From: blgardne@javelin.sim.es.com (Dances With Bikers)
Subject: Re: Mounting radar detectors on bikes
Reply-To: blgardne@javelin.sim.es.com
Organization: Evans & Sutherland Computer Corporation
Date: Thu, 8 Oct 1992 13:42:21 GMT

randy@megatek.com (Randy Davis) writes:
>In article <Oct.7.10.04.29.1992.16046@remus.rutgers.edu> kretz@remus.rutgers.edu (Kevin Kretz) writes:
>|In article <1992Oct6.210846.17355@wam.umd.edu>, delilah@next18pg2.wam.umd.edu (Romeo DeVerona) writes:

>|] nope. there is no transmitting element whatsoever in a radar detector; in  
>|] fact, since it doesn't (like a radio does) have to reproduce the signal it  
>|] receives,

>|Wrong - all detectors with "superheterodyne" circuitry _do_ produce
>|radio waves of the same frequency they are trying to detect.

>  (A nit-pick here.)  In actual practice, almost all dual band radar detectors
>use the same *single* heterodyne frequency that happens to be neither the
>10.525 GHz X-band nor the 24.150 GHz K-band frequency (Ka band detectors use
>two references, as I recall).  It happens to be a different frequency that
>happens to mix well with *both* frequencies and produce the desired
>amplification via harmonics.  It is THIS frequency (something in the 17 GHz
>range seems to stick in my mind) that the detector detectors look for.

From rec.cage yesterday:

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From: yerazunis@cthulu.enet.dec.com
Newsgroups: rec.autos
Subject: Wideband Ka, the Valentine One, and Leaky Detectors.

More experience on Ka-wideband detectors:

Talked with Mike Valentine yesterday, about some (what I thought was) strange
behavior in the Valentine V1.

The weird situation is this:  what appear to be false alarms on Stalker band.
These falses often happen when counter-commuting (i.e. expressway
driving in city, you have open road because you're going against rush-hour
traffic, but there's very heavy rush-hour traffic coming in the other
direction)

Mike Valentine explained it as follows (quotes as best I can remember them):

"Ka-band is the Love Canal of microwaves.  The problem is this: almost all
detectors use a local oscillator frequency of something close to 11.55 GHz,
so that X band is picked up with on an IF frequency of around 800 MHz on
the first harmonic, and K band is picked up on the second harmonic at the
same IF frequency.

The bad news is that the third harmonic of 11.55 GHz is 34.65 GHz- which
is smack-dab in the _middle_ of Stalker band.  Thus, if an X/K band detector
is leaking a little, it shows up as a Stalker false.  The Valentine One
has proprietary software in it to differentiate between leaking detectors
and real Stalkers.  Without the software, you'd get a false alarm on
Stalkers every five minutes or so.  With the software, it should happen
on the average of one a day, but it varies wildly with the traffic
situation.  You might go two weeks with nothing, then get five in one
day.  It's totally random due to the distribution of "leaky" detectors
out there, and the density and traffic patterns around you.

:end of misquotes from Valentine:

-----

Maybe _this_ is why the Passport 3200 wideband has the wideband-disable
switch?  I find it easy enough to look at the front panel on the
V1- if it shows wideband, it's either Stalker or a Stalker false, and I can
modify my behavior accordingly- especially now that I *know* what's going
on.  The false rate at it's worst is still only a few per cent of the
typical X-band false rate due to door openers and burglar alarms.

-Bill

Copyright 1992 William S. Yerazunis (aka Crah the Merciless)
All rights reserved, no responsibility taken.

     "Man did not weave the web of life: he is merely a strand in it."
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-- 
Blaine Gardner @ Evans & Sutherland  blgardne@javelin.sim.es.com  BIX:blaine_g
580 Arapeen Drive, SLC, Utah 84108           Favorite road signs:
Dumper of Dirtbikes #46             FJ1200   Winding Road Next 77 Miles
My other motorcycle is a Quadracer           Caution: Passing Areas Not Marked