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Ultimate GPS with USB external antenna for high altitude bal
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Please be positive and constructive with your questions and comments.

Ultimate GPS with USB external antenna for high altitude bal

by eagoergens on Thu Aug 13, 2020 6:44 pm

The Ultimate GPS with USB is limited to 60kft. If I use an external active GPS antenna that is not limited, will it work over 60kft? Thanks!

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Re: Ultimate GPS with USB external antenna for high altitude

by mikeysklar on Thu Aug 13, 2020 6:57 pm

We have reports of the Ultimate GPS being used above 105,000' and the firmware maxes out just over 131,000'.

We've received reports from customers that have tested this version of the Ultimate GPS module in a high-altitude balloon, and it kept fix up to ~32km! There is a (theoretical, untested) firmware limit of 40Km. However, we provide no guarantee that it will work in all HAB's.

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Re: Ultimate GPS with USB external antenna for high altitude

by eagoergens on Thu Aug 13, 2020 9:03 pm

Thank you. I understand that the non-USB version of the Ultimate GPS can go above 60kft. However, the PA6H chip on the USB version does not. My question is whether adding an active external antenna would remove that limit. I suspect the limit is in the decoding circuitry, but was hoping I could keep my existing equipment.

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Re: Ultimate GPS with USB external antenna for high altitude

by mikeysklar on Fri Aug 14, 2020 12:49 pm

As you originaly stated. The PA6H is rated up to 60,000' according to the spec sheet we have on it.

We have tested the PA6H chip up to 88,582'.

Code: Select all | TOGGLE FULL SIZE
 Maximum Altitude for PA6H: tested at 27,000 Meters


I don't think the antenna will be helpful for logging at higher elevation. Please note our FAQ entry on these GPS items.

Can the Ultimate GPS be used for High Altitude? How can I know?

Modules shipped in 2013+ (and many in the later half of 2012) have firmware that has been tested by simulation at the GPS factory at 40km.

You can tell what firmware you have by sending the firmware query command $PMTK605*31 (you can use the echo demo to send custom sentences to your GPS)

If your module replies with AXN_2.10_3339_2012072601 5223 that means you have version #5223 which is the 40Km-supported firmware version. If the number is higher then 5223 then its even more recent, and should include the 40Km support as well

HOWEVER these modules are not specifically designed for high-altitude balloon use. People have used them successfully but since we (at Adafruit) have not personally tested them for hi-alt use, we do not in any way guarantee they are suitable for high altitude use.
Please do not ask us to 'prove' that they are good for high altitude use, we do not have any way to do so
If you want to measure high altitude with a GPS, please find a module that can promise/guarantee high altitude functionality

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Re: Ultimate GPS with USB external antenna for high altitude

by eagoergens on Fri Aug 14, 2020 12:56 pm

Thank you!

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Please be positive and constructive with your questions and comments.