Dear Marcus, Thank you for your comment. For the moment we have not used RFNoC, but if it helps measuring the replay latency, of course we could look at it. Would that work for measuring the recording latency as well? Do you recommend some configuration or strategy to find actual latency for a record and replay of IQ samples? In any case I should check the RFNoC documentation.
Regards Raul Nieto From: Marcus D. Leech <[email protected]> Sent: jueves, 2 de febrero de 2023 16:40 To: [email protected] Subject: [USRP-users] Re: USRP x300 timing calibration On 02/02/2023 04:56, Raúl Nieto Freire wrote: Dear URSP community, I'd like to launch some questions about the USRP x300 hardware (timing) calibration for a RF Record and Replay experiment using multifrequency GNSS, therefore using the two available RF frontends. I appreciate any help or hint you may provide. The samples recording and replaying starts when a 1 PPS edge is detected.Also a very stable 10 MHz source is used. Would it be possible to measure the actual latency between the time a 1 PPS comes to the sma input port and the actual moment of the samples recording/replaying? If I'm not wrong this would give us, after a GNSS software demodulation and the latency removing, the total propagation delay from the GNSS antenna phase center to the internal USRP DAC. 1. Record setup: USRP x300 is connected to a RF splitter + DC block + and to a GNSS antenna for the recording setup. 1. Replay setup: USRP x300 is connected to the splitter as a combiner to join the two RF channels + DC block + 20dB atenuattor and its output to a GNSS receiver. To perform our tests we have been using the UHD software and we are able to aligned our 1 PPS to a GNSSt timescale. Thank you very much. Best regards, Raul Nieto You're presumably using RFNoC to do the replay? Because otherwise, latency is wildly unpredictable. P Please consider the environment before printing this e-mail.
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