bizarre etrex readings

[Guest guerroloco]

I was on my way to visit a friend in St. Louis last weekend, just after (unsuccessfully) looking for a cache, & I happened to turn on my GPS receiver while tooling down I-64. Now, maybe I'm not the most cautious driver, but I'm pretty sure I wasn't going 324 mph! Also, the distance to my friend's house (which I had waypointed) was given as 600+ miles in the opposite direction, not the actual figure of about 15 miles. I turned the receiver off and on, & it was back to normal. Still, I wonder what could have caused such bizarre readings. Any ideas?

[Guest BGSkierNC]

I have an eTrex Summit and when I turn it on after moving 100+ miles from the last time I used it prompts me (on the screen) to ask whether I have moved several hundred miles from the last location. Perhaps you had moved many miles since you last used yours.

 

Also, getting a sat lock while traveling may have caused the error. Next time, try getting the first lock while you are not moving.

BG

[Guest PneumaticDeath]

I haven't had this happen to me, but I hear that sometimes the GPSR gets two sattelites confused, and that leads to very unusual results.

 

-- Mitch

[Guest Markwell]

It's been a while since I first watched this informational website on how the GPS system works (Click Here) but I seem to remember a section on accommodating clock errors. The site talks about using three sat locks and that, while in motion, it could report your position quite a ways off, and moving at a very fast (unreasonable) speed.

 

Usually, the GPSRs are designed to detirmine which of the two possible readings from a 3 sat lock is the logical one based on that unusual speed. In your case it sounds like it chose the wrong one.

 

That's why most GPSRs need a fourth sat for good readings. That eliminates that possibility of error.

 

Man, I'm starting to agree with my wife...I'm such a GEEK about this stuff!

 

[This message has been edited by Markwell (edited 31 July 2001).]