GPSrChive Discussion Forum

I am a experienced gps user I own about two dozen+ gps receivers.
I just received my etrex-se recently. I like to obtain a stable fix on all my receivers (about 20-30 minutes) then make a waypoint and navigate to that waypoint watching the drift.
The etrex-se while watching the position drift suddenly jumps about 50 feet. It doesn't just drift 50 feet it instantly jumps 50+ feet. This happens in the east-west direction (longitude) as well as the north-south (latitude) directions but never together its always one direction or the other but never both at the same time.
After 40 minutes or so minutes the position will jump back instantly -50 feet where its position is supposed to be. Then after maybe10-30 minutes the position will jump 50+ feet in the other direction but not before is corrects its previous jump.

My obsession with gps stability testing for about 20 years now. I know the latitude and longitude of every part of my backyard without using a gps.

So I was disappointed to find the etrex-se making unexpected jumps that put me in my neighbors yard or on the wrong side of my yard.
These position jumps happen in gps only mode as well as multi-gnss mode. but these jumps alway correct them self.
These position jumps happen with excellent fixes.
I have the elecctronic compass disabled. These jumps happen when the backlight is on continous or off continous.

I believe the etrex-xe is using a constant energy saver which cycles the gps receiver off and on causing these position excursions (50 foot jumps). and enabling unbelievable 168 hour battery life.
My etrex-10 has about 29 hour battery life which I think is exceptionable and it has no problems.
My etrex-se has;
software ver 3.10
host: ver 3.10
gps: ver 2.42
ble: 3.00

I looked at the software upgrade descriptions and didn't see anything that addressed this.

In what part of the world are you located?

Do you have a recorded activity track log you can share that shows these jumps?

Why haven't you updated the firmware?

Will test with our eTrex SE soon to attempt duplication.

epoch_time wrote: Thu Oct 10, 2024 1:12 am I believe the etrex-xe is using a constant energy saver which cycles the gps receiver off and on causing these position excursions (50 foot jumps). and enabling unbelievable 168 hour battery life.

Your conclusion is justified, Expedition mode causes a decrease in the number of points, which causes a greater distance between recorded points (jumps).

I assume that your observations come from a recorded track during a stable position of the device,
during a stop in each device the position "floats", the distance of jumps depends on the set interval of recording the track.

A shorter interval will probably cause more jumps and the distance will be shorter.

I have additional information regard the 50 foot jumps seen with my etrex-se. Also my etrex-se has bluetooth disabled.
The noticeable jumps seemed to have gone away. I think what was happening was this was a brand new gps and had not aquired all the gps satellites yet. As each new satellite came into view for the first time that perticular satellite addition/aquisition would take some time to stabilize.
and I would see those 50 foot jumps.
I now have 60+ hours of continuous operation and I believe the etrex has now stored data for all the satellites.
Thus as each satellite comes into view the etrex see's it as an old friend and welcomes it smoothly without notisable position jumps.
While each satellite aquisition still sends updated information to the etrex there is a smoother acceptance from the etrex.

The etrex-se while navagating to a freshly stored waypoint while standing still drifts faster than the etrex-10.
The etrex-se after 40 hours of navagating to its own location (way point) shows a trip distance of 2 miles. I haven't looked at the 40 hour
navagation log but would imagine it is a bunch of irregular circles with a diameter of maybe 50 or 60 feet?
The etrex-10 with glonass and waas turn off navigating to itself thru the night time hours (minimal ionisphere delays) going by my recollection
and poor memory. Would show a navagation trip distance of about 200 feet. etrex-10 may have some full time energy saver circuitry allowing 29 hour of battery life.

While most of my magelan gps units would show less that 5 foot trip distance over 10-12 hour nightime navigation to its own location while
indoors and has no obvious energy saver abilites.

Sorry for the spelling errors.

How do you notice these 50 feet jumps - on screen map view, on screen distance measurement, from data logs, from some other program/app?
I would suggest to check all settings on eTrex SE to make sure it has all battery saving (expedition) modes off and turn on data logging at 1s interval (if you are interested in best accuracy). Some initial time is needed to get satellite data if unit was turned-off for a long time.

If GPS unit is still for a long time, it will show random walk behavior. Distance measurement of random walk depends on calculation algorithms inside GPS unit - I would not expect them to be the same, thus comparisons of this measurement doesn't mean much. Raw data points would show better picture.

IME eTrex SE has slightly better GPS performance than eTrex 10 (a bit faster to acquire, a bit more accurate and robust in bad signal conditions). Battery wise eTrex SE is much better than eTrex 10 in any mode, no contest.