[sci.electronics] X-Ray countermeasures

hermann@calgary.UUCP (Michael Hermann) (02/18/88)

In article <19869@bu-cs.BU.EDU>, madd@bu-cs.BU.EDU (Jim Frost) writes:
> ...
> Why not go all out and make an X-ray projector?  If you manage to make
> it tight-beam, you'll be able to completely blacken the film (probably
> even the whole roll, to the delight of everyone else that day).  Of
> course, X-rays are sufficiently dangerous that you might hurt the
> operators if you go by them very often.
> 

The power requirements make this impractical. I am not aware of any automotive
alternator rated for 5000+ watts.

An electrical engineering friend of mine had the simplest solution for radar
counter-measures: run a spark-plug wire to your radio antenna (after 
disconnecting radio). At voltages of 15KV and up, your car antenna becomes
a broad-band radio transmitter. This provides X,K, and Ku transmissions of
sufficient power to drown-out the police radar signal and confuse its doppler
circuitry. My friend did this with his old Nova, and had a great time blowing
by radar traps and watching the officer on duty scratch his head as the radar
display rapidly flickered different speeds.
    Be warned, aside from the inconvenience of no radio, and one less
engine cylinder, the broad-band transmission (and it is, being a spark
generating EMR) also jams television, AM/FM radio, police/fire/ambulance
communications, aircraft channels, etc. etc.. If the FCC (or DOC in Canada)
manages to catch you, its a federal offense subject to fine and imprisonment.

    My friend got clued into this, and curtailed his jamming efforts
    thereafter.


-- 
Mike Hermann | hermann@cpsc.calgary.cdn          or
             | ...seismo!ubc-vision!alberta!calgary!hermann
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zrm@eddie.MIT.EDU (Zigurd R. Mednieks) (02/18/88)

In article <1358@vaxb.calgary.UUCP> hermann@calgary.UUCP (Michael Hermann) writes:
>
>An electrical engineering friend of mine had the simplest solution for radar
>counter-measures: run a spark-plug wire to your radio antenna (after 

This seems to be the simplest, most practical jamming system I've yet
heard of. Anyone have any suggestion for how to build a switch I could
safely operate from the dashboard to shunt a spark-plug wire through
an antenna (it need not be the radio antenna). Perhaps a loop of
copper braid attached to the inside of the plastic grille would do?

Any solenoid switches out there that wouldn't weld shut when switching
spark-plug voltages and currents?

-Zigurd
-- 
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Zigurd Mednieks		   MURSU Corporation		(617)424-0146
			   25 Exeter Street
			   Boston, MA 02116

todd@uop.edu (Dr. Nethack) (02/21/88)

Years ago this was discussed in Radio Electronics magazine.

An engineer had cut little dipoles and mounted them on his plugs somehow.
The result was he splattered the desired band with noise..
At the time the article was printed, there were no laws governing
engine noise.. is this still true?

So why don't we now bring this into a discussion of noise jamming,
and how to generate it??

lets see, an old feedhorn pointed down the road...


       "The worst day hacking, is better than the best day working"
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henry@utzoo.uucp (Henry Spencer) (02/21/88)

> ... the broad-band transmission (and it is, being a spark
> generating EMR) also jams television, AM/FM radio, police/fire/ambulance
> communications, aircraft channels, etc. etc.. If the FCC (or DOC in Canada)
> manages to catch you, its a federal offense...

In particular, the FAA (DOT in Canada) has absolutely no sense of humor
about interference with aircraft communications:  they will find you and
jump on you with both feet.  With spiked boots if you hash up communications
enough to kill someone before they find you.  This is a real possibility.
Don't do it.
-- 
Those who do not understand Unix are |  Henry Spencer @ U of Toronto Zoology
condemned to reinvent it, poorly.    | {allegra,ihnp4,decvax,utai}!utzoo!henry

john@anasaz.UUCP (John Moore) (02/23/88)

In article <1098@uop.edu> todd@uop.edu (Dr. Nethack) writes:
>Years ago this was discussed in Radio Electronics magazine.
>An engineer had cut little dipoles and mounted them on his plugs somehow.
>The result was he splattered the desired band with noise..
>At the time the article was printed, there were no laws governing
>engine noise.. is this still true?
>
>So why don't we now bring this into a discussion of noise jamming,
>and how to generate it??
AHEM!!!!
   Puleeze don't do this! Some of us use radio a lot, and we
don't wan't to listen to your spark plugs! Some of us fly airplanes,
and we REALLY don't want to have your spark plugs mess up
our nav/com equipment.
    If you insist on such foolishness (and, I admit, the attractions
are certainly there), get something that will only radiate on or
near the frequency you want to disable.
    And, remember,   if Uncle Charlie (FCC) catches you at this,
you can end up in seriously deep doo-doo (like, for example, Leavenworth)!






-- 
John Moore (NJ7E)   hao!noao!mcdsun!nud!anasaz!john
(602) 870-3330 (day or evening)
The opinions expressed here are obviously not mine, so they must be
someone else's.

fowler@cs.rochester.edu (Rob Fowler) (02/28/88)

A friend who works for a large military electronics contractor doing
electronic warefare kinds of thing once told me that the way to build
a cheap sparkplug-based jammer is to construct a waveguide by gluing
aluminum foil around a piece of 2 by 4.  The plug is screwed into a
hole bored in the side.  The broadband rf from the plugand the
gadget is very crudely tuned by cutting it to an appropriate length
and placing the feed at an appropriate place from the closed end.
Doing this makes cuts down on the interference you generate by limiting
the bandwidth and making it more or less directional.  Of course, you'll
still wipe out most radio communication ahead of you and you might
even manage to jam the pacemaker of the little old man careening
towards you in his Cadillac.  Although it's doable, it's still a bad idea.