"Jerry" wrote in message
...
..

Hi "Sal"

I'd like to know more about the Drooped Cross
Horizontal"). Do you know the frequency it is designed for?

Jerry KD6JDJ

Yes. Its nomenclature is AS-2815/SSR-1A. It was designed for the UHF
satellite "Fleet Broadcast," 240 - 315 MHz, but I have seen it used only in
a narrower range, more like 248 - 262 MHz. The pattern is semi-omni,
essentially taking in a view of the entire sky.

The system is receive-only and has been a mainstay of fleet comms for
decades. The version I grew up with had a 1200 bps digital mux of fifteen
74 baud TTY signals (100 WPM). It may have advanced since then; I don't
know the capabilities of the -A version. (I hope they made it more
idiot-proof.)

Ships are usually fitted with three or four antennas, strategically placed
so that at least one of them is clear of blockage. The system uses what is
called "pre-detection integration," whereby the strongest signal is
demodulated, on the presumption that it's the best quality. It's a form of
diversity reception.

The original AN/SSR-1 system downconverted the received signal to a 19.95
MHz first-IF out on deck, a few feet from the antenna. I believe the
AN/SSR-1A amplifies the received signal and it goes all the way to the radio
room at the d/l frequency. Maybe somebody will know for sure whether that's
right, but I think so.

"Sal"
(KD6VKW)