Re: [Discuss-gnuradio] Timestamps USRP N210

[Josh Blum]

On 08/03/2011 05:08 PM, Sebastian Bader wrote:
> Hello everyone,
> 
> I am currently working with multiple receivers of USRP N210s. I would
> like to correlate the received signal of multiple receivers and
> therefore require them to start sampling at the same time. Is there a
> good way to implement that?
> 
> Regarding to that issue I was curious to see sample timestamps. I have
> seen in various other threads that people have addressed this issue,
> but I could not find any detailed information on how to get exact
> (usec - nsec accuracy) timestamps. Can anyone tell me how to extract
> timestamps from the received samples? Or if I have overseen it, tell
> me where I can find that information?
> 

If you are looking to align multiple channels, the uhd source block will
do that automatically when you set it up for multiple channels.

If you want the timestamps, you can use UHD directly (see the
examples/rx_timed_samples.cpp).

Or from gnuradio, you can make a trivial mod to the source block's work
function to intercept the RX metadata and create a tag for each
timestamp. This tag will get propagated down the chain of processing blocks.

-josh