Garmin eTrex FAQ

A. First, some background: The eMap and eTrex have a problem that other Garmin units do not. With other Garmin units, a backup battery powers both the local time-of-day clock and the waypoint memory. This battery is good for a couple of months, but for longer term storage you must keep batteries in the GPS. Thus, normally the real-time clock is valid. If the unit has been stored for several months without batteries, *all* user memory is lost, and the unit is forced to do an "autolocate" to figure out where it is - and it knows that because of the loss of memory.

The eMap and eTrex use non-volatile memory for waypoints, so you can store them forever without batteries, and without losing waypoints or other info. So, people are more likely to do that. However, there is still a time-of-day clock that needs power. There is apparently a backup capacitor or battery that will power it for a short time (weeks?), but after that it stops.

So, if an eMap/eTrex have been stored for several weeks without batteries, their local time clock may be terribly wrong - but the unit doesn't know this, so it looks for the wrong satellites.

On the eMap, you can pop up a menu while the unit is acquiring, and select "saved without battery". That tells the eMap that the clock contains garbage, and it needs to initiate a satellite search without using it. Once one satellite is found, the unit knows the approximate time again and can continue normally.

I don't think there is any user-selectable way around this problem with the eTrex - you just have to wait several minutes for it to figure out that normal acquisition has failed, and automatically switch to "autolocate" mode. - Dave Martindale

Does the battery meter on the yellow Garmin etrex read "full" when using freshly charged NiMH rechargeable batteries?
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A. I have found my NiMH batteries usually only indicate about 90% when freshly charged.

A set of GP 1600mAh AA batteries, straight off my charger are currently reporting 2.6V in the eTrex diagnostic mode and showing about 90% charge on the battery indicator.

Having tried batteries with differing states of charge the eTrex seems to need approximately 2.7 volts (as reported by my eTrex in diagnostic mode) to get a battery full indication.

I guess some brands of NiMH may hold a higher average voltage, and will therefore show closer
to full. - Ben Johnson

A. Yes - Garmin

Does anyone know what the battery saver mode does?

Q. Does anyone know what the battery saver mode does? (In the eTrex Yellow.) Does it affect the details of tracking or route following? (I presume there's some sort of compromise. Otherwise they would just turn it on permanently.) - Gerry

A. The main thing that battery saver does is turn off the receiver for periods up to 5 seconds or so when it appears that you're not moving, or travelling in a straight line at constant speed. If you start changing direction or speed, the firmware automatically reduces or eliminates the receiver-off periods. Since the track log algorithm automatically saves only infrequent points when you're going in a straight line at constant speed, even in "normal" mode, I don't know whether "battery save" would make any difference to the track. Where it *does* make a difference is in tracking satellites in weak-signal conditions like a forest. In battery saver mode, the receiver section has to re-lock to the satellite signals every time it's turned on. It has a pretty good idea of where to look for those signals, and normally the reacquisition happens very fast - when the signals are strong. But in "normal" mode, the receiver runs continuously, and it once locked to a signal it can "hang onto" it even when it gets weak - too weak to acquire in the first place. Under these conditions, battery saver mode can cause you to lose satellites that would be tracked in normal mode. In addition, the GPS doesn't even bother looking for satellites that are close to the horizon in battery save mode. - Dave Martindale

Does anyone know how much battery current the basic yellow eTrex uses?
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Q. Does anyone know how much battery current the basic yellow eTrex uses.

A. 110-130 mA. Add 80 mA for backlight. - Mark

Does the eTrex track log include a timestamp?
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Q. I've been comparing my etrex with a friends GPS12. He says his GPS12 trackback log includes position (x,y)and timestamp, but no altitude. I know the etrex stores altitude, but does it store a timestamp? - Ido

A. First, neither the GPS 12 nor the eTrex have a "trackback log". Both units also have a "trackback" function, but it operates differently in the two units. They both do have a "track log" which records where you've been while the GPS is turned on and navigating. There is a timestamp in the track log of both units so you can calculate speed. The eTrex also has the ability to store "saved tracks". When you've collected a track log for a while, you can ask the eTrex to save it as a named path. When this is done, the track log is compressed by removing points until it's below a certain size and then it is stored. The timestamps are *not* stored in saved tracks. The eTrex "trackback" function uses a saved track as its path. - Dave

A. Only on the current tracklog, not on the saved tracklogs. - Povl H. Pedersen

eTrex won't switch on
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Q. I tried to turn my eTrex on tonight, and nothing. Tried fresh batteries, another set of fresh batteries, and still nothing. I had left it turned on accidentally all last night and when I woke up this morning and went to get it, it was almost flat, but working fine. I took the batteries out for the day to charge them and when I put them back in tonight... dead. Tried the reset function, cleaned the terminals, nothing. No likely water ingestion. Normal temperature conditions. No other significant factors. - Ben Johnson

A. Try a different set of new batteries. - Sean McConnell

A. There is a possibility that the EPROM that store the unit's programming have lost their information due to the total loss of battery voltage. If you have the capability, you could try to reprogram the eTrex. Good luck! - Frank

A. Contact Garmin customer service. I had the same problem. One morning I couldn't turn it on. Don't know whether it was a dead switch or software. Garmin had it back in a bit over a week, but that won't help you this weekend. FWIW I try not to leave any unit with a back up battery without a main batteries. I keep a set of alkalines around for 'standby' service. Even batteries so run down they can't operate the unit, will off load the backup while you are charging the other set. - Roger Russell

A. Not more than an hour after reading your post, my new Venture crapped out--only 4 days old! Screen locked then I removed and replace the batteries. When nothing happened on the screen after the ON button was depressed, I was depressed.... and I just put the handle bar mount on my bike and was headed out for my first ride!.... oh well, so I won't know my location. I'll just have to fall back on that old adage, "Wherever I go, there I am". I feel your pain, man! I may try leaving the batteries out until Sunday morning and then put 'em back in and hope for a miracle. You never know. If that doesn't work, I hope they're as quick on the turn around as Roger Russell says. - John Clulow

eTrex locks up during operation
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Q. My eTrex sometimes locks up and none of the buttons seem to work?

A. Had my Vista lock up on me a few times. Once was in Paris where pressing back-arrow while searching for attraction would lock it up. It wouldn't show any typed letter, which is why I then backspaced. Removing power helped. Another thing to try is to try and short the +/- inside the battery compartment nearer the top of the unit. That will discharge any leftover power inside the unit. - Povl H. Pedersen

A. I have had to remove the batteries, and then put them back in. Seemed to start up without any problems. - Ben Johnson

Having trouble going to a waypoint
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Q. I just bought the yellow Garmin eTrex. It is supposed to work under heavy foliage and tree canopy. When I get out into the pines it points me everywhere but where my waypoint actually is. I still have a lock on the satellites also. I want to use this to walk to my deerstand in the dark but I think this thing will have me going in all directions. I know this is the bottom end Garmin GPS, but it is supposed to work under these conditions. What experience do others have with this same model? Is there another model you recommend for my needs? - Steve

A. Under similar circumstances, prefer to I use a separate magnetic compass in combination with eTrex BEARING information. The standard eTrex heading info is basically useless when walking in thick scrub or forest, but bearing info is very accurate at any point you are getting decent reception. - Ben Johnson

A. Likely you are thinking that GPS receivers have compasses inside which they generally do not. The standard eTrex does not in any case. If you have a reliable lock and are moving at maybe 5 or 6 mph or more, the "heading" display will give you a fairly reliable pointing angle. This is what many people mistake for a "compass". As you slow to a stop, it no longer has the information to plot your path reliably. Always use the BEARING (to the next waypoint) readout as it is reliable whenever you have a good lock. But when hiking, always use a compass to read your HEADING. - Joe Mehaffey

What sort of processor does the eTrex use?
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All eTrex models are using an ARM processor, which is a 32-bit CPU. This processor does about 1 MIPS pr. MHz. Even the older ARM7 core does 1 MIPS/MHz. In comparison the 386DX does 0.3 MIPS/MHz, and the 386SX is 0.25 MIPS/MHz. - Povl H. Pedersen

Incorrect odometer reading when walking - March 6, 2001
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Q. Recently I went on a hike with my Etrex Summit. It was a mountainous terrain. The GPS Odometer recorded a total distance of 19.9 km. But after coming home I downloaded the data to Gartrip (latest demo version) and on the plot it shows that I had walked 23.6km. I notice that along the path there were small sections where the GPS had lost signals and hence no track points recorded. This would have been due to the mountainous terrain or due to having the GPS inside the jacket when it started to rain. I was wondering whether the distance recorded on the GPS odometer is only the distance along which the GPS recorded data. Therefore excludes any length of track where GPS signals are temporarily lost. But apparently Gartrip calculates the total distance irrespective of any duration where GPS signals are lost. I would very much appreciate if any one could comment on this problem, or has any one experienced this problem before. - Pujitha

A. Breaks in track do not appear to be bridged when computing odometer distance. GPS odometer readings are excellent at normal vehicle speeds but poor when walking. The sky view in a vehicle is seldom blocked long enough to lose lock where as this it is a common occurrence when walking. Other walking speed odometer problems include the low speed cutout that assumes any speed below some threshold to be noise. This was quite necessary while selective availability was in effect, else a stationary receiver would accumulate several miles over night. Without SA the threshold can be reduced, but you wouldn't like the results if there was no threshold at all. - Roger Russell

Backlight won't auto power off when using external power
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Q. Just noticed the backlight on my Etrex will not switch off automatically when plugged into external power.

A. The timed switch-off of the backlight does not occur on my eTrex either when using external power. However, when the eTrex is in auto backlight mode using battery power, the screen will automatically light up when the arrival or turn ahead alarm is activated. This does not work on external power since the light is always on. Since the eTrex lacks an audible alarm, I was hoping to use the backlight coming on as a visual alert when driving at night, when the arrival or turn alarms were activated. I typically will not keep it lit constantly when driving to avoid the distraction. But if you have it on external power, the backlight cannot be used as a visual alarm.

A. Some correspondence someone had with Garmin about this.

"It has come to my attention that when the etrex is connect to external power via the connector the backlight timer will not function. When I drive at night I like the fact that the back light comes on when I approach a waypoint. As I understand it if I connect it to external power this will not work. Will you be changing this in a future firmware update? If not I plan to build a car adapter that can be attached directly to the battery terminals. Will this solve the problem?

Thank you Pete H."

"Dear Mr. H,

Thank you for your message to GARMIN. You have brought something to my attention that I was not aware of. I put the eTrex to the acid test and you are indeed correct. I will mention this to the software engineers and it may be included in the next update. The functionality as you described is evident and we are responsive to good suggestions. I cannot promise that it will happen, and there may be reasons that it is selected against, but it is more than worthy of mention. As far as building your own cables to the battery terminals, I caution that a surge would more than likely cook the board. Be cautious.

Thank you again for your message.

Best Regards,
Thad McCanse
GARMIN INTERNATIONAL"

Improving the eTrex reception? Thomas Piff (Submitted March 6, 2001)
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While flying commercially, I had to jam my etrex against the window to get any inkling of aircraft speed. Move away and forget it ! I couldn't receive when I moved away from airplane window. Then I cradled top end (internal antenna) in a piece of aluminum foil from my lunch and it started picking up satellites ! Not very scientific but it worked. I don't think that this causes multiple path errors since any bounces and reflections are so close to the internal antenna. Try it in a house when you move away from window just enough to lose reception. - Thomas Piff

Tracks and track logs
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Q. What is the maximum # of trackpoints in the active track log before the unit starts to reuse points? Does it start reusing from the beginning of the tracklog or does it reuse "less important" points, thus still showing the entire route (but with less resolution)?

A. It is only 1536 points with software version 2.10, and saved tracks are only 125-128 points. - Povl H. Pedersen

Q. Is the frequency purely time based or is it based somewhat on current travel (for example, fewer trackpoints are necessary for a straight path than for curvy path and/or based on travel speed)? - Jerry Riechert

A. It is based on travel. When you are going straight it will drop fewer then when you are making a lot of turns. - Garmin

A. The eMap and eTrex use a proprietary algorithm in the management of the tracklog. The principle of operation broken down to the simplest level is this: The units are both capable of detecting speed and direction of travel to manage and allocate trackpoints. If you are at a constant speed, with a constant direction of travel, the unit will conserve more points. If you are varying your speed greatly, or making numerous turns, the unit will use more trackpoints to help enhance the accuracy of the tracklog for purposes of trackback. In both units, the average speed will largely determine the number of points dropped. The eMap is currently slightly more advanced in this respect than the eTrex, although it is very likely that the eTrex will catch up in later software updates. If you are moving slow, (on foot) the eTrex will drop more points, more quickly than the eMap. The eMap will trend to be more conservative so that in an automotive application, (say driving in town at slower speeds), the unit does not exhaust the trackpoints as fast as the distance covered on average per trip will be longer. The eMap will still use trackpoints accordingly to provide safe and reliable trackback navigation on foot. The eTrex in the current software version will give fantastic detail in tracklog recording, but at the price of consuming a tracklog more quickly in an automotive environment vs. on foot. No specific details on calculations are available as this technology is proprietary and key to maintaining a competitive products. The frequency of trackpoints being used fully automatic, and without disclosing the actual manner of calculation, there is no way to give a prediction of the actual number of trackpoints to be used in a specific operational state. - Garmin

Q. If I set up the track back function on my etrex, is it possible to jump into the track at any point other than the beginning or end? Can the etrex "pick up the trail" from any point I intersect the back track? - Larry

A. Yes you can drop back into the track at any time but it takes a while for the etrex to work this out - after a 100m or so you will notice the compass rose swing around and start to head you in the right direction. - L. Cooper

Q. I recently bought an etrex and I've been playing with it to see what it can do. I downloaded a copy of Gartrip and looked at the track data and I see that there are no dates on the first few tracks I saved? Somehow I inadvertently saved the whole track log later on and that data shows up labeled "Active Log" and all of its dates are correct? Is this a bug? Why didn't the earlier data get timestamped?

A. No, it sounds completely normal. The "Active Log" is the main tracklog and is the one that the eTrex automatically adds points to whenever the unit is locked-on and moving. This main tracklog is the only one that has time/date stamps associated with each point. When you save the track on the eTrex, a condensed copy of the active log is written to one of the ten stored log locations - the stored logs do not have any time/date stamps. When you upload to Gartrip, the 'Active Log' and any stored logs are all uploaded. You can use the editing functions of Gartrip to eliminate unwanted tracks if desired.

Waypoint marking and datums
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Q. When I mark a waypoint on my eTrex, is the info saved in absolute coordinates or is it saved relative to the 'datum' configuration? What I'm getting at is this: I mark a bunch of waypoints and go home and bring them up on my mapping software and discover I had the eTrex 'datum' set for WGS 84 and the software is based on NAD 27. I assume that if I import the waypoints as is, there'll be errors. The question I have is this. If I change the GPS datum to NAD 27 and then import the waypoints, will the positions now be accurate, or have the waypoints been corrupted? - Mike Fox

A. Everything (tracks, routes, waypoints) is saved internally in WGS-84 -no matter what you have the GPS set to. No, you can't 'corrupt' your waypoints with a mis-set datum... If your software is Ozi or Fugawi, the software knows what the map datum is and adjusts the incoming WGS-84 data accordingly before displaying it on the map... Real-time tracks, however are different... The NMEA data from Garmins (ONLY!!!) is in the datum set in the GPS... All other manufactures use the NMEA standard of WGS-84... Ozi is the only program I know of that can handle this mishmash of NMEA datums, but there may be others... - Jack

A. If the waypoints were marked while you were at those locations, the datum doesn't matter.

A. I think there is a circumstance where an incorrect receiver setting can result in corrupt waypoints. This is quite different to what the original poster was concerned about, but is worth being careful of. If the format is set to a grid that is invalid in for where you currently are, an updated waypoint can (will?) be wrong. I discovered this with a 12XL on a journey between Ireland and UK. In Ireland I had the format set to Irish grid but forgot to change it to OSGB on the return journey. At a motorway service station in UK, I tired to update the waypoint for it I had entered from a small scale map. The resulting waypoint moved several hundred km. What seems to have happened is that I was outside the area covered by the Irish grid but the 12XL tried to interpret the position as being within in the Irish grid area. - Allen Oliver

Maximum data cable length
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Q. I've just finished my do-it-yourself serial port connection between my eTrex and my PC. Lots of fun checking out SA Watch and Visual GPS. But... I now realize that view of the sky was NOT one of the criteria I used in setting up my desk top computer. So I need to know: How LONG can I make the eTrex-to-serial port cable, given the rather low-speed data transfer taking place? As a supplemental question: what would be a good type of wire? I kind of thought telephone four conductor wire would be good. Its got nice connectors, and I've accumulated a large collection of various lengths over the years. - John Morriss

A. I have made a serial cable for my GPSII+ 10m(33ft) from the same cable so that I can operate my GPS outdoors while connected to my PC. No problems. - Neville

A. I use six feet of 4-conductor flat telephone cable with an RJ-11 and an ePlug. Works fine. Just for grins, I added another 50 feet of cable. My regulated 3.3 volts dropped to 1.8 (1.1 volts on the eTrex diagnostic screen plus 0.7 volt), but the data survived that length. I'm having a hard time understanding the voltage drop, though. I'll look at the current. - Tom Becker

A. I have about 25 feet of 4 conductor phone cord. No power though. I think your guess at the .7 internal voltage drop is wrong, though. I measured my Garmin-labelled adapter, attached to my eTrex. It provides 3.15VDC, and the internal readout indicates 2.71 VDC (not the .6 drop that I would expect from a diode) The batteries were supplying 2.59, indicating 2.46 on the internal display, also not a drop I can decipher ;-)

A. Maximum data cable length: The EIA-232 spec says 50 feet, but the eTrex is a tiny little device with low-power transceivers. If your cable has high capacitance, it might not be able to drive the load. Slower baud rates (try 2400 if both ends support it) will give the line drivers more time to slew
the signals around, and might be able to squeak through a very long cable. Your PC's serial port will also play a part, different ports might be more or less sensitive to signals that don't satisfy the voltage swing requirements. Twisted-pair wire will be more immune to interference than
straight "flat phone cord" style wire. Likewise, shielded cable is better
than unshielded. (Ground the shield at one end only.)

As for powering the unit over a very long cable, thicker wire is better. Many cheap phone cords are tinsel, equivalent to 26ga or worse. Cat-5 is 24ga and should work fine, especially if you use all the extra conductors for power. With 8 conductors in the cable, use 2 for data, 3 for power, and
3 for ground. Pair each data conductor with a ground for best noise rejection. Never pair transmit and receive with each other, the crosstalk would be huge! Also consider mounting the voltage regulator near the GPS itself, rather than at the far end of the cable. This way, any voltage losses in the cable will be on the input side of the regulator, and it'll still provide a clean 3V to the GPS unit. Don't forget to add a decoupling capacitor on the input side of the regulator, since the long cable might oscillate otherwise. And if you're going to have a box of circuitry near the GPS itself, you might as well throw in a few line drivers to clean up the RS232 signal before tossing
it onto a too-long cable.

On second thought, maybe just keeping the cables short would be simpler! - Nate

Which batteries are best?
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Q. I have been using Energizer E2 Titanium, but today I found Energizer E2 Lithium. At $9.50 for 4 AA, they should be pretty good. I have tried Rayovac Maximum and Duracell Ultra also, but no one brand has impressed me with its staying power. If you have brand or type of battery you consider outstanding, please post and let us all know why. - Mark

A. I'd recommend just about any brand of NiMH cell over any single-use cell except under unusual circumstances. In my eMap, the 1600 mA-hr NiMH cells give me about 10-11 hours of use per charge as opposed to about 14 hours for a good alkaline. But since the NiMHs can be recharged hundreds of times the overall cost is far lower. I'm willing to carry a spare pair of AAs with me on longer trips in exchange for eliminating the need to repeatedly buy new batteries. Cost for a set of 4 cells plus a smart charger is about $35 and also eliminates the need to have a separate power cord for the GPS. - Peter Rathmann

A. The 1.5 V lithium cells are great as "backup" power - a set of cells that you carry for emergencies but plan to never use in normal circumstances. They have a very long shelf life (10 years), are much lighter than alkalines, and work better in the cold. They can also produce lots of current on demand, which makes them useful for cameras and electronic flash where they will outperform alkalines. But they actually have less capacity than alkalines, and are horrendously expensive for normal use. As others have said, use NiMH rechargeables if you use your GPS receiver very much at all. You'll get about 2/3 the operating time of alkalines, while being able to recharge them hundreds of times so the operating cost is very low. Around here, I can buy 4 NiMH cells for *less* than 4 single-use lithium AAs. Also, if you have electronic flash or a digital camera or other power- hungry electronic device, the NiMH cells are also capable of large discharge current without losing capacity, just like the expensive lithium cells. NiMH will work far longer than alkalines under these conditions. - Dave

A. Type of battery is quite sensitive to the intended use. NiCd's are almost indescrtructible, but often don't have especially high capacity, and have a very flat discharge characteristics, they go dead with very little warning, and the self discharge at about 1% of capacity per day. NiMh has somewhat higher capacity, and similar characteristics, but the self discharge rate is higher, on the order of 1.5% of capacity per day. Alkalines are good choice for high current applications and reasonable shelf life (a couple years), however at low currents, the advantage over conventional Zinc-Carbon batteries doesn't justify the cost differential. Li-Ion are neat, but require a computer controlled charger, and the device needs to run on a multiple of 3 volts. Lithium's AA have high capacity, but what they really excel in is shelf life. If you don't use something very often, but you want to be sure it works when you need it, the Lithium batteries are the way to go. Shelf life often approaches 10 years. They also have high capacity, but don't tolerate very high current draw very well. - Matt Weber

A. An option to run for longer from Ni-MH cells would be welcome, given these receivers' appetite for batteries. It may well be that the unit will operate accurately below the present cutout threshold designed for 1.5v cells, but the user has no way of assessing this. - Mike F

Are there any hidden features on the eTrex?
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A. Yes. Try holding down the PAGE and PAGE UP buttons while you power the unit up. The unit will enter the service mode and display:
Bravo Version
Software Version
Time
Internal temperature of unit
Battery voltage
External voltage
Button presses
Other tech info

You can do a LCD screen check by pressing the PAGE button twice

Caution: While entering the service mode is interesting and useful, be careful which buttons you press because it is also possible to rest the unit to factory settings within this mode. Pressing "up"+"enter"+"on/off" keys in service mode will reset the eTrex to factory defaults. All presets and data will be lost.

To exit just turn it off as normal, and then turn it back on as normal. Unless you deliberately reset the GPS, nothing should have changed. - Ben J

A. This is about invoking the service mode in eTrex. I recently bought an eTrex Vista, and upgraded its firmware from 2.12 to 2.16. I tried to invoke the service mode as mentioned in the FAQ, but it didn't work. But, well, I figure it out. In eTrex Vista, with firmware 2.16, press in and hold the click-stick while turning on the device. That will invoke the service mode. I hope this will be useful for others to know. - Jatin 24Jun01

Is it possible to modify the software myself?
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A. Yes. Visit http://www.etrex.webz.cz/hack.html for details - Ben J

What is the best way to carry my eTrex?
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A. Unfortunately, the antenna on the etrex is somewhat fussy about how it's positioned. It prefers to be close to horizontal to work the best, but if you have a good view of the sky, you can generally get away with just about any position. Your body also presents a problem, as it blocks some of the satellite signals. I've found that the next best thing to carrying my etrex in front of me in my hand is to put it on my shoulder, but I generally have a pack on, and find it very convenient to clip it to a my pack strap. Since you're not using a pack, maybe you could jury rig something. Finally, loosing the satellite lock while you're not using your etrex is only a problem if you're trying to create a fairly accurate tracklog. I've found it regains a position fix quickly enough to still be a good navigational aid for following routes, or guiding me to a specific waypoint. Good luck finding a carrying method that works for you. - Jeff

A. I have an etrex and I hike in forested area's a lot. My etrex looses the satellites when I dangle it around my neck with the cord that comes with it. When I lay it on top of my backpack it doesn't loose track, but it's not a very handy place to keep it. I've tried to just put in in my pocket with mixed results.

A. I have mounted a Garmin handlebar mount to a wood dowel through my hiking staff. The eTrex seems to perform well mounted this way. - Chuck Rushton

A. Wear a shirt with epaulets on the shoulders. Get some sticky-back Velcro and stick it to the underside of the GPS, with a gap in the middle so you don't cover the battery release. Then, get some non-sticky-back "sew-on" velcro, of the opposite gender. Place it under and at right angles to the epaulet, so the velcro sticks out both sides. Then set the GPS on top, so that the epaulet is caught between the velcro sides. Secure the lanyard to something so you don't lose the unit if it falls. If anyone asks about the odd fashion accessory, tell them you're a pirate and the little yellow thing is your parrot. They should leave you alone after that...

If you're out hiking, a hat isn't a bad idea either. Sewing some velcro to the top of your hat will create a nice nest for your eTrex where it can watch the satellites whenever you're not using it. A serious geek would include solar panels and a Pfranc plug to power the unit while it's up
there. In situations like this it would be nice to be able to turn off the
backlight while on external power. - Nate

Uploading multiple tracks
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Q. I hear things about GarTrip being able to upload tracks to the etrex instead of 20 routes. In this way I could use trackback to navigate me and have 20 "routes" programmed at home.

A. First you need a track in GARtrip (either loaded from a GPS or drawn by hand). You can then either load it into the eTrex's active Log and then save it as a saved track. Or, you can download it directly into a saved track. To download it as a saved track you need to write a name for the saved track in the text field of first track point in GARtrip - use GARtrip's track edit function. If the track is larger than 250 points (500 in the eTrex Summit) it is better to load it into the active log and then save it. The eTrex will optimise the compression it uses to suit the length of the original track.

Autozoom
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Q. How does the autozoom work?

A. I'll explain how autozoom works with my etrex while flying our skyhawk. I enter a route with several waypoints (typically navaids) and select to follow it to the destination airport. In autozoom mode the scale will automatically be displayed such that the first waypoint (on the route) is on the screen. As I fly closer to that waypoint the scale automatically zooms to a closer scale ( say from 12 mi. to 8 mi.;then continues with 5 mi., 3 mi., 2 mi., 1.2 mi., 0.8 mi., 0.5 mi., 0.3 mi., 0.2 mi., 800 ft., 500 ft., 300 ft., and then 200 ft.). After passing that waypoint (on the route) the etrex autozooms out again to give a scale whereby the NEXT waypoint (on the route) is displayed on the screen. The etrex, once again, continues zooming the scale as I approach that second waypoint (on the route list). This continues until reaching the destination ("Follow To") waypoint which is typically an airport. Note, that the auto-zoom applies only to those waypoints that have been entered into the route. The autozoom works similarly in the "Go To" navigate mode but with just the single waypoint. - Shannon

eTrex as speedometer
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Q. I use an etrex as speedometer. There is a difference of 5% to the >speedometer of my car. Which one should I trust? I have the eTrex on the dashboard with very good signals. Does it matter if the etrex is in a vertical position or in a horizontal one I think not.

A. Don't trust anyone, Check for your self. However when you have checked with a stopwatch and a measured mile (not a mile off your odometer) you will find that the eTrex to be either right on the spot or damn close. Position won't matter as long as the eTrex shows it is getting good signals.

eTrex altitude capability
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The Etrex saves the elevation with each waypoint, and with each trackpoint which you can then view when you download your tracks. As a result, when used with the right software, you can view an elevation profile of your trip on your computer. Not as convenient as the etrex summit, but a useful tool for bragging rights after a tough hike.

Uploading latest firmware
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Q. I want to put the new 2.10 software on my Garmin Etrex. If I purchase the PC adapter cable, will I also need a power supply, or can I run off batteries while the software is loading?

A. You can use batteries, but it is important to use new batteries because power outage during flash programming may force you to return your etrex to Garmin. (It is the same problem as when you upgrade the bios of your PC) But if you check it, no problem : I upgraded my etrex firmware 6 or 7 times without failure.

How accurate is the eTrex clock?
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Q. I know this may sound like a "how long is a piece of string" question, but I am curious how accurate the eTrex clock is? Would it vary much with signal strength? - Ben J

A. I think as long as it has a lock on the satellites, the clock should be very accurate, within 1 second. When it has not 'seen' a satellite for a long time, i.e., used in door or turned off for a day or two, the clock may drift, once it locks on to a satellite, the clock will correct itself. I compared the GPS time on my eMap to an Oregon Scientific atomic radio clock (very very accurate in my experience), it seems the GPS clock when has a satellite lock is usually within 1 second. - Raymond Chi

A. Well, I had an etrex, and I have one of those radio controlled Clocks from Radio shack, and the seconds always matched each other right on. - Tellu

A. By design, a GPS clock needs to be incredibly accurate to be accurate. An error of a few milliseconds makes a difference across the distance between the user and the satellites.

Do GPS receivers present and radiation health risks?
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A. They are a receiver and do not actively transmit any signal. The signal strength received from the satellites is actually below the background noise level and the receivers integrate over multiple signal transmissions to "cancel out" the random noise.

They do have an oscillator in them like any normal wristwatch, and this oscillator will emit a harmless frequency. There may also be some very small re-radiation from the antennae, but this would be tiny.

How do I perform a factory reset on my eTrex?
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A factory reset may help if you are having issues with the date being displayed incorrectly, or other initialisation problems.

Hold down the PAGE (top right button) and PAGE UP (top left button) buttons down together and then simultaneously turn on the unit. The unit will enter the service mode and display:

Bravo Version
Software Version
Time
Internal temperature of unit
Battery voltage
External voltage
Button presses
Other tech info

You can do a LCD screen check by pressing the PAGE button twice
While entering the service mode is interesting and useful, be careful which buttons you press because it is also possible to rest the unit to factory settings within this mode. Pressing "up"+"enter"+"on/off" keys in service mode will reset the eTrex to factory defaults. All presets and data will be lost.
To exit just turn it off as normal, and then turn it back on as normal. Unless you deliberately reset the GPS, nothing should have changed.

Etrex cant communicate with PC - troubleshooting guide
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I recently had a problem with the yellow eTrex not communicating with my pc
(win98 se). The eMap worked fine but the etrex could not be recognized using
the same COM port and cable with the eTrex set for 'Garmin' and the software
set for 'eTrex'. I received the following trouble shooting procedures from
Garmin. They may be of interest to others 'just in case'. I would presume
that they apply to all eTrex models.

Problem: Expert GPS with eMap communicates fine, confirming
that COM1 and cable are functioning. Unplug eMap, plug in eTrex (Yellow),
set interfaces for Garmin, eTrex. "Device not responding." Try to use
UPDATER with 2.11 .rgn file. "Device not responding". (I had previously
updated the eTrex to 2.11 using this cable and settings.) Cleaned contacts
on eTrex with pencil eraser. Applied slight pressure to connector while
trying to communicate. No luck. Can you help? Thanks!....patrick

FIRST REPLY:
Thanks for contacting GARMIN,
Unit could have corrupt data causing it to perform incorrectly. Please try
the following to correct (this will erase all user stored data):
with unit off press and hold "Enter" "PAGE" and "On/Power" at the same time
when display appears take fingers off buttons
unit will display message that all user stored data will be cleared, select
yes then press enter.
unit will flash off then come back on.
take outside for 15 to 25 minutes for re-initialization and update (at this
point you may also try to interface with PC again.
Once unit has signal date should be correct. You may have to adjust time
offset or zone for you area.

(PS-Please include all email correspondence already written when you reply
to this email so that it can be answered in a timely manner. Erasing the
text may mean a delay in response, or that the email does not reach the
person(s) with whom you are communicating)

C.S. Wheeler
Product Support Specialist
GARMIN INTERNATIONAL, INC
1200 East 151st Street
Olathe Kansas 66062

SECOND REPLY:
Put the unit in NMEA OUT, and see if it will export NMEA sentences in
hyperterminal:
1. No other programs are currently running:
a. Press Ctrl-Alt-Del (opens the close program window).
b. Choose end task for all items except: DO NOT CLOSE "Explorer" or
"Systray"
c. Continue until every program is closed except: DO NOT CLOSE "Explorer" or
"Systray"
d. Try the download again.

2. Confirm that Windows recognizes your COM port:
a. Right-click on "My Computer" Icon and select "properties."
b. Click on Device Manager
c. Confirm your COM port is listed with no errors marked.

3. If any other serial devices (PalmPilots, scanners, digitizers,
trackballs, serial mouse, etc.) you may need to uninstall or disable the
drivers. You may need to contact the device manufacturer for assistance.

Please check to ensure that NMEA data is flowing between your GPS and PC:
You can test the NMEA output of your GPS on many computers as follows:
First, set up your GPS for NMEA output:
1. Go to the Interface menu of your GPS (usually in the System Menu)
2. Change the interface setting to NMEA, or No In, NMEA out.
3. Make sure the Baud rate indicates 4800 if shown.

Next, set up your computer to listen to the GPS as follows:
The following test works on Windows computers with Hyperterminal installed.
1. Click on the Start button.
2. Select "Run..."
3. Type "Hypertrm" (do not type quotation marks) and choose "OK."
4. Enter "GPS" for the name of the connection, and choose "OK."
5. Skip country code, area code, and phone number.
6. Next to "Connect using," use the pull down menu to select the comm port
that your GPS is connected to. (For example: Direct to Com 1) then choose
"OK."

7. Port setting should be set as follows:
Bits Per Second: 4800
Data Bits: 8
Parity: None
Stop bits: 1
Flow control: Hardware

8. Select "OK" to approve settings.

Now, you should see strings of data (letters and numbers) scrolling on the
screen. If the data is visible, then your GPS and computer are able to
communicate. If not, please start back at step one and try with another com
port selected (you may have to try several different ones). If you find the
comm you are able to communicate on, make sure it is selected to that comm
port or choose auto-detect in MapSource. Also, you may need to disable other
devices that use the same com port.

C.S. Wheeler

Disclaimer: These following FAQ's are some which I have found useful and they are not
necessarily endorsed by Garmin. Information should be regarded as a general guide only.

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