USRP Transmission

GNU Radio
1

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 A.

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2

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

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 A.

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