Vehicle-mounted radar system and detection method
First Claim
1. A vehicle-mounted radar system comprising:
- a transmitter for radiating electromagnetic wave which has been amplitude modulated with a low frequency (LF) modulation signal;
a receiver for receiving and detecting reflected electromagnetic wave from a target;
a range measuring unit for detecting the range to said target on the basis of the phase difference between a received LF signal, obtained by said receiver, and said LF modulation signal;
a relative speed operating unit for calculating the relative speed with respect to said target on the basis of range data output from said range measuring unit;
a vehicle speed detector for detecting the traveling speed of a vehicle to which the system is mounted and outputting vehicle speed data; and
a modulation frequency shifter for shifting the frequency of said LF modulation signal in response to said vehicle speed data and said range data from said range measuring unit.
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Accused Products
Abstract
Modulation frequency setting device sets the modulation frequency on the basis of the vehicle speed data from a vehicle speed detector and the detected range data, causing a low frequency oscillator to generate a low frequency signal of the set frequency. A transmitter transmits an electromagnetic wave (e.g., infrared light) which have been modulated with the low frequency signal. A phase comparator detects the phase difference between the low frequency signal and a detector output, and a range operating device produces range data. Relative speed operating unit finds the relative speed based on the range data. In case of a high vehicle speed, the modulation frequency is set low to extend the detection range. If an object in a short distance is detected, the modulation frequency is set high to limit the detection range to a short range, thereby enhancing the range resolution.
41 Citations
18 Claims
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1. A vehicle-mounted radar system comprising:
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a transmitter for radiating electromagnetic wave which has been amplitude modulated with a low frequency (LF) modulation signal; a receiver for receiving and detecting reflected electromagnetic wave from a target; a range measuring unit for detecting the range to said target on the basis of the phase difference between a received LF signal, obtained by said receiver, and said LF modulation signal; a relative speed operating unit for calculating the relative speed with respect to said target on the basis of range data output from said range measuring unit; a vehicle speed detector for detecting the traveling speed of a vehicle to which the system is mounted and outputting vehicle speed data; and a modulation frequency shifter for shifting the frequency of said LF modulation signal in response to said vehicle speed data and said range data from said range measuring unit. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A vehicle-mounted radar system comprising:
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a transmitter for radiating electromagnetic wave which has been amplitude modulated with a low frequency (LF) modulation signal; a receiver for receiving and detecting reflected electromagnetic wave from a target; a range measuring unit for detecting the range to said target on the basis of the phase difference between a received LF signal, obtained by said receiver, and said LF modulation signal; a relative speed operating unit for calculating the relative speed with respect to said target on the basis of range data output from said range measuring unit; and a modulation frequency shifter for shifting the frequency of said LF modulation signal in response to said range data from said range measuring unit. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A detection method practiced in a vehicle for radiating an electromagnetic wave which has been amplitude modulated with a low frequency (LF) modulation signal, receiving reflected electromagnetic wave from an object, detecting a received LF signal, and detecting the range to said object or the relative speed with respect to said object on the basis of the phase difference between said received LF signal and said LF modulation signal, said detection method comprising the step of:
shifting the frequency of said LF modulation signal in response to the traveling speed of said vehicle and said range to said object. - View Dependent Claims (14, 15)
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16. A detection method practiced in a vehicle for radiating electromagnetic wave which has been amplitude modulated with a low frequency (LF) modulation signal, receiving reflected electromagnetic wave from an object, detecting a received LF signal, and detecting the range to said object or the relative speed with respect to said object on the basis of the phase difference between said received LF signal and said LF modulation signal, said detection method comprising the step of:
shifting the frequency of said LF modulation signal in response to said range to said object. - View Dependent Claims (17, 18)
Specification