Radar device and position-determination method

1. A radar device mounted on a moving object, comprising:

a doppler correction phase-rotation controller, which in operation, determines a Doppler correction phase-rotation amount for correcting a Doppler frequency component, based on a movement speed of the moving object;

a radar transmitter, which in operation, repeatedly transmits a corrected radar transmission signal in each radar transmission interval T r , the corrected radar transmission signal including pulse compression codes and being corrected based on the Doppler frequency component; and

a radar receiver, which in operation, includes one or more reception branches, each receiving a reflection wave signal resulting from reflection of the corrected radar transmission signal by a target,

wherein the radar transmitter includes

a radar-transmission-signal generator, which in operation, generates a radar transmission signal, and

a phase rotator, which in operation, corrects the radar transmission signal for each radar transmission interval T r , based on the Doppler correction phase-rotation amount, and that outputs the corrected radar transmission signal; and

wherein the radar receiver includes

a position-determination result outputter, which in operation, calculates a position-determination result of the target by using a result of Doppler-frequency analysis on the reflection wave signal received by the one or more reception branches and the Doppler correction phase-rotation amount.

2. The radar device according to claim 1 ,

wherein the radar receiver includes:

a sampler, which in operation, performs discrete sampling on the received reflection wave signal at determined discrete time points;

a correlation calculator, which in operation, calculates correlation values between each of results of the discrete sampling and each of the plurality of pulse compression codes for the corresponding radar transmission intervals T r ;

an adder, which in operation, outputs an addition result of adding the correlation value N p times, the correlation value being calculated for each radar transmission interval T r , the addition being performed each of N p times of radar transmission interval T r ; and

a doppler-frequency analyzer, which in operation, performs Doppler-frequency analysis based on N c additional results, the N c additional results being obtained in one measurement period, the one measurement period being N p ×N c times of the radar transmission interval T r .

3. The radar device according to claim 1 ,

wherein the Doppler correction phase-rotation amount is the same in the measurement period.

4. The radar device according to claim 1 , comprising:

a transmission-beam controller, which in operation, determines a beam direction of each of one or more transmission antennas,

wherein

the doppler correction phase-rotation controller determines a Doppler correction phase-rotation amount for correcting the Doppler frequency component based on the movement speed of the moving object and the beam direction of each of the transmission antennas;

the radar transmitter includes the one or more transmission antennas, each transmitting the corrected radar transmission signal in the corresponding determined beam direction;

the radar receiver includes an arrival-direction estimator that estimates an arrival direction of the reflection wave signal based on an analysis result of Doppler-frequency analysis on the reflection wave signal received by each of the one or more reception branches; and

the position-determination result outputter calculates a position-determination result of the target, based on the estimated arrival direction and the Doppler correction phase-rotation amount for the beam direction of each of the transmission antennas.

5. The radar device according to claim 1 ,

wherein the radar receiver includes:

a sampler, which in operation, discretely samples the received reflection wave signal at determined discrete time points;

a correlation calculator, which in operation, calculates values of correlation between each of results of the discrete sampling and each of the plurality of pulse compression codes for the corresponding radar transmission intervals T r ;

a first adder, which in operation, performs addition on the correlation value, calculated for each radar transmission interval T r , N p1 times for the respective N p1 radar transmission intervals T r to output a first addition result;

a second adder, which in operation, performs addition on the correlation value, calculated for each radar transmission interval T r , N p2 times for the respective N p2 radar transmission intervals T r , N p2 being smaller than N p1 , to output a second addition result;

a first doppler-frequency analyzer, which in operation, performs first Doppler-frequency analysis on the first addition result each the N p1 radar transmission intervals T r ;

a second doppler-frequency analyzer, which in operation, performs second Doppler-frequency analysis on the second addition result each the N p2 radar transmission intervals T r ; and

a doppler frequency corrector, which in operation, determines whether or not the reflection wave signal received by the one or more reception branches has Doppler frequency aliasing, based on a result of the first Doppler-frequency analysis and a result of the second Doppler-frequency analysis, and that corrects, when the reflection wave signal has Doppler frequency aliasing, a Doppler frequency included in the reflection wave signal received by the one or more reception branches, based on the result of the first Doppler-frequency analysis and the result of the second Doppler-frequency analysis, and

wherein, when the reflection wave signal received by the one or more reception branches has Doppler frequency aliasing, the position-determination result outputter calculates a position-determination result of the target by using the one or more reflection wave signals having the corrected Doppler frequency and the Doppler correction phase-rotation amount.

6. A position-determination method comprising:

determining a Doppler correction phase-rotation amount for correcting a Doppler frequency component based on a movement speed of a moving object;

correcting a radar transmission signal including pulse compression codes for each radar transmission interval T r , based on the Doppler correction phase-rotation amount;

repeatedly transmitting, by a radar transmitter mounted on the moving object, the corrected radar transmission signal in each radar transmission interval T r ;

receiving, by a radar receiver including one or more reception branches and mounted on the moving object, a reflection wave signal resulting from reflection of the corrected radar transmission signal by a target; and

calculating a position-determination result of the target by using a result of Doppler-frequency analysis on the reflection wave signal received by the one or more reception branches and the Doppler correction phase-rotation amount.