Re: [Discuss-gnuradio] [USRP] tracking the transmission/receiving process

[Martin Braun]

On 08.09.2015 15:41, Logan Wu wrote:
> Hello,
> 
> I've been tracking the source code to figure out the procedure of
> transmission/receiving. All I've found out is that the parameters (e.g.
> freq, gain, etc.) are stored in a property tree, and messages are
> inserted to the tail of queue. But how does the transmitter/receiver
> (daughter board) know when to transmit/receive? Specifically, which file
> in UHD host code does the job of notifying the hardware to
> transmit/receive?

I'm not sure if this answers your question, but it's the send() call
that initiates a transmit from the host side. This does a bunch of
things, depending on the device, but mainly starts sending data packets
to the USRP, and once they hit the radio, they're automatically sent.

On the rx, side, you do an issue_stream_cmd() and that will tell the
radio to start sending data to the host. The recv() call then picks up
the data from the host-local buffer.

If you have more specific questions, don't hesitate to drop them here!

Cheers,
Martin