RE: 2 SDRs – Parallel Programming

[Oğuzhan Gedikli]

def switch_source(usrp_source, freq, lo_offset):

    start_souce = time.perf_counter()

    # time.sleep(2)

    usrp_source.set_center_freq(uhd.tune_request(freq, rf_freq=freq - lo_offset,

                                                 rf_freq_policy=uhd.tune_request.POLICY_MANUAL), 0)

    end_souce = time.perf_counter()

    print("Source Switch Time: ", end_souce - start_souce)

def switch_sink(usrp_sink, freq, lo_offset):

    start_sink = time.perf_counter()

    # time.sleep(2)

    usrp_sink.set_center_freq(uhd.tune_request(freq, rf_freq=freq - lo_offset,

                                               rf_freq_policy=uhd.tune_request.POLICY_MANUAL), 0)

    end_sink = time.perf_counter()

    print("Sink Switch Time: ", end_sink - start_sink)

sw_start = time.perf_counter()

with ThreadPoolExecutor(max_workers=2) as ex:

    futures = [

        ex.submit(switch_source, usrp_source=self.uhd_usrp_source_0, freq=freqList[j], lo_offset=lo_offset),

        ex.submit(switch_sink, usrp_sink=self.uhd_usrp_sink_0, freq=freqList[j], lo_offset=lo_offset)]

    wait(futures, timeout=None, return_when=ALL_COMPLETED)

sw_end = time.perf_counter()

print("Total Switch Time: ", sw_end - sw_start)

Hello Jim,

I am sending the code you see above that I wrote before as an example. If you enable the time.sleep(2) commands, you will see that the 'Total Switch Time' takes about 2.2 seconds (this is what I observed). This brings me to the point that if the processor had performed the operation serially it should have taken more than 4 seconds, but instead it took '2 + switch time'. In fact, if you look at it, the code is played in parallel.

The problem starts here: When I comment on the time.sleep(2) commands, and leave only the switch commands, my observation is that it takes about 200 ms and this process takes place serially. Somehow, the SDRs lock the processor and the other one does not start until the process of one is finished. I will try this without the 'Usb Hub', in fact, if you look, it can actually serialize the process.