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
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