Hello,
I currently have a B200 USRP that is supposed to transmit/receive a file after being triggered by a PPS signal. The current file is able to to do this if the PPS signal generator (I am using an FPGA for this and it is accurate enough for my needs) is already on and transmitting the signal before I execute my top_block.py file, but if I attempt to execute my .py file first and then start the PPS signal, then I get the error message:
1) catch time transition at pps edge
Traceback (most recent call last):
File "./top_block.py", line 365, in <module>
main()
File "./top_block.py", line 353, in main
tb = top_block_cls()
File "./top_block.py", line 80, in __init__
self.uhd_usrp_source_0.set_time_unknown_pps(wait_time)
File "/usr/local/lib/python2.7/dist-packages/gnuradio/uhd/uhd_swig.py", line 3909, in set_time_unknown_pps
return _uhd_swig.usrp_source_sptr_set_time_unknown_pps(self, time_spec)
RuntimeError: RuntimeError: Board 0 may not be getting a PPS signal!
No PPS detected within the time interval.
See the application notes for your device.
This makes sense, since there is no PPS signal available yet. My question is, how can I increase the time interval that the USRP looks for a PPS signal in? Here is a code snippet of my USRP sink to show how I currently have it set up.
self.uhd_usrp_source_0 = uhd.usrp_source(
",".join(("", "")),
uhd.stream_args(
cpu_format="fc32",
channels=range(1),
),
)
self.uhd_usrp_source_0.set_time_source('external', 0)
self.uhd_usrp_source_0.set_samp_rate(samp_rate)
self.uhd_usrp_source_0.set_time_unknown_pps(uhd.time_spec())
self.uhd_usrp_source_0.set_start_time( start_time ) # hand coded
self.uhd_usrp_source_0.set_center_freq(2.2e9, 0)
self.uhd_usrp_source_0.set_gain(50, 0)
self.uhd_usrp_source_0.set_antenna('TX/RX', 0)