On 2/1/12 10:12 AM, Attila Kinali wrote:
On Wed, 1 Feb 2012 09:27:30 -0800
Chris Albertson<[email protected]> wrote:
I thought it might be interresting but then found out you need to buy
$2,000+ worth of hardware for even start experimenting. Open Source
SDR needs to run on a common affordable platform or it will never gain
the critical mass of users that it take to make the project live
longer then a few months.
That's because the URSP is a general purpose system. It is designed
to do many things. That makes it expensive. And being expensive,
it has a low production volume, which makes it even more expensive.
I think, a specialized GPS SDR can be build for less than 500 USD
in low (a dozen at max) volumes.
I guestimate, that the RF/ADC part would cost somewhere between
100 to 200 USD in parts. The big uncertainty here is the FPGA.
I have no clue how much logic space for a GPS SDR would be needed
at minimum and how much would be desirable. Hence i have no guess
what the FPGA would cost (could be anything from a cheap 20USD
FPGA to a 300 USD one).
how many channels do you want to track at once?
I can tell you that you can track at least 12 channels simultaneously
with single bit ADC sampling at around 40 MHz in a pair of Virtex II
3000 parts. You might be able to do better (I don't know how full the
two FPGAs are). (that's the published spec for the radio we're flying
on the SCAN Testbed on ISS) It's actually a L1,L2,L5 receiver, but, of
course, the tracking loop is the same for all frequencies, whether you
track 12 S/Vs in L1 or 4 in all three channels.. it's all the same.
You'll have to do the nav solution in some sort of other processor..
that's just running the tracking loops and generating raw observables.
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