Ultimate GPS V3 Speed Limiting Behavior

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heroglider
 
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Ultimate GPS V3 Speed Limiting Behavior

Post by heroglider »

Hello,

I know it has yet to be tested above 40km, but could the Ultimate GPS v3 theoretically obtain a GPS lock at ~150km altitude? How long might it take to obtain a lock at that altitude if it was previously lost? Would the altitude reading be at all accurate?

Also, if the speed were to remain above 515m/s for a period of time (where the chip will refuse to provide data due to the speed restriction) and then drop back below that speed, would the data resume reporting automatically or would a power cycle be required?

Thanks!

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adafruit_support_mike
 
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Re: Ultimate GPS V3 Speed Limiting Behavior

Post by adafruit_support_mike »

The basic rule of thumb WRT GPS capabilities is: "would this make life easier for someone who wanted to build their own ballistic or cruise missiles?" If the answer to that question is "yes", just let it go. You can't possibly make an argument compelling enough to outweigh the evil someone could do with the same technology and capabilities.

Would getting a lock above 150km make life easier for the bomb-makers? Yes. Let it go.

Would getting a lock quickly and easily after dropping below 515m/s make life easier for the bomb makers? Yes. Let it go.

adafruit
 
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Re: Ultimate GPS V3 Speed Limiting Behavior

Post by adafruit »

yeah there's pretty much no way you will get it to work above ~50km, thats a firmware max! we've never managed to get it to go 515m/s so we think it probably locks up

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heroglider
 
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Re: Ultimate GPS V3 Speed Limiting Behavior

Post by heroglider »

Thank you for answering my questions, adafruit. I contacted the manufacturer (GlobalTop) of the PA6H (w/ MTK3339 chip), they indicated that the only reason they weren't sure it would work at 100-150km is because it hasn't been tested yet at that altitude. From what I've gathered, only speed is limited on this chip (please correct me if I'm wrong). 50km seems rather arbitrary, are you sure that's in the newest firmware?

Also, they indicated that once speed returns to under 515 m/s, NMEA reporting would automatically continue, as opposed to locking out.

For the record, this is for a public university project, with clearance from the proper governmental agencies.

Thanks again!

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nova smith
 
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Re: Ultimate GPS V3 Speed Limiting Behavior

Post by nova smith »

Sounds to me a firmware update is needed, lol.

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