RADAR APPARATUS

• US 20130120185A1
• Filed: 07/14/2011
• Published: 05/16/2013
• Est. Priority Date: 07/29/2010
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kishigami, Takaaki, Nakagawa, Yoichi, Mukai, Hirohito
• Granted Patent: US 9,134,405 B2
• Time in Patent Office: Days
• US Class Current: 342/146
• CPC Class Codes: G01S 13/284 using coded pulses
• CPC Class Codes: G01S 13/288 phase modulated
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: G01S 7/285 Receivers

Abstract

A radar apparatus transmits a radio frequency transmission signal from a transmitter antenna in a given transmission period, and receives a signal of a reflected wave reflected by a target via a receiver antenna. The radar apparatus includes a transmission signal generator that generates a first transmission signal obtained by modifying a code having a third sub-code sequence and a fourth sub-code sequence coupled to each other in a first transmission period, and generates a second transmission period obtained by modifying a code having a fifth sub-code sequence and a sixth sub-code sequence coupled to each other in a second transmission period, and a transmitter RF unit that converts the first and second transmission signals into radio frequency transmission signals, and transmits the radio frequency transmission signals from the transmitter antenna.

Claims

1. A radar apparatus which transmits a radio frequency transmission signal from a transmitter antenna in a given transmission period, and receives a signal of a reflected wave reflected by a target via a receiver antenna, comprising:

a transmission signal generator that generates a first transmission signal obtained by modifying a code having a third sub-code sequence and a fourth sub-code sequence coupled to each other in a first transmission period, and generates a second transmission period obtained by modifying a code having a fifth sub-code sequence and a sixth sub-code sequence coupled to each other in a second transmission period, among first and second sub-code sequences each having a sub-code length obtained by dividing a code sequence having a given code length, and third, fourth, fifth, and sixth sub-code sequences obtained by multiplying each of the first and second sub-code sequences by two kinds of different coefficients; and

a transmitter RF unit that converts the first and second transmission signals generated by the transmission signal generator into radio frequency transmission signals, and transmits the radio frequency transmission signals from the transmitter antenna.

2. The radar apparatus according to claim 1, further comprising:

a receiver RF unit that converts the signal of the reflected wave received by the receiver antenna into a received signal of a baseband bandwidth;

a reference transmission signal generator that generates first and second reference transmission signals including the same third, fourth, fifth, and sixth sub-code sequences as those of the transmission signals generated by the transmission signal generator in synchronism with the first transmission period or the second transmission period;

a complex correlation value computation unit that computes, in the first transmission period, a first correlation value between a first received signal and the third sub-code sequence included in the first reference transmission signal, and a second correlation value between the first received signal and the fourth sub-code sequence included in the first reference transmission signal, and computes, in the second transmission period, a third correlation value between a second received signal and the fifth sub-code sequence included in the second reference transmission signal, and a fourth correlation value between the second received signal and the sixth sub-code sequence included in the second reference transmission signal; and

an IQ correction unit that computes a first correction coefficient for making the first correlation value and the second correlation value equal to each other, computes a second correction coefficient for making the third correlation value and the fourth correlation value equal to each other, computes a fifth correlation value obtained by adding the first correlation value and the second correlation value which are corrected by using the first correction coefficient, and computes a sixth correlation value obtained by adding the third correlation value and the fourth correlation value which are corrected by using the second correction coefficient.

3. The radar apparatus according to claim 2, further comprising:

an averaging processor that shifts the second transmission period in the computation of the sixth correlation value to the first transmission period in the computation of the fifth correlation value, and adds the shifted sixth correlation value and the shifted fifth correlation value together, on the basis of the fifth correlation value and the sixth correlation value which are computed by the IQ correction unit.

4. The radar apparatus according to claim 3, further comprising:

an arrival angle distance estimation unit that operates an arrival angle or a range to the target on the basis of the addition result of the averaging processor.

5. The radar apparatus according to claim 1, further comprising:

a first AGC unit that amplifies a level of an in-phase signal of the received signal converted by the receiver RF unit with a gain corresponding to an elapsed time from a start timing of a non-transmission zone in the transmission period; and

a second AGC unit that amplifies a level of a quadrature signal of the received signal converted by the receiver RF unit with a gain corresponding to the elapsed time from the start timing of the the non-transmission zone in the transmission period.

6. The radar apparatus according to claim 5, further comprising:

a first A/D converter that converts the in-phase signal amplified by the first AGC unit into digital data; and

a second A/D converter that converts the quadrature signal amplified by the second AGC unit into digital data.

7. The radar apparatus according to claim 1, further comprising:

a first code sequence storage that stores a code sequence having the third sub-code sequence and the fourth sub-code sequence coupled with each other therein; and

a second code sequence storage that stores a code sequence having the fifth sub-code sequence and the sixth sub-code sequence coupled with each other therein,

wherein the transmission signal generator modulates the respective code sequences stored in the first and second code sequence storages to generate the transmission signals.

8. The radar apparatus according to claim 3, further comprising:

a phase rotation amount computation unit that measures a phase rotation amount in the signal of the reflected wave with movement of the target, on the basis of the added correlation value in a plurality of reference transmission periods, with the first transmission period and the second transmission period in the computation of the correlation value added by the averaging processor as the reference transmission periods; and

a Doppler frequency estimation unit that estimates a Doppler frequency occurring in the signal of the reflected wave with the movement of the target, on the basis of the phase rotation amount computed by the phase rotation amount computation unit.

9. The radar apparatus according to claim 1, wherein the code sequence is a complementary code.

10. The radar apparatus according to claim 1, wherein the coefficient to be multiplied for the third sub-code sequence is 1;

wherein the coefficient to be multiplied for the fourth sub-code sequence is a complex sequence j;

wherein the coefficient to be multiplied for the fifth sub-code sequence is the complex sequence j; and

wherein the coefficient to be multiplied for the sixth sub-code sequence is 1.

11. The radar apparatus according to claim 1, wherein the coefficient to be multiplied for the third sub-code sequence is a complex sequence j;

wherein the coefficient to be multiplied for the fourth sub-code sequence is −

1;

wherein the coefficient to be multiplied for the fifth sub-code sequence is −

1; and

wherein the coefficient to be multiplied for the sixth sub-code sequence is the complex sequence j.

12. The radar apparatus according to claim 1, wherein the coefficient to be multiplied for the third sub-code sequence is −

1;

wherein the coefficient to be multiplied for the fourth sub-code sequence is a complex sequence −

j;

wherein the coefficient to be multiplied for the fifth sub-code sequence is the complex sequence −

j; and

wherein the coefficient to be multiplied for the sixth sub-code sequence is −

1.

13. The radar apparatus according to claim 1, wherein the coefficient to be multiplied for the third sub-code sequence is a complex sequence j;

wherein the coefficient to be multiplied for the fourth sub-code sequence is 1;

wherein the coefficient to be multiplied for the fifth sub-code sequence is 1; and

wherein the coefficient to be multiplied for the sixth sub-code sequence is the complex sequence j.

14. The radar apparatus according to claim 1, wherein the coefficient to be multiplied for the third sub-code sequence is a complex sequence −

j;

wherein the coefficient to be multiplied for the fourth sub-code sequence is −

1;

wherein the coefficient to be multiplied for the fifth sub-code sequence is −

1; and

wherein the coefficient to be multiplied for the sixth sub-code sequence is the complex sequence −

j.

15. The radar apparatus according to claim 1, wherein the coefficient to be multiplied for the third sub-code sequence is −

1;

wherein the coefficient to be multiplied for the fourth sub-code sequence is a complex sequence j;

wherein the coefficient to be multiplied for the fifth sub-code sequence is the complex sequence j; and

wherein the coefficient to be multiplied for the sixth sub-code sequence is −

1.