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Same Trail, Same Day, Wildly Different Track Log

Hi. Newbie here with new etrex Legend hcx. Not sure if this is the correct place to post this, feel free to re-direct if necessary. This device was a gift for my birthday less than a month ago. I thought I was getting the hang of it, till yesterday.

Did parts of a trail nearby that I've mapped several times now with satisfying results till yesterday. On the way south the track log veers east till it gets about 260 metres off the trail. I did not go off the trail but the track log sure does. Then it turns 90 degree to the west, crosses the real trail where I really did go, and eventually gets back to an accurate track. My return trip hits the trail at the crossing point and goes north up the same route I followed south, this time with accurate track logs. The trail I was on is the Trans Canada Trail and it is clearly visible on Google Earth.

I've managed to attach it. See where it goes winging off East and hits Luella Blvd.? I didn't go there. Any idea of what I did wrong? Need more info? Thanks.

Thought of something that may help. There are breadcrumbs along the part that leaves Luella, as if I was really there. Which I wasn't of course. But thought it might be helpful to know the thing didn't suddenly correct with one crumb at the turn and another at the real trail, there are crumbs in between.

0 Former Member over 14 years ago

Well, there are a couple of possibilities that come to mind. One, by a fluke, a bad satellite geometry, perhaps even made worse by a bad placement of the GPS. I've seen a couple of times on my Nuvi 1490T that my location was quite off the road I was traveling on, but it fixed itself after a few miles/minutes. Not much you can do about that, other than making sure your eTrex Legend HCx is well in sight of the sky.

Another possibility is that you may have the lock on road activated and once you got close enough to Luella Blvd it started "taking" you there.

0 Longblades over 14 years ago

Thank you for your ideas. Since I've done this trail before with no such variance I guess I'm going to put it up to a "glitch." You gave me some good ideas to check though, thanks.

I did the same trail yesterday; no veering off towards Luella but veering off to the west this time further south on the trail. Another section I've done before. It was very overcast and parts of the trail are heavily treed, though the leaves are off the hardwoods now. Strangely, the bad track log yesterday was on a more open part of the trail but the section I took through a mixed bush lot was accurate, sort of giving the lie to my overcast and tree cover theory. And no roads to complicate things. I wonder if snow cover makes a difference?

How strange it should be you who helps me out. Nope, change that, not strange at all given your bio. :) On all these outings who is with me? My Labrador Retriever. Since it's usually just the two of us alone in the bush my hope is to map all my usual routes so I can leave a copy at home for the OH to use to find me if I need help some day.

Sending you a PM.

0 Former Member over 14 years ago

I used to have an eTrex Vista, and still remember how lousy its reception was. Now the HCx is better, has a better chip but the patch antenna is not much of an improvement. It needs to be held relatively horizontally to have good and solid acquisition of satellites. Holding it in your hand is a pain but that's the best I can think of. I use a Garmin 62s for SAR. Great GPS unit BTW. It hangs from my radio chest harness, or is in a pocket when not in my hand.

Trees in leaf, clouds etc. used to be a problem with older GPS units, but not today. Neither is snow. Your Legend HCx should not be wrong so often. Can you just see the people who navigate their cars by GPS screaming if this happened to them on every drive?

More on PM.

I have another idea. Maybe the Microsoft map that you are using is not really accurate. First check that your GPS datum is in WGS 84. I can't help you really how to find that, as I don't remember how to do that from my Vista, something like Main Menu, Setup, Position Format.

Now if you don't mind, send me the track (gpx format preferably or whatever you have). I'll put it on a topo and/or aerial and maybe I'll see something that may be an explanation. I doubt it as there is a Golf Course Rd nearby, but who knows.