Radar detection method and apparatus
First Claim
Patent Images
1. A method for detecting an object with a radar system comprising:
- transmitting a transmit signal;
receiving a receive signal generated by at least a portion of the transmit signal impinging the object;
calculating a difference signal in response to the transmit signal and the receive signal;
performing an FFT on the difference signal to provide an FFT output signal;
computing a derivative of the FFT output signal; and
detecting the object in response to a zero crossing of the derivative of the FFT output signal.
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Abstract
A radar detection process includes computing a derivative of an FFT output signal to detect an object within a specified detection zone. In one embodiment, a zero crossing in the second derivative of the FFT output signal indicates the presence of an object. The range of the object is determined as a function of the frequency at which the zero crossing occurs. Also described is a detection table containing indicators of the presence or absence of an object within a respective radar beam and processing cycle. At least two such indicators are combined in order to detect the presence of an object within the detection zone.
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Citations
14 Claims
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1. A method for detecting an object with a radar system comprising:
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transmitting a transmit signal;
receiving a receive signal generated by at least a portion of the transmit signal impinging the object;
calculating a difference signal in response to the transmit signal and the receive signal;
performing an FFT on the difference signal to provide an FFT output signal;
computing a derivative of the FFT output signal; and
detecting the object in response to a zero crossing of the derivative of the FFT output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
establishing a range boundary; and
discarding an object detection if the range of the object is outside of the range boundary.
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4. The method of claim 1 wherein the transmit signal is an FMCW signal.
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5. The method of claim 1 wherein the calculating step comprises calculating a difference between the frequency of the transmit signal and the frequency of the receive signal.
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6. The method of claim 1 wherein the derivative is a selected one of a first derivative and a second derivative.
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7. The method of claim 1 wherein the zero crossing of the derivative of the FFT output signal is a negative-going zero crossing.
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8. A radar system for detecting an object, comprising:
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a transmitter for transmitting a transmit signal;
a receiver for receiving a receive signal generated by at least a portion of the transmit signal impinging the object;
a differencing circuit for calculating a difference signal in response to the transmit signal and the receive signal;
an FFT processor for performing an FFT on the difference signal to provide an FFT output signal;
a derivative processor for computing a derivative of the FFT output signal; and
a detector for detecting the object in response to a zero crossing of the derivative of the FFT output signal. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification