Request for owners of both Garmin and Magellan

[+Searching_ut]

The more I’ve done side by side comparisons with a Garmin Legend, and Magellan Sportrak map, the more I’ve been surprised by the results, especially when I download and view the tracks after a journey through the hills.

 

If possible, I’d really like to see other people’s tracks, where they traversed an out and back trail carrying receivers from both manufactures at the same time. (There has to be a lot of others out there who like me tend to run a couple units at a time.) The reason I like out and back trails is because it keeps you along roughly the same route thus giving an idea of the receivers repeatability. A description of the terrain to go with the track would be a great aid as well.

 

If you don’t have the means to post them, I’d love to get them via e-mail as well. It would be interesting to see this sort of measurable data showing the effects of different terrain etc. from a wide selection of different areas. I also think a few pictures (Tracks) would probably be of great help in explaining the greatly different impressions various people have regarding the different receivers on the market today.

 

Thanks in advance.

 

Jeff

 

http://home.sprynet.com/~searching_ut/

[+slinger91]

So what were your results? I tried that with a legend and a etrex yellow, but they are the same brand. But they always seem to be withen a few feet of each other. btw The Legend doesn't seem to be more accurate with waas enabled.

 

 

"If I knew how thirsty I was going to be this morning, I would have drank more last night."

[+Searching_ut]

I've got an assortment of tracks from my GIII+, Legend, and Sportrak on my webpage right now, and have been swapping which ones I post over the last few months.

 

In observing the tracks, the Legend and sportrak seemed fairly well matched in reception, with both units struggle in the same area, but displaying it in somewhat different ways. The magellan connects all track segments, so it's harder to see when reception was lost, but you can observe where the track quit recording as many data points or was missing obvious turns etc to get an idea of where it was loosing reception.

 

Most noticable though was in moderate to heavy terrain/treecover, the sportrak (All three units I've owned), and one meridian I borrowed, all tend to have very significant positional errors while moving. (position lag and wander) To date, I've yet to record a track where the Sportrak was more accurate, or displayed noticably better reception. In fact, in the canyons, or heavy tree cover, I've come to mistrust the readings from the sportrak unless I've been stationary long enough for the position it reports to stabalize from the averaging.

 

For an example out and back sportrak track, and the kind of errors I'm talking about:

 

http://home.sprynet.com/~searching_ut/images/zionsport.jpg

 

I've found my out and back tracks with my magellan rarely line up very closely if at all in reception problem areas unless I travel more or less straight lines.

 

I think it would be really interesting to see what sort of differences different terrain and types of vegetation produce

 

http://home.sprynet.com/~searching_ut/index.htm

[3fros]

Here's a link that compares the 76S to the sporTrak. It's not a comparison with the legend, but it shows information on the accuracy of the SporTrak which is very enlightening.

 

http://www.gpsinformation.net/mgoldreview/sportrak-pro-trees.html

 

Here's the article that it comes from.

 

http://www.gpsinformation.net/mgoldreview/sportrak-pro-rev.html

[stevesisti]

quote:

---

Originally posted by 3fros:

Here's a link that compares the 76S to the sporTrak. It's not a comparison with the legend, but it shows information on the accuracy of the SporTrak which is very enlightening.

 

http://www.gpsinformation.net/mgoldreview/sportrak-pro-trees.html

 

Here's the article that it comes from.

 

http://www.gpsinformation.net/mgoldreview/sportrak-pro-rev.html

 

I think you are missing the main point here. The tests you quote were done under very specific conditions. A fixed location with Waas enabled.

I too was impressed upon viewing this info until I started reading how real world sportrack users were dissappointed with the accuracy they were getting when laying tracks. I'm not saying it's worse than comparable units, but it looked so good based on this static report, it almost sets you up for "real world" disappontment.

 

I've also heard users say that having WAAS on when you can't get a good read on the WAAS satellites will give you less accuracy than if WAAS were off. Maybe Sportrack users are best off disabling WAAS when they can't get a strong lock. I'd be curious to know if Jeff had WAAS on during his track recording, and if he did, what would the track look like with WAAS off.

 

I was also originally impressed with the reported increased reception under heavy tree cover...again to only hear many people say that in "real world" usage, while the sportrack says it still has a lock when other units "lose lock", in reality it appears to some users that the sportrack is just "guessing" at this point and it's reported positions show wild variatons.

 

Personally I'm back to square one, as I was looking to purchase a Sportrack because of it's perceived higher reception and accuracy. I'm not sure that is true anymore.

 

Steve

[+EtrexRose]

sounds like you know what your talking about man, I agree, it would be interesting to do some more tests.

[+infosponge]

Magellan seems to include a predictive element to your position when in motion, which probably accounts for what you're seeing, at least partially.

It works well when moving fast (i.e. if you're traveling at 10 meters/sec and the fix won't be displayed for a second, then adjusting the fix by 10 meters will give a better estimate of where you ARE than where you WERE). At foot speeds, it seems less useful.

[+Searching_ut]

quote:

---

Originally posted by Stevesisti:

 

...I've also heard users say that having WAAS on when you can't get a good read on the WAAS satellites will give you less accuracy than if WAAS were off. Maybe Sportrack users are best off disabling WAAS when they can't get a strong lock. I'd be curious to know if Jeff had WAAS on during his track recording, and if he did, what would the track look like with WAAS off.

---

 

I've got to sheepishly say I hadn't thought to turn WAAS off, but love the idea and will give it a shot. On my Garmins, I haven't been able to detect much of a difference with my tracks, but then as far as I can tell they don't do any WAAS corrections when they can't see the WAAS bird. I have however concluded that the Sportrak will apply WAAS corrections for quite some time after it looses sight of the WAAS birds, which seems to help it's accuracy out noticably on stationary fixes. It will be interesting to see if it's possible that it degrades accuracy while on the move. If so, it would be neat to have a fix to the problem be as simple as turning off WAAS.

 

If the weather and time constraints allow, I'll try and get out in the terrain and log a few more tracks with WAAS off, which I'll stick up on my web page. In the mean time, I'd still love to see the results others are getting

 

Jeff

[+infosponge]

I believe the WAAS corrections are valid for a period of time (20 minutes?) so Magellan is quite correct to continue to use them for a period of time, even if the WAAS bird is intermittently "visible".

[+Renegade Knight]

My brother in law has a Sport Track Pro and I've got a GPS V. At first we both used to think that the GPS V lost signal more often than the Sport Track. However over time we noticed that the Sport Track wasn't updating right when the V had no signal and finally came to the conclusion that hte GPS V tells you exactly when you don't have a lock and waits until it does to show you a status. The Sport Track Pro seems to try to keep getting a lock while guessing it's position based on whatever factors Magellan built into the software. This same thing is probably related to the overshoot the waypoint/cache thing the Sport Track Pro does.

 

Wherever you go there you are.