Darryl, thanks very much! The links were exactly what I was hoping
for; there's good stuff in there.

This is a bear of a week for me, and I don't have time to dig into the
ramifications of what you've provided.. But I see what you're driving
at, now, and it's clear that I let my ultrasonic work color my
analysis.

Funny thing, I was thinking before you replied about using correlation
on overlapping signals, and sure enough, that's what they're using for
the de-garbling. Don't think I ever saw a hardware correlator,
although I did see a hardware device to do the FFT butterfly once. Do
they still use such things in this computer age?

-John

On Mar 12, 5:53 pm, "
wrote:
John

If you are realy interested I hope this gives you a few key words to
look up if nothing else: Overlapping pulse trains in SSR/transponders
is called garbling, and systems to handle that perform de-garbling.
Specifically you are discussing syncronous garbling where the garbling
is syncronised by the radar interrogation. Systems like TCAS that are
more unidirectional than SSR radar use techniques including wisper-
shout and directional antenas to try to de-garble their signals. A
funky little summary on this stuff is athttp://www.radartutorial.eu/13.ssr/sr01.en.html
(see brief mention athttp://www.radartutorial.eu/13.ssr/sr15.en.html
for a de-garbling algorithm). If you have access to IEEE there are
papers available there on SSR, collision avoidance etc.

As for general UHF/microwave signal processing, you can do pretty
amazing stuff with very low noise / high dynamic range front-ends,
possibly more than you would expect if your background is ultrasonic
signal processing. And in the case being dicussed the closer the
target gets you have less of a signal dynamic range problem.

But who knows exactly what Zaon does. I'd be suprised if they ever got
into details. Again all I was doing was cautioning is it probably
won't be signal blanking, not at least as initilaly described. None of
this stuff is my area/background, A very long time ago I did research
on ultra-low phase noise microwave sources and some exotic
applciations of those and have just been curious in the past about how
SSR worked.

---

BTW I had not poked around the Zaon website in a while and I now
noticed that they have an installation guide what talks about a panel
install kit and "audio enabled" MRX modules that give audio out. Also
they talk about multi-antenna installs. They definitly are not afraid
of getting the MRX antenna too close to the transponder antenna, they
spec only a few feet minimum distance between externally mounted MRX
and tranponder antennas. So I might have to take back my previous
concern about transponder antennas being really close to the MRX
antenna.

Seehttp://www.zaonflight.com/component/option,com_docman/task,cat_view/g...