Strange distance errors?

[moxeyns]

Hubby bought me an eTrex for Christmas. It's only taken 2 years' worth of hinting We've got our first couple of finds under our belts, but are getting increasingly puzzled by the distance the unit is reporting. Today's walk was a linear; 1.7 miles out, 2.8 miles total travelled back at the car. Huh?! Similarly, we both happened to walk the same route at different times a couple of days ago. It said he'd done 2.6 miles; it told me 3 miles. I'd quite like to use the GPS instead of a pedometer to gauge how long I've walked, to save carrying multiple gadgets - but not until I figure out how we're confusing the poor thing! Any hints?

 

Theories I'm mulling over:

- It likes me better. Whilst I like this theory, it's not terribly useful

- If we walk what it considers the same route, it only counts it once.

- It needs constant access to the sky. I tend to hang it outside my clothing, he carries it in a pocket - but I'm not convinced by this either, as it's quite happy in the car. For both legs today, it was slung under my daughter's black wool coat.

 

Thanks for any pointers!

 

Nicky.

[groundhog123]

Hubby bought me an eTrex for Christmas. It's only taken 2 years' worth of hinting We've got our first couple of finds under our belts, but are getting increasingly puzzled by the distance the unit is reporting. Today's walk was a linear; 1.7 miles out, 2.8 miles total travelled back at the car. Huh?! Similarly, we both happened to walk the same route at different times a couple of days ago. It said he'd done 2.6 miles; it told me 3 miles. I'd quite like to use the GPS instead of a pedometer to gauge how long I've walked, to save carrying multiple gadgets - but not until I figure out how we're confusing the poor thing! Any hints?

 

Theories I'm mulling over:

- It likes me better. Whilst I like this theory, it's not terribly useful

- If we walk what it considers the same route, it only counts it once.

- It needs constant access to the sky. I tend to hang it outside my clothing, he carries it in a pocket - but I'm not convinced by this either, as it's quite happy in the car. For both legs today, it was slung under my daughter's black wool coat.

 

Thanks for any pointers!

 

Nicky.

 

The only thing I can think of right off is that maybe the unit does not have a clear view of the sky at all times. It could be obscured by heavy tree cover or maybe you are somehow shielding it from view at times, therefore it is not calculating the total distance. I know my unit will stop recveiving if I stick it in my pocket or walk into thick vegetation.

[+StarBrand]

The etrex line works best when held flat in your hand with its face skyward. Hold it about 1 foot or more from your body for best results. With a continous clear view of the sky and good sat lock - it should give consistent results each time.

 

Also might make sure it has fresh batteries and the latest firmware installed.

[+MountainRacer]

The only thing I can think of right off is that maybe the unit does not have a clear view of the sky at all times. It could be obscured by heavy tree cover or maybe you are somehow shielding it from view at times, therefore it is not calculating the total distance. I know my unit will stop receiving if I stick it in my pocket or walk into thick vegetation.

 

This may be your answer. Certain models of GPS units frequently lose and regain solid satellite capture, resulting in a sort of dotted-line track instead of a solid line. (It may not show up that way, but that's how it's calculated.) The problem is exacerbated if you put the unit under any sort of cover, such as tree canopies or your pocket. eTrexes and Magellan eXplorists are notorious for this.

[+WVRadar]

The GPS Units and Software Forum has several threads dealing with this issue. The newer eTrex series of receivers have a Trip Odometer bug, which causes mileage inaccuracies when moving at slow speed. I have an eTrex Venture HC that has this problem.

 

As far as losing reception, the older models had to be held face up, but the newer models with the high sensitivity receiver are much better. I can wear mine on a lanyard around my neck and have never lost reception. This makes it much better when hiking, as I have both hands free.

[+blb9556]

You shouldn't need constant view of the sky. I used one of those once (I own an Explorest 500LE) in the woods and it was accurate.

[moxeyns]

Thanks, guys - I'll try the holding-flat-in-my-hands (and-trying-not-to-feel-too-stupid) bit whilst I'm saving up for the cable so I can download any firmware updates!

 

Nicky.

[+Miragee]

After you get the cable, and if you get the Topo maps where you can view your Tracks from a day's outing, you might find out why the distances have been so goofy.

 

Here is an image from my erratic GPSr when I was basically standing still.

 

 

Another time, my GPSr lost contact with the satellites, but instead of the Track spiking out to the sides, it went up. I flew at about 9500 feet of elevation for a while as I walked on the trail. That made for an even more odd-looking profile . . .