Re: [Discuss-gnuradio] Receive GPS L1 Signal

[Eddie Sun]

Thanks for the reply, but i still have some questions.

2011/6/21 John Andrews <address@hidden>

A USRP is a baseband IF receiver. Tune it to the GPS L1 frequency with the right decimation rate so that you have your band of interest selected. This should give you the IF signal.

The source block that i used is the "UHD:usrp_source block" for USRP N210 in gniradio companion, after setting the frequency to L1 frequency 1575.42MHz, there is no "decimation" term can be set in the block(only usrp1_source and usrp2_source block have that term, not uhd), so should i use the "Rational resampler" block to instead of it? or other method to complete the decimation.

The flow graph will only be
"UHD:usrp_source block"→"Rational resampler"→"File sink"
is that right?

And I'm still a little confused, why i don't need to down convert the frequency but just do the decimation, i thought decimation is to slowdown the sample rate.

Is that mean the flow graph output from "UHD:usrp_source block" is already a IF signal? If this is true, what is that signal frequency? It can't still have the 1575.42MHz if it's a IF signal, isn't it?

Thanks,

Eddie