Traffic radar system with electronic test signal generation

Abstract

A mobile test unit for verifying an accuracy of vehicle speeds determined by a traffic radar system comprises a test signal generator and a signal mixer. The test signal generator is configured to generate an electronic test signal having a first frequency. The signal mixer is configured to receive the test signal and a radar beam having a second frequency, wherein the radar beam is transmitted from a radar transceiver of a traffic radar system. The signal mixer is further configured to mix the electronic test signal and the radar beam and to generate a mixed signal having frequency components that include the first frequency and the second frequency, wherein the mixed signal is received by the radar transceiver.

1 . A mobile test unit for verifying an accuracy of vehicle speeds determined by a traffic radar system, the mobile test unit comprising:
 a test signal generator configured to generate an electronic test signal having a first frequency; and   a signal mixer configured to receive the test signal and a radar beam having a second frequency, the radar beam transmitted from a radar transceiver of a traffic radar system, the signal mixer further configured to mix the electronic test signal and the radar beam and to generate a mixed signal having frequency components that include the first frequency and the second frequency, the mixed signal received by the radar transceiver.   
     
     
         2 . The mobile test unit of  claim 1 , wherein the first frequency has a range from approximately 1,000 Hertz to approximately 10,000 Hertz. 
     
     
         3 . The mobile test unit of  claim 1 , wherein the first frequency corresponds to a vehicle speed to be tested. 
     
     
         4 . The mobile test unit of  claim 1 , wherein the second frequency is in the Ka band of frequencies. 
     
     
         5 . The mobile test unit of  claim 1 , wherein the signal mixer includes a diode configured to receive the test signal and the radar beam and to generate the mixed signal. 
     
     
         6 . A traffic radar system implemented with a law enforcement patrol vehicle, the traffic radar system comprising:
 a first radar transceiver configured to transmit a first radar beam that has a first frequency and receive a mixed signal, the first radar transceiver further configured to generate a first electronic signal based on the received mixed signal;   a second radar transceiver configured to transmit a second radar beam that has the first frequency and receive the mixed signal, the second radar transceiver further configured to generate a second electronic signal based on the received mixed signal;   a mobile test unit configured to generate the mixed signal having frequency components that include the first frequency and a second frequency; and   a processing element configured to
 receive a plurality of digital data samples derived from the first or second electronic signals, 
 process the digital data samples to calculate a frequency component, 
 determine a test speed corresponding to the frequency component, and 
 determine if the test speed is equal to a speed corresponding to the second frequency. 
   
     
     
         7 . The traffic radar system of  claim 6 , wherein the processing element is further configured to perform a time domain to frequency domain conversion on the digital data samples to calculate the frequency component. 
     
     
         8 . The traffic radar system of  claim 6 , wherein the processing element is further configured to simulate that the patrol vehicle is moving, determine the test speed as a relative test speed, and convert the relative test speed to an absolute test speed using a predetermined value of a speed of the patrol vehicle. 
     
     
         9 . The traffic radar system of  claim 8 , wherein the processing element is further configured to convert the relative test speed to the absolute test speed using addition or subtraction depending upon a direction of travel of a simulated target vehicle relative to a simulated direction of travel of the patrol vehicle. 
     
     
         10 . The traffic radar system of  claim 6 , wherein the first radar transceiver is further configured to generate the first electronic signal to have frequency components excluding the first frequency. 
     
     
         11 . The traffic radar system of  claim 6 , wherein the second radar transceiver is further configured to generate the second electronic signal to have frequency components excluding the first frequency. 
     
     
         12 . The traffic radar system of  claim 6 , wherein the mobile test unit includes a test signal generator configured to generate an electronic test signal having the second frequency. 
     
     
         13 . The traffic radar system of  claim 12 , wherein the mobile test unit includes a signal mixer configured to receive the test signal and the first radar beam or the second radar beam, the signal mixer further configured to mix the electronic test signal and either the first radar beam or the second radar beam and to generate the mixed signal. 
     
     
         14 . The traffic radar system of  claim 6 , further comprising an analog to digital converter configured to receive the first electronic signal and the second electronic signal and output a plurality of front radar digital data samples and a plurality of rear radar digital samples. 
     
     
         15 . A traffic radar system implemented with a law enforcement patrol vehicle, the traffic radar system comprising:
 a first radar transceiver configured to transmit a first radar beam that has a first frequency and receive a mixed signal, the first radar transceiver further configured to generate a first electronic signal based on the received mixed signal;   a second radar transceiver configured to transmit a second radar beam that has the first frequency and receive the mixed signal, the second radar transceiver further configured to generate a second electronic signal based on the received mixed signal;   a test signal generator configured to generate an electronic test signal having a second frequency;   a signal mixer configured to receive the test signal and the first radar beam or the second radar beam, the signal mixer further configured to mix the electronic test signal and either the first radar beam or the second radar beam and to generate the mixed signal having frequency components that include the first frequency and the second frequency; and   a processing element configured to
 receive a plurality of digital data samples derived from the first or second electronic signals, 
 perform a time domain to frequency domain conversion on the digital data samples to calculate a frequency component, 
 determine a test speed corresponding to the calculated frequency component, and 
 determine if the test speed is equal to a speed corresponding to the second frequency. 
   
     
     
         16 . The traffic radar system of  claim 15 , wherein the first radar transceiver is further configured to generate the first electronic signal to have frequency components excluding the first frequency. 
     
     
         17 . The traffic radar system of  claim 15 , wherein the second radar transceiver is further configured to generate the second electronic signal to have frequency components excluding the first frequency. 
     
     
         18 . The traffic radar system of  claim 15 , further comprising an analog to digital converter configured to receive the first electronic signal and the second electronic signal and output a plurality of front radar digital data samples and a plurality of rear radar digital samples. 
     
     
         19 . The traffic radar system of  claim 15 , wherein the processing element is further configured to simulate that the patrol vehicle is moving, determine the test speed as a relative test speed, and convert the relative test speed to an absolute test speed using a predetermined value of a speed of the patrol vehicle. 
     
     
         20 . The traffic radar system of  claim 19 , wherein the processing element is further configured to convert the relative test speed to the absolute test speed using addition or subtraction depending upon a direction of travel of a simulated target vehicle relative to a simulated direction of travel of the patrol vehicle.