I have a GnuRadio C++ program that decodes and records a SmartNet Trunked radio system. It is running great under GnuRadio 22.214.171.124, but it doesn’t seem to be working under 3.7.6.
3.6 is installed in /usr/local and 3.7.6 was installed in my home directory using PyBombs. My updated program compiles against 3.7 with no problem and runs. It will pick up a few of the trunking commands, so it is working, but the ratios is about 1 to 100 compared to 3.6. I also tried running it in a Ubuntu VM with 3.7 installed at /usr/local and had the same results.
I corrected for the change with XlatingFirFilter in 3.7, so it is the opposite offset of 3.6. It looks like it could be a tuning error though, the flow graph seems to be failing mostly at the CRC check. Did anything else change with Blocks in 3.7? I looked at gr-osmosdr but I didn’t notice huge discrepancies between the 3.6 and 3.7 branches.
Are there some obvious things I could be missing? I feel like this is something small and stupid that I missing.
Here is the central code block that does it. Anything obviously dumb here?
float samples_per_second = samp_rate;
float syms_per_sec = 3600;
float gain_mu = 0.01;
float omega_relative_limit = 0.3;
float offset = chan_freq - center_freq; // have to reverse it for 3.7 because it swapped in the switch.
float clockrec_oversample = 3;
int decim = int(samples_per_second / (syms_per_sec * clockrec_oversample));
float sps = samples_per_second/decim/syms_per_sec;
const double pi = boost::math::constants::pi<double>();
cout << "Control channel offset: " << offset << endl;
cout << "Decim: " << decim << endl;
cout << "Samples per symbol: " << sps << endl;
init_loggers(max_loggers, center_freq, samp_rate);
gr::msg_queue::sptr queue = gr::msg_queue::make();
lpf_taps = gr::filter::firdes::low_pass(1, samp_rate, 10000, 12000);
gr::filter::freq_xlating_fir_filter_ccf::sptr prefilter = gr::filter::freq_xlating_fir_filter_ccf::make(decim,
gr::digital::fll_band_edge_cc::sptr carriertrack = gr::digital::fll_band_edge_cc::make(sps, 0.6, 64, 0.35);
gr::analog::pll_freqdet_cf::sptr pll_demod = gr::analog::pll_freqdet_cf::make(2.0 / clockrec_oversample, 2*pi/clockrec_oversample, -2*pi/clockrec_oversample);
gr::digital::clock_recovery_mm_ff::sptr softbits = gr::digital::clock_recovery_mm_ff::make(sps, 0.25 * gain_mu * gain_mu, mu, gain_mu, omega_relative_limit);
gr::digital::binary_slicer_fb::sptr slicer = gr::digital::binary_slicer_fb::make();
gr::digital::correlate_access_code_tag_bb::sptr start_correlator = gr::digital::correlate_access_code_tag_bb::make("10101100",0,"smartnet_preamble");
smartnet_deinterleave_sptr deinterleave = smartnet_make_deinterleave();
smartnet_crc_sptr crc = smartnet_make_crc(queue);
tb->connect(carriertrack, 0, pll_demod, 0);
tb->connect(pll_demod, 0, softbits, 0);
tb->connect(softbits, 0, slicer, 0);
tb->connect(slicer, 0, start_correlator, 0);
tb->connect(start_correlator, 0, deinterleave, 0);
tb->connect(deinterleave, 0, crc, 0);