On 09/18/2017 05:21 PM, John Shields wrote:
On 18/09/17 20:52, Marcus D. Leech wrote:
On 09/18/2017 03:49 PM, John Shields wrote:
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,,*20
GPS 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,
John
p.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?
Integer-N will help, but my understanding of the ADF4351 is that the
re-synch feature, enabled through timed commands, will also work.
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?
Yes, or add features to uhd_fft to do full phase-synch dancing.
It already has --clock-source --time-source and --sync options. You
could modify it to add the timed-commands thing.
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