fish@gemed.com (Mark Fisher) (08/15/90)
What do you guys and gals think of this idea? Mount 4 or so corner reflectors on a rotating frame such as a plastic bicycle tire. Coat the back of the reflector with resistive foam to dissipate the radar energy. Make the corner reflector large enough RCS (Radar Cross Section) wise to be much brighter than your car. Turn the reflectors at a constant rate of something like 120 RPM. And wa-la your car's dominate doppler shift will be ~ 10 mph less than you are actually going. That is assumming you can figure out which way to turn the reflectors ;) The apparent speed of the reflectors will have a sinusoidal modulation to it from going around in circles. This may prevent the radar from getting a good lock on the doppler shift and lock in on the steady doppler shift from the car even though it is dimmer RCS wise. If this is so then you put your corner reflectors on a flat belt and rotate them like a belt sander. I would hate to get caught with something like this on the top of my car. :^) -- // Mark M. Fisher // fish@gemed.ge.com // uunet!crdgw1!gemed!fish // sun!sunbrew!gemed!fish
a143@mindlink.UUCP (Ed Meyer) (08/15/90)
> fish@gemed.com writes: > > Msg-ID: <FISH.90Aug14183156@his.gemed.com> > Posted: 14 Aug 90 23:31:56 GMT > > Org. : GE Medical Systems, Milwaukee, WI > Person: Mark Fisher > > What do you guys and gals think of this idea? > > Mount 4 or so corner reflectors on a rotating frame such as > a plastic bicycle tire. Coat the back of the reflector with resistive > foam to dissipate the radar energy. Make the corner reflector large > enough RCS (Radar Cross Section) wise to be much brighter than your > car. Turn the reflectors at a constant rate of something like 120 > RPM. And wa-la your car's dominate doppler shift will be ~ 10 mph > less than you are actually going. That is assumming you can figure > out which way to turn the reflectors ;) > > Mark, if memory serves, this was tried about a dozen years ago: the corner > reflectors caught the airstream as the car went forward and as expected the > radar facing the oncoming car detected a much lower speed due to the relative > retrogressive motion of the reflectors. However, a radar (like the so-called > radar camera) would see the reflectors receding at higher speed than the car. > So, if they don't get you coming, they get you going.
ee5391aa@hydra.unm.edu (Duke McMullan n5gax) (08/15/90)
In article <FISH.90Aug14183156@his.gemed.com> fish@gemed.ge.com (Mark Fisher, GE Medical, Milwaukee WI, x4-6553) writes: >Mount 4 or so corner reflectors on a rotating frame such as >a plastic bicycle tire. >Turn the reflectors at a constant rate of something like 120 >RPM. And wa-la your car's dominate doppler shift will be ~ 10 mph >less than you are actually going. ... >The apparent speed of the reflectors will have a sinusoidal modulation >to it from going around in circles. This may prevent the radar from >getting a good lock on the doppler shift and lock in on the steady >doppler shift from the car even though it is dimmer RCS wise. ... >I would hate to get caught with something like this on the top of my >car. :^) Hmmm. Mark, I'd think it would backfire, since the radar will sense the _largest_ doppler shift it finds. In any event, shielding the rest of the car to have a significantly less bright reflection than the reflectors would be a major nuisance. However, I don't _think_ there's anything unlawful about it per. se. Some years back, 73 Magazine ran an article on how an active ECM system for police radar could be constructed around a Gunnplexer. Said article claimed that it was sufficient to AM the uwave carrier at an audio frequency (the frequency being proportional to the speed which the fuzzdar will display). The assertation was that the front end of the fuzzdar receiver is untuned, so the Gunnplexer output would register, even though it's "out of band". They even had a photo of a pair of thumbwheel switches on the dash displaying double nickles. They also had a disclamer to the effect that actually _doing_ this was almost certainly illegal. Sure, it's in a ham band, but it's also deliberate interference with another service, a standard ham no-no. I've thought about building such a thing from time to time, but even aside from cost and illegality, I just don't drive that abusively, and I don't speed that often or that much. My little radar detector (still legal, most places) keeps me out of most trouble on the occasions when I'm an unlawful hurry. 1001001, d -- When you're up to your butt in alligators, it's difficult to remember that the initial objective was to drain the swamp. -- traditional Duke McMullan n5gax nss13429r phon505-255-4642 ee5391aa@hydra.unm.edu
tuv@pmafire.UUCP (Mark Tovey) (08/15/90)
In article <FISH.90Aug14183156@his.gemed.com> fish@gemed.ge.com (Mark Fisher, GE Medical, Milwaukee WI, x4-6553) writes: >What do you guys and gals think of this idea? > >Mount 4 or so corner reflectors on a rotating frame such as >a plastic bicycle tire. Coat the back of the reflector with resistive >foam to dissipate the radar energy. Make the corner reflector large >enough RCS (Radar Cross Section) wise to be much brighter than your >car. Turn the reflectors at a constant rate of something like 120 >RPM. And wa-la your car's dominate doppler shift will be ~ 10 mph >less than you are actually going. That is assumming you can figure >out which way to turn the reflectors ;) > >The apparent speed of the reflectors will have a sinusoidal modulation >to it from going around in circles. This may prevent the radar from >getting a good lock on the doppler shift and lock in on the steady >doppler shift from the car even though it is dimmer RCS wise. If this >is so then you put your corner reflectors on a flat belt and rotate >them like a belt sander. > >I would hate to get caught with something like this on the top of my >car. :^) >-- >// Mark M. Fisher >// fish@gemed.ge.com >// uunet!crdgw1!gemed!fish >// sun!sunbrew!gemed!fish Sounds like a pretty snazzy hood ornament to me!
depolo@eniac.seas.upenn.edu (Jeff DePolo) (08/16/90)
In article <1990Aug15.112532.17516@ariel.unm.edu> ee5391aa@hydra.unm.edu (Duke McMullan n5gax) writes: > >Hmmm. Mark, I'd think it would backfire, since the radar will sense the >_largest_ doppler shift it finds. In any event, shielding the rest of the >car to have a significantly less bright reflection than the reflectors would >be a major nuisance. However, I don't _think_ there's anything unlawful about >it per. se. Most every radar gun will display the _strongest_ echo, not the one with the largest shift. This is after being filtered through a bandpass filter. Most radar guns will filter out post-mixing signals that would yield a reading of less than approximately 20 MPH and more than 99 or 199 MPH, depending on the model of radar gun. If it was the case that the gun would display the signal with the largest shift (i.e. the fastest car in the beam), target identification would be impossible if there was more than one car in the beam. Obviously the "strongest signal" method isn't foolproof either, but that's another story. --- Jeff -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Jeff DePolo N3HBZ Twisted Pair: (215) 386-7199 depolo@eniac.seas.upenn.edu RF: 146.685- 442.70+ 144.455s (Philadelphia) University of Pennsylvania Carrier Pigeon: 420 S. 42nd St. Phila PA 19104
bwhite@oucsace.cs.OHIOU.EDU (Bill White) (08/16/90)
In article <FISH.90Aug14183156@his.gemed.com> fish@gemed.ge.com (Mark Fisher, GE Medical, Milwaukee WI, x4-6553) writes: >What do you guys and gals think of this idea? > [........] > >I would hate to get caught with something like this on the top of my >car. :^) I got a better idea. Why not build a "stealth car"? I mean, they recently forumlated a radar-absorptive paint; all you have to do is angle your metal stuff in the car to avoid reflection, and paint it with the radar-absorbing stuff. Which will still do you no good, because the cop will still be able to eyeball your general speed. Heck, why not just mount a Stinger missile in your trunk, or use a CO2 laser to burn out his/her tires, or go for the real stuff, say heck with cars, and fly an SR-71 at ground level. About as likely to work. >// Mark M. Fisher >// fish@gemed.ge.com >// uunet!crdgw1!gemed!fish >// sun!sunbrew!gemed!fish -- | Bill White Internet: bwhite@oucsace.cs.ohiou.edu | | ETORRE'S OBSERVATION: | | The other line moves faster. |
vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) (08/17/90)
Radar countermeasures: When I worked at Sanders in a radar countermeasures group I asked one of our Phd guru types about passive measures like a simple fan in front of the radiator. He said it probably would work quite well BUT even passive countermeasures would be construed as obstruction of justice. In the same sense that your license plate must be visible for all to see, your radar image must also be "plainly visible". He was at one time a consultant on police radar and worked for the state police investigating backscatter for potential health risk. I guess he inquired at that time . Anyhow, he convinced me not to persue it.
olbers@bobcat.ent.ohiou.edu (Robert Olbers ece) (08/17/90)
In article <2835@mindlink.UUCP> a143@mindlink.UUCP (Ed Meyer) writes: >> fish@gemed.com writes: >> >> Mount 4 or so corner reflectors on a rotating frame such as [...] >> car. Turn the reflectors at a constant rate of something like 120 >> RPM. And wa-la your car's dominate doppler shift will be ~ 10 mph >> less than you are actually going. That is assumming you can figure >> out which way to turn the reflectors ;) >> >> Mark, if memory serves, this was tried about a dozen years ago: the corner >> reflectors caught the airstream as the car went forward and as expected the >> radar facing the oncoming car detected a much lower speed due to the relative >> retrogressive motion of the reflectors. However, a radar (like the so-called >> radar camera) would see the reflectors receding at higher speed than the car. >> So, if they don't get you coming, they get you going. What about deliberately causing the radar to overestimate your speed? What could the cops do if they clocked you at, say 150mph in a Yugo? It seems that at least the radar evidence would be useless in court. (Of course, they can still clock you from airplanes... ~B^> ) R. L. Olbers 'Being disintegrated makes me very angry' olbers@bobcat.ent.ohiou.edu - Marvin Martian 'Being disinformed makes me very angry' - RLO
evans@decvaxdec.com (Marc Evans Ultrix Q/A) (08/18/90)
In article <6154@tekred.CNA.TEK.COM>, vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) writes: |> When I worked at Sanders in a radar countermeasures group I asked |> one of our Phd guru types about passive measures like a simple fan |> in front of the radiator. He said it probably would work quite well |> BUT even passive countermeasures would be construed as obstruction |> of justice. [...] Does this imply that my Saab 99 Turbo which has dual fans on the front of the radiator for cooling purposes could be 1) lowering my radar footprint, 2) considered an obstruction of justice? My personal opinion is that 1 is maybe, and 2 is no, but I thought I would check your opinion(s)... - Marc ======================================================================== ==== Marc Evans - WB1GRH - evans@decvax.DEC.COM | Synergytics (603)635-8876 Unix and X Software Contractor | 21 Hinds Ln, Pelham, NH 03076 ======================================================================== ====
depolo@eniac.seas.upenn.edu (Jeff DePolo) (08/18/90)
In article <2835@mindlink.UUCP> a143@mindlink.UUCP (Ed Meyer) writes: > reflectors caught the airstream as the car went forward and as expected the > radar facing the oncoming car detected a much lower speed due to the relative > retrogressive motion of the reflectors. However, a radar (like the so-called > radar camera) would see the reflectors receding at higher speed than the car. > So, if they don't get you coming, they get you going. Maybe I'm not picturing it right, but if you had reflectors moving toward the rear of the car, a radar gun pointed at the front of a moving vehicle would display a lower speed, and likewise, a radar gun pointed at the rear would also display a lower speed. When pointed at the front, the reflectors are approaching the radar gun at a slower rate than the car is because they are moving away from the radar gun. When pointed at the rear, the reflectors are moving away from the radar gun at a slower speed than the car, because they are moving toward the radar gun. Either way, it should yield a lower radar reading, unless I'm missing something. Remember that a radar gun only measures absolute difference in frequency. In the oncoming car case, the doppler shift is positive, making the reflector-induced shift less than the normal shift. In the receeding car case, the doppler shift is negative, making the reflector-induced shift more than the normal shift. But in both cases, the absoute value of the shifts is less when reflector-induced. Did that make sense? Probably not...it's 3:45 AM. Anyone planning on testing this theory? ;-) --- Jeff -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Jeff DePolo N3HBZ Twisted Pair: (215) 386-7199 depolo@eniac.seas.upenn.edu RF: 146.685- 442.70+ 144.455s (Philadelphia) University of Pennsylvania Carrier Pigeon: 420 S. 42nd St. Phila PA 19104
colinm@runxtsa.runx.oz.au (Colin McCormack) (08/20/90)
What would be really useful is a paint which flouresces in the band used by police doppler radar. As an aside, local courts have defined police doppler radar devices as precision instruments (or some such quaint legalese) which means that no defense of inaccuracy can expect to prevail. -- --------- Internet: colinm@runxtsa.oz.au --------- UUCP: uunet!runxtsa.oz.au!colinm "The appropriation of radical thinking by lazy, self-obsessed hippies is a public relations disaster that could cost the earth" - Ben Elton, Stark.
waltw@mentor.com (Walt Wilson) (08/23/90)
In article <6154@tekred.CNA.TEK.COM> vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) writes: >Radar countermeasures: > >When I worked at Sanders in a radar countermeasures group I asked >one of our Phd guru types about passive measures like a simple fan >in front of the radiator. He said it probably would work quite well >BUT even passive countermeasures would be construed as obstruction >of justice. In the same sense that your license plate must be visible >for all to see, your radar image must also be "plainly visible". >He was at one time a consultant on police radar and worked for the >state police investigating backscatter for potential health risk. >I guess he inquired at that time . Anyhow, he convinced me not to >persue it. Many RADAR guns use frequencies listed officially with the FCC as "shared" frequencies with amateur (HAM) radio. It occurs to me, since the purpose of HAM radio is to encourage the advancement of the art and science of radio, mounting my home-made anti- collision device on the dash fits the stated purpose of HAM radio. Since I would have no way of knowing when the police might choose to "share" this frequency, and I have a very good driving record eliminating the excuse of "probable cause", I doubt their radar would be able to see anything through the up to 1000 watts I'm allowed to use. (A couple might be enough.) Just a thought. WWIII
tuv@pmafire.UUCP (Mark Tovey) (08/24/90)
In article <1751@oucsace.cs.OHIOU.EDU> bwhite@oucsace.cs.OHIOU.EDU (Bill White) writes: > >I got a better idea. Why not build a "stealth car"? I mean, they >recently forumlated a radar-absorptive paint; all you have to do is >angle your metal stuff in the car to avoid reflection, and paint it with >the radar-absorbing stuff. > Seems to me I heard something about Corvettes and their fiberglass bodys were sometimes difficult to pick up on a radar system. Anyone know anything about this?
bill@vrdxhq.verdix.com (William Spencer) (08/25/90)
> In article <FISH.90Aug14183156@his.gemed.com> fish@gemed.ge.com (Mark Fisher, GE Medical, Milwaukee WI, x4-6553) writes: >>What do you guys and gals think of this idea? >>Mount 4 or so corner reflectors on a rotating frame such as >>a plastic bicycle tire. Coat the back of the reflector with resistive >>foam to dissipate the radar energy. Make the corner reflector large >>enough RCS (Radar Cross Section) wise to be much brighter than your >>car. Turn the reflectors at a constant rate of something like 120 >>RPM. And wa-la your car's dominate doppler shift will be ~ 10 mph >>less than you are actually going. That is assumming you can figure >>out which way to turn the reflectors ;) I've heard that radar can not be used (will not stand up in court) on motorcycles with mag wheels due to the radar fooling effect (can be higher or lower in speed). bill S.
dlou@dino.ucsd.edu (Dennis Lou) (08/25/90)
In article <1990Aug24.160330.1441@pmafire.UUCP> tuv@pmafire.UUCP (Mark Tovey) writes: >In article <1751@oucsace.cs.OHIOU.EDU> bwhite@oucsace.cs.OHIOU.EDU (Bill White) writes: >>I got a better idea. Why not build a "stealth car"? I mean, they >>recently forumlated a radar-absorptive paint; all you have to do is >>angle your metal stuff in the car to avoid reflection, and paint it with >>the radar-absorbing stuff. >> > Seems to me I heard something about Corvettes and their >fiberglass bodys were sometimes difficult to pick up on a radar >system. Anyone know anything about this? I heard this too. I also heard that this difficulty was compounded by the fact that the radiator is angled (because it's a bottom breather) and reflected the signal skyward rather than back to the radar gun. -- Dennis Lou Disclaimer: I don't use lame disks. dlou@dino.ucsd.edu "But Yossarian, what if everyone thought that way?" [backbone]!ucsd!dino!dlou "Then I'd be crazy to think any other way!"
henry@zoo.toronto.edu (Henry Spencer) (08/26/90)
In article <1990Aug23.002733.1080@mentor.com> waltw@mntgfx.UUCP (Walt Wilson) writes: >... mounting my home-made anti- >collision device on the dash fits the stated purpose of HAM radio. >Since I would have no way of knowing when the police might choose >to "share" this frequency, and I have a very good driving record >eliminating the excuse of "probable cause"... The police have no, repeat *no*, sense of humor about such things. Defending yourself successfully against criminal charges is often lengthy and expensive. Which class of users has official priority in those bands? Betcha it's not the hams. Lack of obvious criminal intent isn't necessarily a viable defense against criminal charges like "interfering with a police officer in the conduct of his duties". A criminal record can be a serious nuisance even if the judge considers your driving record and gives you a suspended sentence. -- Committees do harm merely by existing. | Henry Spencer at U of Toronto Zoology -Freeman Dyson | henry@zoo.toronto.edu utzoo!henry
dlou@dino.ucsd.edu (Dennis Lou) (08/26/90)
In article <1990Aug25.210746.4753@zoo.toronto.edu > henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1990Aug23.002733.1080@mentor.com> waltw@mntgfx.UUCP (Walt Wilson) writes: >>... mounting my home-made anti- >>collision device on the dash fits the stated purpose of HAM radio. >>Since I would have no way of knowing when the police might choose >>to "share" this frequency, and I have a very good driving record >>eliminating the excuse of "probable cause"... > >The police have no, repeat *no*, sense of humor about such things. >Defending yourself successfully against criminal charges is often >lengthy and expensive. > >Which class of users has official priority in those bands? Betcha it's >not the hams. > >Lack of obvious criminal intent isn't necessarily a viable defense >against criminal charges like "interfering with a police officer in >the conduct of his duties". A criminal record can be a serious nuisance >even if the judge considers your driving record and gives you a suspended >sentence. >-- >Committees do harm merely by existing. | Henry Spencer at U of Toronto Zoology > -Freeman Dyson | henry@zoo.toronto.edu utzoo!henry Okay, enough with the legal speculation! Does anyone know of any "real" cases where someone was caught interfering with police radar? -- Dennis Lou Disclaimer: I don't use lame disks. dlou@dino.ucsd.edu "But Yossarian, what if everyone thought that way?" [backbone]!ucsd!dino!dlou "Then I'd be crazy to think any other way!"
dodgeT@batman.moravian.EDU (Asmodeus) (08/26/90)
In article <1990Aug23.002733.1080@mentor.com>, waltw@mentor.com (Walt Wilson) writes: > > Since I would have no way of knowing when the police might choose > to "share" this frequency, and I have a very good driving record > eliminating the excuse of "probable cause", I doubt their radar > would be able to see anything through the up to 1000 watts I'm > allowed to use. (A couple might be enough.) > > Just a thought. > > WWIII I have followed this thread concerning radar illusion and evasion for quite some time now. I have always thought that one could destroy the radar gun with enough of a return signal. Considering that these guns work with about one-millionth of the energy that they output, is seems to me that 1000 watts (yes, i know, it wont all go towards the radar gun -- little pre-emptive flamage there) that mr. wilson claims available should pretty much melt some key connections in the gun. In all likelihood, the cop will suspect something, (cops being cops) but it is a point to ponder. BTW, i also think that if you returned *enough* power to the gun, it would possible alight *grin*, and the cop would be far more occupied w/his gun than you. Just dont get caught, ha! -- Timothy Dodge Bernhardt 207 ,Box 134, Moravian College, Bethlehem PA 18018 --------------- CSNET/INTERNET....dodgeT@moravian.edu __________________ The obvious is| UUCP......!rutgers!liberty!batman!dodgeT|--space for rent-- that which is never understood until someone expresses it simply-A.Galambos
depolo@eniac.seas.upenn.edu (Jeff DePolo) (08/27/90)
In article <1990Aug24.160330.1441@pmafire.UUCP> tuv@pmafire.UUCP (Mark Tovey) writes: >In article <1751@oucsace.cs.OHIOU.EDU> bwhite@oucsace.cs.OHIOU.EDU (Bill White) writes: >>I got a better idea. Why not build a "stealth car"? I mean, they >>recently forumlated a radar-absorptive paint; all you have to do is >>angle your metal stuff in the car to avoid reflection, and paint it with >>the radar-absorbing stuff. >> > Seems to me I heard something about Corvettes and their >fiberglass bodys were sometimes difficult to pick up on a radar >system. Anyone know anything about this? Mid 70's vintage Corvettes also had a sloping radiator that reflected most of the radar upward, making the radar gun's usable range quite limited. A test was done a way back when and from what I could remember, the gun's normal range was cut to less than 50% when attempting to clock one of these Corvettes. --- Jeff -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Jeff DePolo N3HBZ Twisted Pair: (215) 386-7199 depolo@eniac.seas.upenn.edu RF: 146.685- 442.70+ 144.455s (Philadelphia) University of Pennsylvania Carrier Pigeon: 420 S. 42nd St. Phila PA 19104
alvitar@xavax.com (Phillip Harbison) (08/27/90)
In article <1990Aug25.210746.4753@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: > In article <1990Aug23.002733.1080@mentor.com> waltw@mntgfx.UUCP (Walt > Wilson) writes: > > ... mounting my home-made anti-collision device on the dash fits the > > stated purpose of HAM radio. > > The police have no, repeat *no*, sense of humor about such things. In the only case I know of where someone was convicted of building an active radar jammer, the fines were in the six figure range. That is more than I'm willing to risk for the luxury of driving at whatever speed I desire. I understand that HAMs with a `technician' license are allowed to use some of the same frequencies used by police radar; however, FCC rules forbid the use of the airwaves for this purpose. I think a passive (or pseudo-passive) approach is a good alternative. I had an idea similar to the bicycle wheel idea recently mentioned in this group, in fact, I had intended to someday market such a device. What I planned to do was build something like a weatherman's annemometer (the gadget that measures windspeed); however, instead of using hemispherical cups I would use corner reflectors. This device would be mounted on my dashboard, so there would be no problems with wind drag (but perhaps some major problems with visibility :-). An electric motor would cause the device to rotate (since there wouldn't be any wind). I talked with an engineer whose specialty is radar, and he felt that the device would probably work if the reflectors were large enough. He did't think the reverse side of the reflectors would be a problem, since the behavior of an inverse corner reflector is the opposite of a corner reflector, i.e. dispersal of the reflected waves. The corner reflectors, as viewed by police radar, would be constantly moving backwards. The only problem might be police radar behind me. It would also see the reflectors moving away, but in this case, it would add to the relative speed. A shield would probably do ok her, and another device might be mounted in the rear window to fool radar behind me. Another idea we talked about is to build a spark gap. The principal is that while a spark gap isn't really a `transmitter', it does emit large amounts of power over the entire spectrum. My radar expert believes this might be enough to fry the radar speed detectors front end. Unfortunately, it would also fry the front end of any radar detectors in the vicinity. I could build a spark device that was triggered by my own radar detector, and which shorted together the input to my front end just before it fired, but this wouldn't help the other people. Their detector would be fried, result- ing in a false sense of confidence and probably a speeding ticket. Stealth techniques will probably work, but you'll have to be willing to compromise the appearance of your vehicle. All the RF absorbing materials I've seen are flat black, which isn't exactly my idea of a nifty color for sports cars. :-) Does anyone know if it is possible to paint over these materials with conventional auto paints without loosing their absorbing qualities? As for the legalities, the spark gap may have some problems. While it isn't what I would consider a `transmitter', it certainly isn't passive. I also wouldn't want to go down the road frying the radar detectors of my fellow drivers, because I know I wouldn't want someone to do the same to me. I rely on my detector to help me keep a semi-clean record, and I know many others do the same. The corner reflector pinwheel is truly passive; therefore I can't see how it could be deemed to be illegal. It might be cited for obstructing my field of vision (if it is very large) but it certainly isn't a transmitter. I can't see anything illegal about the stealth technique either. There certainly isn't any law against painting your car, nor is there a requirement that your car have surfaces which are orthogonal to oncoming radar waves. Why go to all this trouble just to avoid traffic tickets? Well, for one thing there is alot more cost involved than just the tickets. Insurance rates in the USA tend to skyrocket when you get more than one ticket in a three year period. Enough tickets can also result in a revoked license. I habitually exceed the speed limit, especially when I'm driving on the interstate or other limited access highway. I know myself to well to assume that I'm going to change anytime soon. I've saved alot of hassle already by religiously using a radar detector. I turn it on anytime I start the car, even if I'm just driving down the block. I turn it on right as I start the car. My model is one of those which put out an annoying series of beeps as it performs a self test, so I put on my seat belts while it self tests, then turn up the volume. In fact, using a radar detector has succeeded at doing what driving school and all those TV commercials failed to do: get me to wear a seat belt. :-) I think passive countermeasures is the next logical step in my defense against police radar. In fact, if radar detectors are banned nationwide, passive countermeasures may be our only defense. :-( -- Live: Phil Harbison, Xavax, P.O. Box 7413, Huntsville, AL 35807 Uucp: alvitar@xavax.com Bell: 205-883-4233, 205-880-8951
sandin@uicbert.eecs.uic.edu (08/27/90)
I suspect this was covered already, and I'm no radar expert, but... I have seen for sale at a place in Chicago (Warshawski's "everything automotive"), a radar gun. This looks to be the sort one sees on TV when there is a demonstration of a pitcher's fastball or some such thing. However, if such a thing were to use the same frequency as police radar (which it probably does not, but bear with be) What would happen if one were to mount this on the hood of ones car? I mean, as I understand it, the police sensor is expecting to recieve a signal shifted by amount X, from getting bounced 180 degrees. Wouldn't the same device on my car register X/2 : in other words, if I was doing 100 MPH, it would read 50, wouldn't it? There are a few subtleties, like the fact that a radar gun presumably emits pulses and you would have to match timing. It would seem that everyone is looking at it from a "stealth" point of view. However, we do not wish to be invisible, we simply wish to seem like we are going slower than we are. So, is my theory full of shit, or what? Stephan Meyers c/o sandin@uicbert.cc.uic.edu
a575@mindlink.UUCP (Michael G. Henders) (08/27/90)
This is not entirely on the thread, but I have got to ask... to those of you
reading this stuff in Europe, or Australia, etc., do you have this same sort of
cat-and-mouse game between the speed patrol and the speeders? Or is it purely
a North American phenomenon? Please satisfy my curiosity!
Obligatory stuff.electronics: What type of radar sets do they use?
Mike Henders a575@mindlink.UUCPvekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) (08/27/90)
FRYING RADAR FRONT ENDS: Any transmitter with enough power to fry a radar front end will also cause serious or fatal brain damage and cataracts to those in its path. Radars use high peak power but very low duty factor. Remember anything that emits rf ,even unintentionally, is subject to FCC class B regulations. I hope no one will be driving down the road with an open microwave oven on their roof.
depolo@eniac.seas.upenn.edu (Jeff DePolo) (08/28/90)
In article <1990Aug27.054252.12099@uicbert.eecs.uic.edu> sandin@uicbert.eecs.uic.edu writes: >I have seen for sale at a place in Chicago (Warshawski's "everything >automotive"), a radar gun. This looks to be the sort one sees on TV when >there is a demonstration of a pitcher's fastball or some such thing. >However, if such a thing were to use the same frequency as police radar >(which it probably does not, but bear with be) It probably does. X and K are the two most popular bands. The major leagues use X band guns made by Jugs (whose guns are or were actually made by CMI) and Decatur. Kustom used to make a K band pitching gun, but it isn't very popular. S band used to be used by police, but that was a long time ago and I don't think that anybody ever bothered to make a handheld S band gun - it would be pretty bulky anyway. >What would happen if one were to mount this on the hood of ones car? >I mean, as I understand it, the police sensor is expecting to recieve a >signal shifted by amount X, from getting bounced 180 degrees. Wouldn't >the same device on my car register X/2 : in other words, if I was doing >100 MPH, it would read 50, wouldn't it? Sorry, but the answer is no. The big problem with trying to transmit a CW carrier back at the police's radar gun is that radar guns aren't very frequency-stable. They tend to drift quite a bit. The way they determine speed is by transmitting a CW carrier and mixing the transmitted signal with the returning signal to get AF baseband which is fed into a counter (simplified version). Since the frequency shift is only a few hundred Hertz for a car moving at highway speeds at microwave frequencies, the chances of you getting your carrier right on frequency to cause a "better" reading are pretty slim. You can AM your carrier and superimpose a shift that the AF counter will interpret as a Doppler shift, however. This is the most common type of jammer and works to some degree, but is definately not foolproof. Many radar guns now have "jammer detectors" built in, so the police may catch on rather easily. >There are a few subtleties, like the fact that a radar gun presumably >emits pulses and you would have to match timing. All radar guns are Doppler or psuedo-Doppler (PLL) devices. They don't use pulse timing as does the new laser-based speed device. >So, is my theory full of shit, or what? It's a good idea, and has been kicked around sci.electronics, rec.ham-radio, and rec.autos a number of times. Unfortunately, we always come to the same conclusion - jammers are bad news. > Stephan Meyers c/o sandin@uicbert.cc.uic.edu --- Jeff -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Jeff DePolo N3HBZ Twisted Pair: (215) 386-7199 depolo@eniac.seas.upenn.edu RF: 146.685- 442.70+ 144.455s (Philadelphia) University of Pennsylvania Carrier Pigeon: 420 S. 42nd St. Phila PA 19104
depolo@eniac.seas.upenn.edu (Jeff DePolo) (08/28/90)
In article <6215@tekred.CNA.TEK.COM> vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) writes: >FRYING RADAR FRONT ENDS: > >Any transmitter with enough power to fry a radar front end will >also cause serious or fatal brain damage and cataracts to those >in its path. Radars use high peak power but very low duty factor. >Remember anything that emits rf ,even unintentionally, is subject >to FCC class B regulations. I hope no one will be driving down >the road with an open microwave oven on their roof. Good advice, but let me just throw in a comment. Police radar guns are continuous-duty devices (well, CW, sometimes switched off, but not in a pulse fashion). The highest power one I know if is 8 watts ERP. Most are between 800 mW and 4 watts ERP. This isn't really high power, however, there was a study done and the cancer rate of police officers who had been using radar for a number of years was on the order of 3 times higher than those who didn't. Don't remember who did the actual study, but it was published by APCO a few years ago. --- Jeff -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Jeff DePolo N3HBZ Twisted Pair: (215) 386-7199 depolo@eniac.seas.upenn.edu RF: 146.685- 442.70+ 144.455s (Philadelphia) University of Pennsylvania Carrier Pigeon: 420 S. 42nd St. Phila PA 19104
john@qip.UUCP (John Moore) (08/28/90)
In article <6215@tekred.CNA.TEK.COM> vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) writes:
]FRYING RADAR FRONT ENDS:
]
]Any transmitter with enough power to fry a radar front end will
]also cause serious or fatal brain damage and cataracts to those
]in its path. Radars use high peak power but very low duty factor.
This is not true, in several ways:
(1) The amount of power necessary to fry radar front ends is measured
in Watts peak. At these levels, the microwave beam is innocuous
unless you spend a lot of time in it.
(2) Police radars use neither high peak power nor low duty factor.
I used to work on an aircraft with 160 kW peak X-band radar. While
I wouldn't recommend standing in the beam at 3 feet (which inadvertently
happened to me once), you are relatively safe at 1000 feet. However,
we used to fry radar receiver front ends at 2500 feet of range (by
accident - we didn't realize that the nice reflector we would tune
up the radar on was the GCA site, and contained radar receivers.
--
John Moore HAM:NJ7E/CAP:T-Bird 381 {ames!ncar!noao!asuvax,mcdphx}!anasaz!john
USnail: 7525 Clearwater Pkwy, Scottsdale,AZ 85253 anasaz!john@asuvax.asueas.edu
Voice: (602) 951-9326 FAX:602-861-7642 Advice: Long palladium, Short Petroleum
Opinion: Support ALL of the bill of rights, INCLUDING the 2nd amendment!martin@hq.af.mil (Gregory.J.Martin) (08/28/90)
In article <6215@tekred.CNA.TEK.COM> vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) writes: >FRYING RADAR FRONT ENDS: > >Any transmitter with enough power to fry a radar front end will >also cause serious or fatal brain damage and cataracts to those >in its path. Radars use high peak power but very low duty factor. >Remember anything that emits rf ,even unintentionally, is subject >to FCC class B regulations. I hope no one will be driving down >the road with an open microwave oven on their roof. No Sh*t!!!
danielce@ecr.mu.oz.au (Daniel Ake CAROSONE) (08/29/90)
In article <2959@mindlink.UUCP>, a575@mindlink.UUCP (Michael G. Henders) writes: > This is not entirely on the thread, but I have got to ask... to those of you > reading this stuff in Europe, or Australia, etc., do you have this same sort of > cat-and-mouse game between the speed patrol and the speeders? Or is it purely > a North American phenomenon? Please satisfy my curiosity! We have it here too, to some extent. I have heard nothing of detector detectors or anything, but radar detectors are fairly popular, certainly for frequent highway users. Governments are mostly concerned (at this stage) with interstate heavy vehicles (trucks, coaches, etc) speeding, as there have been several major tragic accidents involving them of late. This does not mean that speeding cars will be overlooked. It is EXTREMELY easy to exceed the state maximum speed limits (100/110 km/h) especially on the best interstate freeways, even if you are not deliberately speeding, as I am sure you know. > Obligatory stuff.electronics: What type of radar sets do they use? Hand held guns, X or K band; roadside/vehicle mounted X/K/S band. In addition, particularly here in the state of Victoria, they have new (nasty) automatic speed-cameras that (technically) don't even require a policeman in attendance (ecxept to stop the camera getting attacked :-) These can be perfectly invisible until you pass them and look in the mirror, and can be triggered by laser amphometer, a radar, or laser speed meter. The first you know about it is when you get a notice in the mail...
asmith@acorn.co.uk (Andy Smith) (08/31/90)
In article <2959@mindlink.UUCP> a575@mindlink.UUCP (Michael G. Henders) writes: >This is not entirely on the thread, but I have got to ask... to those of you >reading this stuff in Europe, or Australia, etc., do you have this same sort of >cat-and-mouse game between the speed patrol and the speeders? Or is it purely >a North American phenomenon? Please satisfy my curiosity! > >Obligatory stuff.electronics: What type of radar sets do they use? > > Mike Henders a575@mindlink.UUCP The problem over here is that the police are a little more clever, and use such things as video and Vascar equipment to hall in speeders. However you are usually safe upto about 10mph over the limit (thats 80mph on a motorway). I suppose there is a bit of a cat and mouse game, but the cat has the advantage of non radar detection devices in unmarked cars, so you take your chance. I do not think we have enough of them to think seriously of counter measures. Andy
iws@sgfb.ssd.ray.com (Ihor W. Slabicky) (09/01/90)
In article <6154@tekred.CNA.TEK.COM>, vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) writes: > Radar countermeasures: > > He was at one time a consultant on police radar and worked for the > state police investigating backscatter for potential health risk. What were the results of these investigations of potential health risks? Ihor
vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) (09/01/90)
In article <236@sgfb.ssd.ray.com> iws@sgfb.ssd.ray.com (Ihor W. Slabicky) writes: >In article <6154@tekred.CNA.TEK.COM>, vekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) writes: >> Radar countermeasures: >> >> He was at one time a consultant on police radar and worked for the >> state police investigating backscatter for potential health risk. > >What were the results of these investigations of potential health >risks? > >Ihor He claimed that the units placed on the dash and aimed out the windshield were terrible because the window is very near the Bragg angle and causes a large reflection. He also said that cataracts are much more common among officers. Microwave radiation and even rf is much more dangerous than many people think. It can cause brain damage and other things that are difficult to trace or quantify. Please reserve comments about cops being blind or brain dead etc. This is sci.electronics not MAD Magazine.