US 12,117,516 B2
Radar apparatus and distance measurement method
Tatsuya Iizuka, Musashino (JP); Fumihiko Ishiyama, Musashino (JP); Yohei Toriumi, Musashino (JP); and Jun Kato, Musashino (JP)
Assigned to Nippon Telegraph and Telephone Corporation, Tokyo (JP)
Appl. No. 17/637,662
Filed by Nippon Telegraph and Telephone Corporation, Tokyo (JP)
PCT Filed Aug. 23, 2019, PCT No. PCT/JP2019/033030
§ 371(c)(1), (2) Date Feb. 23, 2022,
PCT Pub. No. WO2021/038628, PCT Pub. Date Mar. 4, 2021.
Prior Publication US 2022/0276366 A1, Sep. 1, 2022
Int. Cl. G01S 13/34 (2006.01); G01S 7/35 (2006.01); G01S 13/38 (2006.01)
CPC G01S 13/341 (2013.01) [G01S 7/356 (2021.05); G01S 13/38 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A radar apparatus comprising:
a transmitting unit comprising an antenna and configured to transmit a signal having a constant frequency or a continuous wave signal obtained by modulating the signal;
a receiving unit comprising one or more receiving antennas and configured to receive a reflected wave that is the continuous wave signal reflected by an object;
a mixer configured to mix the received reflected wave and the continuous wave signal to obtain a beat signal;
a frequency estimation unit comprising an analog-digital converter and configured to estimate a frequency of the beat signal; and
a distance estimation unit configured to estimate a distance to the object based on the frequency of the beat signal,
wherein estimating the frequency of the beat signal comprises:
obtaining a sequence of discrete signal values by sampling the beat signal at predetermined intervals,
determining an autoregressive model represented by a linear combination of the sequence of discrete signal values using a set of autoregressive coefficients,
calculating each autoregressive coefficient of the autoregressive model, wherein the calculated autoregressive coefficients minimize the linear combination, and
estimating the frequency of the beat signal using a base frequency that is based on a pole of the autoregressive model.