Hello everyone I am trying to achieve frequency hopping in GSM using twinrx with usrp x310. Here I am using timed command for tuning a single port across a given frequency list. During hopping it stays in each frequency for 4msecs and till the time frequency hopping continues, I am able to identify FCCH using phase difference. But as soon as the hopping is over and it tunes back to the actual frequency containing the broadcast channel, I am not getting phase difference greater than 0 and thus not able to demodulate the GSM burst. Can anyone please help where I am going wrong below is the snippet of the code, responsible for hopping.
Function handling hopping: uhd::tune_request_t tune_request(rf_freq); tune_request.rf_freq_policy = uhd::tune_request_t::POLICY_MANUAL; tune_request.dsp_freq_policy = uhd::tune_request_t::POLICY_MANUAL; tune_request.rf_freq = rf_freq; tune_request.dsp_freq = dsp_freq; uhd_src->set_rx_freq(tune_request, chan_num); { If(verbose_lvl==3){ char msg[100]={0x00}; sprintf(msg,"info: DSP freq: changed to channel %d: %fMHz offset %fMHz", chan_num, uhd_src->get_rx_freq(chan_num)/1e6, dsp_freq); vipl_printf(msg,error_lvl, __FILE__, __LINE__); } } //uhd_src->clear_command_time(); usleep(110000); // allow LOs to lock Module for setting back to original frequency with broadcast: uhd_src->clear_command_time(); uhd::tune_request_t tune_request(rf_freq, 0x00); //considering LO-Offset to be zero tune_request.rf_freq_policy = uhd::tune_request_t::POLICY_AUTO; tune_request.dsp_freq_policy = uhd::tune_request_t::POLICY_AUTO; tune_request.rf_freq = rf_freq; //tune_request.dsp_freq = -dsp_freq; uhd_src->set_rx_freq(tune_request, channel); { char msg[100]={0x00}; sprintf(msg,"info: freq: set to channel %d: %fMHz requested freq %fMHz", channel, uhd_src->get_rx_freq(channel)/1e6, rf_freq/1e6); vipl_printf(msg,error_lvl, __FILE__, __LINE__); } usleep(110000); My UHD version is 3.14.0.0 USRP: X310 Daughter board: 2 sets of Twinrx OS: Debian 10 Interface: 10gig sfp+ ethernet Thanks!! Regards Snehasish Kar Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
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