Re: [Discuss-gnuradio] using PPS signal to trigger the received data storage in Pyton

[Josh Blum]

On 11/23/2011 01:52 PM, Yan Nie wrote:
> Dear all,
> 
> I am using USRP N200 with LFRX +UHD to design a receiver, which works
> fine to continuously receive data. I need to use PPS signal to
> trigger the received data storing only for 1ms every second after
> detecting the edge of PPS signal every second.
> 
> I tried the approach introduced in the gnuradio example,
> rx_timed_samples, detecting the PPS signal, then setup streaming,
> then fill out rx-meta-data by recv(). Eventually, I got to know the
> stream_cmd and recv are not swigged, which means I could use this
> method in Python.
> 

You may be interested, on my uhd_work branch, I added a set_start_time
call: http://gnuradio.org/cgit/jblum.git/log/?h=uhd_work

You can use this call to control when streaming will begin. So you
should use PPS to synchronize the usrp time registers, then set the
start time to be one second later, then start the flow graph.

-Josh