On Sat, 09 Jul 2005 09:48:34 +0200, "Ralph A. Schmid, DK5RAS"
wrote:

krackula wrote:


the opto R10 or R11 will blow the doors off the current so called
" close call " receivers and it " does not " find ANY of the
equipment in the mentioned comms vehicle. ( nor would
any of the , less sophisticated , close call rigs )

I guess they use some kind of spread spectrum.


roger that ralph. I'd guess , since it's guarding the president,
that no expense has been spared and much of their
commo equipment is tied into the " extensively deployed "
UWB equipment that the military now uses. some of government's
UWB systems are into the 3rd generation ( phase ) by now.

http://www.google.com/search?hl=en&l...&btnG =Search
http://www.computing.co.uk/vnunet/ne...e-uwb-wireless

military deployment of UWB equipment is ( of course ) far in advance
of what us average civilians usually know about , look at how
the military had spread spectrum for 15 years before " we "
got wind of it. guess UWB is supposed to be more difficult
to detect than even SS was .....




dunno about the " digital " signal intercept receiver made
by opto called the " digital explorer " ...... haven't tried it
near one of those comms suvs yet. maybe " it " could capture
some comms since it ( unlike MOST other equipment )
can " see " digital signals.

After some tests with a digital capable counter, it was able to
discover GSM carriers, and it shows the frequencies of WLANs. Also it
shows the frequency of the very short bursts which are used by MPT1327
to register or request a connection.

it'd be interesting to be able to get some civilian UWB equipment
( which is due out pretty soon )

http://www.asiatele.com/ViewArt.cfm?...id=5&subcat=48
http://www.med.govt.nz/rsm/spp/uwb/d...ussion-05.html

to use as a signal source and then develop some kind of very wide
band mixer ( the injection oscillator being an ultra wide sweep gen
) and " then " drop the product into a detector of some type ( maybe
a standard hp microwave in-line detector ) then into your digital
counter. this to , at least , be able to detect the " presence " of
these UWB devices. if all the nanny cams and wi-fi links etc. of
the near future are going to switch over to UWB ( as the industry is
projecting ) then a LOT of us are going to want to ( at least ) find
these devices , even if they aren't hackable ( ie: SS ) .
judging from the difficulty that SS presents ( of detection ) ,
this isn't gonna be an easy task.

since UWB signals have such different characteristics , the wide band
mixer
, mentioned above , would need some kind of variable width
injection oscillator and a comparators circuit that samples
the product for amplitude and adjusts it's width automatically
to the signal detected . this to optimize the mixing bandwidth to the
signal present. it would be simple to limit the narrow most aperture
of the mixer to about ( say ) half a meg ( or maybe several megs )
to preclude the possibility of " ordinary " signals from becoming a
problem, and guarantee that you are hearing a UWB signal.








regards - Ralph