2009/8/8 Jonathan Coveney
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My goal is to be able to read a frequency other than the frequency that was tuned to draw samples using usrp_rcv_cfile (ie I used 93.3M, and want to be able to demodulate 92.5M...I'd try to use lessons learned from wfm_rcv2 but that uses set_rx_freq in the pipelines, which obviously I don't have access to)
Taking a cue from this http://www.nabble.com/Frequency-Hopping-td20538730.html
I tried to shift by -.8Mhz
mix_freq = -.8e6
Cosine = gr.sig_source_f(usrp_rate,gr.GR_COS_WAVE,mix_freq,1,0)
Sin = gr.sig_source_f(usrp_rate,gr.GR_SIN_WAVE,mix_freq,1,0)
self.expjw = gr.float_to_complex()
self.connect(Cosine,(self.expjw,0))
self.connect(Sin,(self.expjw,1))
self.mixer = gr.multiply_cc()
self.connect (self.u, (self.mixer, 0))
self.connect (self.expjw, (self.mixer, 1))
self.connect (self.mixer, gr.throttle(gr.sizeof_gr_complex, usrp_rate), chan_filt, self.guts, self.volume_control, audio_sink)
I also tried using freq_xlating_fir_filter_ccf (which googling looked like it was overkill) to no effect. In both cases I just hear a noisy version of 93.3M, I can't get it to focus on something that wasn't the center of the frequency that my samples were taken.
Any ideas?