Hello Derek, I thought the “set_time_unknown_pps” checks to confirm that the time is correctly set? If that doesn’t, how do I know that the sync is set correctly without using a spectrum analyzer?
Thanks From: Derek Kozel [mailto:derek.ko...@ettus.com] Sent: Wednesday, August 2, 2017 7:33 AM To: Cho, Daniel J (332C) <daniel.j....@jpl.nasa.gov> Cc: usrp-users@lists.ettus.com Subject: Re: [USRP-users] PPS sync with USRP E310 timeout error Hello Daniel, There is no check in your code to confirm that the time is correctly set. The 1PPS signal should be a square wave rather than a sine wave. It is a logic signal rather than an RF one and the sync port is designed to handle it. http://files.ettus.com/manual/page_usrp_e3x0.html#e3x0_hw_pps The Octoclock which we use produces a 20% duty cycle square wave with 5V high and 0V low. Regards, Derek On Wed, Aug 2, 2017 at 2:10 AM, Cho, Daniel J (332C) via USRP-users <usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com>> wrote: Hello – I am using 2 USRP E310 which I would like to frequency sync together. I am using a frequency generator which is generating a 1 PPS (1Hz sine wave) signal which I put through a power splitter to provide both USRPs with the same 1 PPS signal. I configured the rx_samples_to_file and tx_samples_from_file codes to allow me to use the external 1PPS signal by including the following into the code: //sleep off if gpsdo detected and time next pps already set boost::this_thread::sleep(boost::posix_time::seconds(1)); //set time source if specified if (not time_source.empty()) usrp->set_time_source(time_source); //set the time at an unknown pps (will throw if no pps) std::cout << std::endl << "Attempt to detect the PPS and set the time..." << std::endl << std::endl; usrp->set_time_unknown_pps(uhd::time_spec_t(0.0)); std::cout << std::endl << "Success!" << std::endl << std::endl; When I run the rx_samples_to_file code with the above code included, I get a timeout error. I found that it was due to the line “usrp->set_time_unknown_pps(uhd::time_spec_t(0.0));” How can I get my two USRPs frequency synced without getting this error? Also, I saw that the 1 PPS signal provided to the USRP should be 3.3V – 5V. When I put a 1 PPS signal that strong on the spectrum analyzer, it shows a power output above +10 dBm. I know that the max RX input power is -15 dBm so I was hesitant to input a 1 PPS signal that strong. The 1 PPS signal I put into the sync port was 100 mV. Even with a 1 PPS signal with an output power of 100mV, I am still able to run the test_pps_input program successfully. So in summary, should I just send a 1 PPS signal with a power output above +10 dBm which equates to the 3.3V – 5V to the sync port even though I am able to run the test_pps_input program successfully with 100mV? How can I get the rx_samples_to_file program to run successfully without giving me a timeout error using the above lines of code? Thanks _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com<mailto:USRP-users@lists.ettus.com> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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