Method and apparatus for digitally measuring speed
First Claim
1. A doppler radar device for use in law enforcement and service vehicle speed surveilance and for determining the speed of an approaching target vehicle when the radar platform vehicle is either moving or stationary, said device comprising:
- means for producing a continuously running time base;
a single means for receiving a composite doppler signal having components relating to the speed of said target vehicle and the speed of the radar platform vehicle;
means for separating said doppler frequency into a first frequency component and a second frequency component;
means for correlating the frequency of said first frequency component with said time base;
means for correlating the frequency of said second frequency component with said time base;
means for counting cycles of each of said time base correlated frequency components, said correlating means and said frequency component counting means cooperating to count each of said frequency components in a preselected time increment, said time increment relating to said time base;
means for subtracting said counted cycles of said first frequency component from said counted cycles of said second frequency component; and
means for displaying the result from said subtracting means in unit indicative of speed of said approaching vehicle.
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Accused Products
Abstract
A digital display doppler radar unit has a moving mode and a stationary mode. The incoming doppler signal, which in the moving mode, represents both speed of the radar platform and speed of an approaching target vehicle, is separated into two signal components by selective filtering. One component represents the sum of the ground speeds for the radar platform and approaching vehicles. A time base is generated by a crystal control means and the time base is utilized for correlating the received doppler signals, indicative of speed, with the time base. Each doppler signal component is converted to binary coded decimal (BCD) information and a digital counter counts the cycles of each reeived doppler signal and compares the count with an amount previously stored. Circuit means are provided to validate the received doppler signal, allowing their continual processing only after a preselected number of valid comparisons are made. The radar signal component representing the ground speed sum for the radar platform and the approaching target vehicle, and the component representing radar platform speed are combined. The radar platform speed is subtracted from the combined component, resulting in a digital count representing approaching target vehicle speed. In the stationary mode, there is no radar platform doppler pulses in the radar return and consequently, the returning pulses may be processed directly and no subtracting function is performed. Speeds corresponding to the valid received doppler signals are suitably displayed to indicate a speeding violation.
35 Citations
20 Claims
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1. A doppler radar device for use in law enforcement and service vehicle speed surveilance and for determining the speed of an approaching target vehicle when the radar platform vehicle is either moving or stationary, said device comprising:
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means for producing a continuously running time base; a single means for receiving a composite doppler signal having components relating to the speed of said target vehicle and the speed of the radar platform vehicle; means for separating said doppler frequency into a first frequency component and a second frequency component; means for correlating the frequency of said first frequency component with said time base; means for correlating the frequency of said second frequency component with said time base; means for counting cycles of each of said time base correlated frequency components, said correlating means and said frequency component counting means cooperating to count each of said frequency components in a preselected time increment, said time increment relating to said time base; means for subtracting said counted cycles of said first frequency component from said counted cycles of said second frequency component; and means for displaying the result from said subtracting means in unit indicative of speed of said approaching vehicle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for determining the speed of an approaching moving vehicle, said method comprising the steps of:
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receiving a composite doppler signal with a single receiving means; separating said composite dopper signal into a first frequency component and a second frequency component; digitally producing a precise time base; digitally correlating said first doppler signal frequency component with said time base; digitally correlating said second doppler signal frequency component with said time base; counting the cycles of said first correlated doppler signal frequency component; counting the cycles of said second correlated doppler signal frequency component; subtracting the count of said first doppler signal frequency component from said second coppler signal frequency component; and displaying the result of said subtracted count of correlated cycles. - View Dependent Claims (17, 18, 19, 20)
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Specification