123 lines
4.8 KiB
Python
123 lines
4.8 KiB
Python
#!/usr/bin/env python
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##################################################
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# Gnuradio Python Flow Graph
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# Title: GSM wideband input adaptor
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# Author: Piotr Krysik
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# Co-author: Pieter Robyns
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# Description: Adaptor of input stream for the GSM receiver. Contains frequency ofset corrector doing also resampling to integer multiplies of GSM sample rate and LP filter filtering GSM channel.
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##################################################
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from gnuradio import filter
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from gnuradio import gr
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from gnuradio import eng_notation
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from gnuradio.filter import firdes
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import grgsm.arfcn as arfcn
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import grgsm
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class gsm_wideband_input(grgsm.hier_block):
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def __init__(self, ppm=0, osr=4, fc=925.2e6, samp_rate_in=20e6, ca=[], band='P-GSM'):
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self.num_streams = len(ca)
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grgsm.hier_block.__init__(
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self, "GSM wideband input adaptor",
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gr.io_signature(1, 1, gr.sizeof_gr_complex*1),
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gr.io_signature(self.num_streams, self.num_streams, gr.sizeof_gr_complex*1),
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)
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##################################################
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# Parameters
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##################################################
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self.ppm = ppm
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self.osr = osr
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self.fc = fc
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self.samp_rate_in = samp_rate_in
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self.ca = ca
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self.blocks_fir_filters = {}
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self.blocks_resamplers = {}
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self.blocks_ocs = {}
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self.band = band
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##################################################
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# Variables
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##################################################
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self.samp_rate_out = samp_rate_out = 1625000.0/6.0*osr
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##################################################
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# Blocks
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##################################################
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self.ppm_in = None
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self.message_port_register_hier_in("ppm_in")
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#self.lpf = firdes.low_pass(1, samp_rate_out, 125e3, 5e3, firdes.WIN_HAMMING, 6.76)
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self.lpf = firdes.low_pass(1, samp_rate_in, 125e3, 75e3, firdes.WIN_HAMMING, 6.76)
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self.gsm_clock_offset_corrector_0 = grgsm.clock_offset_corrector(
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fc=fc,
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ppm=ppm,
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samp_rate_in=samp_rate_in,
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)
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center_arfcn = arfcn.downlink2arfcn(fc, band)
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fc_str = eng_notation.num_to_str(fc)
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print("Extracting channels %s, given center frequency at %sHz (ARFCN %d)" % (str(ca), fc_str, center_arfcn))
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self.connect((self, 0), (self.gsm_clock_offset_corrector_0, 0))
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output_port = 0
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for channel in ca:
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channel_freq = arfcn.arfcn2downlink(channel, band)
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if channel_freq is None:
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print("Warning: invalid ARFCN %d for band %s" % (channel, band))
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continue
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freq_diff = channel_freq - fc
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freq_diff_str = "+" if 0 <= freq_diff else ""
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freq_diff_str += eng_notation.num_to_str(freq_diff)
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print("ARFCN %d is at %sHz %sHz" % (channel, fc_str, freq_diff_str))
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self.blocks_resamplers[channel] = filter.fractional_resampler_cc(0, samp_rate_in/samp_rate_out)
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self.blocks_fir_filters[channel] = filter.freq_xlating_fir_filter_ccc(1, self.lpf, freq_diff, samp_rate_in)
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self.connect((self.gsm_clock_offset_corrector_0, 0), (self.blocks_fir_filters[channel], 0))
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self.connect((self.blocks_fir_filters[channel], 0), (self.blocks_resamplers[channel], 0))
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self.connect((self.blocks_resamplers[channel], 0), (self, output_port))
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output_port += 1
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##################################################
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# Asynch Message Connections
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##################################################
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self.msg_connect(self, "ppm_in", self.gsm_clock_offset_corrector_0, "ppm_in")
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def get_ppm(self):
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return self.ppm
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def set_ppm(self, ppm):
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self.ppm = ppm
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self.gsm_clock_offset_corrector_0.set_ppm(self.ppm)
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def get_fc(self):
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return self.fc
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def set_fc(self, fc):
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self.fc = fc
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self.gsm_clock_offset_corrector_0.set_fc(self.fc)
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def get_osr(self):
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return self.osr
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def set_osr(self, osr):
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self.osr = osr
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self.set_samp_rate_out(1625000.0/6.0*self.osr)
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def get_samp_rate_in(self):
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return self.samp_rate_in
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def set_samp_rate_in(self, samp_rate_in):
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self.samp_rate_in = samp_rate_in
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for channel in self.blocks_resamplers:
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self.blocks_resamplers[channel].set_resamp_ratio(self.samp_rate_in / self.samp_rate_out)
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self.gsm_clock_offset_corrector_0.set_samp_rate_in(self.samp_rate_in)
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def get_samp_rate_out(self):
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return self.samp_rate_out
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def set_samp_rate_out(self, samp_rate_out):
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self.samp_rate_out = samp_rate_out
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for channel in self.blocks_resamplers:
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self.blocks_resamplers[channel].set_resamp_ratio(self.samp_rate_in / self.samp_rate_out)
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