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Magellan GPS 315 -- off by ~100m


dfh99

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I am rocking a Magellan GPS315, and the coordinates it gives me are consistently off by upwards of about 100m -- the right vicinity, but pretty useless for geocaching. I have made sure it has a clear view of the sky, fresh batteries, time to average, &c. I am wondering if perhaps the projection/datum are wrong? I am using whatever the Magellan defaults to -- would this match the lat/long used by geocaching sites, google maps, and so on? The Magellan instruction book is fairly useless.

 

Thanks for any advice you can give--

 

Dan

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That's an old unit. Probably not WAAS enabled so it may never get any better than that. You could check the Magellan website for any software updates and install them if available.

 

That was my first GPS. A great unit at the time. In fact, I still have a 330m that I keep as a backup.

Good luck,

AF

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Thanks, Cacheoholic -- the datum was set to ASTRO, whatever that it is. Now that it is set to WGS84, it is working much better. I suspected this might have been the problem, but I just somehow couldn't seem to find the datum switch.

 

And thanks also to you, Amoebaface -- it is an older unit, and I am thinking I might pick up a newer unit at some point anyway.

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Just a quick note. I have been using the Magellan GPS315 until just a few weeks a go. I have compaired the accuracy with a Garmin 60Cx and a Magellan eXplorist 500 and in both cases the units matched almost exactly. I love the GPS 315's easy to use buttons and wish that my new eXplorist 500 had the same options for screens! I will keep my old 315 as a back-up GPSr unit as I still trust it to get me where I want to go

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What kind of an accuracy hit am I taking by not having the latest firmware (I've never updated, so the firmware is mid/late-90s vintage)? I would need to find and buy a data cable -- is it worth it, considering I may be buying a new unit at some point anyway?

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I’m guessing you are in the 15’ – 25’ range depending on your surrounding environment. Some people make a big deal about WAAS but many people have it intentionally turned off and still Geocache. The biggest shortfall with a 315 is no maps. Other than that, it’s a good old unit. I still have a couple that I loan out to people to try Geocaching. To find your firmware version turn on the unit. Press enter and the firmware version is the second line on that second screen. It will say:

 

GPS 315/320

REV 3.15

 

I’m guessing you probably have 3.07 firmware.

 

Is there anyone around you that has a Meridian or Sportrak that you could borrow their cable? I don’t think I would spend $15 - $20 for a cable if you are buying another GPS soon.

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I have an old 330 as a back up to my 60CSX. Your 315 is almost the same. The 330 is a lot slower to up-date it's postion. Just give it time to settle down when you get close to the cache. Other wise you will go past the cache and have to backtrack. FYI the 60CSX has almost the same button lay out. Other the the extra features the learning curve was very fast.

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What kind of an accuracy hit am I taking by not having the latest firmware (I've never updated, so the firmware is mid/late-90s vintage)? I would need to find and buy a data cable -- is it worth it, considering I may be buying a new unit at some point anyway?

 

Find This Benchmark and set your GPSr on it for a few minutes and then compare the coordinates on the 'datasheet' with you GPSr position coordinates. The benchmark coordinates are accurate to less than an inch. Your unit should get you within 10-15 feet of the benchmark.

 

This little test will tell how well your GPSr is doing and help you decide if you wish to upgrade.

 

John

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Will check it out, thanks (though if I test how accurate/inaccurate the gps is at the benchmark, will the GPS necessarily be as accurate/inaccurate in the field? Or is it a bit more random than that?).

 

What kind of an accuracy hit am I taking by not having the latest firmware (I've never updated, so the firmware is mid/late-90s vintage)? I would need to find and buy a data cable -- is it worth it, considering I may be buying a new unit at some point anyway?

 

Find This Benchmark and set your GPSr on it for a few minutes and then compare the coordinates on the 'datasheet' with you GPSr position coordinates. The benchmark coordinates are accurate to less than an inch. Your unit should get you within 10-15 feet of the benchmark.

 

This little test will tell how well your GPSr is doing and help you decide if you wish to upgrade.

 

John

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Will check it out, thanks (though if I test how accurate/inaccurate the gps is at the benchmark, will the GPS necessarily be as accurate/inaccurate in the field? Or is it a bit more random than that?).

 

What kind of an accuracy hit am I taking by not having the latest firmware (I've never updated, so the firmware is mid/late-90s vintage)? I would need to find and buy a data cable -- is it worth it, considering I may be buying a new unit at some point anyway?

 

 

Find This Benchmark and set your GPSr on it for a few minutes and then compare the coordinates on the 'datasheet' with you GPSr position coordinates. The benchmark coordinates are accurate to less than an inch. Your unit should get you within 10-15 feet of the benchmark.

 

This little test will tell how well your GPSr is doing and help you decide if you wish to upgrade.

 

John

 

 

If you do a goto just like you would do for a cache, then you will see how well your GPSr does with the current firmware. Most GPSrs will get the user within 15 feet of the benchmark so some hunting for the benchmark may be required. Be sure to print out the benchmark page to have along for the written description of where the benchmark is located. As accurate as the coordinates are, you want to make sure you have the coordinates entered correctly and have the description along just in case something has happened to the disk and you are having a problem finding it.

 

The coordinates for the benchmark were achieved using a Professional Grade GPSr costing several thousand dollars. Our GPSr will consistently get us within 10 feet of the benchmarks that have adjusted coordinates. If you leave the GPSr unit sit on the disk for a few minutes, it should read within (+ or - ) 00.003' on both the latitude and longitude of the given coordinates for that benchmark. These are typical field conditions and you can expect the results to follow through on other goto's that you do using that GPSr.

 

Hope this helps.

 

John

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My first GPS is a 315. I still got it and its in like new condition. Now i got a 60cx and i love it too as it does the extra things i want. Compare the two units the 60 gets the reading much faster and holds on better. But if i let the 315 sit for a min or two the reading are very close 90% of the time. Make sure you got the latest update for the 315 and its a keeper. It does seems like alot of the older units last a long time both from garmin and magelan. I guess they just do the basics.

 

Alex

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