- Nico:Ouch! You have made my head hurt with so much mathematical description. I think I had better make myself an Italian soda to make it feel better. If that doesn't work, I'll move on to Barbaresco :^)Thanks for the description, and I hope to see the co-channel interference surpressor in a future Perseus version sometime.73,Guy-----Original Message-----
**From:**perseus_SDR@yahoogroups.com [mailto:perseus_SDR@yahoogroups.com]**On Behalf Of**Nico iv3nwv**Sent:**Thursday, July 03, 2008 5:33 PM**To:**perseus_SDR@yahoogroups.com**Subject:**[perseus_SDR] Re: AM Splatter Rejection vs. MW Co-channel Interference SuppressionHi, Guy.

The AM Splatter Rejection has nothing to do with my earlier tests with

co-channel interferers. The AM Splatter Rejection algorithm is very

simple (but quite useless, imho). I've just added it to the Perseus

software so that users could experience what can be done and what cannot.

The co-channel interference suppressor, instead, is something I

believe much more. Some time ago Leif Asbrink has already demonstrated

the results on this group with its original developments using a PLL

which locks to the carrier of (one of) the interferers.

What I've thought for long is something quite different and not based

on PLLs at all. Unfortunately it is much more complex from the

algorithmic point of view, probably much more demanding in terms of

CPU usage and finally it requires some nice algebra operations like

i.e. the diagonalization of a large matrix, finding its eigenvalues

and eigenvectors, and finding the (complex) roots of a polynomial of

high degree. All of these functions are already implemented in matlab,

so it has been quite easy for me to make some tests in short time. But

unfortunately for real time users this algebra is not readily

available in Windows C++ libraries. I passed more than one night

studying practical algorithms for the Schur matrix decomposition

(which has the interesting application of solving iteratively for the

roots of a polynomial), or for a more simple real time diagonalization

of an hermitian matrix (for which I already wrote a variation on the

classical Jacobi method in matlab language) but, uhm uhm, the complete

real time implementation of what I conceived is not easy at all, at

least for a 47 years old EE like me (neurons have a shorter life, you

know).

Furthermore I'm not sure that I will get results better than those

Leif got with a more simple technique. I would like to, of course, but

I'm not yet in the position to say if this will really happen or not.

> Is there still the possibility we will see a co-channel

> MW supression tool, to help audibly separate stations on the same

> nominal frequency?

I would not miss it.

Nico - Hi Leif,

> > > I would have thought that something based on FFTs would

The variance of the estimate depends upone the carrier(s) to noise

> > > be far more efficient:-)

> >

> > And it is, at least from the computational point of view.

> > But given a data samples block length, you can estimate the frequency

> > of one or more sinusoidal tones with methods which offer a much better

> > frequency resolution than FFTs.

>

> This I find really hard to believe assuming, of course,

> that there is also significant amounts of random noise.

ratio, of course.