fv1609 Posted July 28, 2013 Author Share Posted July 28, 2013 No bouncing this was a line of sight receiver only with a range of about a mile. It was a one-way IR photophone for either telephony or MCW. There is no description of it on the internet other than the transmitter at the other end. See page 4 of http://www.hmvf.co.uk/pdf/Tabby03.pdf It also repeated on some other sites who have lifted the article without my permission :shocked: Quote Link to comment Share on other sites More sharing options...
Lauren Child Posted July 28, 2013 Share Posted July 28, 2013 Interesting stuff. I wonder if the beams would have shown up under night vision gear? Quote Link to comment Share on other sites More sharing options...
fv1609 Posted July 28, 2013 Author Share Posted July 28, 2013 Interesting stuff. I wonder if the beams would have shown up under night vision gear? Lauren obviously if you were in the path of the beam yes. Whether you could see anything laterally would depend on dust or mist in the same way that visible light would be scattered with a beam from a torch. There were some WW2 expectations that IR could be used to see through fog etc but these expectations were not realised. Quote Link to comment Share on other sites More sharing options...
fv1609 Posted July 28, 2013 Author Share Posted July 28, 2013 The way in which this worked was for a jungle patrol to be equipped with the receiver & would periodically stop to obtain fresh instructions. The receiver head would be hoisted on the pole towards the transmitter that remains at a fixed point. A torch was flashed into the receiver's mirror to give the location. The transmitter was aligned & an IR beam was sent with a beam width of 0.15 to 3 degrees. This made it pretty secure, the beam was modulated with speech or keyed with a tone. The receiver had an IR filter and lens with a photoelectric cell at the focal point of the concave mirror. The signal was amplified & fed to headphones. The transmitter was arranged so that it could also receive, but a receiver was unable to transmit. Quote Link to comment Share on other sites More sharing options...
andym Posted July 28, 2013 Share Posted July 28, 2013 Ah - I was thinking more of an airborne transmitter than a land-based one. Andy Quote Link to comment Share on other sites More sharing options...
fv1609 Posted July 28, 2013 Author Share Posted July 28, 2013 Ah - I was thinking more of an airborne transmitter than a land-based one. Andy Andy sorry I see I missed replying to your post. When I come back to the PC there are often a number of posts to respond to, then if new posts appear whilst I'm replying then that can get lost in my replies. Phew lucky for me you didn't give the correct answer in your post! Anyway I hope you enjoyed the journey through the mysteries of the jungle to discover an ungooglable Japanese curiosity Quote Link to comment Share on other sites More sharing options...
Locolines Posted July 28, 2013 Share Posted July 28, 2013 Oh beaten again doh :cry: Quote Link to comment Share on other sites More sharing options...
fv1609 Posted July 28, 2013 Author Share Posted July 28, 2013 Oh beaten again doh :cry: Roy there was a stage when you were submitting answers with 4 components of which the first 3 were correct! After that you went off course a bit Quote Link to comment Share on other sites More sharing options...
Locolines Posted July 28, 2013 Share Posted July 28, 2013 Yes still a bit "green " at this military stuff so to speak. Quote Link to comment Share on other sites More sharing options...
Tony B Posted July 29, 2013 Share Posted July 29, 2013 Sounds very similar to a rather bizzare signalling method used by the British in WW2. A person who has had a catarct operation, removal of the lens of the eye becomes responsive to UV light. Aparently such people were carried on submarines to pick up agents who could signal their position using UV which is normaly invisible. Quote Link to comment Share on other sites More sharing options...
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