Police traffic radar using digital data transfer between antenna and counting unit
First Claim
1. A traffic surveillance radar apparatus, comprising:
- an antenna for transmitting radar energy and for receiving reflected radar energy;
a mixer for mixing a sample of the transmitted radar energy with the reflected radar energy to generate at an output an analog audio signal that includes frequencies which are dependent upon the speed of any targets painted by said radar and the speed of the police patrol car;
a clock for supplying a clock signal;
an analog-to-digital converter having a clock input coupled to receive said clock signal, and having an analog signal input coupled to said output of said mixer and having a digital signal output, for converting said analog audio signal to a plurality of digital samples in serial digital data format and outputting said serial digital data at said digital signal output, and having a clock output for outputting said clock signal and having a frame sync output, said analog-to-digital converter for generating a periodic frame sync signal at said frame sync output, each said frame sync signal being separated from immediately adjacent frame sync pulses on either side thereof by a predetermined plurality of clock pulses;
a gate array having an input coupled to said digital signal output to receive said serial format digital data samples, and having an input coupled to said frame sync output for receiving said frame sync signals, and having an RFI input coupled to receive said clock signal from said analog-to-digital converter, and having an input for receiving an RFI signal indicating the presence of radio frequency interference, said gate array having a transmit data output and a serial clock output, said gate array for outputting, in synchronization with said clock signal received from said analog-to-digital converter, said serial format digital data samples received from said analog-to-digital converter at said transmit data output as a transmit data signal formatted as a plurality of frames of serial data, only a portion of each frame being dedicated to transmitting digital data samples from said analog-to-digital converter, and for altering said clock signal received from said analog-to-digital converter by deleting a predetermined number of clock signals from every frame sync interval so as to create a silent interval comprising one or more bit times during which no clock signal occurs, the end of said silent interval being a predetermined number of bit times before the end of the next frame, and for outputting the so-modified clock signal at said serial clock output as a serial clock signal, said gate array including means for using a portion of each frame sync interval not dedicated to transmitting digital data samples received from said analog-to-digital converter to include within each frame of digital data samples data indicating whether radio frequencyinterference is or is not present; and
a radio frequency detector having an output coupled to said RFI input of said gate array, for detecting the presence of radio frequency interference and for generating said RFI signal when radio frequency is present.
1 Assignment
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Accused Products
Abstract
A police radar utilizing digital data transmission from the antenna unit to a separately housed counting and display unit. The antenna has a double balanced mixer to suppress even order harmonics. The counting and display unit has a computer programmed to perform digital signal processing on the digital data received from the antenna to improve the quality and accuracy of calculated speeds for patrol speed, strongest target speed and fastest target speed. Fastest target speed can be displayed simultaneously with strongest target speed. Signal processing techniques are used to suppress false signals caused by double and triple bounce, harmonics, intermodulation products, video display terminal interference, etc.
58 Citations
48 Claims
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1. A traffic surveillance radar apparatus, comprising:
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an antenna for transmitting radar energy and for receiving reflected radar energy; a mixer for mixing a sample of the transmitted radar energy with the reflected radar energy to generate at an output an analog audio signal that includes frequencies which are dependent upon the speed of any targets painted by said radar and the speed of the police patrol car; a clock for supplying a clock signal; an analog-to-digital converter having a clock input coupled to receive said clock signal, and having an analog signal input coupled to said output of said mixer and having a digital signal output, for converting said analog audio signal to a plurality of digital samples in serial digital data format and outputting said serial digital data at said digital signal output, and having a clock output for outputting said clock signal and having a frame sync output, said analog-to-digital converter for generating a periodic frame sync signal at said frame sync output, each said frame sync signal being separated from immediately adjacent frame sync pulses on either side thereof by a predetermined plurality of clock pulses; a gate array having an input coupled to said digital signal output to receive said serial format digital data samples, and having an input coupled to said frame sync output for receiving said frame sync signals, and having an RFI input coupled to receive said clock signal from said analog-to-digital converter, and having an input for receiving an RFI signal indicating the presence of radio frequency interference, said gate array having a transmit data output and a serial clock output, said gate array for outputting, in synchronization with said clock signal received from said analog-to-digital converter, said serial format digital data samples received from said analog-to-digital converter at said transmit data output as a transmit data signal formatted as a plurality of frames of serial data, only a portion of each frame being dedicated to transmitting digital data samples from said analog-to-digital converter, and for altering said clock signal received from said analog-to-digital converter by deleting a predetermined number of clock signals from every frame sync interval so as to create a silent interval comprising one or more bit times during which no clock signal occurs, the end of said silent interval being a predetermined number of bit times before the end of the next frame, and for outputting the so-modified clock signal at said serial clock output as a serial clock signal, said gate array including means for using a portion of each frame sync interval not dedicated to transmitting digital data samples received from said analog-to-digital converter to include within each frame of digital data samples data indicating whether radio frequency interference is or is not present; and a radio frequency detector having an output coupled to said RFI input of said gate array, for detecting the presence of radio frequency interference and for generating said RFI signal when radio frequency is present. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a police traffic surveillance radar having an antenna unit of any conventional design for transmitting radar signals and receiving a spectrum of radar signals reflected from stationary and moving objects, and a frequency counting and display unit of any conventional design having at least one display window, the improvement comprising:
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digital data transmission path coupling said antenna unit to said frequency counting and display unit; digitizing means coupled to said antenna unit for digitizing said spectrum of received radar signals reflected from stationary and moving objects and transmitting the digital data resulting therefrom to said frequency counting and display unit via said digital data transmission path; and wherein said antenna unit and said frequency counting and display unit are in separate housings. - View Dependent Claims (21)
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9. In a police traffic surveillance radar having an antenna unit of conventional design for transmitting radar signals and receiving a spectrum of radar signals reflected from stationary and moving objects, and a frequency counting and display unit of conventional design having at least one display window, the improvement comprising:
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digital data transmission;
path coupling said antenna unit to said frequency counting and display unit;digitizing means coupled to said antenna unit for digitizing said spectrum of received radar signals reflected from stationary and moving objects and transmitting the digital data resulting therefrom to said frequency counting and display unit via said digital data transmission path;
wherein said digital data transmission path is configured so as to carry serial format data, and further comprising framing circuitry coupled to said digital data transmission path and said digitizing means for organizing said digital data resulting from operations of said digitizing means into a plurality of frames of serial format data and for transmitting said frames of serial format data over said digital data transmission path;wherein said digital data transmission path is configured so as to carry serial format data. - View Dependent Claims (10, 11)
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12. An apparatus for a police traffic surveillance radar, comprising:
- an antenna unit comprising;
an oscillator for generating a radar frequency carrier signal; a microwave antenna coupled to receive said carrier signal from said oscillator, for transmitting radar signals, said microwave antenna also for receiving reflected radar signals; an amplifier coupled to said microwave antenna unit so as to amplify said received radar signals in accordance with a variable gain set in accordance with a digital gain control signal comprised of one or more bits applied to a digital gain control input; an analog-to-digital converter coupled to receive the analog output signal of said amplifier and convert said analog signal to a plurality of bytes of serial format digital data and output said bytes of digital data in synchronization with a clock signal which is also output; timing generator and data formatting means for receiving said clock signal and outputting said digital data as a plurality of frames of serial format digital data, each said frame comprised of a plurality of bit times, only some of which are used to transmit digital data received from said analog-to-digital converter; means for supplying for control and/or status data to said timing generator and data formatting means for inclusion in said frames of serial format digital data during bit times not used to transmit data from said analog-to-digital converter; and means controlled by said timing generator and data formatting means for receiving serial format control and status data including said digital gain control signal and for parsing out said one or more bits of said digital gain control signal and applying said bits to said digital gain control input of said amplifier. - View Dependent Claims (13, 14, 15, 16, 17, 20, 22)
- an antenna unit comprising;
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18. An apparatus for a police traffic surveillance radar, comprising:
- an antenna unit comprising;
an oscillator for generating a radar frequency carrier signal; a microwave antenna coupled to receive said carrier signal from said oscillator, for transmitting radar signals, said microwave antenna also for receiving reflected radar signals; an amplifier means coupled to said microwave antenna unit for amplifying said received radar signals in accordance with a variable gain set in accordance with an analog gain control signal received at a gain control input; a level detector means coupled to receive the amplified signals output by said amplifier means for comparing the levels of said amplified signal to upper and lower limits, and for generating said analog gain control signal based upon the results of said comparison and transmitting said analog gain control signal to said gain control input; a first analog-to-digital converter coupled to receive the analog output signal of said level detector and convert said analog signal to a plurality of bytes of serial format digital data and output said bytes of digital data in synchronization with a clock signal which is also output; a second analog-to-digital converter coupled to receive the analog gain control signal output by said level detector for converting said analog gain control signal to one or more bytes of data; timing generator and data formatting means for receiving said clock signal and outputting said digital data as a plurality of frames of serial format digital data, each said frame comprised of a plurality of bit times, only some of which are used to transmit digital data received from said analog-to-digital converter; means for supplying control and/or status data to said timing generator and data formatting means for inclusion in said frames of serial format digital data during bit times not used to transmit data from said analog-to-digital converter; and a counting/display unit coupled to said antenna unit by a digital data path, and including a computer programmed to receive said plurality of frames of digital data including data generated by said first analog-to-digital converter and said digital data from said second analog-to-digital converter and calculate from said plurality of frames of digital data generated by said first analog-to-digital converter the speed of the patrol car to which said antenna unit is mounted and the speed of the strongest received radar signal reflected from a moving target, and programmed to use the value of said digital data encoding said gain control signal generated by said level detector for determining the true power of predetermined ones of said received reflected radar signals, and for using the information about true power said predetermined ones of said reflected radar signals to improve the accuracy of selection of reflected radar signals for purposes of calculation of patrol speed and the speed of the moving target having the strongest reflected signal by applying predetermined selection criteria based at least upon the true power of predetermined ones of said reflected radar signals. - View Dependent Claims (19)
- an antenna unit comprising;
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23. An apparatus for a police traffic surveillance radar, comprising:
- an antenna unit comprising;
an oscillator for generating a radar frequency carrier signal; a microwave antenna coupled to receive said carrier signal from said oscillator, for transmitting radar signals, said microwave antenna also for receiving reflected radar signals; an amplifier coupled to said microwave antenna unit so as to amplify said received radar signals; a clock for outputting a clock signal; an analog-to-digital converter coupled to receive said clock signal and to receive the analog output signal of said amplifier and convert said analog signal to a plurality of bytes of digital data and output said digital data in synchronization with said clock signal and for outputting said clock signal; a counter/display unit including circuitry to receive said digital data from said analog-to-digital converter and calculate therefrom the patrol car speed and the speed of the moving target having the strongest legitimate reflected radar signal and for displaying said patrol speed and said speed of said moving target; a digital data path for conveying said digital data to said counter/display unit; and means for conveying status and control data from said antenna unit to said counter/display unit or vice versa by encoding the data to be sent into said clock signal by modification of one or more attributes of said clock signal.
- an antenna unit comprising;
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24. In a police traffic surveillance radar having an antenna unit having RF and analog circuitry of conventional design for transmitting radar signals and receiving a spectrum of radar signals reflected from stationary and moving objects, and a frequency counting and display unit of conventional design having at least one display window, wherein said antenna unit and said counting and display unit are electrically coupled by a cable having one or more conductors but are housed in separate housings which are physically separated, the improvement comprising:
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analog-to-digital circuitry in said antenna unit to generate digital data from said received spectrum of reflected radar signals; serial digital data transmission path within said cable coupling said antenna unit to said frequency counting and display unit for carrying serial format digital data generated by said analog-to-digital circuitry; and wherein said conductors in said cable are configured so as to minimize pickup of electrical noise. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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32. A police traffic surveillance radar apparatus, comprising:
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a microwave antenna unit having a microwave horn moving at the same speed as a police patrol vehicle for transmitting and receiving microwave energy, and having a microwave oscillator with an on/off control input for receiving an on/off control signal which causes said oscillator to oscillate and generate microwave energy at an output when said on/off control signal is in an on state, and which causes said oscillator to stop oscillating when said on/off control signal is in an off state, said output of said microwave oscillator being coupled to said microwave horn, said microwave antenna unit including circuitry for receiving microwave energy reflected from stationary and moving objects which are in the path of microwave energy emitted from said microwave horn, said circuitry for generating a radar returns signal from said received microwave energy using an amplifier having a variable gain, said gain established by a gain control circuit having a gain control input for receiving a multibit digital gain control signal, said radar returns signal indicating the relative speed of said stationary and moving targets relative to said microwave horn; a processing and display unit coupled to receive said radar returns signal and for processing said radar returns signal to derive the speed of the patrol vehicle and the speed of the moving target having the strongest signal and for displaying both said computed speeds, said processing and display unit coupled to said on/off control input of said oscillator and to said gain control input by a serial format digital data link, said processing and display unit including circuitry to generate said on/off control signal as a digital signal having one or more bits and circuitry to generate said multibit digital gain control circuit, and further comprising transmission circuitry for joining said digital on/off control signal and said multibit digital gain control signal in a control word and for transmitting said control word to said microwave antenna unit; and wherein said microwave antenna unit includes parsing circuitry for receiving said control word and parsing said control word and applying said on/off control signal to said on/off control input of said oscillator and applying said multibit digital gain control signal to said gain control input of said gain control circuit. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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46. In a police traffic surveillance radar having an antenna unit of conventional design for transmitting radar signals and receiving a spectrum of radar signals reflected from stationary and moving objects, and a frequency counting and display unit of conventional design having at least one display window, and wherein the antenna unit is separated from the counting and display unit but electrically coupled thereto by a cable, the improvement comprising:
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digital data transmission path within said cable and coupling said antenna unit to said frequency counting and display unit; digitizing means at the location of said antenna unit for digitizing said spectrum of received radar signals reflected from stationary and moving objects and transmitting the digital data resulting therefrom to said frequency counting and display unit via said digital data transmission path; and wherein said antenna unit and said frequency counting and display unit are in separate housings and are separated by an appreciable physical distance which is long enough to cause said cable to act as an antenna to pick up electrical noise and radio frequency interference; a radio frequency interference detector at the location of said antenna unit and electrically coupled to said counting and display unit through a cable for generating a radio frequency interference warning signal and sending said radio frequency interference warning signal to said counting and display unit through said cable coupling said radio frequency interference detector to said counting and display unit.
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47. In a police traffic surveillance radar having an antenna unit having RF and analog circuitry of conventional design for transmitting radar signals and receiving a spectrum of radar signals reflected from stationary and moving objects, and a frequency counting and display unit of conventional design having at least one display window, said counting and display unit electrically coupled to said antenna unit but separated from said antenna unit by some appreciable distance, the improvement comprising:
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analog-to-digital circuitry in said antenna unit to generate digital data from said received spectrum of reflected radar signals; digital data transmission path in said cable coupling said antenna unit to said frequency counting and display unit for carrying said digital data generated by said analog-to-digital circuitry; one or more line driver circuits at the location of said antenna unit and coupled between said analog-to-digital circuitry and said digital data transmission path for receiving said digital data from said analog-to-digital circuitry and transmitting said digital data to said counting and display unit via said digital data transmission path; and wherein said counting and display unit performs digital signal processing on said digital data received from said antenna unit, and further comprising one or more line driver circuits at the location of said counting and display unit and electrically coupled to said digital data transmission path for transmitting digital data generated by said counting and display unit to said antenna unit.
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48. In a police traffic surveillance radar having an antenna unit of conventional design for transmitting radar signals and receiving a spectrum of radar signals reflected from stationary and moving objects, and a frequency counting and display unit of conventional design having at least one display window, and wherein the antenna unit is separated from the counting and display unit but electrically coupled thereto by a cable having one or more conductors therein, the improvement comprising:
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digital data transmission path within said cable and coupling said antenna unit to said frequency counting and display unit; digitizing means at the location of said antenna unit for digitizing said spectrum of received radar signals reflected from stationary and moving objects and transmitting the digital data resulting therefrom to said frequency counting and display unit via said digital data transmission path; and wherein said antenna unit has an amplifier therein which has a variable gain; and wherein said antenna unit and said frequency counting and display unit are in separate housings; and wherein said counting and display unit sends gain control information to said amplifier in said antenna unit via a conductor in said cable.
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Specification