Heckler, Gregory W. (GSFC-596.0) wrote:
Have you ruled out the USRP overflowing? I have had that problem bite me
too. It causes all of the tracking
channels to dump in my receiver, but I could see how it could also cause
a jump in the frequency estimate
(delay in time domain == shift in frequenc
acquisition.
-Original Message-
From: [EMAIL PROTECTED] on behalf of Chris Stankevitz
Sent: Mon 6/2/2008 8:54 PM
To: Heckler, Gregory W. (GSFC-596.0)
Cc: discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] DBSRX used for GPS: cycle slip
Heckler, Gregory W. (GSFC-596.0) wrote:
> I
Heckler, Gregory W. (GSFC-596.0) wrote:
I was referring to the Doppler estimate output by your PLL over time
(traditional tracking), whereas
you indicated that you were looking at repeated acquisition attempts.
Greg,
While performing traditional tracking with a PLL using "prompt"
accumulatio
6/2/2008 6:34 PM
To: Heckler, Gregory W. (GSFC-596.0)
Cc: 'discuss-gnuradio@gnu.org'
Subject: Re: [Discuss-gnuradio] DBSRX used for GPS: cycle slip
Gregory W Heckler wrote:
> Chris:
>
> So you are not tracking the signal in the traditional sense, only
> looking at t
Gregory W Heckler wrote:
Chris:
So you are not tracking the signal in the traditional sense, only
looking at the frequency and delay estimate of your FFT acquisition. How
far spaced are your Doppler bins in the FFT acquisition? If you are
using a 1 ms integration time, and hence a 500 Hz bin
Chris:
So you are not tracking the signal in the traditional sense, only
looking at the frequency and delay estimate of your FFT acquisition. How
far spaced are your Doppler bins in the FFT acquisition? If you are
using a 1 ms integration time, and hence a 500 Hz bin spacing, if the
signal's
Peter Monta wrote:
How sudden are the shifts and how often do they happen? Do they look
They are sudden (happen within 10 ms) and they happen about once a
second. I visualize them by continuously acquiring a GPS signal and
watching the peak move along the freq axis in the 3D plot of freque
Matt Ettus wrote:
What are your PLL settings? If you minimize the R divide ratio, you
can eliminate this. The larger R divide will put you further from
right on frequency, but the DDC will put you right back in the right
place.
Yes. You can also try setting the frequency to 1575 rather t
Chris Stankevitz wrote:
Chris Stankevitz wrote:
I am seeing sudden freq shifts at the local oscillator on the order
of ~500Hz which make it impossible to track GPS.
It appears that this problem happens on only one of my two DBSRX boards.
What are your PLL settings? If you minimize the R div
Chris Stankevitz wrote:
I am seeing sudden freq shifts at the local oscillator on the order of
~500Hz which make it impossible to track GPS.
It appears that this problem happens on only one of my two DBSRX boards.
Chris
___
Discuss-gnuradio mailing
Chris Stankevitz wrote:
1. Can someone provide a schematic of the DBSRX in pdf or tell me how to
read the one at http://www.gnuradio.org/trac/browser/usrp-hw/trunk/dbsrx
I found that I can open the .ps version.
Thanks,
Chris
___
Discuss-gnuradio
Hi,
I am seeing sudden freq shifts at the local oscillator on the order of
~500Hz which make it impossible to track GPS.
We suspect under certain conditions there are cycle slips in the DBSRX PLL.
Questions:
1. Can someone provide a schematic of the DBSRX in pdf or tell me how to
read the
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