HAB: Dragino GPS module should be usable

[Al Johnson]

The Seeed page for the Dragino [1] lists the dynamic maximum altitude, 18km,
but that 's not the whole story. It uses a Quectel L80 [2] and they say it has
a Balloon Mode for altitudes up to 80km. unfortunately you need username and
password to get to the command reference. Other people seem to have found the
correct command to enable Balloon Mode:
$PMTK886,3*2B<cr><lf>
Formatting and checksumming is like an NMEA sentence, and PMTK is MediTek's
namespace - the L80 uses their MTK3339 chip. I've seen the same namespace used
in some GlobalTop GPS module datasheets, but that command isn't in them.
The most interesting reference to this I saw was in a github project [3] for a
hab payload and groundstation. The comment in the source file [4] has the
explanation of the sentence above, but the commit note says it's untested.
Another source [5] gives a link to the docs for the Quectel L76 [6] which has
essentially the same documentation for PMTK886 as the source above.

I've not seen anyone say they've had success using this module in a flight.
This would make it an interesting secondary payload as we'd be able to report
one way or the other.

[1] https://www.seeedstudio.com/Raspberry-Pi-LoRa%2FGPS-Hat-support-868M-frequency-p-2695.html
[2] http://quectel.com/product/l80.htm
[3] https://github.com/kgoba/zinoo
[4] https://github.com/kgoba/zinoo/blob/master/firmware/lora-sky/src/
quectel.cpp
[5] https://forum.pycom.io/topic/2442.rss
[6] http://quectel.com/UploadImage/Downlad/
Quectel_L76_Series_Protocol_Specification_V2.0.pdf#%5B%7B%22num%22%3A133%2C
%22gen%22%3A0%7D%2C%7B%22name%22%3A%22XYZ%22%7D%2C51%2C510%2C0%5D

[Tony Brookes]

Hi

The GPS project Al & I had a go at a few years ago has an MTK3339 chip connected to an Arduino. It’s sat there being unused…..From memory, the 3339 documentation was somewhat opaque at the best of times.

Tony

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