Re: [Discuss-gnuradio] direct conversion compensation

[Eric Blossom]

On Sun, Dec 09, 2007 at 07:47:37PM -0800, Peter Monta wrote:
> > [ I/Q compensation ]
>
> There's some discussion in Razavi's "RF Microelectronics", section 5.2.2,
> and Kenington's "Software Defined Radio", section 5.3.1.1.  The distinction
> you mention between DC and AC might come from this LO self-mixing
> business, a nonlinear effect, and indeed only at DC since it involves
> the LO mixing with itself at some random amplitude and phase.  AC
> coupling would eliminate this artifact, but it would do nothing for the
> linear I/Q mismatch errors.
>
> Maybe future versions of the dbsrx could have I/Q compensation parameters
> in the EEPROM.  Or is something there already?
>
> Cheers,
> Peter

It's on the list of things to do.  Nobody's gotten to it yet.
It sounds like you may be the person we've been looking for ;)

There is room in the daughterboard EEPROM for storing the parameters.
We can work out a specific location when you're ready.

If you've got the time and inclination, please have a go at the I/Q
compensation.  It would be great to have.  Please post any questions,
etc.  

Eric