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From: | John Shields |
Subject: | Re: [Discuss-gnuradio] Python synchronisation of 2xUSRP N200 with SBX in one UHD container. |
Date: | Mon, 18 Sep 2017 21:21:21 +0000 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 |
On 18/09/17 20:52, Marcus D. Leech wrote:
On 09/18/2017 03:49 PM, John Shields wrote:Integer-N will help, but my understanding of the ADF4351 is that the re-synch feature, enabled through timed commands, will also work.Thanks,I have attached the GRC. I should note that before I run, I wait until GPS is locked as evinced by the query_gpsdo_sensor utility:GPS Locked Trying to align the device time to GPS time... GPS and UHD Device time are aligned. last_pps: 1505763709 vs gps: 1505763709. Printing available NMEA strings:GPS_GPGGA: $GPGGA,194149.00,4331.1729,S,17234.2461,E,2,09,1.5,32.2,M,8.5,M,,*7B GPS_GPRMC: $GPRMC,194149.00,A,4331.1729,S,17234.2461,E,0.2,0.0,180917,,*20GPS Epoch time at last PPS: 1505763710.00000 seconds UHD Device time last PPS: 1505763710.00000 seconds UHD Device time right now: 1505763710.01897 seconds PC Clock time: 1505763710 seconds Done! Kind Regards, Johnp.s. In Jan 2016, Nigel wrote that one of the steps needed to align included 'Use integer_N_ mode for PLL' when I tried to use the method you recommended, I got an error so ceased that line of investigation for the moment - is integer_N_mode tuning required?Also, the "uhd_fft" command has a --phase-relations option that will plot relative-phase between two input channels. You might look at that.
Thanks Marcus,I can see that uhd_fft has a phase-relations option but, as far as I can tell from looking at the source, it doesn't synch the channels so, just to make sure I understand the point of your e-mail, uhd_fft uses a QT widget to display relative phase and I could investigate modifying my FG to use that method to display relative phase between the two channels?
Kind Regards, John
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