>-----Original Message----- >From: Hjálmar Árnason [mailto:hjal...@mi.is] >Sent: Thursday, March 27, 2003 3:14 PM >To: emc-p...@majordomo.ieee.org >Subject: Calibrating police radar guns > > > >Hi Forum > >I can recall back in November 2000 there was some discussions here in >this group on how to fight speeding tickets and many of you had good >advices. > >I'm about to start on a project which includes calibrating and >repairing >police radar guns. This will probably involve setting up a >semi-anechoic >chamber or OATS. I have access to a room which can be used to set-up >a chamber and want to restrict the set-up to the radar freq. >around 25 and >35 GHz. > >I would appreciate if you could give some advice and direct me to the >right websites to get information. I need both test equipment >and material >for the chamber. The budget is low so second hand equipment is my goal. >Anyone selling his set-up ?. > >Thank you kindly, > >Hjalmar Arnason >Reykjavik >Iceland >hjal...@mi.is >
Hjalmar: The only calibration performed on police radar guns that I am aware of is verification of the Doppler shift response. This is done by whacking a factory-supplied tuning fork, and holding the tines in the radar beam. The vibrating tines reflect a Doppler-shifted signal, and the gun display counter is adjusted to read the appropriate speed. For the US market, the only tuning forks I have ever seen were designated for 55 MPH. To independently verify the calibration, you could measure the audio frequency of the tuning fork and relate that to peak velocity of the tuning fork tine. (I'm not certain, but, IIRC, the velocity of the tine should also be 55 MPH. Maybe we should dig out our high-school Physics book.) AFAIK, no measurements are made on such interesting things as RF power output, beam width, range, multipath rejection or rejection of undesired signals. Further, I don't know about Iceland, but in the USA, I would want "malpractice" insurance if I was "certifying" the performance of devices that regularly served as trial evidence. Who would want to enter a market like that? Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
