A radar apparatus includes: a transmission circuit; a reception circuit; a Doppler filter that discriminates baseband signals per distance and per Doppler frequency corresponding to the speed of an object; a threshold processing unit group that removes unwanted signals from output signals of the Dop
A radar apparatus includes: a transmission circuit; a reception circuit; a Doppler filter that discriminates baseband signals per distance and per Doppler frequency corresponding to the speed of an object; a threshold processing unit group that removes unwanted signals from output signals of the Doppler filter; and an estimation unit that estimates a position and speed of the object from the output signals removed of the unwanted signals. The threshold processing unit group includes threshold processing units corresponding to respective discriminated Doppler frequencies. Each threshold processing unit calculates a threshold value for a corresponding Doppler frequency using a peak value of the output signals in a range of distance corresponding to an object detection area, and determines output signals in the range that are no greater than the threshold value to be the unwanted signals.
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1. A spread spectrum radar apparatus that detects an object by use of a detection radio wave that is spectrum-spread, the spread spectrum radar apparatus comprising: a transmission circuit that generates a spread spectrum signal and radiates the spread spectrum signal as the detection radio wave, th
1. A spread spectrum radar apparatus that detects an object by use of a detection radio wave that is spectrum-spread, the spread spectrum radar apparatus comprising: a transmission circuit that generates a spread spectrum signal and radiates the spread spectrum signal as the detection radio wave, the spread spectrum signal being spectrum-spread by combining an oscillating signal and a first pseudo noise code;a reception circuit that receives the detection radio wave reflected back from the object as a reception signal, extracts, based on (i) a second pseudo noise code obtained by time-delaying the first pseudo noise code and (ii) the oscillating signal, a signal of a specific frequency band from a despread output of the reception signal, and generates baseband signals by separating the extracted signal by distance, each of the distances corresponding to an amount of time delay between the first pseudo noise code and the second pseudo noise code;a Doppler filter that, for each of the distances, discriminates a time series of the baseband signals based on Doppler frequencies to output output signals, each of which indicates a strength and is associated with one of the distances and one of the Doppler frequencies, the Doppler frequencies each being a difference between a frequency of the detection radio wave radiated from the transmission circuit and a frequency of the detection radio wave received by the reception circuit;a removal unit that includes a plurality of threshold processing units provided corresponding to the Doppler frequencies resulting from the discrimination and is configured to remove an unwanted signal from the output signals output by the Doppler filter; andan estimation unit configured to estimate a position and a speed of the object from the output signals removed of the unwanted signal,wherein each of the threshold processing units is configured to calculate a threshold value for a corresponding one of the Doppler frequencies using a peak value which is a maximum value of the output signals in a range of distance corresponding to a detection area for the object, and determine the output signals in the range of distance that are no greater than the calculated threshold value to be the unwanted signal. 2. The spread spectrum radar apparatus according to claim 1, wherein the threshold value is a greater one of a first threshold value and a second threshold value, the first threshold value being determined from the peak value and the second threshold value being determined from a noise floor of the output signals output by the Doppler filter when the detection radio wave is not reflected back from the object. 3. The spread spectrum radar apparatus according to claim 2, wherein the first threshold value is a product of an out-of-range leakage signal strength and a first allowance factor that is no less than one, the out-of-range leakage signal strength being a quotient of a signal strength of the peak value and an out-of-range signal suppression ratio being determined by a self-correlation characteristic of the first pseudo noise code,the second threshold value is a product of a signal strength of the noise floor and a second allowance factor that is no less than one, andthe second allowance factor is greater than the first allowance factor. 4. The spread spectrum radar apparatus according to claim 2, wherein the estimation unit is configured to estimate a distance from the object using distance data indicating a distribution of strength with respect to the distances in each of the Doppler frequencies, from among the output signals removed of the unwanted signal,estimate a speed of the object using Doppler frequency data indicating a distribution of strength with respect to the Doppler frequencies in each of the distances, from among the output signals removed of the unwanted signal and in a given range of distance from the estimated distance, andtrack the object using a time series of the estimated distances and speeds. 5. The spread spectrum radar apparatus according to claim 4, wherein the removal unit further includes a speed incomplete flag provided for each of the distances for indicating that the Doppler frequency data in a corresponding one of the distances is incomplete among the output signals, andwhen a signal lower in strength than the first threshold value and higher in strength than the second threshold value is present among the output signals, turns on the speed incomplete flag corresponding to the distance to which the signal belongs. 6. The spread spectrum radar apparatus according to claim 5, wherein when at least one of the speed incomplete flags corresponding to the given range of distance is turned on, the estimation unit is configured to omit the Doppler frequency data for the distances to which the speed incomplete flags correspond and estimate the distance of the object. 7. The spread spectrum radar apparatus according to claim 6, wherein, for the distances flagged with the speed incomplete flag, the estimation unit is configured to estimate the speed of the object from a time series of the estimated distance of the object. 8. A method of controlling a spread spectrum radar apparatus that detects an object by use of a detection radio wave that is spectrum-spread, the method comprising: generating a spread spectrum signal and radiating the spread spectrum signal as the detection radio wave, the spread spectrum signal being spectrum-spread by combining an oscillating signal and a first pseudo noise code;receiving the detection radio wave reflected back from the object as a reception signal, extracting, based on (i) a second pseudo noise code obtained by time-delaying the first pseudo noise code and (ii) the oscillating signal, a signal of a specific frequency band from a despread output of the reception signal, and generating baseband signals by separating the extracted signal by distance, each of the distances corresponding to an amount of time delay between the first pseudo noise code and the second pseudo noise code;discriminating, for each of the distances, a time series of the baseband signals based on Doppler frequencies to output output signals, each of which indicate a strength and is associated with one of the distances and one of the Doppler frequencies, the Doppler frequencies each being a difference between a frequency of the detection radio wave radiated from the transmission circuit and a frequency of the detection radio wave received by the reception circuit;removing an unwanted signal from the output signals output in the discriminating; andestimating a position and a speed of the object from the output signals removed of the unwanted signal,wherein the removing includes:calculating a threshold value for a corresponding one of the Doppler frequencies using a peak value which is a maximum value of the output signals in a range of distance corresponding to a detection area for the object, the threshold value being for removing the unwanted signal, andremoving signals in each of the Doppler frequencies that are no greater than the calculated threshold value.
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