You idea is a good one. Period. That is all you should take away from
my remarks. I had not even begun to think of doing coherent processing
with the software receivers except to suck off interfering sidebands
from other signals in our passband. Thank you. John lovingly calls it
the Bob Sucker. DUMB. ;-).
Bob
Jim Barber wrote:
Thanks for the reply, Bob.
I have no axe to grind with regard to any particular algorithm, but I
did want to make sure what I thought would be the simplest/most common
case would be covered; IE one antenna available and the desire for the
most effective noise reduction/cancellation. Having done that, I'll
retract my nose and let you guys get back to your (excellent) work.
Thanks & 73,
Jim Barber, N7CXI
Bob McGwier wrote:
Jim:
We can do this right now with a software receiver. We need to make
the oscillators coherent in the same way we have done (in software).
So this will be usable by SDR-1000 and Flex3000 owners. Good idea.
I do not agree that the algorithm you suggest is the correct one but
it will be the first one because it is easy. It will be applicable to
HF broadcast very quickly.
The algorithms based on MUSIC and ESPRIT are better suited,
especially to the typical amateur installation where the elements are
not identical and not spaced the correct distance apart.
http://eprints.eemcs.utwente.nl/15144/01/final_report_Jasper_Vrielink.pdf
http://www.springerlink.com/content/y8001q047g520398/
These algorithms allow for much more than two elements and are pretty
efficient when only two elements are involved.
My work partners and I are running a phased array with SDR design
contract with a well known (not Flex) SDR hardware manufacturer and
these algorithms will be part of the adaptive phased array work that
must be done. Again, open source will benefit all.
Happy Cinco de Mayo to all!
http://twitpic.com/4mqnv
We are about to embark on some SERIOUS adaptive algorithm development
with DttSP, Flex, Gnuradio, etc. all involved. All of us will benefit.
Jim Barber wrote:
Not being familiar with the architecture or sources, would there be
any value in developing a 2-input, LMS-style noise reduction scheme
using the same antenna for both receivers and a small frequency
offset? (RX2 would be tuned to an unoccupied "noise" frequency as
close as possible to the "active" RX1 operating frequency)
That technique has been successfully used elsewhere and has the
advantage of adaptively canceling any static or long-term difference
in "phase" between the signals. (primarily group delay in this
case?). The obvious disadvantage is having to choose a suitable
noise frequency on a busy band, assuming one is available.
Thoughts?
Thanks,
Jim Barber, N7CXI
--
(Co)Author: DttSP, Quiktrak, PowerSDR, GnuRadio
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
"You don't need to see the whole staircase, just
take the first step.", MLK.
Twitter:rwmcgwier
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