, the capacity decreases about 2% per full discharge/ recharge cycle. They also have about 20% less capacity than normal alkaline batteries. Also the fuel gauge reads more accurately than with NiCd's. The chargers are about $16 US and the 4 AA batteries cost about $7 US. Unlike NiCd batteries, Renewal batteries will last much longer if you charge them often. They are available at large discount stores such as Walmart, K-mart, & Target in the US. NiCd: Nickel Cadmium batteries are much cheaper long term than standard alkaline batteries or even Renewals if you use your unit a real lot. Unfortunately the battery life is about 5 hours per charge instead of 8 hours for Renewals or 10-12 hours for standard alkaline batteries (assuming that you are not in BatterySave mode). Unfortunately, the fuel gauge gives a less accurate state of charge for NiCd batteries because they have a more constant voltage over their discharge cycle instead of the gradually decreasing voltage of alkaline. You probably should carry a spare set of NiCd batteries with you because the fuel guage can drop off very quickly. I believe that Renewal rechargeable alkaline batteries are a better choice unless you use your GPS unit very, very often (like myself) and don't want the expense of replacing your renewal batteries about every 25 charges. I have used both types of batteries very successfully. Several people have reported that some batteries (particular some NiCd batteries) are slightly larger than normal alkalines and may fit tightly. They could be very difficult to get out if you force them in! It would be preferable to avoid larger diameter batteries. | Lithium Batteries (not rechargeable): | AA Lithium batteries are available and last MUCH longer than any other batteries of the same size. They are more expensive and are not usually rechargeable. | -Other battery/external power options? Of course an optional cord could be used if you have some other DC power available at the appropriate voltage such as in a car or boat. Do not forget the 1/4 A fuse! Some people have also hooked an optional power cord to an external battery pack that could supply power for days of use. Select your battery pack voltage carefully! Usually, you do not want most types of batteries to be discharged below 0.9 V /cell. See a previous section for info on current consumption at different voltages (for the GPS 45 only). Again, do not forget the 1/4 A fuse. For a GPS 40/38 (which has an input voltage of 5-8 V), 5 D-cell alkaline batteries would work out well (5 x 1.5V = 7.5V). For a GPS 40 with NiCd's, 5 or 6 cells should work. (6 cells would be too high a voltage with other types of batteries). -How long is memory conserved without batteries? I am told that older versions of the 40/45 used a capacitive circuit to maintain memory while the batteries were changed. As a rule of thumb, the batteries should not be left out for more than one hour. While in the field, if the batteries go kaput leave them in the unit. There's still more than enough juice to maintain the memory until fresh batteries can be installed. >From the Owner's Manual and Reference, GPS45 Personal Navigator, Software Version 2.20 or above, 1994, Garmin International, part number 190-00070-00 Rev. B, page 47, "Never store your GPS45 without batteries. A built in capacitor will save almanac and waypoint data while you are changing batteries, but will only save data for a period of time (a few hours). If you are storing the unit for the season, put in a fresh set of alkaline batteries to help prevent the loss of stored data." DUDLEY2@QUCDN.QueensU.CA Newer versions (since about mid/late 1995), have an internal rechargeable lithium battery than maintains the memory when batteries are temporarily removed. These batteries should last the life of the unit. I believe the GPS 90 has always had the lithium battery. -Does the serial I/O consume much more power when it is enabled? I have measured [the current consumption] with the 45, 50, and 75 and could see no change measuring down to +/- 1mA. So if it does it is negligible. Tom Miller (tmiller@umabnet.ab.umd.edu) I tested the GPS 40 and it too does the same. davew@cruzio.com 5.00 SERIAL/POWER INTERFACE: ----------------------- -External serial/power connector alternatives? Garmin uses a non-standard 4 pin (for GPS 45) round connector (a center pin is added for the GPS 40/38). I personally recommend buying the cable with the correct connector from Garmin. Garmin sells a data/power cable for the GPS 45 with the unusual connector and 4 wires for about $30 list. However, some dealers sell it for much less. One person reported that a Amphenol connector type T3109-001 will work if you modify it slightly. I can't find it in the Amphenol catalog. Perhaps it is only a partial part number. Reportedly it costs around $15! I personally feel that building your own cable is risky because of the possibility of mis-indexing the connector which could damage the unit. Also, there is a risk of intermittent operation due to the mismatch between the pin and socket size if you do not replace the sockets. I have experienced this. Some people have substituted a 5 or 8 socket DIN connector for the GPS 40/38 or a 4 or 7 socket DIN connector for the GPS 45. There are several socket arrangements for the DIN connectors (even with the same number of sockets!). You should plug any unused holes (epoxy works) and if you are using the DIN sockets (not as reliable), you should bend the contacts in to improve the reliability of the contact with the smaller pins of the GPS 45/40. You also should wrap the connector with tape and/or heat shrink tubing to bring it out to the correct diameter. If you do not do a good job on this last step, you risk damaging your unit due to mis-indexing the connector. Here is a much better design for a home built cable using Radio Shack parts that addresses the contact problems above: The connector for the Garmin GPS 45/40 has been the subject of a number of inquiries since I last posted my description of how to make one. It is easy and inexpensive. Here are instructions: 1. Remove sockets from RS-274-001 4-pin mike connector and drill out holes (1/8"). Drill 5/64" hole for center post (GPS 40). Wrap with (2 turns) tape (for snugger fit), and cut out tape at key. [heat shrink works well too] 2. Solder (or crimp) D-Sub socket-pins [RS-276-1538] on cable wires. Put plastic (heat-shrink works) tubing on socket-pins and insert them in connector holes. Fix them in place temporarily with pieces of plastic tubing pushed in from ends so as to press socket-pins outward (bolt- circle of GPS pins is larger than that of connector holes). 3. Insert connector into GPS body and push socket-pins down onto GPS pins. Apply epoxy resin (ca. 3 drops) to inner ends of socket- pins (too much could run too far down and ooze out end - the tubing that was pushed into the holes helps prevent this). 4. After epoxy is set, tighten cable clamp to cable, wire cable to computer/power interfaces, and enjoy. Rane L. Curl N8REG ranecurl@engin.umich.edu Larry Berg of Purple Computing (purple@cdsnet.net) has molded a bunch of Garmin 45/40/38 connectors at a very good price. It is nice of him to help out. See his site in the www/ftp sites section. There are at least several optional power cables available from Garmin. They are serial data only, power only, and both. You must supply the appropriate connectors for the computer end of the cable that has both power and data. There is even a Garmin to Garmin transfer cable so that you can upload the stored data from one unit to another. See the accessories list elsewhere in this FAQ. Several people have reported that if you buy the data cable, you can cut the insulation near the computer connector end and the red power wire is there although it is not connected to the computer connector of course. | See the next section for the pin out. -How do I interface the GPS 45/40/38 to an IBM-PC compatible computer? Garmin DB-25 DE-9 Function color* socket socket -------- ------ ----- ---- data in white 2 3 data out brown 3 2 ground black 7 5 power in red N/A N/A (for ext. power only, do not forget to add a 1/4 Amp fuse!) *Garmin 45 manual, Appendix F I strongly recommend using Garmin's wire colors (as also stated in the manual) to minimize confusion. Or for those that like diagrams: 25-pin -or- 9-pin female female brown>--------------->o3---------------o2 white<---------------