Distance/velocity measuring method and radar signal processing device
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsMasashi Mitsumoto, Takamitsu Okada, Takahiko Fujisaka, Yoshio Kosuge, Koichi Kai
Life of this patent
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Abstract
A distance and speed measuring method and a radar signal processing apparatus using the method are provided which are capable of obtaining highly reliable measurement results while reducing the number of false targets and undetectable targets, by obtaining the relative distance and the relative speed of each target based on the frequencies of a beat signal of up (or down) phase alone through the use of information in a time series direction of the frequencies of the beat signal of up (or down) phase.
Claims7
A distance and speed measuring method in which a relative distance and a relative speed of a target are measured based on a beat signal generated from a transmission signal and a reception signal of a continuous wave radar, which is frequency modulated by a triangular wave,
- said method being characterized by comprising:
- a present measurement stage in which beat frequencies are extracted from the beat signal in an up phase (modulation frequency increase period) and in a down phase (modulation frequency decrease period), and a frequency pair of beat frequencies corresponding to the target is selected among the extracted frequencies, the relative distance and the relative speed of the target being obtained based on the thus selected frequency pair as observed values, from which a relative distance, a relative speed and a beat frequency of the target are obtained as predicted values at the next observation time;
- and
- next and following measurement stages in which relative distances and relative speeds of the target at the next and following observation times are measured by using only beat frequencies in either one of the up phase and the down phase.
A radar signal processing apparatus in which a relative distance and a relative speed of a target are measured based on a beat signal generated from a transmission signal and a reception signal of a continuous wave radar, which is frequency modulated by a triangular wave,
- said apparatus being characterized by comprising:
- frequency analysis means adapted to receive the beat signal in an up phase and in a down phase, respectively, for extracting frequencies of the beat signal;
- frequency pair selection means for selecting a frequency pair corresponding to the target from the frequencies of the beat signal in the up phase and in the down phase extracted by said frequency analysis means;
- distance and speed deriving means adapted to receive the frequency pair selected by said frequency selection means for obtaining the relative distance and the relative speed of the target at present;
- distance and speed prediction means adapted to receive the relative distance and the relative speed of the target at present from said distance and speed deriving means for calculating an predicted distance value and an predicted speed value of the target after a lapse of a prescribed time while assuming the movement of the target;
- frequency prediction means adapted to receive the predicted distance value and the predicted speed value from said distance and speed prediction means for calculating an predicted frequency value of the beat signal in the up phase or in the down phase;
- frequency comparison means for making a comparison between the predicted frequency value of the beat signal predicted by said frequency prediction means and the frequency thereof after a lapse of the prescribed time thereby to determine the presence or absence of a beat frequency whose difference in the above comparison result exists in the range of a preset allowable frequency width;
- and
- distance and speed smoothing means for calculating a smoothed distance value and a smoothed speed value based on the predicted distance value and the predicted speed value from said distance and speed prediction means, the predicted beat frequency from said frequency prediction means, and an observed frequency value of the beat signal after a lapse of the prescribed time obtained by said frequency analysis means;
- wherein relative distances and relative speeds of the target at the next and following observation times are obtained by said distance and speed smoothing means through the use of only the beat frequency in either one of the up phase and the down phase obtained by said frequency prediction means.
Dependencies are inferred from the claim text.