Re: [Paparazzi-devel] question about paparazzi on sounding rocket

[Hector Garcia de Marina]

Thanks for the explanation Chris,

I believed that for an accurate and fast estimation, the GPS system required ASIC/FPGAs "expensive" propietary architectures, more than one receptor along the fuselage (allowing for measuring Euler angles), etc.

One off-topic question, is the hardware is not a limit, why some GPS modules are limited to about 20km of altitude? is this done deliberated? and this is not an actual limitation in firmware/hardware? I can not see why the system could work at 13km of altitude and not at 20km, the atmosphere layer is the same, the signal/line of sight should be better, etc.

On Tue, Feb 14, 2012 at 11:29 AM, Chris Gough <address@hidden> wrote:

About GPS measuring Ground Speed and ECEF Position at high velocity, I really do not know about how the accuracy is affected, Doppler effect, etc.

It's not physics, it's firmware. Limits are result of treaties.

Http://armscontrol.org/documents/mtcr

See section 11.

But it seems that you need an expensive GPS module.

The firmware/hardware isn't more expensive, only the paperwork. You have to prove you won't pass it on, among other things.

Chris Gough

Héctor.

On Tue, Feb 14, 2012 at 2:34 AM, Chris Gough <address@hidden> wrote:

> Does the paparazzi code accomodate velocities as large as Mach 2- Mach 3?

I don't know, sorry (don't see why not though, try it in
simulation...). Maybe someone else can comment on that.

Do I understand you correctly:
 * the rocket will go directly where you aimed it, it's not actively "navigated'
 * the autopilot is not responsible for maintaining vertical attitude
 * your instruments require a constant orientation (roll in the
rocket's frame of reference) during the preiod between boost and apex.
 * your experiments require position and attitude logging during the
same flight phase.

Chris Gough


> Best regards,

> Florin Mingireanu
>
>
>
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