[time-nuts] Slightly OT - GPS-Based Accurate Direction Finding

Attila Kinali attila at kinali.ch
Thu Aug 26 15:24:47 UTC 2010

On Thu, 26 Aug 2010 06:58:01 -0700
jimlux <jimlux at earthlink.net> wrote:

> If you get a bit "closer to the metal" you could use two GPS L1 samplers 
> running off a common clock, and do the PN code acq and track, which 
> would give you carrier phase.  If you do the nav solution, you know the 
> "look angle" to the various SVs, which would tell you the phase 
> differential vs azimuth.
> I believe that there are open source codes out there to do the 
> processing.  The data rate isn't all that high.. the GPS samplers are 1 
> bit.  There's certainly lots of papers from grad students on this kind 
> of thing.

Yes, but for this you have either to build a GPS module yourself,
which is not trivial (neither is it to get GPS chips in single 
quantities) or you have to get one of those GPS experimentation
boards which are not really cheap.

Not to mention that you are then running your own GPS code
which is probably more than the OP was asking for.

IMHO it's simpler to use available precision modules that provide
phase data and use that for the caluculation. If additional accuracy
is required, both modules can be modified to run from the same OCXO
instead of the TXCO they usually use.

			Attila Kinali
If you want to walk fast, walk alone.
If you want to walk far, walk together.
		-- African proverb

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