Radar system
Respective sector radars generate first and second transmission signals by multiplying any one Spano code sequence and any one orthogonal code sequence, selected among 2 (N+1) first and second Spano code sequences which are different from each other and 2 (N+1) first and second orthogonal code sequences which are different from each other, in a predetermined order in each transmission period, where N is an integer of 1 or greater. Respective sector radars convert the first and second transmission signals into first and second high frequency signals, and transmit the first and second high frequency signals through first and second transmission antennas. The 2 (N+1) first orthogonal code sequences and the 2 (N+1) second orthogonal code sequences used in the respective sector radars are orthogonal over transmission periods of M multiples of 2 (N+1) , where M is an integer of 2 or greater.
1. A radar system that includes at least two sector radars, the radar system comprising:
a first sector radar including
a first transmission signal generator that generates a first transmission signal by multiplying any one first Spano code and any one first orthogonal code selected among 2 (N+1) first Spano code sequences and 2 (N+1) first orthogonal code sequences, in a predetermined order in each transmission period, where N is an integer of 1 or greater, and
a first transmission RF section that converts the first transmission signal into a first high frequency signal and transmits the first frequency signal through a first transmission antenna; and
a second sector radar including
a second transmission signal generator that generates a second transmission signal by multiplying any one second Spano code and any one second orthogonal code selected among 2 (N+1) second Spano code sequences and 2 (N+1) second orthogonal code sequences, in a predetermined order in each transmission period, and
a second transmission RF section that converts the second transmission signal into a second high frequency signal and transmits the second high frequency signal through a second transmission antenna, wherein
the 2 (N+1) first orthogonal code sequences and the 2 (N+1) second orthogonal code sequences are orthogonal to each other over transmission periods of M multiples of the 2 (N+1) , where M is an integer of 2 or greater.
2. The radar system according to claim 1 , wherein
the first orthogonal code sequences include a plurality of types of orthogonal code sequences,
the first transmission signal generator generates the first transmission signal by multiplying the first Spano code sequences by the plurality of types of first orthogonal code sequences,
the second orthogonal code sequences include a plurality of types of orthogonal code sequences, and
the second transmission signal generator generates the second transmission signal by multiplying the second Spano code sequences by the plurality of types of second orthogonal code sequences.
3. The radar system according to claim 1 , wherein
the first transmission signal generator includes
a first transmission code storage in which the 2 (N+1) first Spano code sequences are stored,
a first orthogonal code storage in which the 2 (N+1) first orthogonal code sequences are stored, and
a first orthogonal code multiplier that multiplies the any one first Spano code by the any one first orthogonal code in a predetermined order in each transmission period, and wherein
the second transmission signal generator includes
a second transmission code storage in which the 2 (N+1) second Spano code sequences are stored,
a second orthogonal code storage in which the 2 (N+1) second orthogonal code sequences are stored, and
a second orthogonal code multiplier that multiplies the any one second Spano code by the any one second orthogonal code in a predetermined order in each transmission period.
4. The radar system according to claim 1 , wherein
the first sector radar includes
a first reception RF section that receives a reflected wave signal obtained as the first high frequency signal is reflected by a target through a first reception antenna and generates a reception baseband signal,
a first correlator that calculates a correlation value between the first transmission signal obtained by the multiplication of the first orthogonal codes and the reception baseband signal, and
a first coherent adder that adds first correlation values calculated over respective transmission periods of M multiples of 2 (N+1) , and wherein
the second sector radar includes
a second reception RF section that receives a reflected wave signal obtained as the second high frequency signal is reflected by the target through a second reception antenna and generates a reception baseband signal,
a second correlator that calculates a correlation value between the second transmission signal obtained by the multiplication of the second orthogonal codes and the reception baseband signal, and
a second coherent adder that adds second correlation values calculated over the respective transmission periods of M multiples of 2 (N+1) .
5. The radar system according to claim 1 , wherein
N=M=2,
the first orthogonal code sequence corresponding to first 2 (N+1) transmission periods is [1, 1, 1, 1, 1, 1, 1, 1],
the first orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [1, 1, 1, 1, 1, 1, 1, 1],
the second orthogonal code sequence corresponding to 2 (N+1) transmission periods is [1, 1, 1, 1, 1, 1, 1, 1], and
the second orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [−1, −1, −1, −1, −1, −1, −1, −1].
6. The radar system according to claim 1 , wherein
N=M=2,
the first orthogonal code sequence corresponding to first and second 2 (N+1) transmission periods is [1, −1, 1, −1, 1, −1, 1, −1],
the second orthogonal code sequence corresponding to first 2 (N+1) transmission periods is [−1, 1, −1, 1, −1, 1, −1, 1], and
the second orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [1, −1, 1, −1, 1, −1, 1, −1].
7. The radar system according to claim 1 , wherein
N=M=2,
the first orthogonal code sequence corresponding to first 2 (N+1) transmission periods is [1, 1, 1, 1, 1, 1, 1, 1],
the first orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [1, −1, 1, −1, 1, −1, 1, −1],
the second orthogonal code sequence corresponding to first 2 (N+1) transmission periods is [−1, 1, −1, 1, −1, 1, −1, 1], and
the second orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [1, 1, 1, 1, 1, 1, 1, 1].
8. The radar system according to claim 1 , wherein
N=1 and M=2,
the first orthogonal code sequence corresponding to first and second 2 (N+1) transmission periods is [1, −1, 1, −1],
the second orthogonal code sequence corresponding to first 2 (N+1) transmission periods is [−1, 1, −1, 1], and
the second orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [1, −1, 1, −1].
9. The radar system according to claim 1 , wherein
N=1 and M=2,
the first orthogonal code sequence corresponding to first 2 (N+1) transmission periods is [1, 1, 1, 1],
the first orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [1, −1, 1, −1],
the second orthogonal code sequence corresponding to first 2 (N+1) transmission periods is [−1, 1, −1, 1], and
the second orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [1, 1, 1, 1].
10. The radar system according to claim 1 , wherein
N=1 and M=2,
the first orthogonal code sequence corresponding to first and second 2 (N+1) transmission periods is [1, 1, 1, 1],
the second orthogonal code sequence corresponding to first 2 (N+1) transmission periods is [1, 1, 1, 1], and
the second orthogonal code sequence corresponding to second 2 (N+1) transmission periods is [−1, −1, −1, −1].