Explorist 210

[Pfitz]

Hello, I new to Geocaching and I just got a Explorist 210 as my first GPSr. Overall I like the controls and features but am not too sure about the accuracy. I would like some help understanding if I got a bad unit or if this is the best that is expected. Sometimes when I am on a hike or drive and have a track log going it will show my path as much as 100 to 150 feet off the road or off my own path. This occures even when the GPS accuracy is reading less than 20 feet. I guess that it what bugs me the most. If I hike down a path and then come back the exact same way the track does not follow exactly and may be off 100 feet. Is this normal? Should I have got a garmin?

 

-Pfitz

[+map4navigation]

Hello, I new to Geocaching and I just got a Explorist 210 as my first GPSr. Overall I like the controls and features but am not too sure about the accuracy. I would like some help understanding if I got a bad unit or if this is the best that is expected. Sometimes when I am on a hike or drive and have a track log going it will show my path as much as 100 to 150 feet off the road or off my own path. This occures even when the GPS accuracy is reading less than 20 feet. I guess that it what bugs me the most. If I hike down a path and then come back the exact same way the track does not follow exactly and may be off 100 feet. Is this normal? Should I have got a garmin?

 

-Pfitz

I feel that my 210 is very accurate. I use it hiking and on my bike. Sometimes tree cover and such do affect accuracy. I just downloaded the newest update and it even seems more accurate and locks on much quicker when I first turn it on. Overall, as my first GPS I am very satisfied.

[+geognerd]

This happens on my 400. The track I take back from a cache is rarely on top of the track I took to the cache, even though I took the same trail. I suspect this is caused by the sampling interval for the tracklog. Perhaps if you tell the GPSr to record track points more often, the track going to and from a location will be closer to each other. With a longer interval between track points, the track has more of an opportunity to have vertices/track points in different locations, which would cause the tracks not to line up.

[+EScout]

Good points made here. I usually carry my eXplorist in my front pocket while hiking. It gets excellent reception there, but it may have different satellites received in one direction compared to the reverse. Usually the tracks are very close.

 

Please try this:

At the end of your hike, save the track log to a file. Remove the file and run it through the program: GPSBabel to convert it to .gpx format. Then import it into Google earth photo. See how your track compares to the trail/sidewalk/street.

 

Also remember to set your Track Mode detail in the Map Setup. Smaller intervals/more points give a more accurate track.

[Pfitz]

Thanks to all for your thoughts and advice. I spent some time since my last post to learn a little more about track logs and figured out how to change the intervals it takes points. After setting it to the highest setting of .01 miles I set out on two tests. The first one I walked up and down our street which is curvy. The unit tracked back much better than I have seen in the past so I assume this was my problem all along. On the second test I drove across town and again saw an improved tracking.

 

On the drive test it still did not follow the road perfectly and may have been off 50-100 feet in spots. I am assuming that the detail map I downloaded from Topo USA is not exact. Has anyone else had this issue. I will try and import this track into GoogleEarth and see how it looks.

 

Thanks, Pfitz

[+geognerd]

There is a possibility that the road was not digitized correctly in the Topo USA map data. You should also know the aerial photography in Google Earth/Maps can have registration errors, so the aerial photo itself may not be in the correct location geographically either.

[Pfitz]

After doing several more tracks at the higher sampling rate I am much happier with this unit. For the price the Explorist 210 is pretty nice. Thanks all for helping me out.

 

-Pfitz

[Meckers]

After doing several more tracks at the higher sampling rate I am much happier with this unit. For the price the Explorist 210 is pretty nice. Thanks all for helping me out.

 

-Pfitz

 

Does anyone know what the what the memory cost is of the higher sampling rate ("Detailed Auto")? For example if you were to walk a ten mile zig zagged track while tracking Detailed Auto, would that exhaust the 210's memory?

[+geognerd]

After doing several more tracks at the higher sampling rate I am much happier with this unit. For the price the Explorist 210 is pretty nice. Thanks all for helping me out.

 

-Pfitz

 

Does anyone know what the what the memory cost is of the higher sampling rate ("Detailed Auto")? For example if you were to walk a ten mile zig zagged track while tracking Detailed Auto, would that exhaust the 210's memory?

According to Magellan's website, the 210 can store 2000 points in each track log. Using the 0.01mi mile recording detail, you would theoretically need only 1000 points for that 10 mile track. The track log files are just text files. Magellan says the 210 can store 150 track log files.

 

I use the auto-detail setting on my 400, and I don't think I've ever had a track log file larger than 100KB. I just took a look at one of my track logs. It measured about 60mi, and was only 15KB in size.

[+paleolith]

I have found myself standing on top of a cache and my eXplorist 210 says I'm 350' away.

 

I've learned to turn it off and back on if I don't find the cache immediately. This often changes the reported position by 20' to 100'.

 

In the case noted above, I cycled it and it said I was only 100' away. Plowed into the bushes and zeroed on an unlikely spot. Cycled again and it pointed me 100' in yet another direction. Put it in my pocket, walked back to the obvious location, spent five minutes looking around and found the cache there.

 

I'm wondering if this is common experience with all units, or only with the 210, or only with mine.

 

My guess is that it's a software issue. I know enough about the math required to know that the solution to the GPS equations could settle into a local minimum which is away from the best solution and have trouble breaking out of it. This is tricky business. (Think of trying to find the lowest spot in a nearly flat valley by always going downhill. A puddle isn't always the lowest spot.) Some GPSrs might have better solftware for solving the equations. However, this is definitely only a guess.

 

Edward