Garmin eTrex Glitch?

[jimmea]

Going out for a ride today i reset the Garmin readings to zero, returned home after 70k* only to find the Garmin reading 296k with an average speed of 84.5 kph ?? no idea what caused it but it has happened a couple of times now?

*I know this because the tracklog uploaded to Strava showing the correct distance.

[Karla]

Which Etrex is it?  If it's one of the Touch 25/35 series, they're buggier then a nest of hornets and about as painful to use.

[Ian H]

Was your previous ride some distance away?

[jimmea]

Which Etrex is it?  If it's one of the Touch 25/35 series, they're buggier then a nest of hornets and about as painful to use.

Sorry, forgot to put that it’s a 30x

[Phil W]

You rode from home and no car or train journey involved? To eliminate the obvious.

[jimmea]

Was your previous ride some distance away?

Ireland!

[jimmea]

You rode from home and no car or train journey involved? To eliminate the obvious.

Yes started and finished at home, eTrex had all previous track and trip data wiped before i set out.

[Phil W]

To eliminate Ireland you can confirm it isn't 220km as the crow flies and you have not had the GPS on between Ireland and home?

[fuaran]

Did you wait for it to get the position from GPS, before resetting the trip data?

[jimmea]

Did you wait for it to get the position from GPS, before resetting the trip data?

Yes, unit was fully on before i reset it.

[Kim]

You rode from home and no car or train journey involved? To eliminate the obvious.

Yes started and finished at home, eTrex had all previous track and trip data wiped before i set out.

Yes, but if it hasn't had a GPS fix in the new location yet, the old location will be in the buffer when it starts recording data, and you get a long crow-flies jump at the start.  Annoying, but easy to work around when you're aware of it.

OTOH, if "fully on" means you waited for a fix before resetting, maybe it's something else...

I suggest plotting the track on a map in your analysis tool of choice.  The nature of the glitch may be obvious.  If it's not the first point bug, then my bet would be random wandering due to marginal signal at some point during the ride, possibly in a way that can be explained by the location where it happened (under a roof, urban canyon, proximity to power lines, radar, etc).

[grams]

Sometimes GPSes pick up a completely random coordinate miles from where you actually are in the middle of your track. Strava filters them out when you upload a track.

Can you see anything like this on the track on the eTrex screen?

[jimmea]

Sometimes GPSes pick up a completely random coordinate miles from where you actually are in the middle of your track. Strava filters them out when you upload a track.

Can you see anything like this on the track on the eTrex screen?

No track looks as it should.

[Cudzoziemiec]

I had a possibly related oddity earlier this month. Or in fact last month. I loaded a track, then decided I wasn't going to ride it that day. Did ride it a week or so later. Before setting out I reset all the timers. Got home, sent the track to the DIY audax organiser and he told me it had started recording a week before I started the ride! I've always thought (and experienced) that resetting the timers means it starts counting again from that point, and when I got home the ride data just showed what I'd ridden that day. Something odd there, but I don't know what. The eTrex series are great and generally reliable but just occasionally behave in an unexpected way.

[Kim]

I think that's a variation on what I describe above (possibly related to saving tracks or not).  I bet if you look at the XML in a text editor you'll have the first point from the previous week followed by a perfectly good track, while the trip counters etc have had the sense to disregard it.

These bugs mostly get me when I do a train-assisted ride.  Workaround seems to be:

    Turn on eTrex, wait for it to acquire a GPS fix (which can take a while if the battery has been changed or you've moved some distance).
    Reset track/odometers.
    Ride bike.
    Save track.
    Switch off.

If you follow this procedure every time, it works as expected.

[grams]

Sometimes GPSes pick up a completely random coordinate miles from where you actually are in the middle of your track. Strava filters them out when you upload a track.

Can you see anything like this on the track on the eTrex screen?

No track looks as it should.

I seem to recall the eTrex logs a point fairly infrequently, so it’s possible the trip counter say the erroneous point but the coordinate was back to normal by the time the track log point saver next kicked in.

[Kim]

I suppose that could happen if you're logging at fixed time intervals.  If you've got it set to 'Auto' the spurious movement should cause it to log a point.


Another thought: Could you simply have failed to reset the trip counters properly, perhaps due to gloves or cold fingers?  It's easy to sselect the wrong thing in the reset menu by pushing 'up' followed by 'select' in one motion on the joystick thingy, giving you a "are you sure?" screen that looks superficially the same as the one you're expecting...  (DAHIKT)

[Cudzoziemiec]

I think that's a variation on what I describe above (possibly related to saving tracks or not).  I bet if you look at the XML in a text editor you'll have the first point from the previous week followed by a perfectly good track, while the trip counters etc have had the sense to disregard it.

These bugs mostly get me when I do a train-assisted ride.  Workaround seems to be:

    Turn on eTrex, wait for it to acquire a GPS fix (which can take a while if the battery has been changed or you've moved some distance).
    Reset track/odometers.
    Ride bike.
    Save track.
    Switch off.

If you follow this procedure every time, it works as expected.

I think your first para is what's going on. However, in my case the bike hadn't moved (at least with the Garmin on) in the intervening time. But I do usually turn it on a couple of minutes before riding and I think in this case I didn't turn it on till I was already out the door (which is only a couple of metres from where the bike lives but it doesn't get a signal indoors). 

[jimmea]

Another outing today but glad to report no issues with the Garmin, i can only think that it still thought it was in Ireland. It was switched off after the outing in Ireland and wasn't put back on until yesterday but it was reset? Just putting it down to gremlins in the system!

[pdm]

I once had an error with one of my previous eTrex HCx devices.
Its initial lock put me in the middle of Celtic Sea (600+km away!), travelling at some speed....
It eventually changed its lock to where it should have been but the distance travelled was rather excessive!
I suspect you may have suffered a similar erroneous fix glitch as well?

[Ben T]

Was your previous ride some distance away?

Ireland!

The further away your previous ride was , the longer it takes to get a fix, so it might be that it hadn't got a fix before you reset it.

[Karla]

Another outing today but glad to report no issues with the Garmin, i can only think that it still thought it was in Ireland. It was switched off after the outing in Ireland and wasn't put back on until yesterday but it was reset? Just putting it down to gremlins in the system!

Resetting the trip computer is not the same thing as resetting the GPS lock.  This is the important distinction.

[frankly frankie]

When you power down on an E30, it writes its current position to a GPX file consisting of a single Waypoint. 
The file is on the device and named - .Position.gpx (note the initial dot which will make it invisible to some OSs).

Presumably when it is powered up 'luke-warm' or 'cold' it makes some use of this stored information.