[psas-software] Re: Real-time rocket tracking PSAS

Josh Triplett josh at psas.pdx.edu
Thu Dec 15 22:47:29 PST 2005


[CCed to the PSAS software list.]

Henk Hofstra wrote:
> We at NERO Haarlem would like to do the same. Would you be so kind to
> give us some pointers to get started? We own a u-blox module, which
> we are going to interface with a Pic18xxx, which is connected to a
> flight-controller via I2C. We are not currently usingt CAN, but we
> are planning to use this bus-system in the future. Hope to hear from
> you and we are happy to get some pointers to get us started.

Sorry for the greatly-delayed response; we had a less-than-optimal
"landing" of our most recent rocket, and thus we've been focusing on
getting the next rocket up and running, so I haven't been working on the
rocket-tracking stuff I started on.

The basic operation of the rocket-tracking method consisted of two
separate parts:

* Getting GPS data down to the ground; since we already transmit all CAN
messages down to the ground anyway, including all GPS messages, I simply
filtered out all but the GPS messages, and fed those to a FIFO.

* Tracking the rocket using that GPS data; this is the more challenging
issue.  I experimented with using gpsd and gpsdrive, but this solution
seemed unreliable, and the 2D display was not particularly suitable for
our purposes.  As part of our rocket simulator, we currently have a nice
3D real-time display of the rocket position relative to the earth (soon
to include the local landscape), and we're planning on detaching that
from the simulator and using it to track the actual rocket.

You might also be interested in the GPL-GPS project
<http://gps.psas.pdx.edu>, which provides a full GPS implementation
using Free Software and stock consumer GPS hardware.

>From a look at the NERO website, you're doing some pretty impressive
stuff with your rockets; our two groups should probably work together more.

- Josh Triplett
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