Hi Young,
I am not an expert, but I have three suggestions:
1) Using 'Unknown PSS' or any other sync method should not have no
affect, as this is for syncing two or more USRPs. You have only one FPGA
and that is in sync with itself ;)
2) Did you tried using timed commands? (see function set_command_time())
3) If that does not work, maybe the FPGA can handly only one command at
a time - even if you tell him to execute two. Then it may be possible to
start one command timed before the other and extend that sequence of
samples with the correct amount of zeros.
Best regards,
Fabian
Am 30.07.2018 um 08:34 schrieb YoungC_Park via USRP-users:
Hi all,
I hope someone could help me on my situation. I could not find similar
cases on the usrp archive.
I have one USRP X310 that has UBX-160(slot A) , LFTX board(slot B) and
GPS module installed.
- my UHD is 3.11.0
- Using uhd API based on tx_samples from_file.cpp, I can generate dual
output bursts from UBX160 and LFTX with 200MHz master clock and 100Msps
on USRP X310.
- However, the second output (ch 1, red in the picture) is lagged from
the first one (ch 0, yellow) by about (~10us with +-4us uncertainty)
- The baseband burst is a sawtooth waveform of two cycles(2000 samples
long). and UBX160 modulates it into fc = 1GHz whereas LFTX generates it
as is.
- This lagging is quite constant (10us) even if I change the sampling
rate (10,20,50, 100MSps).
- Tried 'Unknown PPS', 'gpsdo', 'internal',,, but no difference.
- When I switch the order of channels to (1,0) as opposed to (0,1), then
the ch0 lags behind the ch1, which seems that this is related to some
sequenced process…
We are seeking for helps on the cause and cure about this lagging…
Thanks,
Young C. Park
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