[USRP-users] B210 Re-tuning in rx_timed_samples causes timeout after fixed number of samples

Patrick Sathyanathan wpats at hotmail.com
Tue Jul 21 21:25:52 EDT 2015


Hi,
 
Ping... anyone know what the issue is and how to fix it ?
 
Thanks,
 
--Patrick
 
> To: usrp-users at lists.ettus.com
> Date: Sat, 18 Jul 2015 18:24:33 -0700
> Subject: [USRP-users] B210 Re-tuning in rx_timed_samples causes timeout after fixed number of samples
> From: usrp-users at lists.ettus.com
> 
> Hi,
> 
> I modified the rx_timed_samples example to measure retuning time on my B210. I added the following function to retune as in the UHD manual:
> 
> void retune(uhd::usrp::multi_usrp::sptr usrp, double frequency)
> {
>   uhd::tune_request_t tune_req(frequency, 0);
>   tune_req.args = uhd::device_addr_t("mode_n=integer");
>   boost::timer my_timer;
>   usrp->set_rx_freq(tune_req);
>   while (not usrp->get_rx_sensor("lo_locked").to_bool()) {
>     //sleep for a short time in milliseconds
>     boost::this_thread::sleep(boost::posix_time::milliseconds(10));
>   }
>   double lo_lock_time = my_timer.elapsed();
>   printf("Retune to %g time = %g ms\n", frequency, lo_lock_time*1000);
> }
> 
> And before the while loop in the main function:
> 
>     double frequency = 100e6;
>     double increment = 16e6;
>     retune(usrp, frequency);
>     frequency += increment;
> 
> and at the end of the while loop:
> 
>         retune(usrp, frequency);
>         frequency += increment;
> 
> When I run the sample with: "rx_timed_samples --nsamps 10000000"
> I get the following timeout error after exactly 80169 samples. The last few lines of the output are:
> 
> Received packet: 2044 samples, 1 full secs, 0.512107 frac secs
> Retune to 7.08e+08 time = 1.021 ms
> Received packet: 2044 samples, 1 full secs, 0.512434 frac secs
> Retune to 7.24e+08 time = 1.315 ms
> Received packet: 453 samples, 1 full secs, 0.512761 frac secs
> Retune to 7.4e+08 time = 1.16 ms
> OReceive timeout before all samples received...
> 
> Done!
> 
> This happens every time I run it after exactly the same number of samples. I have tried increasing the timeout value to 0.3 from 0.1 but that doesn't work.
> 
> My UHD version is: linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.009.git-186-geb9cfef4
> 
> What is going on and how can I fix it ?
> 
> Thanks,
> 
> --Patrick
> 
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