Re: [Discuss-gnuradio] UHD: samples alignment

[Josh Blum]

> 1- Is it enough to do this? Shouldn't I tell the USRP2 to start streaming at
> a specific timestamp? I have looked into the UHD files but wasn't able to
> spot a function to do this, though.
>

yes, the stream_cmd must have a time stamp specified so both usrp2s
start streaming at the exact same time. Currently, it defaults to
stream now: 
http://www.ettus.com/uhd_docs/doxygen/html/structuhd_1_1stream__cmd__t.html

this change will require modifications to the gr-uhd source in the
call to issue_stream_cmd

> 2- If I don't use the clock_config, what are the defaults?
>
internal ref clock, sma pps

> 3- In the runtime, how can I print the received packet timestamp to make
> sure they are aligned?
>

print the first metadata.time_spec in the gr-uhd source work function

should you be willing to wait, I am working on exactly this issue of
multiple usrp2 alignment and I hope to push something up next week
when I get it all working.

-Josh