Re: [Discuss-gnuradio] Setting the DSP frequency in the UHD blocks

[Mike Jameson]

Hi Frank,

Use the following line as the frequency variable for the 'UHD Source' & 'UHD Sink' blocks in GRC:

uhd.tune_request(center_freq, rf_freq=(center_freq+lo_offset),rf_freq_policy=uhd.tune_request.POLICY_MANUAL)

Where 'center_freq' and 'lo_freq' are variables which need to be defined.

Using the lo_offset on the TX side prevents local oscilator leakage on the TX frequency, to prevent giving the false impression that it is transmitting after stopping the flowgraph.

Regards,

Mike

--
Mike Jameson M0MIK BSc MIET
Email: address@hidden
Web: http://scanoo.com

On Mon, Jul 1, 2013 at 6:38 PM, Wallace, Frank L CIV NSWCDD, Q41 <address@hidden> wrote:

In gnu radio companion for a UHD block, how do I set the DSP frequency as well as the RF frequency.  I have done this in my C code which doesn't use gnuradio using the tune_request_t structure.  From the comments in the python code, it appears that there is some way to do it.

I understand that I want to use the DSP LO so that the DC component from the ADC is moved outside the baseband.  Is there a good value or is  anything outside my receive bandwidth is ok?

Is there a reason to use the DSP LO on the transmit side? Does the up conversion happen before or after the DSP LO?

Thanks,
Frank Wallace

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