Re: acoustic imager

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

Cursitor Doom <cd@notformail.com> wrote:

[...] "passive

bistatic radar" > For example: >
https://sspd.eng.ed.ac.uk/sites/sspd.eng.ed.ac.uk/files/attachments/basi
cpage/20171219/Session%201.0.pdf > > > John >
 
For a long time, too. IIRC the first successful radar experiment used
the reflection from a BBC transmitter.

 

Radar and code-breaking really saved Britain's bacon in WW2. Plus a
bit of assistance from the old colonies. :->
 

 
Yeah, Auntie was useful for something back then.

The BBC transmitter was only used for the initial experiments to show
that radio detection of aircraft was possible - after that, Chain Home
stations each had their own transmitter which 'floodlit' the search area
with pulses of RF.  Navy transmitting valves were used st first but soon
special types were developed to cope with high pulsed power.  They were
time-jittered to avoid mutual interference but all basically locked to
the 50 c/s mains.

The Germans were experimenting with radar in the VHF region and thought
we would be doing the same.  When they sent two airships on a radio
intelligence-gathering mission, up and down the North Sea coast just out
of visual comtact, they concluded that the HF signals were just
interference (becuase they were mains-locked) and we had no radar
capabilities.

In fact we had been watching them the whole time with our radar.  At one
point they radioed their position and got it wrong - our radar operators
were SO tempted to tell them!


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~ Liz Tuddenham ~
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