Re: [Discuss-gnuradio] USRP Transmission

[Eric Blossom]

On Fri, Apr 17, 2009 at 03:58:56PM -0700, Somya Ajmera wrote:

> Hi all, Did any body else had a problem while transmitting through
> USRP board? I am using Basic Tx/Rx board. When I tried to send a
> sinusoidal signal of 50Khz (through GRC) and tried to look at at the
> transmitted signal on to the oscilloscope by probing the Tx SMA
> connector, it displayed a sinusoid of 25Mhz with a constant DC
> offset. I guess there is an up conversion to an IF frequency is been
> done in USRP, but do anybody know is there any fixed frequency the
> signal is up converted to? At what mamimum power can a signal be
> transmitted using USRP?Is there a way we can control Transmission
> Power?
>
> Also when I unplugged the power to USRP and the USB cable, then also
> I was able to see a sinusoid, on the scope, of 60Mhz.
>
> Is there anything we need to enable in order to make the transmitter
> work? Also is there any kind of reference manual available for the
> Basic TX/Rx Daughter board?
>
> Thanks & Regards,
> Somya Ajmera

Try this:

  $ usrp_siggen.py -i 64 --sine -w 50k -a 16000 -f 5M

And look at it with a spectrum analyzer.  You'll see a sine wave at
5.050 MHz.  The Basic Tx has a transformer-coupled output, and that
will attenuate output below 1MHz.

For help understanding the above command, try

  $ usrp_siggen.py --help

Eric