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Re: [Discuss-gnuradio] GPS with DBSRX, Almost There

From: Gregory W Heckler
Subject: Re: [Discuss-gnuradio] GPS with DBSRX, Almost There
Date: Tue, 06 Mar 2007 16:57:55 -0500
User-agent: Thunderbird 2.0b2 (Windows/20070116)


From what I see it does not continuously stream data, which is a requirement for my needs. Additionally I am looking at recording GPS L2C and the new Galileo frequencies, so a tuneable front end is a must.


Brian Padalino wrote:
On 3/6/07, Gregory W Heckler <address@hidden> wrote:
I've noticed that the DLL of my software receiver settles to +15 Hz, and
the true IF is +24 kHz from the predicted IF. This would indicate that
the 64 MHz board clock is ~1 kHz from its spec value. This, in itself is
not a problem, but I was wondering if this was within tolerances of the
onboard XO?

I believe the XO on the USRP has a 50ppm spec, so 1kHz is well within that.

The real problem lies in the fact that the carrier tracking loop (a 3rd
order PLL) of my software receiver cannot achieve phase lock. The phase
jitter looks high, and the LO frequency drifts so much it dominates over
the Doppler derived from satellite motion.

If anyone would like any GPS IF data I would be happy to email it to
your personal email address (indicate how many seconds of data you would
like). Thanks!

On a side note, have you seen that SiGe device available from Spark
Fun Electronics?  I posted earlier today about it.  It might be of



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