🚀 go-pugleaf

In article <careyj.727992636@spot.Colorado.EDU>, careyj@spot.Colorado.EDU (CAREY JOSEPH M) writes:
> np4@prism.gatech.EDU (Nick Pomponio) writes:
> 
>>The ECM device can be a simple repeater applying amplitude modulation to
>>the received signal. The AM frequency would be a function of the actual
>>velocity, the desired (deception) velocity, and radar signal wavelength.
>>Simple AM will produce two false velocity "targets"; the undesired one
>>could be supprssed by using a single sideband AM scheme.
> 
>>-- 
>>POMPONIO,NICHOLAS A
> 
> Okay, in theory I'll buy this, but lets see how it would work in
> practice.  You'd need to detect (very quickly) the signal, have some
> kind of a system wired up that would determine how much frequency
> (i.e. apparent doppler) shift to apply, and retransmit that signal
> (presumably with something that radiates independently of phi, like
> a dipole).  Further, you would need to make sure that you would not
> detect the signal that you would be transmitting, which is only
> a few hundred Hz (if memory serves we're talking about 30 Hz/mph,
> but I could be wrong) off the one you received, or your repeater would
> lock up.  And keep in mind that you'll be transmitting significantly
> more power than that which is received.
> 
> Yeah, I'll believe that it can be done.  It would even provide some
> interesting engineering challenges, but this strikes me as the kind
> of problem people solve for the fun of solving it, not because they
> really need ECM for their CAR (an F-16, yeah, but not my Plymouth).
> Also, to design this properly, you would need some pretty expensive gear.
> 
> Just a thought.  I'd sure like to see the results somebody else comes
> up with, but for me this reminds me of hacking computers -- an interesting
> problem that I don't want to spend too much time on.
> 
> 
> Sure is an interesting discussion, though.
> 
> Joe Carey
> joe@lobos.colorado.edu
> 
O.K. how are we gonna do this?  A linear transponder with (30 hz /mph
upconverter?);  Problems with in/out isolation.
 Maybe since we really
don't need a truckload of transmit signal (the radar unit is seeing
1 / (it's signal * 4PI * dist to car^2 * refl coef * dist back^2)
so if we retransmit say +10 dBm into a horn with 10 db gain that
should cover it.
A balanced modulator would have to be used for mixing as the signals
would be too close in frequency to filter; but the image being present
may give us trouble too (does the radar care if it's "coming or going?".
I am going to guess that
two horns facing forward spaced say two feet apart are going to have
about 40+ dB isolation, so this limits the throughput gain (again since
the freqs are too tight to filter),  What about polarization?


-- 
Chris Scott,  C/E Public Radio,  Western KY Univ,  (502) 745-3834
SCOTTCR@WKUVX1.BITNET      fx off: 745-2084     fx hm: 781-1232