1 files changed, 255 insertions, 0 deletions
diff --git a/src/demod/osmosdr-tetra_demod_fft.py b/src/demod/osmosdr-tetra_demod_fft.py
new file mode 100755
index 0000000..81fbe9d
--- /dev/null
+++ b/src/demod/osmosdr-tetra_demod_fft.py
@@ -0,0 +1,255 @@
+#!/usr/bin/env python
+
+# Copyright 2012 Dimitri Stolnikov <horiz0n@gmx.net>
+
+# Usage:
+# src$ ./demod/python/osmosdr-tetra_demod_fft.py -o /dev/stdout | ./float_to_bits /dev/stdin /dev/stdout | ./tetra-rx /dev/stdin
+#
+# Adjust the center frequency (-f) and gain (-g) according to your needs.
+# Use left click in Wideband Spectrum window to roughly select a TETRA carrier.
+# In Wideband Spectrum you can also tune by 1/4 of the bandwidth by clicking on the rightmost/leftmost spectrum side.
+# Use left click in Channel Spectrum windows to fine tune the carrier by clicking on the left or right side of the spectrum.
+
+
+import sys
+import math
+from gnuradio import gr, gru, eng_notation, blocks, filter
+from gnuradio.filter import pfb
+from gnuradio.eng_option import eng_option
+from gnuradio.wxgui import fftsink2, scopesink2, forms, TRIG_MODE_AUTO
+from grc_gnuradio import wxgui as grc_wxgui
+from optparse import OptionParser
+import osmosdr
+import wx
+
+try:
+    import cqpsk
+except:
+    from tetra_demod import cqpsk
+
+# applies frequency translation, resampling and demodulation
+
+class top_block(grc_wxgui.top_block_gui):
+  def __init__(self):
+    grc_wxgui.top_block_gui.__init__(self, title="Top Block")
+
+    options = get_options()
+
+    self.ifreq = options.frequency
+    self.rfgain = options.gain
+
+    self.src = osmosdr.source(options.args)
+    self.src.set_center_freq(self.ifreq)
+    self.src.set_sample_rate(int(options.sample_rate))
+
+    if self.rfgain is None:
+        self.src.set_gain_mode(1)
+        self.iagc = 1
+        self.rfgain = 0
+    else:
+        self.iagc = 0
+        self.src.set_gain_mode(0)
+        self.src.set_gain(self.rfgain)
+
+    # may differ from the requested rate
+    sample_rate = self.src.get_sample_rate()
+    sys.stderr.write("sample rate: %d\n" % (sample_rate))
+
+    symbol_rate = 18000
+    sps = 2 # output rate will be 36,000
+    out_sample_rate = symbol_rate * sps
+
+    options.low_pass = options.low_pass / 2.0
+
+    if sample_rate == 96000: # FunCube Dongle
+        first_decim = 2
+    else:
+        first_decim = 10
+
+    self.offset = 0
+
+    taps = filter.firdes.low_pass(1.0, sample_rate, options.low_pass, options.low_pass * 0.2, filter.firdes.WIN_HANN)
+    self.tuner = filter.freq_xlating_fir_filter_ccf(first_decim, taps, self.offset, sample_rate)
+
+    self.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)
+
+    self.output = blocks.file_sink(gr.sizeof_float, options.output_file)
+
+    rerate = float(sample_rate / float(first_decim)) / float(out_sample_rate)
+    sys.stderr.write("resampling factor: %f\n" % rerate)
+
+    if rerate.is_integer():
+        sys.stderr.write("using pfb decimator\n")
+        self.resamp = pfb.decimator_ccf(int(rerate))
+    else:
+        sys.stderr.write("using pfb resampler\n")
+        self.resamp = pfb.arb_resampler_ccf(1 / rerate)
+
+    self.connect(self.src, self.tuner, self.resamp, self.demod, self.output)
+
+    self.Main = wx.Notebook(self.GetWin(), style=wx.NB_TOP)
+    self.Main.AddPage(grc_wxgui.Panel(self.Main), "Wideband Spectrum")
+    self.Main.AddPage(grc_wxgui.Panel(self.Main), "Channel Spectrum")
+    self.Main.AddPage(grc_wxgui.Panel(self.Main), "Soft Bits")
+
+    def set_ifreq(ifreq):
+        self.ifreq = ifreq
+        self._ifreq_text_box.set_value(self.ifreq)
+        self.src.set_center_freq(self.ifreq)
+
+    self._ifreq_text_box = forms.text_box(
+        parent=self.GetWin(),
+        value=self.ifreq,
+        callback=set_ifreq,
+        label="Center Frequency",
+        converter=forms.float_converter(),
+    )
+    self.Add(self._ifreq_text_box)
+
+    def set_iagc(iagc):
+        self.iagc = iagc
+        self._agc_check_box.set_value(self.iagc)
+        self.src.set_gain_mode(self.iagc, 0)
+        self.src.set_gain(0 if self.iagc == 1 else self.rfgain, 0)
+
+    self._agc_check_box = forms.check_box(
+        parent=self.GetWin(),
+        value=self.iagc,
+        callback=set_iagc,
+        label="Automatic Gain",
+        true=1,
+        false=0,
+    )
+
+    self.Add(self._agc_check_box)
+
+    def set_rfgain(rfgain):
+        self.rfgain = rfgain
+        self._rfgain_slider.set_value(self.rfgain)
+        self._rfgain_text_box.set_value(self.rfgain)
+        self.src.set_gain(0 if self.iagc == 1 else self.rfgain, 0)
+
+    _rfgain_sizer = wx.BoxSizer(wx.VERTICAL)
+    self._rfgain_text_box = forms.text_box(
+        parent=self.GetWin(),
+        sizer=_rfgain_sizer,
+        value=self.rfgain,
+        callback=set_rfgain,
+        label="RF Gain",
+        converter=forms.float_converter(),
+        proportion=0,
+    )
+    self._rfgain_slider = forms.slider(
+        parent=self.GetWin(),
+        sizer=_rfgain_sizer,
+        value=self.rfgain,
+        callback=set_rfgain,
+        minimum=0,
+        maximum=50,
+        num_steps=200,
+        style=wx.SL_HORIZONTAL,
+        cast=float,
+        proportion=1,
+    )
+
+    self.Add(_rfgain_sizer)
+
+    self.Add(self.Main)
+
+    def fftsink2_callback(x, y):
+        if abs(x / (sample_rate / 2)) > 0.9:
+            set_ifreq(self.ifreq + x / 2)
+        else:
+            sys.stderr.write("coarse tuned to: %d Hz\n" % x)
+            self.offset = x
+            self.tuner.set_center_freq(self.offset)
+
+    self.scope = fftsink2.fft_sink_c(self.Main.GetPage(0).GetWin(),
+        title="Wideband Spectrum (click to coarse tune)",
+        fft_size=1024,
+        sample_rate=sample_rate,
+        ref_scale=2.0,
+        ref_level=0,
+        y_divs=10,
+        fft_rate=10,
+        average=False,
+        avg_alpha=0.6)
+
+    self.Main.GetPage(0).Add(self.scope.win)
+    self.scope.set_callback(fftsink2_callback)
+
+    self.connect(self.src, self.scope)
+
+    def fftsink2_callback2(x, y):
+        self.offset = self.offset - (x / 10)
+        sys.stderr.write("fine tuned to: %d Hz\n" % self.offset)
+        self.tuner.set_center_freq(self.offset)
+
+    self.scope2 = fftsink2.fft_sink_c(self.Main.GetPage(1).GetWin(),
+        title="Channel Spectrum (click to fine tune)",
+        fft_size=1024,
+        sample_rate=out_sample_rate,
+        ref_scale=2.0,
+        ref_level=-20,
+        y_divs=10,
+        fft_rate=10,
+        average=False,
+        avg_alpha=0.6)
+
+    self.Main.GetPage(1).Add(self.scope2.win)
+    self.scope2.set_callback(fftsink2_callback2)
+
+    self.connect(self.resamp, self.scope2)
+
+    self.scope3 = scopesink2.scope_sink_f(
+        self.Main.GetPage(2).GetWin(),
+        title="Soft Bits",
+        sample_rate=out_sample_rate,
+        v_scale=0,
+        v_offset=0,
+        t_scale=0.001,
+        ac_couple=False,
+        xy_mode=False,
+        num_inputs=1,
+        trig_mode=TRIG_MODE_AUTO,
+        y_axis_label="Counts",
+    )
+    self.Main.GetPage(2).Add(self.scope3.win)
+
+    self.connect(self.demod, self.scope3)
+
+def get_options():
+    parser = OptionParser(option_class=eng_option)
+
+    parser.add_option("-a", "--args", type="string", default="",
+        help="gr-osmosdr device arguments")
+    parser.add_option("-s", "--sample-rate", type="eng_float", default=1800000,
+        help="set receiver sample rate (default 1800000)")
+    parser.add_option("-f", "--frequency", type="eng_float", default=394.4e6,
+        help="set receiver center frequency")
+    parser.add_option("-g", "--gain", type="eng_float", default=None,
+        help="set receiver gain")
+
+    # demodulator related settings
+    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__':
+        tb = top_block()
+        tb.Run(True)