Re: [Discuss-gnuradio] Switch Freq when packet transmitting

[Eric Blossom]

On Mon, Jun 02, 2008 at 10:29:22PM -0400, KC Huang wrote:
> Hi:

> Lately, I have tried to modify tunnel.py to switch freq in the
> middle of packet transmitting. But I have two problems.

> 1. When I tried to switch freq in the same daughterboard, should I
> have to stop the original transmission thread(tb.start) and start a
> new thread with new freq? Or are there any way to change the setting
> without stop the original thread?

There's no need to stop the graph to change the frequency.  Just call
the tune method like you do at initialization time.

> 2. Also, I wanna switch freq between different daughterboards, e.g.,
> switching between 400MHz and 2.4GHz. How should I do? I first tried
> to assign a string "B" to "options.tx_subdev_spec", but it turns out
> not a string format. If we don't assign the value to this options,
> how could we do to switch different daughterboard?

First, be sure you understand what's really going on and how the Tx
and Rx muxes work.  See http://gnuradio.org/trac/wiki/UsrpRfxDiagrams

Also if you haven't already, it would be good to work through the
python tutorial http://www.python.org/doc, and look at the rest of the
python docs there as well.

The daughterboard objects (u._db) are instances of subclasses of
db_base.py (gr-usrp/src/db_base.py)  To change from one side to the
other on the fly you need to configure the muxes properly.
Documentation on the muxes can be found in usrp/host/lib/legacy/usrp_standard.h
Search for set_mux.  There are two classes that implement set_mux,
usrp_standard_rx and usrp_standard_tx.  The arguments are interpretted
differently for each of them.

Eric