Re: [Discuss-gnuradio] Re: Single-tone test using USRP2 with RFX2400 and XCVR2450

[Matt Ettus]

Changkyu Seol wrote:
> Matt Ettus wrote:
> > Yongsang Kim wrote:
> >
> > What you are seeing are normal transmitter non-idealities, including DC
> > offset (aka carrier feedthrough), and IQ imbalance (aka sideband
> > suppression.  These can be improved through tuning, but they are not bad
> > as is.  Also, on the XCVR you are seeing the phase noise skirts as well.
> >
> > Matt
>
> With the XCVR2450 and USRP2, we also observed that the 2MHz (at 
> baseband) is
> appearing at (f_c-2MHz) not (f_c+2MHz) where f_c is the center 
> frequency. It
> seems that the complex conjugate of original baseband signal is 
> transmitted at
> XCVR2450.
>
> We verified this with OFDM signal which is demodulated
> successfully when we flip the left and right of the FFT ouput before
> processing (integer frequency offset compensation, channel estimation, 
> etc)
> at the receiver.


Please update your firmware and try again.  I believe I have fixed this 
problem now.

Matt