On Feb 17, 9:39*pm, tom wrote:
On 2/17/2011 6:22 PM, J. C. Mc Laughlin wrote:

K1TTT has nailed it! Effecting a null that is deep enough to produce
something useful is difficult. In any case, the patent examiners will
find that the telephone people did something like this a long time ago.
73, Mac N8TT

J. C. Mc Laughlin
Michigan U.S.A.
Home:

One big difference is that the hybrid in a POTS phone doesn't want a
deep null. *They want enough left of what is called "side tone" to give
feedback to the ear with receiver on it. *If you don't they are
uncomfortable and also think the call has been dropped. *It would be in
the -10 to -30dB range I'd guess.

On the other hand the null for this antenna array would need to be maybe
90dB or better to be really useful. *Maybe with processing it could be
done with less, but I'd have to say, I don't know.

tom
K0TAR

Normal level on a phone is about -25db I think sidetones are about 10
or 12db below that. Take that with a little salt my comm days are long
time past.

Jimmie