Garmin Etrex - inaccurate to approx 150m...

[+VenomousHarridan]

 

I bought a second hand GPS (received today) for a friend.

 

I took it out with mine today to do a geocache and check all the settings were ok (i.e. metric not imperial etc etc) and that it was all fine, but every waypoint I've put in has been in excess of 150metres out . When I 'mark' a spot it is also out by about the same. Whilst I accept there will be some difference between my GPS, and another - nothing like this!!!

 

Is there any default that can be changed, or is this GPS broken in some way and should be returned?

 

Thanks all,

Julia aka VenomousHarridan

[+Tahoe Skier5000]

 

I bought a second hand GPS (received today) for a friend.

 

I took it out with mine today to do a geocache and check all the settings were ok (i.e. metric not imperial etc etc) and that it was all fine, but every waypoint I've put in has been in excess of 150metres out . When I 'mark' a spot it is also out by about the same. Whilst I accept there will be some difference between my GPS, and another - nothing like this!!!

 

Is there any default that can be changed, or is this GPS broken in some way and should be returned?

 

Thanks all,

Julia aka VenomousHarridan

 

Which datum are you set to? Should be WGS-84.

[+PDOP's]

Is the datum set to WGS84?

[+VenomousHarridan]

Is the datum set to WGS84?

 

Yes it is - I restored defaults to get it to this, as it wasn't..... still got the problem though.

 

Settings are:

hdd mm.mmm; wgs 84; metric; magnetic; and variance = 003 deg West

 

only difference between this and mine (etrex H) is the variance is showing as 002deg West

 

I don't seem to be able to change this though - but would it make a difference?

 

Thanks for any suggestions

[+Cardinal Red]

Is the datum set to WGS84?

 

Yes it is - I restored defaults to get it to this, as it wasn't..... still got the problem though.

 

Settings are:

hdd mm.mmm; wgs 84; metric; magnetic; and variance = 003 deg West

 

only difference between this and mine (etrex H) is the variance is showing as 002deg West

 

I don't seem to be able to change this though - but would it make a difference?

 

Thanks for any suggestions

 

As others have suggested, my first thought was a DATUM mismatch. If the settings you provided are the same on both units, I am at a loss to diagnose your problem. I wish I could check both units and choose those settings manually.

 

I can say that the Magnetic Declination (variance) is NOT contributing to this issue. It makes absolutely no difference, but if you set the North reference to TRUE instead or MAGNETIC that 1 Degree Magnetic difference would not display.

[+PDOP's]

Can you give an example of what you're seeing ( the coordinates displayed by each while at the same spot)?

[+RonFisk]

I assume it came from another area and that it hasn't been used for a while. Be sure to rebuild the almanac. This can be done by starting the unit and setting it out with a clear view of the sky for about a half hour. Turn on WAAS and disable the battery save option. A system reset shouldn't be necessary, but an almanac reset is recommended if that unit has one.

[+VenomousHarridan]

Can you give an example of what you're seeing ( the coordinates displayed by each while at the same spot)?

 

I did a mark earlier with both GPS's.

 

The results are:

 

BAD GPS: N051 23.026 E000 32.842

GOOD GPS: N051 23.078 E000 32.926

[+VenomousHarridan]

I assume it came from another area and that it hasn't been used for a while. Be sure to rebuild the almanac. This can be done by starting the unit and setting it out with a clear view of the sky for about a half hour. Turn on WAAS and disable the battery save option. A system reset shouldn't be necessary, but an almanac reset is recommended if that unit has one.

 

not sure whether this has an almanac reset option. I've just bunged it, turned on, in the garden and will leave it there for half an hour. It's in "normal" mode, not battery save mode.

 

What's WAAS?

 

Thanks all

[+VenomousHarridan]

 

 

Love your signature btw!

[+VenomousHarridan]

I've just brought the bad GPS in from the garden and it works!!!

 

Thank you so much everyone for your tips.

 

I'd still like to know what WAAS is though!

 

Thanks again

 

Julia aka VenomousHarridan

[+coggins]

I've just brought the bad GPS in from the garden and it works!!!

 

Thank you so much everyone for your tips.

 

I'd still like to know what WAAS is though!

 

Thanks again

 

Julia aka VenomousHarridan

In your area you turn it on to get EGNOS

[+VenomousHarridan]

In your area you turn it on to get EGNOS

Thanks Coggins - so much to learn with this geocaching malarky!

[+coggins]

In your area you turn it on to get EGNOS

Thanks Coggins - so much to learn with this geocaching malarky!

I would set it WAAS on and run with that. It can't hurt and `ol time stories of diminishing cell life are over exaggerated.

[sau00btk]

Hi, I've just had exactly the same thing! Bought a second hand unit (ex-mod) that arrived the other day, went out to find some caches and was consistently about the same distance off each time. My sat nav put me straight on the caches though! It's been outside for 20 mins so far (using previous posters advice) so will see how it goes!

[+VenomousHarridan]

I just had to read through this whole thread - I didn't even remember posting it!

 

Hope the leaving it outside plan works - not very technologically advanced I accept, but it worked for me!

 

Good luck!

Julia AKA VenomousHarridan

[sau00btk]

I tried it but it didn't work! If I mark a waypoint with it, it will then navigate back to that point perfectly but is approx 150yds off caches that I know the location of....argh!

[+Viajero Perdido]

After setting datum to WGS84, re-enter any cache coords you entered by hand using the wrong datum.