Transmission beamforming device, transmission beamforming program, reception beamforming device, reception beamforming program, and radar device

Abstract

To improve the beam resolution and side lobe characteristics of a combined transmission / reception beam (a transmission beam + a one-direction reception beam) even though the one-direction reception beam cannot achieve a deep null due to the presence of phase errors, mutual coupling, or the like between reception antenna elements when applying phased-array antennas or digital beamforming in a radar device that detects targets in multiple directions.SOLUTION: First, when phase-modulating a comb-type transmission beam, a sequence of phase-modulation amounts for multiple pulses is set to be uncorrelated for respective main beams in multiple directions. Next, when phase-demodulating a reception signal, the sequence of phase-demodulation amounts for the multiple pulses is set, for all directions, to a sequence of phase-demodulation amounts that cancels the phase-modulation amounts set only for one direction. Then, for the phase-demodulated signal, an integrated signal is calculated over all of the multiple pulses.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a technique for improving high-speed observation performance in multiple directions, beam resolution, and side lobe characteristics in a radar device that detects targets in multiple directions. [Background technology]

[0002] 2. Description of the Related Art A phased array antenna or digital beamforming is applied to a radar device (such as a weather radar device) that detects targets (such as rain) in multiple directions.

[0003] The technology prior to Non-Patent Document 1 forms a fan transmission beam that spans multiple directions, and forms a unidirectional reception beam that has a main beam in only one direction and a null in the other direction. This allows for high-speed observation performance in multiple directions to be maintained compared to when a parabolic antenna is used, but it is not possible to improve the beam resolution and side lobe characteristics of the total transmission and reception beam (fan transmission beam + unidirectional reception beam), making it impossible to obtain accurate target reception power, Doppler velocity, and distribution information.

[0004] The technology disclosed in Non-Patent Document 1 forms a comb-shaped transmission beam with a main beam in multiple directions, and a unidirectional reception beam with a main beam in only one direction and a null in the other direction. This makes it possible to maintain high-speed observation performance in multiple directions compared to when a parabolic antenna is used, and also improves the beam resolution and side lobe characteristics of the total transmission and reception beam (comb-shaped transmission beam + unidirectional reception beam), making it possible to obtain accurate target reception power, Doppler velocity, and distribution information. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Yoshikawa, E., Ushio, T., & Kikuchi, H., “A Study of Comb Beam Transmission on Phased Array Weather Radars”, IEEE Transactions on Geoscience and Remote Sensing, 59(8), 2021, pp. 6346-6356. Summary of the Invention [Problem to be solved by the invention]

[0006] The integration and averaging process of the received signal of a one-directional receive beam in the prior art is shown in Figure 1. First, a comb-shaped transmit beam is formed with a main beam in multiple directions D1, D2, D3, and D4. Here, the transmit phases of the multiple directions D1, D2, D3, and D4 are Φ for all of the first pulse, second pulse, ..., and Nth pulse. T1 , Φ T2 , Φ T3 , Φ T4 is.

[0007] Next, a one-way receiving beam is formed, which has a main beam in only one direction D2, but nulls in the other directions D1, D3, and D4. Here, for the first pulse, second pulse, ..., and Nth pulse, the receiving strength in one direction D2 is higher than the receiving strength in the other directions D1, D3, and D4, and the receiving phases (transmitting phase + propagation phase) in the multiple directions D1, D2, D3, and D4 are each Φ T1 +Φ P1 , Φ T2 +Φ P2 , Φ T3 +Φ P3 , Φ T4 +Φ P4 is.

[0008] Next, for the received signals from multiple directions D1, D2, D3, and D4, the integrated signal is calculated over all N pulses, and the average signal for one pulse is calculated. Then, the received strength in one direction D2 is the highest, and the received phase (transmission phase + propagation phase) in one direction D2 is Φ T2 +Φ P2 is.

[0009] Figure 2 shows the ideal situation for transmit / receive / total transmit / receive beams in the prior art. In the upper part of Figure 2, a comb-shaped transmit beam is formed with a main beam in multiple directions D1, D2, D3, and D4. In the middle part of Figure 2, a unidirectional receive beam is formed with a main beam in only one direction D2, while having deep nulls in the other directions D1, D3, and D4. Here, in an ideal situation, there is no phase error or mutual coupling between the receive antenna elements, so the nulls in the unidirectional receive beam can be made deep. In the lower part of Figure 2, the beam resolution and sidelobe characteristics of the total transmit / receive beam (comb-shaped transmit beam + unidirectional receive beam) can be improved.

[0010] Figure 3 shows the problems that conventional techniques face in transmitting / receiving / total transmitting / receiving beams. In the top part of Figure 3, a comb-shaped transmitting beam is formed with a main beam in multiple directions D1, D2, D3, and D4. In the middle part of Figure 3, a unidirectional receiving beam is formed with a main beam in only one direction D2, while shallow nulls are formed in the other directions D1, D3, and D4. However, in actual situations, due to phase errors and mutual coupling between receiving antenna elements, the nulls of the unidirectional receiving beam cannot be deepened. In the bottom part of Figure 3, the beam resolution and sidelobe characteristics of the total transmitting / receiving beam (comb-shaped transmitting beam + unidirectional receiving beam) cannot be improved.

[0011] A simulation of the transmit / receive / total transmit / receive beams of the prior art is shown in Figure 4. As in Figure 3, in Figure 4, due to the existence of phase errors and mutual coupling between the receive antenna elements, the nulls of the one-way receive beam cannot be deepened, and the beam resolution and side lobe characteristics of the total transmit / receive beam (comb-shaped transmit beam + one-way receive beam) cannot be improved.

[0012] Therefore, in order to solve the above problem, the present disclosure aims to improve the beam resolution and side lobe characteristics of the total transmitting and receiving beam (transmitting beam + one-way receiving beam) when a phased array antenna or digital beamforming is applied to a radar device that detects targets in multiple directions, even if the null of the one-way receiving beam cannot be deepened due to the existence of phase errors and mutual coupling between receiving antenna elements. [Means for solving the problem]

[0013] To solve the above problem, first, when phase-modulating a comb-shaped transmission beam, the sequence of phase modulation amounts of multiple pulses is set to be "uncorrelated" for each main beam in multiple directions. Here, the sequence of phase modulation amounts of multiple pulses is a binary or multi-level pseudo-random number sequence.

[0014] Next, when phase demodulating the received signal, a sequence of phase demodulation amounts for multiple pulses is set across all directions to a sequence of phase demodulation amounts that "cancels out" the phase modulation amount set for "only one direction." Next, for the phase demodulated signal, an integrated signal is calculated across all of the multiple pulses, and an average signal for one pulse is calculated.

[0015] Since the reception phase (transmission phase + propagation phase) in one direction is consistent across multiple pulses, the reception intensity in one direction becomes the signal level through coherent integration. On the other hand, since the reception phase (transmission phase + propagation phase) in the other direction is not consistent across multiple pulses, the reception intensity in the other direction becomes the noise level through spectrum spreading.

[0016] Specifically, the present disclosure provides a transmission beam forming device comprising: a transmission beam forming unit that forms a comb-shaped transmission beam having main beams in multiple directions; and a transmission phase modulation unit that, when phase-modulating the comb-shaped transmission beam, sets a sequence of phase modulation amounts of multiple pulses to be uncorrelated for each main beam in the multiple directions.

[0017] According to this configuration, when a phased array antenna or digital beamforming is applied to a radar device that detects targets in multiple directions, even if it is not possible to deepen the null of a unidirectional receiving beam due to the existence of phase errors and mutual coupling between receiving antenna elements, it is possible to maintain the gain of the main beam in only one direction of the comb-shaped transmitting beam while artificially reducing the gain of the main beam in the other directions.

[0018] The present disclosure also provides a transmission beamforming program for causing a computer to sequentially execute the processing steps executed by the processing units included in the transmission beamforming device described above.

[0019] According to this configuration, it is possible to provide a program having the above-described effects.

[0020] The present disclosure also provides a receiving beam forming device comprising: a receiving beam forming unit that forms a unidirectional receiving beam that has a main beam in only one direction among the multiple directions in which the comb-shaped transmitting beam formed by the transmitting beam forming device described above has a main beam, while having nulls in the other directions; a receiving phase demodulation unit that, when phase demodulating the signal received by the receiving beam forming unit, sets a sequence of phase demodulation amounts of the multiple pulses across all of the multiple directions to a sequence of phase demodulation amounts that cancels out the phase modulation amount set for only the one direction; and a receiving signal integration unit that calculates an integrated signal across all of the multiple pulses for the phase demodulated signal by the receiving phase demodulation unit, and calculates an average signal for one pulse.

[0021] According to this configuration, when a phased array antenna or digital beamforming is applied to a radar device that detects targets in multiple directions, phase errors and mutual coupling exist between receiving antenna elements, so even if the null of the unidirectional receiving beam cannot be deepened, the beam resolution and side lobe characteristics of the total transmitting and receiving beam (comb-shaped transmitting beam + unidirectional receiving beam) can be improved to higher performance.

[0022] The present disclosure also provides a receiving beam forming device comprising: a receiving beam forming unit that forms a fan receiving beam having a fan shape in all directions from one end direction to the other end direction among the multiple directions in which the comb-shaped transmitting beam formed by the transmitting beam forming device described above has a main beam; a receiving phase demodulation unit that, when phase demodulating the signal received by the receiving beam forming unit, sets a sequence of phase demodulation amounts of the multiple pulses to a sequence of phase demodulation amounts that cancels out the phase modulation amount set for only one direction, across all of the multiple directions; and a receiving signal integration unit that calculates an integrated signal over all of the multiple pulses for the phase demodulated signal by the receiving phase demodulation unit, and calculates an average signal for one pulse.

[0023] According to this configuration, when a phased array antenna or digital beamforming is applied to a radar device that detects targets in multiple directions, phase errors and mutual coupling exist between receiving antenna elements, so even if the null of the unidirectional receiving beam cannot be deepened, the beam resolution and side lobe characteristics of the total transmitting and receiving beam (comb-shaped transmitting beam + fan receiving beam) can be improved at a lower cost.

[0024] The present disclosure also provides a beamforming program for receiving signals that causes a computer to sequentially execute the processing steps executed by the processing units included in the beamforming apparatus for receiving signals described above.

[0025] According to this configuration, it is possible to provide a program having the above-described effects.

[0026] The present disclosure also provides a radar device including the above-described transmitting beam forming device, the above-described receiving beam forming device, a transmitting antenna device, and a receiving antenna device.

[0027] According to this configuration, it is possible to provide a radar device having the above-described effects. [Effects of the Invention]

[0028] In this way, the present disclosure enables the application of a phased array antenna or digital beamforming to a radar device that detects targets in multiple directions, and even if the null of the unidirectional receive beam cannot be deepened due to the existence of phase errors and mutual coupling between the receive antenna elements, it is possible to improve the beam resolution and side lobe characteristics of the total transmit and receive beam (transmit beam + unidirectional receive beam). [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing the integration and averaging process of the received signal of a unidirectional receive beam according to the prior art. [Figure 2] FIG. 1 illustrates an ideal situation for a transmit / receive / sum beam in the prior art. [Figure 3] FIG. 1 illustrates a problem to be solved by a transmit / receive / transmit / receive sum beam in the prior art. [Figure 4] FIG. 1 shows a simulation of a transmit / receive / sum beam of the prior art. [Figure 5] FIG. 1 is a diagram illustrating a configuration of a radar device according to the present disclosure. [Figure 6] FIG. 10 is a diagram showing the procedure of the transmitting and receiving beamforming process of the present disclosure. [Figure 7] 10A and 10B are diagrams illustrating a sequence of a phase modulation amount and a phase demodulation amount according to the present disclosure. [Figure 8] FIG. 10 is a diagram illustrating a phase demodulation process for a received signal of a unidirectional receive beam according to the present disclosure. [Figure 9] FIG. 10 is a diagram illustrating a phase demodulation process for a received signal of a fan receive beam according to the present disclosure. [Figure 10] FIG. 10 is a diagram illustrating a pseudo phase demodulation process of a comb-shaped transmit beam according to the present disclosure. [Figure 11] FIG. 1 illustrates a transmit / receive / transmit-receive sum beam solution of the present disclosure. [Figure 12] A diagram showing a simulation of the transmit / receive / transmit-receive sum beam of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0030]

[0023] The following embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementation of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0031] (Configuration of the radar device of the present disclosure) The configuration of a radar device according to the present disclosure is shown in Fig. 5. The radar device R is a radar device (such as a weather radar device) that detects targets (such as rain) in multiple directions, and includes a transmitting and receiving antenna device 1, a transmitting and receiving beam forming device 2, and a radar signal processing device 3.

[0032] The transmitting and receiving beam forming device 2 uses a phased array antenna or digital beam forming to form the transmitting beam and the receiving beam. The transmitting and receiving antenna device 1 emits and receives the transmitting pulse and the reflected pulse. The radar signal processing device 3 acquires accurate target receiving power, Doppler velocity, and distribution information.

[0033] The transmitting and receiving beamforming device 2 includes a transmitting beamforming unit 21, a transmitting phase modulating unit 22, a receiving beamforming unit 23, a receiving phase demodulating unit 24, and a receiving signal integrating unit 25, and can be realized by installing the transmitting and receiving beamforming program shown in Figure 6 in a computer.

[0034] As an outline of the present disclosure, first, when phase-modulating a comb-shaped transmission beam, a sequence of phase modulation amounts of multiple pulses is set to be "uncorrelated" for each main beam in multiple directions. Here, the sequence of phase modulation amounts of multiple pulses is a binary or multi-level pseudo-random number sequence.

[0035] Next, when phase demodulating the received signal, a sequence of phase demodulation amounts for multiple pulses is set across all directions to a sequence of phase demodulation amounts that "cancels out" the phase modulation amount set for "only one direction." Next, for the phase demodulated signal, an integrated signal is calculated across all of the multiple pulses, and an average signal for one pulse is calculated.

[0036] Since the reception phase (transmission phase + propagation phase) in one direction is consistent across multiple pulses, the reception intensity in one direction becomes the signal level through coherent integration. On the other hand, since the reception phase (transmission phase + propagation phase) in the other direction is not consistent across multiple pulses, the reception intensity in the other direction becomes the noise level through spectrum spreading.

[0037] (Procedure of transmit and receive beamforming processing of the present disclosure) The procedure for the transmit and receive beamforming process of the present disclosure is shown in Figure 6. The sequence of the phase modulation amount and phase demodulation amount of the present disclosure is shown in Figure 7. The transmit beamformer 21 forms a comb-shaped transmit beam having a main beam in multiple directions (step S1). In the upper part of Figure 7, the comb-shaped transmit beam has main beams in multiple directions D1, D2, D3, and D4.

[0038] When phase-modulating the comb-shaped transmission beam, the transmission phase modulation unit 22 sets the sequence of phase modulation amounts of multiple pulses to be uncorrelated for each main beam in multiple directions (step S2). In the upper part of Fig. 7, the sequence of phase modulation amounts of the first pulse, the second pulse, ..., the (N+1)th pulse, and the Nth pulse is set as follows: (1) for the main beam in direction D1, it is set to 0, 0, ..., +π, 0; (2) for the main beam in direction D2, it is set to 0, +π, ..., 0, +π; (3) for the main beam in direction D3, it is set to 0, +π, ..., +π, 0; and (4) for the main beam in direction D4, it is set to 0, 0, ..., 0, +π.

[0039] The receive beam former 23 forms, as the receive beam of the first embodiment, a unidirectional receive beam that has a main beam in only one direction out of multiple directions in which the comb-shaped transmit beam formed by the transmit beam former 21 has a main beam, while having nulls in the other directions (step S3). In the lower part of Fig. 7, the unidirectional receive beam has a main beam in only one direction out of multiple directions D1, D2, D3, and D4, while having nulls in the other directions.

[0040] The receive beam former 23 forms, as a receive beam of the second embodiment, a fan receive beam having a fan shape extending in all directions from one end direction to the other end direction among the multiple directions in which the comb-shaped transmit beam formed by the transmit beam former 21 has a main beam (step S4). In the lower part of Fig. 7, the fan receive beam has a fan shape extending in all directions D1, D2, D3, D4 from one end direction D1 to the other end direction D4.

[0041] When the reception phase demodulator 24 phase-demodulates the received signal by the reception beamformer 23, the reception phase demodulator 24 sets the sequence of phase demodulation amounts of multiple pulses across all of the multiple directions to a sequence of phase demodulation amounts that cancels out the phase modulation amount set for only one direction (step S5). In the lower part of Fig. 7, the sequence of phase demodulation amounts for the first pulse, the second pulse, ..., the (N+1)th pulse, and the Nth pulse is set to 0, 0, ..., -π, 0 across all of the multiple directions when (1) phase demodulating the direction D1, (2) 0, -π, ..., 0, -π across all of the multiple directions when phase demodulating the direction D2, (3) 0, -π, ..., -π, 0 across all of the multiple directions when phase demodulating the direction D3, and (4) 0, 0, ..., 0, -π across all of the multiple directions when phase demodulating the direction D4.

[0042] The received signal integrator 25 calculates an integrated signal over all of the pulses of the phase-demodulated signal by the received phase demodulator 24, and calculates an average signal for one pulse (step S6). In Figures 8 and 9, the integrated signal and average signal are calculated for each of the multiple directions D1, D2, D3, and D4 over all of the first pulse, second pulse, ..., (N+1)th pulse, and Nth pulse.

[0043] The phase demodulation process for the received signal of a one-way receive beam according to the present disclosure is shown in Figure 8. The phase demodulation process for the received signal of a fan receive beam according to the present disclosure is shown in Figure 9. First, a comb-shaped transmit beam is formed with main beams in multiple directions D1, D2, D3, and D4. Here, based on the sequence of phase modulation amounts of N pulses shown in the upper part of Figure 7, (1) in the first pulse, the transmit phases in multiple directions D1, D2, D3, and D4 are each Φ T1 , Φ T2 , Φ T3 , Φ T4 (2) In the second pulse, the transmission phases of the multiple directions D1, D2, D3, and D4 are Φ T1 , Φ T2 +π, Φ T3 +π, Φ T4 (N) At the N-th pulse, the transmission phases of the multiple directions D1, D2, D3, and D4 are Φ T1 , Φ T2 +π, Φ T3 , Φ T4 +π.

[0044] Next, a unidirectional receive beam is formed, with a main beam in only one direction D2 and nulls in the other directions D1, D3, and D4. Here, the receive strength in one direction D2 is higher than the receive strength in the other directions D1, D3, and D4 for all of the first, second, ..., and Nth pulses. Alternatively, a fan receive beam is formed, with a fan shape, spanning all directions D1, D2, D3, and D4 from one end direction D1 to the other end direction D4. Here, the receive strength in all directions D1, D2, D3, and D4 is approximately equal for all of the first, second, ..., and Nth pulses if the distribution of targets (rainfall, etc.) is uniform.

[0045] Based on the sequence of phase modulation amounts of N pulses shown in the upper part of FIG. 7, (1) at the first pulse, the reception phases (transmission phases + propagation phases) of the multiple directions D1, D2, D3, and D4 are respectively Φ T1 +Φ P1 , Φ T2 +Φ P2 , Φ T3 +Φ P3 , Φ T4+Φ P4 (2) At the second pulse, the reception phase (transmission phase + propagation phase) of the multiple directions D1, D2, D3, and D4 is Φ T1 +Φ P1 , Φ T2 +π+Φ P2 , Φ T3 +π+Φ P3 , Φ T4 +Φ P4 (N) At the N-th pulse, the reception phase (transmission phase + propagation phase) of the multiple directions D1, D2, D3, and D4 is Φ T1 +Φ P1 , Φ T2 +π+Φ P2 , Φ T3 +Φ P3 , Φ T4 +π+Φ P4 is.

[0046] Next, the received signal is phase-demodulated by the receiving beam former 23. Here, based on the sequence of phase demodulation amounts of N pulses shown in the lower part of Fig. 7, (1) at the first pulse, the receiving phases (transmitting phases + propagation phases) in the multiple directions D1, D2, D3, and D4 are respectively Φ T1 +Φ P1 , Φ T2 +Φ P2 , Φ T3 +Φ P3 , Φ T4 +Φ P4 (2) At the second pulse, the reception phase (transmission phase + propagation phase) of the multiple directions D1, D2, D3, and D4 is Φ T1 +Φ P1 -π, Φ T2 +π+Φ P2 -π(=Φ T2 +Φ P2 ), Φ T3 +π+Φ P3 -π(=Φ T3 +Φ P3 ), Φ T4 +Φ P4 -π, and (N) at the Nth pulse, the reception phases (transmission phase + propagation phase) of the multiple directions D1, D2, D3, and D4 are Φ T1 +Φ P1 -π, Φ T2+π+Φ P2 -π(=Φ T2 +Φ P2 ), Φ T3 +Φ P3 -π, Φ T4 +π+Φ P4 -π(=Φ T4 +Φ P4 )

[0047] Next, the phase demodulated signal from the receive beam demodulator 24 is integrated over all N pulses, and the average signal for one pulse is calculated. When a unidirectional receive beam is formed, the receive intensity in one direction D2 becomes a signal level due to coherent integration, and the receive intensity in other directions D1, D3, and D4 becomes a fairly low noise level due to spectrum spreading. On the other hand, when a fan receive beam is formed, the receive intensity in one direction D2 becomes a signal level due to coherent integration, and the receive intensity in other directions D1, D3, and D4 becomes a noise level to some extent due to spectrum spreading. When any receive beam is formed, the receive phase (transmit phase + propagation phase) in one direction D2 is Φ T2 +Φ P2 is.

[0048] Thus, when a phased array antenna or digital beamforming is applied to a radar device R that detects targets in multiple directions, the null of the unidirectional receive beam may not be deep due to the phase error and mutual coupling between the receive antenna elements. However, the present disclosure can improve the beam resolution and side lobe characteristics of the combined transmit and receive beam (comb-shaped transmit beam + unidirectional receive beam) to a higher level of performance. Furthermore, the present disclosure can improve the beam resolution and side lobe characteristics of the combined transmit and receive beam (comb-shaped transmit beam + fan receive beam) at a lower cost.

[0049] (Pseudo Phase Demodulation Processing of Comb-Shaped Transmission Beams of the Present Disclosure) 5 to 9 illustrate the "actual processing" phase demodulation process of the "received signal" of the present disclosure. 10 to 12 illustrate the "pseudo" phase demodulation process of the "comb-shaped transmit beam" of the present disclosure. In other words, even when the nulls of the "unidirectional receive beam" cannot be deepened "in actual processing," the beam resolution and side lobe characteristics of the total transmit and receive beam can be improved by "pseudo" deepening the nulls of the "comb-shaped transmit beam."

[0050] Fig. 10 shows the pseudo phase demodulation process of the comb-shaped transmission beam of the present disclosure. First, similar to the phase demodulation process in the actual processing of the received signal of the present disclosure shown in Figs. 8 and 9, a comb-shaped transmission beam having main beams in multiple directions D1, D2, D3, and D4 is formed. Here, based on the sequence of phase modulation amounts of N pulses shown in the upper part of Fig. 7, (1) in the first pulse, the transmission phases in multiple directions D1, D2, D3, and D4 are respectively Φ T1 , Φ T2 , Φ T3 , Φ T4 (2) In the second pulse, the transmission phases of the multiple directions D1, D2, D3, and D4 are Φ T1 , Φ T2 +π, Φ T3 +π, Φ T4 (N) At the N-th pulse, the transmission phases of the multiple directions D1, D2, D3, and D4 are Φ T1 , Φ T2 +π, Φ T3 , Φ T4 +π.

[0051] Next, one direction D2 of the comb-shaped transmission beam is subjected to pseudo phase demodulation. Here, based on the sequence of phase demodulation amounts of N pulses shown in the lower part of Figure 7, (1) in the first pulse, the transmission phases of the multiple directions D1, D2, D3, and D4 are respectively Φ T1 , Φ T2 , Φ T3 , Φ T4 (2) In the second pulse, the transmission phases of the multiple directions D1, D2, D3, and D4 are Φ T1 -π, Φ T2 +π-π(=Φ T2 ), ΦT3 +π-π(=Φ T3 ), Φ T4 -π, (N) At the N-th pulse, the transmission phases of the multiple directions D1, D2, D3, and D4 are Φ T1 -π, Φ T2 +π-π(=Φ T2 ), Φ T3 -π, Φ T4 +π-π(=Φ T4 )

[0052] Next, for the comb-shaped transmit beam after the pseudo phase demodulation, the integrated signal is calculated over all N pulses, and the average signal for one pulse is calculated. Then, the transmit intensity in one direction D2 becomes the signal level by coherent integration, and the transmit intensity in the other directions D1, D3, and D4 becomes the noise level by spectrum spreading, and the transmit phase in one direction D2 is Φ T2 is.

[0053] The transmit / receive / total transmit / receive beam solution of the present disclosure is shown in Figure 11. In the upper part of Figure 11, a pseudo-comb transmit beam is formed, which has a strong main beam in only one direction D2, while having shallow nulls or weak main beams in the other directions D1, D3, and D4. In the middle part of Figure 11, a unidirectional receive beam is formed, which has a main beam in only one direction D2, while having shallow nulls in the other directions D1, D3, and D4. However, in actual equipment, the nulls of the unidirectional receive beam cannot be deepened due to phase errors and mutual coupling between the receive antenna elements. In the lower part of Figure 11, the beam resolution and sidelobe characteristics of the total transmit / receive beam (pseudo-comb transmit beam + unidirectional receive beam) can be improved.

[0054] A simulation of the transmit / receive / total transmit / receive beams of the present disclosure is shown in Fig. 12. As in Fig. 11, even in Fig. 12, due to the existence of phase errors and mutual coupling between the receive antenna elements, the null of the one-way receive beam cannot be made deep, but the beam resolution and side lobe characteristics of the total transmit / receive beam (pseudo comb-shaped transmit beam + one-way receive beam) can be improved.

[0055] Thus, when a phased array antenna or digital beamforming is applied to a radar device R that detects targets in multiple directions, the null of the unidirectional receive beam may not be deep due to the phase error and mutual coupling between the receive antenna elements. However, the present disclosure can maintain the gain of the main beam in only one direction of the comb-shaped transmit beam while artificially reducing the gain of the main beam in other directions. Therefore, the present disclosure can improve the beam resolution and side lobe characteristics of the total transmit and receive beam (the pseudo comb-shaped transmit beam + the unidirectional receive beam). [Industrial Applicability]

[0056] The transmit beam forming device, transmit beam forming program, receive beam forming device, receive beam forming program, and radar device of the present disclosure can be applied to radar devices (such as weather radar devices) that use a phased array antenna or digital beam forming to detect targets (such as rain) in multiple directions. [Explanation of symbols]

[0057] R: Radar equipment 1: Transmitting and receiving antenna device 2: Transmitting and receiving beam forming device 3: Radar signal processing unit 21: Transmit beam forming unit 22: Transmit phase modulation unit 23: Receiving beam forming unit 24: Receive phase demodulation unit 25: Received signal integrator

Claims

1. a transmission beam forming unit that forms a comb-shaped transmission beam having main beams in multiple directions; a transmission phase modulation unit that sets a sequence of phase modulation amounts of a plurality of pulses to be uncorrelated for each of the main beams in the plurality of directions when phase-modulating the comb-shaped transmission beam; A transmitting beam forming device comprising:

2. A transmission beamforming program for causing a computer to sequentially execute each processing step executed by each processing unit included in the transmission beamforming device according to claim 1.

3. a reception beam former that forms a unidirectional reception beam having a main beam in only one direction among the plurality of directions in which the comb-shaped transmission beam formed by the transmission beam former according to claim 1 has a main beam, and having nulls in other directions; a reception phase demodulation unit that, when phase demodulating the reception signal by the reception beam forming unit, sets a sequence of phase demodulation amounts of the plurality of pulses across all of the plurality of directions to a sequence of phase demodulation amounts that cancels out the phase modulation amount set for only the one direction; a received signal integration unit that calculates an integrated signal over all of the plurality of pulses of the phase demodulated signal by the received phase demodulation unit and calculates an average signal for one pulse; A receiving beamforming device comprising:

4. a receiving beam former that forms a fan receiving beam having a fan shape in all directions from one end direction to the other end direction among the plurality of directions in which the comb-shaped transmitting beam formed by the transmitting beam former according to claim 1 has a main beam; a reception phase demodulation unit that, when phase demodulating the reception signal by the reception beam forming unit, sets a sequence of phase demodulation amounts of the plurality of pulses across all of the plurality of directions to a sequence of phase demodulation amounts that cancels out a phase modulation amount set for only one direction; a received signal integration unit that calculates an integrated signal over all of the plurality of pulses of the phase demodulated signal by the received phase demodulation unit and calculates an average signal for one pulse; A receiving beamforming device comprising:

5. A beamforming program for receiving signals that causes a computer to sequentially execute the processing steps executed by the processing units of the beamforming apparatus for receiving signals according to claim 3 or 4.

6. 5. A radar device comprising: a transmitting beam forming device according to claim 1; a receiving beam forming device according to claim 3; a transmitting antenna device; and a receiving antenna device.

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