Interesting part

From: Tom Jennings <tomj_at_wps.com>
Date: Mon Jun 14 15:28:30 2004

On Mon, 2004-06-14 at 13:08, William Donzelli wrote:
> > They originated in WWII radar, where they were used to remember the last
> > received signal pass, so they could detect differences with the current
> > signal pass, and cancel out stuff that didn't change.
>
> Just post war, actually, at least in Allied radars. The Germans had some
> sort of MTI technology in World War 2, but I don't know what they used.

Got my chronology wrong, thanks for the repair!

(They were also *analog* memories, not digital, and used no refresh, the
data being replaced every scan, so they were probably a lot easier to
implement than digital ones.)

> AN/APQ-15, a spoofer. It used an odd oil I have never heard of before,
> filled into a tank. A received pulse was amplified and sent to a
> transducer in the tank. The (now) acoustic pulse would bounce around in a
> semi-random pattern, and another transducer would pic up these echoes,
> then retransmitted back to the offending radar. The idea was that one
> AN/APQ-15 could "look" like a whole squadron of bombers, simulated in a
> tank of oil.

Shows what you can do with a little ingenuity and (very) little
technology.
Received on Mon Jun 14 2004 - 15:28:30 BST