Add UHD based demodulator script (tested with N200+WBX)

src/demod/python/uhd-tetra_demod.py

@@ -0,0 +1,119 @@
+#!/usr/bin/env python
+
+import sys
+import math
+from gnuradio import gr, gru, audio, eng_notation, blks2, optfir
+from gnuradio import uhd
+from gnuradio.eng_option import eng_option
+from optparse import OptionParser
+
+# Load it locally or from the module
+try:
+    import cqpsk
+except:
+    from tetra_demod import cqpsk
+
+# accepts an input file in complex format 
+# applies frequency translation, resampling (interpolation/decimation)
+
+class my_top_block(gr.top_block):
+    def __init__(self, options):
+        gr.top_block.__init__(self)
+
+        # Create a UHD source
+        self._u = uhd.usrp_source(
+               device_addr=options.device_addr,
+               io_type=uhd.io_type.COMPLEX_FLOAT32,
+               num_channels=1)
+        
+        sample_rate = 100e6/512
+        symbol_rate = 18000
+        sps = 2
+        
+        # set sampling rate and antenna port
+        self._u.set_samp_rate(sample_rate)
+        self._u.set_antenna(options.antenna, 0)
+        
+        # output rate will be 36,000
+        ntaps = 11 * sps
+        new_sample_rate = symbol_rate * sps
+        
+        # Set receive daughterboard gain
+        if options.gain is None:
+            g = self._u.get_gain_range()
+            options.gain = float(g.stop()+g.start())/2
+            print "Using mid-point gain of", options.gain, "(", g.start(), "-", g.stop(), ")"
+        self._u.set_gain(options.gain)
+ 
+        # Set receive frequency
+        if options.lo_offset is not None:
+            self._u.set_lo_offset(options.lo_offset)
+
+        tr = self._u.set_center_freq(options.freq)
+        if tr == None:
+            sys.stderr.write('Failed to set center frequency\n')
+            raise SystemExit, 1
+
+        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._u, FILTER, INTERPOLATOR, DEMOD, OUT)
+
+def get_options():
+    parser = OptionParser(option_class=eng_option)
+    # usrp related settings
+    parser.add_option("-d", "--device_addr", type="string", default="",
+                      help="UHD device address [default=%default]")
+    parser.add_option("-a", "--antenna", type="string", default="TX/RX",
+                      help="daughterboard antenna [default=%default]")
+    parser.add_option("-f", "--freq", type="eng_float", default=None,
+                      help="set frequency to FREQ", metavar="FREQ")
+    parser.add_option("-g", "--gain", type="eng_float", default=None,
+                      help="set gain in dB (default is midpoint)")
+    parser.add_option("", "--lo-offset", type="eng_float", default=None,
+                      help="set daughterboard LO offset to OFFSET [default=hw default]")
+
+    # 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
+    
+    if options.freq is None:
+        parser.print_help()
+        sys.stderr.write('You must specify the frequency with -f FREQ\n');
+        raise SystemExit, 1
+    
+    return (options)
+
+if __name__ == "__main__":
+    (options) = get_options()
+    tb = my_top_block(options)
+    try:
+        tb.run()
+    except KeyboardInterrupt:
+        tb.stop()