Radar desigend to acquire radar data with high accuracy
First Claim
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1. A radar apparatus for a vehicle comprising:
- a transmitter working to emitting a transmit signal in the form of a radar wave which has a frequency so modulated as to increase, decrease, and be kept constant in sequence;
a first and a second receiver circuit including a first and a second antenna located at a given interval away from each other, the first and second receiver circuits each working to receive a return of the radar wave from an object to produce receive signals and produce a first and a second beat signal each of which has a frequency corresponding to a difference in frequency between the transmit signal and a corresponding one of the receive signals;
each of the first and second beat signals having a first frequency component in a modulated frequency-rising range wherein the frequency of the transmit signal increases, a second frequency component in a modulated frequency-falling range wherein the frequency of the transmit signal decreases, and a third frequency component in a constant modulated frequency range wherein the frequency of the transmit signal is kept constant; and
a signal processor working to determine an angular direction of the object using the receive signals provided by said first and second receiver circuits, said signal processor including a first and a second angular direction determining section, the first angular direction determining section determining the angular direction of the object based on a phase difference between the first and second beat signals at a peak frequency that is at least one of frequencies of the first and second beat signals in at least one of the modulated frequency-rising and -falling ranges which have peaks, when peak frequencies that are frequencies of the first and second beat signals arising form a plurality of objects which have peaks in at least one of the modulated frequency-rising and -falling ranges overlap each other, the second angular direction determining section determining the angular direction of the object using a phase difference between the first and second beat signals at peak frequencies that are frequencies of the first and second beat signals in the constant modulated frequency range.
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Abstract
A radar is provided which transmits a radar wave whose frequency is so modulated as to rise, fall, and be kept constant cyclically. The radar uses beat signals produced by the radar wave and radar echoes received by two antennas to produce radar data on a target. When it is impossible to pair frequency peaks of the beat signals in a modulated frequency-rising and -falling ranges, the radar determines that the frequency peaks have arisen from different objects so that they overlap each other and uses frequency peaks of the beat signals in a constant modulated frequency range to acquire the radar data.
71 Citations
12 Claims
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1. A radar apparatus for a vehicle comprising:
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a transmitter working to emitting a transmit signal in the form of a radar wave which has a frequency so modulated as to increase, decrease, and be kept constant in sequence;
a first and a second receiver circuit including a first and a second antenna located at a given interval away from each other, the first and second receiver circuits each working to receive a return of the radar wave from an object to produce receive signals and produce a first and a second beat signal each of which has a frequency corresponding to a difference in frequency between the transmit signal and a corresponding one of the receive signals;
each of the first and second beat signals having a first frequency component in a modulated frequency-rising range wherein the frequency of the transmit signal increases, a second frequency component in a modulated frequency-falling range wherein the frequency of the transmit signal decreases, and a third frequency component in a constant modulated frequency range wherein the frequency of the transmit signal is kept constant; and
a signal processor working to determine an angular direction of the object using the receive signals provided by said first and second receiver circuits, said signal processor including a first and a second angular direction determining section, the first angular direction determining section determining the angular direction of the object based on a phase difference between the first and second beat signals at a peak frequency that is at least one of frequencies of the first and second beat signals in at least one of the modulated frequency-rising and -falling ranges which have peaks, when peak frequencies that are frequencies of the first and second beat signals arising form a plurality of objects which have peaks in at least one of the modulated frequency-rising and -falling ranges overlap each other, the second angular direction determining section determining the angular direction of the object using a phase difference between the first and second beat signals at peak frequencies that are frequencies of the first and second beat signals in the constant modulated frequency range. - View Dependent Claims (2, 3, 4)
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5. A radar apparatus for a vehicle comprising:
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a transmitter working to emitting a transmit signal in the form of a radar wave which has a frequency so modulated as to increase and decrease in sequence;
a first and a second receiver circuit including a first and a second antenna located at a given interval away from each other, the first and second receiver circuits each working to receive a return of the radar wave from an object to produce receive signals and produce a first and a second beat signal each of which has a frequency corresponding to a difference in frequency between the transmit signal and a corresponding one of the receive signals, each of the first and second beat signals having a first frequency component in a modulated frequency-rising range wherein the frequency of the transmit signal increases and a second frequency component in a modulated frequency-falling range wherein the frequency of the transmit signal decreases; and
a signal processor working to determine an angular direction of the object using the receive signals provided by said first and second receiver circuits, said signal processor being designed to perform a angular direction determining function and a prohibiting function, the angular direction determining function serving to determine the angular direction of the object based on a phase difference between the first and second beat signals at a peak frequency that is at least one of frequencies of the first and second beat signals in at least one of the modulated frequency-rising and -falling ranges which have peaks, the prohibiting function serving to verify a measure of correctness of waveform representing the peak frequencies in each of the modulated frequency-rising and -falling ranges, when the measure of correctness in each of the modulated frequency-rising and -falling ranges is lower than a given degree, the prohibiting function being performed to prohibit the angular direction determining function from determining the angular direction of the object. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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Specification