USRP 2920 for GPS

[abedyassine93]

Greetings,

I am currently doing my final year project. The project requires me to transmit a GPS signal with the desired coordinates through a USRP. The problem is that I only have a USRP 2920, which is not GPS disciplined. I searched the web for a solution, and found two OCXO clock modules that may help. The two modules are:

1) GPS1300-10-1000

2) PT626 - 1000 - GPS

I need to know if the above modules may help me or not before buying any? If yes, which one is better? If not, What do you recommend to do in this case?

On another note, do I need to have the LabVIEW GPS toolkit, or can I work without it when generating the GPS signals ?

Thanks for your time.

Regards. 

[JÞB]

the USRP should be capable of streaming IQ data fast enough to simulate a GPS constelation.  There are a few tricks:

-First you need to generate a raw file that would simulate the signal seen at any point from a GPS contelation.  The GPS toolkit is useful to generate this file but feel free to do all the calculations yourself.

-Then you wind up with questions about the unit you are trying to use to recieve thee simulated GPS signal.  You can't just ask a guy nicely to shut off GPS for a bit to get all those real satalite signals out of your way so, you might just drive the reciever insane when it sees a mix of real and simulated signals and can't decide where or when it is (The reciever thinks its in a tardus driven by a drunken timelord)

-Finally you need to think about the oscillator stability (Like you seem to have started doing) since if the timebase has too much jitter the it will appear ecaxtly the same (to the reciever) that all those satillites are shaking and wobbling up there in orbit.  Most revievers look at quality of signal and screen out "Bad" satalites before they attempt to get a fix.

With all that in mind-  You are better off quering NSAT (Number of satalites the reciever sees) and ignore weather or not you can get a fix.