The number of pulses per second is found by dividing the number of pulses per mile by the number of seconds per hour.Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.).Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.).Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.).
In moving mode, when the patrol vehicle comes to a stop, no pulses are received by the DSP and therefore the patrol speed is set to zero, eliminating false association with other moving targets. Such a DSP radar is disclosed, for example, in U.S. Pat. No. 5,528,246 to Henderson et al., owned by the assignee herein. ![]() Another problem can occur when the radar is in moving mode and the patrol vehicle comes to a stop at a traffic light. A return from moving traffic can be confused with the patrol vehicle and a wrong patrol vehicle speed is displayed resulting in an inaccurate calculation of a target speed. The signal processing system of the radar unit converts the pulses from the speedometer and calculates the speedometer speed. Using this speed as the center of a search window, the system searches for the patrol vehicle radar return signal that falls within the search window. Once the patrol speed is found, other targets can be found and their speed accurately determined. If the radar is in moving mode and the patrol vehicle comes to a stop, there will be no pulses from the electronic speedometer and the patrol speed will be calculated to be zero eliminating the need to search for a non-existent patrol vehicle radar return signal. If no patrol vehicle radar return signal is found within the search window, a search for the patrol vehicle radar return is conducted using methods known in the prior art. Likewise, if speedometer pulses are not detected at start-up, the search for the patrol vehicle return signal may employ prior art methods. Radar return signals received by antenna 12 are converted from analog to digital by A to D converter 14, and input to signal processing system 16 containing a digital signal processor (DSP). It should be understood that a DSP traffic radar unit transmits a single frequency microwave signal toward moving and stationary targets. A portion of the microwave signal is reflected by the targets and is received, mixed, and amplified by the receiver section of antenna 12. The signal received is a composite of all signals reflected by the moving and stationary targets. Conversion of the signal from the time domain to the frequency domain by the DSP separates the targets by frequency, which is directly proportional to the speed of the target. Logic control system 18 and signal processing system 16 work in tandem to control calculation, configuration, and display of targets and patrol speed. Output 22 from a patrol car electronic speedometer 20 is connected to the DSP of signal processing system 16. As in a conventional traffic radar, a display window (not shown) is provided to display the patrol vehicle speed. A common value of speedometer pulses is 8,000 pulses per mile. Therefore, when the patrol vehicle is traveling at a speed of one mile per hour, the speedometer will output (8,000 pulses per mile 1 mile per hour) pulses per hour.
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