Re: [Discuss-gnuradio] Carrier leakage on transmit

[Johnathan Corgan]

On Tue, May 25, 2010 at 05:53, Charles Brain <address@hidden> wrote:

> You can offset the carrier with UHD by passing a 2nd parameter
> in the set_tx_freq call. Unfortunately it only seems to work with small
> offsets, far too small to take it outside the passband of my
> signal. :-(

I haven't had the opportunity to try recent versions of UHD; I'll get
to that this week.  But you should be able to move the LO at least
10-12 MHz away.

> I think some form of calibration routine is going to be necessary.

Yes, the feedthrough is daughterboard and USRP2 specific, i.e., the DC
offset required to be added to the DAC sample values is unique to each
combination.  Fortunately, I've found that the compensation is stable
over time and temperature, so once calibrated, I've been able to put
it in a config file and leave it alone.

> I guess I will just have to be patient and wait.

Your feedback on the TX side issues you've encountered have already
been very useful, thanks.

Johnathan