RADAR APPARATUS
Provided is a radar apparatus whose performance is enhanced. The radar apparatus, includes: signal generation circuitry, which, in operation, generates a plurality of chirp signals; and a transmission antenna, which, in operation, transmits the plurality of chirp signals. The signal generation circuitry configures a transmission delay for the plurality of chirp signals for each of a predetermined number of transmission periods, where the predetermined number is greater than or equal to two. The signal generation circuitry changes a center frequency of the plurality of chirp signals for each of the predetermined number of transmission periods.
1 . A radar apparatus, comprising:
signal generation circuitry, which, in operation, generates a plurality of chirp signals; and
a transmission antenna, which in operation, transmits the plurality of chirp signals, wherein:
the signal generation circuitry configures a transmission delay for the plurality of chirp signals for each of a predetermined number of transmission periods, the predetermined number being greater than or equal to two, and
the signal generation circuitry changes a center frequency of the plurality of chirp signals for each of the predetermined number of transmission periods.
2 . The radar apparatus according to claim 1 , wherein the transmission delay is configured differently in each of the predetermined number of transmission periods.
3 . The radar apparatus according to claim 1 , wherein the transmission delay changes in a round in the predetermined number of transmission periods.
4 . The radar apparatus according to claim 1 , wherein a change in the center frequency is configured based on an amount of the transmission delay.
5 . The radar apparatus according to claim 1 , further comprising reception circuitry, which, in operation, performs AD conversion on a plurality of reflected wave signals that is the plurality of chirp signals reflected by an object, wherein
in each of the transmission periods, a section in which the AD conversion is performed and a timing at which the AD conversion is started are constant.
6 . The radar apparatus according to claim 5 , wherein the predetermined number is configured based on a length of the section in which the AD conversion is performed.
7 . The radar apparatus according to claim 1 , wherein the transmission antenna transmits the plurality of chirp signals having been subjected to code multiplexing.
8 . The radar apparatus according to claim 7 , wherein the predetermined number is configured to an integer multiple of a code length of a code sequence to be used in the code multiplexing.
9 . The radar apparatus according to claim 7 , wherein the transmission delay varies for each transmission period corresponding to a code length of a code sequence to be used in the code multiplexing.
10 . The radar apparatus according to claim 7 , further comprising reception circuitry, which, in operation, performs, in a range that is greater by a factor (of a code length of a code sequence to be used in the code multiplexing) than a Doppler analysis range with respect to a plurality of reflected wave signals that is the plurality of chirp signals reflected by an object, aliasing determination in a Doppler frequency domain of the plurality of reflected wave signals.
11 . The radar apparatus according to claim 10 , wherein:
the transmission antenna transmits the plurality of chirp signals having been subjected to code multiplexing based on, among a plurality of code sequences, one or some of the plurality of code sequences; and
the reception circuitry performs the aliasing determination based on, among the plurality of code sequences, another code sequence or other code sequences different from the one or some of the plurality of code sequences.
12 . The radar apparatus according to claim 1 , wherein the transmission antenna performs time division transmission of the plurality of chirp signals.
13 . The radar apparatus according to claim 12 , wherein the predetermined number is configured to an integer multiple of a number of a plurality of the transmission antennas to be used in the time division transmission.