diff options
author | Dimitri Stolnikov <horiz0n@gmx.net> | 2012-05-31 00:44:01 +0200 |
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committer | Dimitri Stolnikov <horiz0n@gmx.net> | 2012-05-31 01:36:22 +0200 |
commit | 2037ebeac6382ffae565c3c0ad92d0a234af2661 (patch) | |
tree | 032ad3876561ec96635cfc3f5caa9c6f284f0ac8 /src/demod | |
parent | 617dacf7b9c571abd74459f26dd05b33e1487176 (diff) |
add rtlsdr based receiver with click & tune functionality
Call it with
src$ ./demod/python/rtlsdr-tetra_demod_fft.py -s 1.8e6 -f 394.6e6 -g -1 -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 Full Spectrum window to roughly select a TETRA carrier.
- Use left click to fine tune the carrier by clicking on the left or right side of the spectrum.
Diffstat (limited to 'src/demod')
-rwxr-xr-x | src/demod/python/rtlsdr-tetra_demod_fft.py | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/src/demod/python/rtlsdr-tetra_demod_fft.py b/src/demod/python/rtlsdr-tetra_demod_fft.py new file mode 100755 index 0000000..49cf2a0 --- /dev/null +++ b/src/demod/python/rtlsdr-tetra_demod_fft.py @@ -0,0 +1,151 @@ +#!/usr/bin/env python + +# Copyright 2012 Dimitri Stolnikov <horiz0n@gmx.net> + +# Call it with +# src$ ./demod/python/rtlsdr-tetra_demod_fft.py -s 1.8e6 -f 394.6e6 -g -1 -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 Full Spectrum window to roughly select a TETRA carrier. +# Use left click 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, audio, eng_notation, blks2, optfir +from gnuradio import audio +from gnuradio.eng_option import eng_option +from gnuradio.wxgui import fftsink2 +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.src = osmosdr.source_c() + self.src.set_center_freq(options.frequency) + self.src.set_sample_rate(int(options.sample_rate)) + + if options.gain is None: + self.src.set_gain_mode(1) + else: + self.src.set_gain_mode(0) + self.src.set_gain(options.gain) + + # may differ from the requested rate + sample_rate = self.src.get_sample_rate() + + symbol_rate = 18000 + sps = 2 # output rate will be 36,000 + new_sample_rate = symbol_rate * sps + + options.low_pass = options.low_pass / 2.0 + + taps = gr.firdes.low_pass(1.0, sample_rate, options.low_pass, options.low_pass * 0.2, gr.firdes.WIN_HANN) + + first_decim = 10 + + self.offset = 0 + + self.tuner = gr.freq_xlating_fir_filter_ccf(first_decim, taps, self.offset, sample_rate) + + sys.stderr.write("sample rate: %d\n" % (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 = gr.file_sink(gr.sizeof_float, options.output_file) + + rerate = float(sample_rate / float(first_decim)) / float(new_sample_rate) + sys.stderr.write("resampling factor: %f\n" % rerate) + + #self.resamp = gr.fractional_interpolator_cc(0, rerate) + self.resamp = blks2.pfb_arb_resampler_ccf(1 / rerate) + + self.connect(self.src, self.tuner, self.resamp, self.demod, self.output) + + def fftsink2_callback(x, y): + sys.stderr.write("selected channel at offset: %d Hz\n" % x) + self.offset = -x + self.tuner.set_center_freq(self.offset) + + self.scope = fftsink2.fft_sink_c(self.GetWin(), + title="Full Spectrum (click to coarse tune)", + fft_size=1024, + sample_rate=sample_rate, + ref_scale=2.0, + ref_level=-30, + y_divs=10, + fft_rate=10, + average=False, + avg_alpha=0.6) + + self.Add(self.scope.win) + self.scope.set_callback(fftsink2_callback) + + self.connect(self.src, self.scope) + + def fftsink2_callback2(x, y): + sys.stderr.write("fine tuning channel: %d Hz\n" % x) + self.offset = self.offset - (x / 10) + self.tuner.set_center_freq(self.offset) + + self.scope2 = fftsink2.fft_sink_c(self.GetWin(), + title="Narrow Spectrum (click to fine tune)", + fft_size=1024, + sample_rate=new_sample_rate, #sample_rate / first_decim, + ref_scale=2.0, + ref_level=-30, + y_divs=10, + fft_rate=10, + average=False, + avg_alpha=0.6) + + self.Add(self.scope2.win) + self.scope2.set_callback(fftsink2_callback2) + + self.connect(self.resamp, self.scope2) + +def get_options(): + parser = OptionParser(option_class=eng_option) + + 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=394.6e9, + 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) |