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Permalink Reply by Larry Grater on November 24, 2011 at 11:15am

Does anyone know of any >60k ft capable modules that have been integrated with APM?  I'm interested in using GPS for HAB cut-down, autorelease + navigation.  I will be running the MediaTek up in the simulator over the next few weeks but I'm pretty confident that I already know the outcome. This test will be mainly to see how well it recovers. I'd prefer not to fly open loop.  There is a 2010 thread mentioning Inventek though I don't see evidence that it's been integrated with APM.

Additionally, does anyone have experience with the BMP085 above it's 9k spec?

Regards,  Larry

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Permalink Reply by Gary Hunkin on January 22, 2012 at 6:18am

I have worked directly with sirf on high altitude , high dynamics firmware. I you have the sirf source code and
an arm ads or realview compiler you can make some changes. However there are still caps on aquisition dynamics etc.
SIRF have to supply you libraries to allow true high G, high dynamics. We supplied such software to military users only
after Sirf coverd the legal paperwork. Balloons only had to have peak altitude limits adjusted, this was less of an issue as they did not travel at speeds higher than say 120 knots.

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Permalink Reply by Ian Garcia on January 23, 2012 at 11:46am

Thanks for responding! (even though this was a while ago). I ended up with my tried and true Novatel which can have the limits easily removed for $1k but I am still interested on this if it's possible.

The project is for DARPA, so we could be considered "government users" to a certain extent. Do you still do this modification work?

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Permalink Reply by Gary Hunkin on January 23, 2012 at 12:24pm

Hi, I would ask my colleagues to supply the right firmware for the right module. It would have to be a Navman
Ss3 or Ss4 module. These are being used in mil and civil aerospace programs.You can check on navmanwirelessoem.com

They have now become part of Telit. But the LA based Navman Gps team are now the Gps core R&D for Telit.

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Permalink Reply by Larry Grater on January 23, 2012 at 8:24pm

There may be a couple of COTS receivers that will work though I share Gary's concern about high dynamics.  A couple are listed in this thread: Link  If you have access to a simulator you can test.  In my case high dynamics are most likely after balloon release.  The risk being that the reciever would loose GPS and not reaquire until the airframe is flying normally, perhaps to lower enough velocity.  The Venus GPS spec says that either limit, not both, can be violated (search SparkFun).  Another thread on this topic with more listings: link2 link3 Inventek GPS reference: Inventek.  Some anecdotal info from HAB launches exists since these payloads are travelling at relatively high velocities and spinning while either keeping GPS or reacquiring.  Some GPS position and velocity data is posted at various sites.  Hopefully this is helpful. 

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