Traffic radar with digital signal processing
First Claim
1. A method of processing Doppler return information in a traffic radar comprising the steps of:
- (a) receiving Doppler return information containing at least one return signal derived from a target vehicle,(b) presenting said Doppler return information as digital data,(c) transforming said data into the frequency domain to provide a spectrum that includes frequency components corresponding to Doppler return signals contained in said information,(d) storing said components in a memory,(e) searching said components in memory for the component that meets preselected magnitude or frequency criteria, and(f) indicating the speed of the target vehicle corresponding to the component that meets said criteria.
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Accused Products
Abstract
A traffic radar processes Doppler return information by analysis of the received frequency spectrum in order to improve target identification and minimize interference and unwanted harmonics. Digital signal processing including transformation of the return information into the frequency domain is employed to provide multiple modes of operation including a stationary mode where either the strongest or the fastest Doppler return signal may be selectively recognized, and moving modes for monitoring traffic moving in both the opposite direction and the same direction as the patrol vehicle. In the moving modes either strongest or fastest signal processing may be elected, and operation when the patrol and target vehicles are moving in the same direction is provided irrespective of whether the patrol vehicle is moving faster or slower than the target vehicle. The speed of the patrol car is determined by recognizing a signature that exhibits an asymmetry due to the cosine effect. Interference and harmonics are detected and suppressed by recognizing unwanted harmonic patterns and eliminating signal magnitudes at the harmonic frequencies.
57 Citations
21 Claims
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1. A method of processing Doppler return information in a traffic radar comprising the steps of:
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(a) receiving Doppler return information containing at least one return signal derived from a target vehicle, (b) presenting said Doppler return information as digital data, (c) transforming said data into the frequency domain to provide a spectrum that includes frequency components corresponding to Doppler return signals contained in said information, (d) storing said components in a memory, (e) searching said components in memory for the component that meets preselected magnitude or frequency criteria, and (f) indicating the speed of the target vehicle corresponding to the component that meets said criteria. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a traffic radar, apparatus for processing Doppler return information comprising:
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means for receiving Doppler return information containing at least one return signal derived from a target vehicle, and for presenting said information as digital data, means for transforming said data into the frequency domain to provide a spectrum that includes frequency components corresponding to Doppler return signals contained in said information, memory means for storing said components, means for searching the components stored in said memory means to identify the component that meets preselected magnitude or frequency criteria, and means responsive to the identified component for indicating the speed of the target vehicle corresponding thereto. - View Dependent Claims (17, 18, 19)
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20. In a traffic radar, apparatus for processing Doppler return information comprising:
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means for receiving Doppler return information containing at least one return signal derived from a target vehicle, and for presenting said information as digital data, means for transforming said data into the frequency domain to provide a spectrum that includes frequency components corresponding to Doppler return signals contained in said information, means for determining the magnitude and frequency of each of said components, memory means for storing said components, search means for providing a plurality of modes of operation, including a mode in which a target vehicle component of greatest magnitude in said memory means is identified and a mode in which a target vehicle component of highest frequency in said memory means is identified, and means under operator control for selecting either a greatest magnitude or highest frequency search, whereby either strongest signal or fastest signal target identification is provided. - View Dependent Claims (21)
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Specification