text: It was pretty clear from the fact that you have asked this twice that you did not get the answer that you were looking for so here is my try !!!\n\nThe First Answers on the other question were good, but doppler was made a little bit clearer when put to me like this.When applied to Sound Waves.  Have you heard a train horn coming toward you then away from you? The same horn at first sounds higher in frequency as the waves are compressing together in front of the train. Then as it passes, goes away the same horn sounds lower in frequency because now the waves are stretching out, reaching us at a lower rate per second this is the doppler effect.  I only say a train because it is the only vehicle that usually single=horned you can hear clearly like this.  A car passing if it blows it's horn will create the same effect and do the exact same thing. It's just not so noticeable.\n\nDoppler is how the Police catch you speeding! The early radar units were actually calibrated by the officers in the field using the back and forth motion of a common music tuning fork! (The back and forth motion of a certain note represented a certain specific MPH).\n\nDoppler really only refers to the change of frequency reflected from the target. If it is higher, then the target is coming toward the receiving antenna. If it is lower in frequency, the target is going away from the receiving antenna. The more the frequency shift, the faster the movement. \n\nConventional radar only shows the return signal, and does not measure its frequency shift from that which was transmitted.\n\nHope this helps you.\n\nThats basic Doppler 101\n\nThere is a Display (if it is a Weather type Radar) , a Transmitter / Receiver ,  Waveguide ( looks like square hollow copper tubing, conducts the radar signal ), Feed Horn (connects waveguide to antenna)  Parabolic Antenna ( Focus signal into Feed Horn)\n\nBy the wayI just remembered in the days of space travel and satelites.  When we tune in satelites the frequencies change as the satelite moves due to this doppler effect.  Now during re-entry when speeds are greater the shifts are noticeable.  And you can actually tell a difference from a ground station on the same frequency!\n\nOh yeah by the way no big problems with doppler,  except that some operator could aim the darn thing wrong I guess and single out the wrong vehicle for speeding.  Guess he would be cross eyed!!!  Mistakes happen in just about every thing that is done everywhere!  But doppler is very accurate people make mistakes.  Some few Police are true JERKS most are just humans doing their job and are actually well meaning people trying to save lives!!!!  If you feel you are unfairly stopped for speeding, now I mean you were really NOT speeding, calmly talk to the officer and just see what he can do for you.  Explain Just BE CALM the worst thing will be he will give you the ticket!  The best he will give you a warning!  DO NOT ARGUE WITH HIM! Be sympathetic!  It will work.  OR HE IS A JERK!\n\nI AM NOT A JERK, AND I HAVE CARRIED A BADGE!\n\nHey have a good day. Hope I have helped you in some way!!\n\nOH YEA ... " DRIVE CAREFUL HEAR "\n\nAPS