OK got your file, and it is working fine here on a N210+WBX, and a B200, when fed with a signal generator.
1) You must be using GR 3.6 or earlier as some blocks don't import into 3.7.5. I replaced the rational resampler and nbfm_rx with your same settings. 2) I assume you are using an USRP2 or N2x0 since you are using an IP address. The gain should be 31 maximum for the WBX. I measure the minimum detectable signal at this gain is about -90 dBm, for 1 kHz tone on NBFM with 5 KHz deviation. 3) I also added a resampler to 48k, 10x gain, and an audio sink. I did verify the wav file is being written. Are you sure you are on frequency and signal is strong enough? Any tune warning from UHD? Can you tune a strong signal like 162.55 MHz NOAA, or equivalent in your area? At least you are getting noise. <http://gnuradio.4.n7.nabble.com/file/n49889/uhd_rx_sample.png> Thanks, Lou KD4HSO madengr wrote > Post your GRC file. I tried it just as you implemented and it is working > here. I would have choose different sample rates and topology, but > nonetheless it works. Gain of 100 (dB) should not be a valid UHD value as > it tops out at 81 for the B200, and 31 for the WBX. It still works > though. > > Can you trace the signal down the flow with the GUI instrumentation? > Weaver, Tyler [GCS] wrote >> MPT1327 uses MSK on its control channel. I am attempting to use NBFM >> Receive to demodulate the signal into a WAV file that I can play back and >> use sdrtrunk to decode it. So far my best attempt is set up as follows: >> >> USRP >> Sample Rate: 250k >> Center Freq: 652.625M >> Gain: 100 >> >> Frequency Xlating FIR Filter >> Decimation: 1 >> Taps: firdes.low_pass(100,samp_rate,10e3,1e3) >> Center Frequency: 0 >> Sample Rate: 250k >> >> Rational Resampler >> Decimation: 250k >> Interpolation: 192k >> >> NBFM Receive >> Audio Rate: 192k >> Quadrature Rate 192k >> >> Wav File Sink >> Sample Rate: 192k >> Bits per Sample: 16 >> >> The output of this seems to be just noise and is not working. >> >> Thank you. >> >> --tyler >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@ >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio -- View this message in context: http://gnuradio.4.n7.nabble.com/Demodulating-a-MPT1327-signal-tp49824p49889.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
