Re: [Discuss-gnuradio] GPS, DBS-RX, and interference?

[Matt Ettus]

Krzysztof Kamieniecki wrote:
> GPS update:
>   I have my GPS simulated signal source and GPS correlator working in
> GNURadio.
>   I also have the DBS-RX up and running.
>   Next step is to feed the DBS-RX signal into the GPS correlator, and
> get them to work together.
> 
> Questions:
> While using dbs_debug.py I have come across a signal at ~1575.254 MHz
> (while the GPS L1 signal should be at 1575.42MHz) Could the frequency be
> that far off on the DBS-RX board, or is this some sort of
> interference/real signal? If I put my hand close to the antenna the
> signal attenuates to the noise floor. Any ideas?


The oscillator on the USRP is spec'ed to 50 ppm, so you could be as much
as 79 kHz off plus doppler.  The hand near antenna experiment confirms
that it is an external signal, not something on the USRP/DBSRX.

Matt