new_contents: #!/usr/bin/env python
  
  import sys
  import math
  from gnuradio import gr, gru, audio, eng_notation, blks2, optfir
  from gnuradio import audio
  from gnuradio.eng_option import eng_option
  from gnuradio.wxgui import stdgui2, fftsink2
  from optparse import OptionParser
  
  try:
      import cqpsk
  except:
      from tetra_demod import cqpsk
  
  # applies frequency translation, resampling (interpolation/decimation) and cqpsk demodulation
  
  class my_top_block(stdgui2.std_top_block):
      def __init__(self, frame, panel, vbox, argv):
          stdgui2.std_top_block.__init__(self, frame, panel, vbox, argv)
  
  	self.frame = frame
  	self.panel = panel
  
  	options = get_options()
  
  	sample_rate = int(options.sample_rate)	
  
  	self.asrc = audio.source(sample_rate, options.audio_device, True)
  
  	self.f2c = gr.float_to_complex(1)
  
  	self.connect((self.asrc, 1), (self.f2c, 1))
  	self.connect((self.asrc, 0), (self.f2c, 0))
  
          symbol_rate = 18000
          sps = 2
          # output rate will be 36,000
          ntaps = 11 * sps
          new_sample_rate = symbol_rate * sps
  
          channel_taps = gr.firdes.low_pass(1.0, sample_rate, options.low_pass, options.low_pass * 0.1, gr.firdes.WIN_HANN)
  
          FILTER = gr.freq_xlating_fir_filter_ccf(1, channel_taps, options.calibration, sample_rate)
  
          sys.stderr.write("sample rate: %d\n" %(sample_rate))
  
          DEMOD = cqpsk.cqpsk_demod( samples_per_symbol = sps,
                                   excess_bw=0.35,
                                   costas_alpha=0.03,
                                   gain_mu=0.05,
                                   mu=0.05,
                                   omega_relative_limit=0.05,
                                   log=options.log,
                                   verbose=options.verbose)
  
          OUT = gr.file_sink(gr.sizeof_float, options.output_file)
  
          r = float(sample_rate) / float(new_sample_rate)
  
          INTERPOLATOR = gr.fractional_interpolator_cc(0, r)
  
          self.connect(self.f2c, FILTER, INTERPOLATOR, DEMOD, OUT)
  
  	self.scope = fftsink2.fft_sink_c(panel, fft_size=512,
  					 sample_rate=sample_rate,
  					 ref_scale=2.0,
  					 ref_level=-30, y_divs=10,
  					 fft_rate=10,
  					 average=True,
  					 avg_alpha=0.2)
  	self.connect(self.f2c, self.scope)
  
  def get_options():
      parser = OptionParser(option_class=eng_option)
  
      parser.add_option("-r", "--sample-rate", type="eng_float", default=96000,
  	          help="set sample rate to RATE (96000)")
      parser.add_option("-D", "--audio-device", type="string", default="",
  	          help="pcm input device name.  E.g., hw:0,0 or /dev/dsp")
  
      # demodulator related settings
      parser.add_option("-c", "--calibration", type="int", default=0, help="freq offset")
      parser.add_option("-l", "--log", action="store_true", default=False, help="dump debug .dat files")
      parser.add_option("-L", "--low-pass", type="eng_float", default=25e3, help="low pass cut-off", metavar="Hz")
      parser.add_option("-o", "--output-file", type="string", default="out.float", help="specify the bit output file")
      parser.add_option("-v", "--verbose", action="store_true", default=False, help="dump demodulation data")
      (options, args) = parser.parse_args()
      if len(args) != 0:
          parser.print_help()
          raise SystemExit, 1
  
      return (options)
  
  if __name__ == "__main__":
      app = stdgui2.stdapp(my_top_block, "OsmoTETRA FCDP", nstatus=1)
      app.MainLoop()
  
subject: add FCDP based modulator with FFT output during demodulation