diff options
| -rwxr-xr-x | gr-uhd/examples/usrp_am_mw_rcv.py | 58 |
1 files changed, 27 insertions, 31 deletions
diff --git a/gr-uhd/examples/usrp_am_mw_rcv.py b/gr-uhd/examples/usrp_am_mw_rcv.py index b9132e45a..130bdcf56 100755 --- a/gr-uhd/examples/usrp_am_mw_rcv.py +++ b/gr-uhd/examples/usrp_am_mw_rcv.py @@ -74,30 +74,29 @@ class wfm_rx_block (stdgui2.std_top_block): self.freq = 0 # build graph - - #TODO: add an AGC after the channel filter and before the AM_demod - self.u = uhd.usrp_source(device_addr=options.address, io_type=uhd.io_type.COMPLEX_FLOAT32, num_channels=1) + + usrp_rate = 256e3 + demod_rate = 64e3 + audio_rate = 32e3 + chanfilt_decim = int(usrp_rate // demod_rate) + audio_decim = int(demod_rate // audio_rate) - usrp_rate = 256e3 self.u.set_samp_rate(usrp_rate) - usrp_rate = self.u.get_samp_rate() - - chanfilt_decim = 4 - demod_rate = usrp_rate / chanfilt_decim # 64 kHz - audio_decimation = 2 - audio_rate = demod_rate / audio_decimation # 32 kHz - - chan_filt_coeffs = gr.firdes.low_pass_2 (1, # gain - usrp_rate, # sampling rate - 8e3, # passband cutoff - 4e3, # transition bw - 60) # stopband attenuation + dev_rate = self.u.get_samp_rate() - #print len(chan_filt_coeffs) - self.chan_filt = gr.fir_filter_ccf (chanfilt_decim, chan_filt_coeffs) + # Resample signal to exactly self.usrp_rate + # FIXME: make one of the follow-on filters an arb resampler + rrate = usrp_rate / dev_rate + self.resamp = blks2.pfb_arb_resampler_ccf(rrate) + + chan_filt_coeffs = gr.firdes.low_pass_2 (1, # gain + usrp_rate, # sampling rate + 8e3, # passband cutoff + 4e3, # transition bw + 60) # stopband attenuation if self.use_IF: # Turn If to baseband and filter. @@ -107,8 +106,9 @@ class wfm_rx_block (stdgui2.std_top_block): usrp_rate) else: self.chan_filt = gr.fir_filter_ccf (chanfilt_decim, chan_filt_coeffs) - self.am_demod = gr.complex_to_mag() + self.agc = gr.agc_cc(0.1, 1, 1, 100000) + self.am_demod = gr.complex_to_mag() self.volume_control = gr.multiply_const_ff(self.vol) audio_filt_coeffs = gr.firdes.low_pass_2 (1, # gain @@ -116,25 +116,26 @@ class wfm_rx_block (stdgui2.std_top_block): 8e3, # passband cutoff 2e3, # transition bw 60) # stopband attenuation + self.audio_filt=gr.fir_filter_fff(audio_decim, audio_filt_coeffs) - self.audio_filt=gr.fir_filter_fff(audio_decimation,audio_filt_coeffs) # sound card as final sink self.audio_sink = audio.sink (int (audio_rate), options.audio_output, False) # ok_to_block # now wire it all together - self.connect (self.u, self.chan_filt, self.am_demod, - self.audio_filt, self.volume_control, - self.audio_sink) + self.connect (self.u, self.resamp, self.chan_filt, self.agc, + self.am_demod, self.audio_filt, + self.volume_control, self.audio_sink) self._build_gui(vbox, usrp_rate, demod_rate, audio_rate) if options.gain is None: g = self.u.get_gain_range() if True: - # if no gain was specified, use the mid gain - options.gain = (g.start() + g.stop())/2.0 + # if no gain was specified, use the mid gain + options.gain = (g.start() + g.stop())/2.0 + options.gain = g.stop() if options.volume is None: v = self.volume_range() @@ -163,7 +164,7 @@ class wfm_rx_block (stdgui2.std_top_block): return self.set_freq(kv['freq']) - if 1: + if 0: self.src_fft = fftsink2.fft_sink_c(self.panel, title="Data from USRP", fft_size=512, sample_rate=usrp_rate, ref_scale=32768.0, ref_level=0.0, y_divs=12) @@ -276,11 +277,6 @@ class wfm_rx_block (stdgui2.std_top_block): @param target_freq: frequency in Hz @rypte: bool - - Tuning is a two step process. First we ask the front-end to - tune as close to the desired frequency as it can. Then we use - the result of that operation and our target_frequency to - determine the value for the digital down converter. """ r = self.u.set_center_freq(target_freq + self.IF_freq, 0) |