I and Q SNR in a IQ mixer

Eric Jacobsen wrote:
> On 2 Nov 2005 19:30:22 -0800, "Mark" <makolber@yahoo.com> wrote:
>
> >Question for you guys (that are smarter than I am)....
>
> Don't think that for a second...  ;)
>
> >If the (random AWGN)  noise were added near  the front end of the radio
> >(as is the normal case) and then the signal were hard limited  (as is
> >the normal case for an FM system)... would the hard limiter impact the
> >SNR of the I and Q differently?  I'm thinking the limiter removes much
> >of the AM noise but does not reduce the FM (phase) noise.  But I'm not
> >clear if this translates into I and Q that way or even if the OP is
> >hard limiting his signal before demodulation.
>
> No, it should affect I and Q the same.   Remember, the definitions of
> which is I and which is Q are more or less arbitrary.   It is often up
> to the receiver to sort out the phase ambiguity by using something
> embedded in the signal, otherwise there's no way to tell which is I
> and which is Q.   The amps and noise sources can't tell either, until
> they're actually separated by the mixer.
>
>
> Eric Jacobsen
> Minister of Algorithms, Intel Corp.
> My opinions may not be Intel's opinions.
> http://www.ericjacobsen.org

ok thanks
Mark