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Opinion --- Do GPSrs wear out?


ibycus
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The other day I was out caching while on holiday. Went for a 'micro in the parking lot', just to be able to say I'd found a cache in California. Anyways, I've been away from the game for a while (still am, really, thanks to school/work keeping me very busy), and when I powered up my GPSr, it was giving me to strange behavior.

 

I had a clear view of the sky, good fix on lots of sats (estimated error 4m), but the GPS would periodically zero out in one place, and then 2 seconds later, would say I was 30m away, I'd go where it said, and it direct me back to another point.

 

It was probably some weird sat configuration, or maybe some kind of multipath issue, but I'd never experienced quite this type of problem before with my trusty 60CS, and I've cached in all kinds of terrain. I'm wondering if there might be some kind of hardware issue going on (Nice fresh batteries in it too).

 

Thoughts?

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How long had it been since you powered up the GPS?? And how long was it running before it started this behavior? Could be the result of an outdated almanac. And although 30m is a little far, could just be the result of the unit recalculating its position and your proximity to the location.

 

Just one guess.

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Almanac data not being sufficient comes to mind as JBnW mentioned - but your guess of multipath fade, distortion in a metropolitan area could also be the culprit.

 

Just a thought - since the state of California is paying their state employees with I.O.U.'s it could also be possible that they are Jamming GPS signals to prevent Californians from finding their way out...

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The other day I was out caching while on holiday. Went for a 'micro in the parking lot', just to be able to say I'd found a cache in California. Anyways, I've been away from the game for a while (still am, really, thanks to school/work keeping me very busy), and when I powered up my GPSr, it was giving me to strange behavior.

 

I had a clear view of the sky, good fix on lots of sats (estimated error 4m), but the GPS would periodically zero out in one place, and then 2 seconds later, would say I was 30m away, I'd go where it said, and it direct me back to another point.

 

It was probably some weird sat configuration, or maybe some kind of multipath issue, but I'd never experienced quite this type of problem before with my trusty 60CS, and I've cached in all kinds of terrain. I'm wondering if there might be some kind of hardware issue going on (Nice fresh batteries in it too).

 

Thoughts?

 

Yep they die, we had 3 Etrex Legends bite the dust and our 60C is about to go. It has a switch problem so I have to keep it cool to start it and pop a battery if it gets too hot to shut it off.

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If you had a solid fix, it's probably not due to almanac issues. Certainly, the almanac was out of date when you powered up. But the only thing that would cause is a long time until you got the initial fix. The GPSr would have had to perform a full sky search to locate the satellites overhead at the time. But once it identified the satellites and acquired ephemeris data from each, the almanac was no longer relevant. In other words, a fix is a fix is a fix -- no matter how you got there.

 

What you are describing is classic multi-path issues, possibly coupled with a poor constellation. The fact that you have lots of satellites does not mean you will necessariliy get an accurate fix. The geometry has a lot to do with it.

 

And yes, like all electronic devices, GPSrs do wear out. Even the non-moving parts are eventually affected by heat, humidity, and so forth. Since the unit is mostly digital, you'd hope for a catastrophic failure rather than just poor performance, but I guess anything is possible.

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Technically yes they do wear out, but realistically a GPS will last almost forever if kept in good condition. Unlike other electronics, GPSrs have little moving parts, experience little temperature fluctuation internally (less fatigue, unlike a computer on the other hand), and are for the most part, self-correcting.

 

Case in point, I still have a GPS 90 from 1995 that works like it did from day one. My etrex legend from 2002, still works like it did from the beginning.

 

It is all dependent on how well you take care of it.

Edited by Tahoe Skier5000
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I agree with Tahoe Skier5000. My Sony gps (circa 1991) is almost like new and my Trimble Scout (circa 1992) works A1, although the lcd display has some dead pixels. My eTrex yellow, bought in 2001, is in better shape than my 3 year old eTrex Venture Cx. I keep good care of all of them.

 

It seems that gps receivers are replaced for newer and better features more than anything else, which makes it a buyer's market for collectors of old equipment. I paid under $100 for both the Sony and Trimble, but they were $1000 and $800 new, respectively. Unfortunately they aren't so great for geocaching and they eat batteries like crazy.

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I agree with Tahoe Skier5000. My Sony gps (circa 1991) is almost like new and my Trimble Scout (circa 1992) works A1, although the lcd display has some dead pixels. My eTrex yellow, bought in 2001, is in better shape than my 3 year old eTrex Venture Cx. I keep good care of all of them.

 

It seems that gps receivers are replaced for newer and better features more than anything else, which makes it a buyer's market for collectors of old equipment. I paid under $100 for both the Sony and Trimble, but they were $1000 and $800 new, respectively. Unfortunately they aren't so great for geocaching and they eat batteries like crazy.

:( My GPS "Wears out" a little more every time a newer model comes out! LOL

 

Sorry - I couldn't resist

 

DD

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