eugene@pioneer.arpa (Eugene Miya N.) (12/29/87)
In article <2576@calmasd.GE.COM> jnp@calmasd.GE.COM (John Pantone) writes: >Adrian Hurt: >>Incidentally, how good is radar against non-metallic targets? How good are >>infra-red missiles against piston-engined planes? > >Radar (at least the radar used by police to detect speeders) can detect >non-metallic objects quite well. I have had the opportunity to test them >against a number of substances, and know the results to be true. The best >reflectors were (non-metallic): >Fiberglass, plywood (especially marine), doped canvas (like airplanes) and >solid hardwoods (oak and maple). Soft wood was less reflective (like balsa) >but was not at all invisible. Ah! A terrible posting by one a member one of the companies who make radar! Ah! Radar depends on many things. Get Skolnik's book Introduction to Radar Systems (now 3rd ed.) if you want to learn more. Basically, the radar equation is a O(distance^4) equation with terms for the cross-section of an object, the dielectric constant, the wave-length of the signal, etc. etc. There are different radar for rain drops, clouds, air defense, imaging, etc. Then the article which posted this: >to home in on. In a related story, I heard that the B1 bomber has >1 / 1000 the radar signiture of a B52. It might be that the British Not quite that good. It depends on a lot of things like if the plane is banking, climbing, etc. IR also has other problems since it encompasses much broader bandwidths than wide light. It depends what IR ranges. From the Rock of Ages Home for Retired Hackers: --eugene miya, NASA Ames Research Center, eugene@ames-aurora.ARPA "You trust the `reply' command with all those different mailers out there?" "Send mail, avoid follow-ups. If enough, I'll summarize." {uunet,hplabs,hao,ihnp4,decwrl,allegra,tektronix}!ames!aurora!eugene
gazit@bein.cs.duke.edu (Hillel Gazit) (09/17/88)
I was caught by a police radar which claimed that I was going 65 MPH. My speed was 55 MPH. I think that something was wrong with the radar, so I want to challenge the policeman in court. Can someone please post a list of things that can wrong with a radar? (I want to ask the policeman if he is absolutly sure that his radar was OK, and then ask him to explain to me why cannot all the things on the list happen). Can someone post, in addition, what went wrong with the radar of the ship that has shot down the Iranian airliner? (I want to ask the policeman how comes his radar cannot make any mistakes, when the radar of a very expensive warship has made them.) Thanks Hillel gazit@cs.duke.edu
henry@utzoo.uucp (Henry Spencer) (09/19/88)
>Can someone post, in addition, what went wrong with the radar of the ship >that has shot down the Iranian airliner? >(I want to ask the policeman how comes his radar cannot make any mistakes, >when the radar of a very expensive warship has made them.) Unfortunately, the answer will probably not be of any real use to you. The Vincennes' radar was functioning properly and doing its job. The problem was in human interpretation of the results. -- NASA is into artificial | Henry Spencer at U of Toronto Zoology stupidity. - Jerry Pournelle | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
eli@spdcc.COM (Steve Elias) (09/19/88)
followups to rec.autos In article <12462@duke.cs.duke.edu> gazit@bein.UUCP (Hillel Gazit) writes: > >I was caught by a police radar which claimed that I was going 65 MPH. >My speed was 55 MPH. I think that something was wrong with the radar, >so I want to challenge the policeman in court. >Can someone please post a list of things that can wrong with a radar? there's a good book about fighting radar speeding tickets. (i don't recall the name -- go ask the folks in rec.autos!) the units can have calibration problems. usually the cop has to prove that he has calibrated the unit properly within the previous few days... or some 'suitable' time limit. if there were other cars around, he may have gotten a reading from a faster car... >Can someone post, in addition, what went wrong with the radar of the ship >that has shot down the Iranian airliner? from what i understand, the Vincennes radar made no mistakes and worked as expected under the short range conditions it was being used in. the radar operator and the captain made the mistake... a comprehensive discussion on this issue can be found in back issues of comp.risks. military radars and police radars are very different beasts. their missions are worlds apart... >(I want to ask the policeman how comes his radar cannot make any mistakes, >when the radar of a very expensive warship has made them.) be careful about asking cops such things! be real nice! good luck with your ticket. 65 in a 55 is one wimpy ticket. are the California fuzz usually so picky?
glenns@sco.COM (Glenn Schmall) (09/19/88)
In article <12462@duke.cs.duke.edu> gazit@bein.UUCP (Hillel Gazit) writes: > >I was caught by a police radar which claimed that I was going 65 MPH. >My speed was 55 MPH. I think that something was wrong with the radar, >so I want to challenge the policeman in court. > >Hillel gazit@cs.duke.edu I dont know how highwary patrol handle things out there in NY, but here on the west coast, If a patrol tags you with radar, you have the right to ask the officer to show you the gun showing the speed that he is going to right you up for. Now if the gun has been cleared, You can bring this up in court and they will toss the case out. Out here at least, you cannot be tagged by radar only (except in special circumstances designated by city/county ordances) {Im assuming that this all happened on the highway}. The highway patrol must clock you in addition to zapping you with radar to make it stick. As for evidence that the gun itself is screwy, I heard that there are reports done by some federal agency proving that the guns were not "a sure means of determining speed". {Hence the highway patrol must clock you in addition to using the gun} I would assume that you could get your hands on one of these reports down at you local federal repository. {It would be worth $$$$ to me to go down and investigate.} good luck and stick the suckers. -glenns@sco. ps. my information comes to me by means of an unfortunate friend of mine who went to traffic school. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ What do you mean it just stopped....?! | ucbvax!ucscc!sco!glenns. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++