commgrp@silver.ucs.indiana.edu (BACS Data Communications Group) (08/01/90)
to sci.electroics and rec.autos: jkimble@bally.Bally.COM (The Programmer Guy) writes: Subject: Detecting Radar Detectors >I saw a story on the world news a few weeks ago regarding drivers >(primarily 18-wheelers) using radar detectors. During the news >segment, the reporter was talking to a highway patrol officer who was >using a device to detect if the oncomming vehicle was using a radar >detector. >...How do these detectors of radar detectors work? ... A friend sent me an article from a Virginia newspaper, _Lessburg Today_, July 13, 1990, entitled "Radar 'Detector Detictor' Cruises Local Primary Roads." "...The $1100 device detects microwaves "leaking" from operating radar detectors... Originally developed in Canada, where radar detectors are illegal... The VX6-2 detector is being fornished at no cost on a loan basis to the state police by the Insurance Institute for Highway Safety, a private research organization funded by insurance companies..." There's a picture of the beast, which is housed in a box aprox. 3 x 4 x 6", with two knobs and a LED on the front. It looks home-brewed. --- This article seems to confirm rumors that the insurance cartel wants to outlaw radar detectors everywhere in the U.S., either through the legislators they own, or by excommunicating/sh*tlisting policyholders who use them. These devices have been used in Canada for several years. They are for real, and apparently very effective. Superhet radar detectors work like little spectrum-analyzers: The local oscillator (11.5 GHz +/-) is a Gunn diode with a varactor to sweep its frequency. The first i.f. is 1 GHz, followed by further conversion and circuits which detect valid alarm conditions. K-band is detected via a harmonic of the local oscillator; I haven't done the arithmetic. The advantage of this method is that it searches a wide band but retains high sensitivity. The local oscillator, varactor and mixer diodes are all inside a cavity at the end of the horn antenna. A series of screws projecting into the horn form a trap to suppress local oscillator radiation, but are only partially effective. Some brands of radar detector mutually interfere because of local-oscillator radiation. In WW II, the Germans installed radar detectors on U-boats. These also had a problem with local-oscillator radiation, and Allied ASW aircraft were able to home-in on them without radar. A detector-detector could probably be made by modifying a conventional radar detector: Mechanically retune its local oscillator to 1 GHz above or below 11.5 GHz, and remove the trap screws. -- Frank Reid W9MKV reid@ucs.indiana.edu 26 states on 10 GHz. ZAP! ;-)
bbesler@vela.acs.oakland.edu (Brent Besler) (08/02/90)
The insurance Gestapo wanting to ban radar detectors is nothing new. GEICO tried to refuse policies to people who use them and were ordered to reinstate the policies in two states, I don't remember which. THe radar detector detector picks up the 11.5 Ghz reference signal most detectors put out. MAYBE the new Solo, which is pretty low powered and uses a GaAs FET rather than a Gunn diode may not be detectable by it. Anybody on sci.electronics who would know the answer please share it with us.
commgrp@silver.ucs.indiana.edu (BACS Data Communications Group) (08/02/90)
bbesler@vela.acs.oakland.edu (Brent Besler) writes: >The insurance Gestapo wanting to ban radar detectors is nothing new. >... >The radar detector detector picks up the 11.5 Ghz reference signal >most detectors put out. MAYBE the new Solo, which is pretty low >powered and uses a GaAs FET rather than a Gunn diode may not be >detectable by it. Anybody on sci.electronics who would know the >answer please share it with us. The Gunn diode is a simple/inexpensive but inefficient (about 2%) way to produce microwaves. That's the main reason why most radar detectors require so much power that it is impractical to operate them from internal batteries. (Although the physics are different, you can think of a Gunn diode as a LED which emits microwaves instead of light, except that it must be inside a resonant cavity to do so, and the cavity determines the microwave frequency.) The new generation of radar detectors (e.g. Solo) with FET local oscillators require less DC power, however, the local oscillator RF level is probably the same as in older types, and probably has equivalent leakage. -- Frank Reid reid@ucs.indiana.edu "Aha! The alien Zorg battle cruiser's BMW disguise is flawed by a suspicious lump on the dash. Set nuclear nerd neutralizer to medium- well!"
chrispi@microsoft.UUCP (Chris Pirih) (08/08/90)
In rec/autos "commgrp@silver.ucs.indiana.edu" might have said: ;Subject: Detecting Radar Detectors ; ;These devices have been used in Canada for several years. They are ;for real, and apparently very effective. I guess what we need now is a radar detector detector detector. (Or did you already say that?) --- chris