Congrats Paul!
I don't think I mentioned it on list, but PSAS flew a rocket a couple
of weeks ago with our home-built raw-RF GPS board. We also have high
quality IMU data from the flight.
We're still clawing our way through the data. Very early results are
promising, we can see what looks like Doppler shifts due to rocket
velocity in the data, just from a few instantaneous cross correlation
results. we don't have full solutions yet. However it's starting to
look like we had some data loss. Not sure why or how much but I think
our log is peppered with dozens of millisecond long holes.
Our raw data is here:
http://annex.psas.pdx.edu/Launch-12/
However it's packed in a binary format. See
https://github.com/psas/psas_packet for reference, but probably just
wait until we finish unpacking everything, we'll host the GPS and IMU
logs in the same location when we've exhausted our data recovery
efforts.
Paul, is there any chance you would be willing to share your raw RF
data? We'd love to run it through our soft correlator.
(https://github.com/psas/gps)
-Nathan
PSAS
On Mon, Aug 3, 2015 at 12:37 PM, Lars Osborne <lars.osborne@xxxxxxxxx> wrote:
You can use an accelerometer to estimate doppler with the stationary
frequency source.
That would be great. It sounds hard though.
At that point, why not skip the ground station and try to compensate for the
crystal's frequency shift using the on-board accelerometers?
Thanks,
Lars Osborne
On Mon, Aug 3, 2015 at 12:48 AM, George Herbert <george.herbert@xxxxxxxxx>
wrote:
You can use an accelerometer to estimate doppler with the stationary
frequency source.
George William Herbert
Sent from my iPhone
On Aug 2, 2015, at 6:54 PM, Ken Biba <kenbiba@xxxxxx> wrote:
Perhaps. Below 500 m/s I simply do not see that.
Ken Biba
Novarum, Inc.
415-577-5496
On Aug 2, 2015, at 6:52 PM, Henrik Schultz <henrik@xxxxxx> wrote:
Doppler shift kills that idea - rocket is travelling away from frequency
reference at high velocity. Some are using that for determining speed, so it
is noticable.
/H
------ Original Message ------
From: "George Herbert" <george.herbert@xxxxxxxxx>
To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
Sent: 8/2/2015 6:23:42 PM
Subject: [AR] Re: GPS again....
Out of curiosity... Has anyone considered a different frequency source
while under acceleration?
Freerunning PLL? Have a crystal on the ground transmitting the frequency?
...
George William Herbert
Sent from my iPhone