Radar apparatus and radar method
View Patent ↗A radar apparatus includes a radar transmitter that transmits a radar signal in a predetermined transmission cycle and a radar receiver that receives a reflection wave signal being a reflection of the radar signal on a target. The radar transmitter includes a phase rotation controller that randomly varies a pattern of a phase rotation every period corresponding to a plurality of transmission cycles, the pattern being to be applied to the radar signal within a period, and a transmission phase rotator that assigns a first phase rotation to the radar signal in accordance with the pattern. The radar receiver includes a reception phase rotator that assigns a second phase rotation in a direction opposite to a direction of the first phase rotation to the reflection wave signal in accordance with the pattern.
1. A radar apparatus, comprising:
a radar transmitter which, in operation, transmits radar signals in a plurality of transmission cycles; and
a radar receiver which, in operation, receives reflection wave signals, the reflection wave signals being reflections of the radar signals on a target,
wherein
the radar transmitter includes
a phase rotation controller which, in operation, assigns a unit phase rotation amount every N e transmission cycles of the plurality of transmission cycles, and generates a phase rotation amount change signal that controls a phase rotation amount,
N e being an integer greater than one,
the phase rotation amount of the phase rotation amount change signal being constant within each of the plurality of transmission cycles,
the phase rotation amount of the phase rotation amount change signal being changed within the N e transmission cycles according to the unit phase rotation amount and a predetermined pattern, and
a transmission phase rotator which, in operation, assigns first phase rotations to the radar signals in accordance with the phase rotation amount change signal, and
the radar receiver includes a reception phase rotator which, in operation, assigns second phase rotations, which are in directions opposite to directions of the first phase rotations, to the reflection wave signals in accordance with the phase rotation amount change signal.
2. The radar apparatus according to claim 1 , wherein a difference between phase rotation amounts in patterns different from each other is 0 or π.
3. The radar apparatus according to claim 1 , wherein the predetermined pattern is based on a pseudo random code.
4. The radar apparatus according to claim 1 , wherein a total phase shift amount of the phase rotation amount change signal within N e transmission cycles is an integral multiple of 2π.
5. The radar apparatus according to claim 4 , wherein,
a complementary code is used to generate the radar signals, and
the phase rotation controller, in operation, assigns phase rotations such that a phase shift is not made within every two transmission cycles where a pair of codes constituting the complementary code are transmitted, and a predetermined phase shift is made between two transmission cycles.
6. The radar apparatus according to claim 1 , wherein predetermined pattern is different between a plurality of radar apparatuses.
7. The radar apparatus according to claim 1 , wherein
the radar transmitter includes a plurality of transmission antennas, and
the predetermined pattern is different between the transmission antennas.
8. A radar method, comprising:
transmitting radar signals in a plurality of transmission cycles; and
receiving reflection wave signals, the reflection wave signals being reflections of the radar signals on a target, wherein
transmitting the radar signals includes:
assigning a unit phase rotation amount every N e transmission cycles of the plurality of transmission cycles, and
generating a phase rotation amount change signal that controls a phase rotation amount, and
assigning first phase rotations to the radar signals in accordance with the phase rotation amount change signal,
N e being an integer greater than one,
the phase rotation amount of the phase rotation amount change signal being constant within each of the plurality of transmission cycles,
the phase rotation amount of the phase rotation amount change signal being changed within the N e transmission cycles according to the unit phase rotation amount and a predetermined pattern, and
receiving the reflection wave signals includes:
assigning second phase rotations, which are in directions opposite to directions of the first phase rotations, to the reflection wave signals in accordance with the phase rotation amount change signal.
9. The radar apparatus according to claim 1 , wherein the phase rotation controller, in operation, changes the predetermined pattern every N e transmission cycles.