----- Original Message ----- From: "Bruce Napier" <[email protected]> To: <[email protected]> Sent: Thursday, February 26, 2009 4:06 PM Subject: Re: [canals-list] Re: trolleys on Jeremy Vine
On 26 Feb 2009, at 14:16, Bru wrote: > They weren't entirely mythical but they probably couldn't do all > that was > claimed for them - however, they were hardly *covert* surveillance > cover (as > somebody suggested)! More a blatant gimmick really. I think you may have missed the point: they could be used for other kinds of surveillance (Fuzz, MI5 and the like) without alerting the target, as they were at one time a semi common sight around urba areas. > Yup ideal cover I'd imagine since the detecting kit they would have carried would be similar at least in principle to some of what was used in covert wireless surveillance. There used to be an urban myth that they could knock on the door and tell you what channel you were watching, except that AFAIK it wasn't an urban myth! IIRC the very early detectors picked up the emission fromn the line output transformer but later kit could detect the mixer oscillator used to obtain the fixed intermediate frequency (superhet receiver). This is different for each channel. Peter Wright describes a very similar system which he used to detect the frequencies that russian embassy transmitters were using. What ever you think of his Roger Hollis obsession, for a techie his descriptions of some of their kit and techniques is fascinating. Cheers Guy -- Guy Morgan First Light Services nb Virgo, WFB, Stockton, GU
