On 06/15/2020 03:42 PM, Aaron Smith wrote:
I am using the python api.
usrp = uhd.usrp.MultiUSRP()
# Set gain, clock rate, sample rate etc...
usrp.set_clock_source('external')
usrp.set_time_source('external')
ts_reset = uhd.types.TimeSpec(0.0)
usrp.set_time_next_pps(ts_reset)
time.sleep(1.0)
last_pps = usrp.get_time_last_pps().to_ticks(1e9)
if last_pps % int(1e9) != 0:
print("Error failed to align clock")
# The signal is complex float data, scaled to a max amplitude of 0.9
approx 0.1 secs in duration
signal_data = numpy.fromfile('signal.dat',dtype=numpy.complex64)
wirefmt = 'sc16'
sa = uhd.usrp.StramArgs('fc32',wirefmt)
sa.channels = [0]
stream = usrp.get_tx_stream(sa)
# Send 3 seconds in future
send_time = usrp.get_time_last_pps().get_real_secs() + 3.0
metadata = uhd.type.TXMetadata()
metadata.has_time_spec = True
metadata.time_spec = uhd.types.TimeSpec(send_time)
stream.send(signal_data, metadata)
# Ensure the transmission is complete before returning
time.sleep(4.0)
sys.exit(0)
This probably has to do with uncertainty in the way the 1PPS signal is
flopped into the device. What sample rate are you using, and what
master clock rate?
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