Am I expecting too much?

[rapracing]

During the summer I had picked up an Etrex 30. I wasn't happy with it. It seemed that is was not accurate or consistent so I returned it. Forward to today:

 

I had recently purchased 2 Etrex 30x units for the kids at the church to use on outings. I took one for about a 4 mile walk today. When I left to start the elevation said it was 942ft. In the Satellite screen it said 10ft accuracy. I set 2 waypoints during the walk. When I returned to the first one I was about 60ft away from where I had set it. The second was well over 120ft away when I returned to it. When I returned to the starting point it told me elevation was 1062ft. This was all done in less than a 2 hour time frame.

 

Is this common for these units?

 

If so, it seems it could become very frustrating finding any caches if it takes you 100ft or more from where they actually are.

 

If I'm hunting and need to find my truck I know that is plenty close but it seems that it should be taking me a little closer, especially when it says within 10ft. I am not going to give these to 10 and 12 year olds to find stuff with when they don't work any better or more consistent than they do.

Edited December 17, 2015 by rapracing

[kjun12]

I'm having similar problems and would appreciate if those with more experience contributed to this topic.

[+Walts Hunting]

The errors you are seeing are pretty high. When you marked the positions what were the conditions. Were you under tree cover or a narrow canyon? The satellite accuracy has nothing to do with elevation. That is barometric pressure reading and that much elevation error isn't all that uncommon.

 

How long did you pause when marking the points. It can take a little bit of time to settle down. My Montana consistently gets me back within 30 feet of a marking.

[+wmpastor]

I can second the point that there is sometimes a bit of lag with units. The lag time seems to vary from almost none to very noticeable. Bad conditions make it worse, but sometimes lag happens for no apparent reason. I find that slowing down near GZ pretty well solves that problem (but keep moving, especially if the unit is lagging).

[rapracing]

The first waypoint had some tree but not bad. Satellite signals were very good. The second was in a wide open field over 1400ft elevation. No obstruction whatsoever for sure on the second.

 

I probably was at the locations for 8 or 10 seconds. Maybe that was the reason?

[+colleda]

You said you set a waypoint, how did you do that? If you just used the Mark Waypoint on the menu it just 'snaps' a coordinate. The correct way to do it would be by using Waypoint Averaging. it may take a minute or three but you get an accurate coordinate.

BTW one can Backtrack to find your way back to your starting point.

[+Team Microdot]

The first waypoint had some tree but not bad. Satellite signals were very good. The second was in a wide open field over 1400ft elevation. No obstruction whatsoever for sure on the second.

 

I probably was at the locations for 8 or 10 seconds. Maybe that was the reason?

 

8 or 10 seconds really isn't very long at all for the purposes of taking an accurate waypoint.

 

According to the owner's manual the Etrex 30 seems to support waypoint averaging which should help to increase the accuracy of your waypoints.

 

Here's a link to an online version of the owner's manual where you can read about the waypoint averaging feature.

 

And

demonstrating waypoint averaging. The video is on the Etrex 20 but as the owner's manual is the same for the 30 and the 20 I'll assume the video will be relevant to your needs.

[+Happy Humphrey]

I've used an Etrex 20 for a couple of years and don't have any problems with accuracy (and it's almost the same as the 30 so should behave in similar fashion).

 

I often set caches which have been proved over time to have very accurate coordinates (<10 feet out on repeat visits). I have used waypoint averaging but don't see a lot of benefit. To set a waypoint for a cache location I'll take a few minutes (not seconds), and spend some time walking away and back again to simulate a cacher's approach - so that when it looks like I'm about 20 feet away the reading is 20 feet. I'll switch off the unit and walk away, then restart and approach again.

 

That gets me REALLY consistent results. But I find that even a quick waypoint (if there's a good view of the sky) is accurate to within 30 feet or so (at worst). I can only think that you're suffering because you aren't giving the GPSr time to settle once you've returned to the waypoint. Sometimes I find a cache and think that the coordinates are 50 feet out, as this is the distance to target displaying on arrival - but by the time I've signed the log it's settled to 10 feet or less. I'm not sure why this lag occurs but it does seem to be a feature. Try giving it two minutes at the waypoint before getting too critical.

[rapracing]

I'll give it another shot. It's raining here today so I'm not going to mess with it today. Maybe Saturday or Sunday afternoon I'll get out again. I'll report back after that.

 

If it doesn't get any better than what I've seen I really see no point in messing with them. I can be almost as accurate with a compass and map and they're a whole lot cheaper. And probably more fun. I had used the etrex 30 for over two months 4 or 5 times a week on hikes and had the same results I'm getting with this. Maybe it's just not for me

[+Team Microdot]

I'll give it another shot. It's raining here today so I'm not going to mess with it today. Maybe Saturday or Sunday afternoon I'll get out again. I'll report back after that.

 

If it doesn't get any better than what I've seen I really see no point in messing with them. I can be almost as accurate with a compass and map and they're a whole lot cheaper. And probably more fun. I had used the etrex 30 for over two months 4 or 5 times a week on hikes and had the same results I'm getting with this. Maybe it's just not for me

 

You're welcome.

[+BAMBOOZLE]

You said you set a waypoint, how did you do that? If you just used the Mark Waypoint on the menu it just 'snaps' a coordinate. The correct way to do it would be by using Waypoint Averaging. it may take a minute or three but you get an accurate coordinate.

BTW one can Backtrack to find your way back to your starting point.

 

You have too much error and I think this is your answer.....it may take 5-10 minutes in some cases for waypoint averaging to lock in. On long hikes I have set points in deep woods and on the way out I'll be within a couple of feet.As said the altimeter is a different animal and you may see variations....I will say that on long vacations in the mountains I was amazed how many times my units have been dead on according to highway signs.

[+JohnCNA]

I have had the best (most accurate) results with my eTrex 30 and 64s if I let the GPS settle for 3-5 minutes or so before I mark a waypoint, when high accuracy is desired.

 

Like you mentioned, just marking things on the fly will give me coordinates of 50 feet or more away, sometimes. If all I need to do is mark the position of a suitable creek crossing or where I parked the car, that will be accurate enough. I can see it from there. For the most accurate coordinates, like for placing a geocache, I'll put my GPS down for 3-5 minutes, and then mark the position, then use the averaging function to tighten it up even more.

[+Harry Dolphin]

Yeah. I'd say three to five minutes to let the coords settle down on my eTrex 30. I will use the averaging when placing a cache. But the most change I see is about six feet. Often when finding a cache, I may be ten to twenty feet off, but by the time I sign the log I'm often at six feet. I don't know if other GPSr units do better than that. But, it works for me.

[Pup Patrol]

When you took the gps out of the box, did you set it outside and let it find its location?

 

New out of the box, a gps needs to find itself, so to speak. Let it sit outside and leave it for an hour or so.

 

B.

[rapracing]

When you took the gps out of the box, did you set it outside and let it find its location?

 

New out of the box, a gps needs to find itself, so to speak. Let it sit outside and leave it for an hour or so.

 

B.

 

Yes I did

[+ecanderson]

When you took the gps out of the box, did you set it outside and let it find its location?

 

New out of the box, a gps needs to find itself, so to speak. Let it sit outside and leave it for an hour or so.

 

B.

Ideally, once the unit is fully booted, it should never take more than ~12.5 minutes to pull down all of the almanac data necessary from one satellite to know all that is needed about all of the others.

[+briansnat]

Bad coords happen. I recall one cache where I used two different brands of GPS (Magellan and Garmin) and averaged both. People still had issues with the coords. One finder posted his coords and I updated to use those and no complaints since. More recently I used my Garmin 62S to obtain coords and averaged for about 5 minutes. The coords turned out to be off by about 100 feet.

 

Some units seem to be better than others. I never, ever had complaints about coords obtained from my old Garmin 60CSX or my DeLorme PN40. I now use my Garmin 62S to find caches, but when I'm hiding I go back to my Delorme PN40 or my Garmin 60CSX.

[+wmpastor]

Bad coords happen. I recall one cache where I used two different brands of GPS (Magellan and Garmin) and averaged both. People still had issues with the coords. One finder posted his coords and I updated to use those and no complaints since. More recently I used my Garmin 62S to obtain coords and averaged for about 5 minutes. The coords turned out to be off by about 100 feet.

 

Some units seem to be better than others. I never, ever had complaints about coords obtained from my old Garmin 60CSX or my DeLorme PN40. I now use my Garmin 62S to find caches, but when I'm hiding I go back to my Delorme PN40 or my Garmin 60CSX.

 

My system for getting good coords when hiding a cache is to do the averaging and do it again on at least one other day. This has been easy because I never hide a cache at the same time as I first identify a good location.

 

When searching, I find approaching gz from several angles - getting close and walking away from gz in different directions, then returning - gives me the best assurance that i'm actually at gz. This is especially helpful where conditions give bouncy readings.

[+ecanderson]

More recently I used my Garmin 62S to obtain coords and averaged for about 5 minutes. The coords turned out to be off by about 100 feet.

Assuming nothing was transposed or fat fingered after the fact, what did the EPE read on your 62S when you were 100' off?

[rapracing]

I have been out three more times with the unit since my last post. I guess maybe I'm too particular but I am not satisfied at all with these units. One time it will take me too within 30 ft or so of a waypoint and the next I may be 100+ ft away (same one). On my map it shows a different line for the route almost every time. A lot of it is on tram roads so I am walking with in a couple of feet of the same line each time. I will show me as much as 50+ ft difference in the line on the map.

 

I had a similar issue with the regular etrex 30 and I was told the X should be better. I see no difference. Fortunately I have 90 days to return them if not happy. I'm thinking that is probably best. I haven't actually tried finding a cache yet. If it's going to be off by 100 ft I'm not going out there and just looking around hoping to find it.

Edited December 29, 2015 by rapracing

[+ecanderson]

Unless your EPE is telling you that your reception is quite poor, 100' out is excessive even if you try to take a 'snap' reading where you've stopped for 8~10 seconds. If your EPE is good, then this begins to sound like a configuration issue. But we really do need to know the device's reported EPE in order to determine whether we're looking at a reception problem or a configuration problem. If your device is reporting some huge EPE (e.g., 100'), then the results you achieved wouldn't be any surprise at all, and we'd really be trying to pin down where the heck you were that was causing such awful reception. I keep the EPE up on the display at all times in an attempt to tailor my expectations about accuracy in the moment.

[+msrubble]

Since you say you've let the unit sit out for several minutes to acquire satellites, here's another possible reason for coordinates to be way off: is the unit set to lock on road? Setup --> Routing. Also, what kind of routing do you have set?

[+colleda]

Since you say you've let the unit sit out for several minutes to acquire satellites, here's another possible reason for coordinates to be way off: is the unit set to lock on road? Setup --> Routing. Also, what kind of routing do you have set?

I was thinking that also. Try setting Routing to off-road.

[rapracing]

Unless your EPE is telling you that your reception is quite poor, 100' out is excessive even if you try to take a 'snap' reading where you've stopped for 8~10 seconds. If your EPE is good, then this begins to sound like a configuration issue. But we really do need to know the device's reported EPE in order to determine whether we're looking at a reception problem or a configuration problem. If your device is reporting some huge EPE (e.g., 100'), then the results you achieved wouldn't be any surprise at all, and we'd really be trying to pin down where the heck you were that was causing such awful reception. I keep the EPE up on the display at all times in an attempt to tailor my expectations about accuracy in the moment.

 

It is usually between 8 and 13 so I don't think that's the issue.

 

I was out again today with it. Took the dogs for a walk. I hit five of the waypoints that I had stored. The worse one today was 23ft off. I had one 12ft, one 5ft and one 4ft and one 0.

I don't understand it. When walking the track on the map was off by as much as 50 ft walking on tram roads. I did notice if I'm moving at all and watching the map it is all over the place. The track will swing 120 to maybe 150 degrees. That is a constant thing if I'm moving

[rapracing]

Since you say you've let the unit sit out for several minutes to acquire satellites, here's another possible reason for coordinates to be way off: is the unit set to lock on road? Setup --> Routing. Also, what kind of routing do you have set?

I was thinking that also. Try setting Routing to off-road.

 

I looked and I cannot find anything like that on the Etrex. It does show highways on the map but I don't believe that is an option on this unit.

 

ETA: I just went and checked again. I did find what your talking about. It is set to "off road". Lock on Road is "Off"

 

ETA: 1-1-15: Was out again today and the waypoints that were close yesterday were anywhere from 23 to 90 feet off. Seems to be junk to me. EPE was 8ft when I checked it (3 times).

Edited January 1, 2016 by rapracing

[+niraD]

Under ideal conditions, a consumer GPSr will be accurate to about 3m (10ft). That applies both to your device when you're searching for the waypoint, and to whatever device was used to create the waypoint (yours, or a cache owner’s). So a waypoint may be 5-6m (16-20ft) from ground zero under ideal conditions. Under less than ideal conditions, both GPSr readings can be much less accurate.

 

So I really wouldn't worry about the error of 23ft, even if the EPE was much lower than that.

 

But the only times I've seen readings 90-100ft off have been in locations with terrible GPS reception (steep canyons, heavy tree cover, that sort of thing). Sometimes, the owners of caches in such locations provide hints to help you narrow down your search, since the GPS signal is so unreliable.

[+ecanderson]

It is usually between 8 and 13 so I don't think that's the issue.

 

I was out again today with it. Took the dogs for a walk. I hit five of the waypoints that I had stored. The worse one today was 23ft off. I had one 12ft, one 5ft and one 4ft and one 0.

I don't understand it. When walking the track on the map was off by as much as 50 ft walking on tram roads. I did notice if I'm moving at all and watching the map it is all over the place. The track will swing 120 to maybe 150 degrees. That is a constant thing if I'm moving

With EPE readings between 8 and 13, your reception is about as good as it gets, and IF you take a few moments to do the original position logs with "Average Waypoint" (vs. "Mark Waypoint"), you should be back with 15' or so the next time you visit.

 

Now as for watching in real-time, that's another story. "...if I'm moving at all and watching the map it is all over the place. The track will swing 120 to maybe 150 degrees." It should run more true than that, but it makes me wonder what mode you are using. Your compass and chevron movement can be impacted by 'hot battery syndrome'. In short, best to avoid doing compass calibration immediately after installing two very freshly charged batteries. For who-knows-what reason, the 3-axis compass chip in every Garmin I've held that had one is voltage sensitive. Run the unit for 15 minutes or so before performing the calibration. Might be your issue, might not. Wasn't there to watch you work. Next, under 'Heading Settings' (see page 34 of your manual), note that your device can change from using your GPS heading (calculates your heading based upon difference in your coordinates as you move more quickly) to the magnetic compass (uses magnetic compass to determine your heading). The latter is a GOOD thing because there will always be some minor drift in your calculated GPS position, and when you are moving slowly, that drift accounts for a fair % of your actual movement, and that will cause things to spin around quite a bit.

 

Last, there's the issue of elevation and the configuration for that. Read pages 34~35 VERY carefully. I've argued this point with someone here before, but I think Garmin has made it as clear as possible in the docs and in the config items on newer units. In 'Variable Elevation' mode, the barometer assumes that pressure changes are a function of change in altitude. in 'Fixed Elevation' mode, the device assumes you're not changing elevation, and that any pressure changes are a function of actual local barometric pressure. If using the barometer for elevation, you MUST be in 'Variable Elevation' mode. On the whole -- if you take time at a known elevation to calibrate the altimeter (see page 20), the barometric sensor will be more accurate as long as there's not a storm front moving in , but it's only accurate for as long as your local barometric pressure isn't moving around. Tomorrow? Must recalibrate again.

 

Hope some part of that helped.