JP7210178B2 - Receiving system, radar system and signal processing method - Google Patents

Description

Embodiments of the present invention relate to receiving systems, radar systems and signal processing methods.

There is digital beam forming (DBF: Digital Beam Forming) in which arbitrary multi-beams are formed by digital signal processing of signals transmitted and received by all antenna elements provided in an array antenna (Non-Patent Documents 1 and 2). When applying DBF to signals received by an array antenna, it is necessary to convert all the signals received by each antenna element into digital signals. Must be provided for each antenna element.

Increasing the number of antenna elements in an array antenna to improve the observation performance of a radar system increases the scale of the hardware, and also increases the number of analog signals to be processed and their data volume. To increase. Due to an increase in the scale of hardware and an increase in the scale of software accompanying an increase in the amount of data to be processed, it has sometimes become difficult to implement a system with desired observation performance.

Yoshida, "Revised Radar Technology", The Institute of Electronics, Information and Communication Engineers, 1996, pp. 289-291 Edited by the Institute of Electronics, Information and Communication Engineers, "Antenna Engineering Handbook (2nd Edition)", Ohmsha, 2008, pp. 418-420 Yoshida, "Revised Radar Technology", The Institute of Electronics, Information and Communication Engineers, 1996, pp. 134-135

The problem to be solved by the present invention is to provide a receiving system, a radar system, and a signal processing method that can facilitate system implementation while improving observation performance while suppressing an increase in hardware scale. be.

The receiving system of the embodiment has a beamformer, a sampler, a transformer, and a beam combiner. The beam forming unit can time-divide orthogonal reception beams with different directivity directions obtained by dividing the number of antenna elements provided in the array antenna by the number of divided observation spaces for each divided observation space obtained by dividing the observation space of the array antenna. formed in an array antenna. The sampling unit samples the received signal obtained from each of the orthogonal receiving beams at a high sampling frequency obtained by multiplying the sampling frequency corresponding to the bandwidth of the signal to be detected by the number of orthogonal receiving beams. The transform unit performs an inverse Fourier transform on the sampled values obtained by the sampling unit to obtain a transform output corresponding to the number of antenna elements. The beam synthesizing unit synthesizes after adding a phase forming a reception beam in the observation space to each of the converted outputs.

1 is a block diagram showing a configuration example of a reception system according to a first embodiment; FIG. FIG. 4 is a diagram showing an arrangement example of subarray antennas in the array antenna according to the first embodiment; FIG. 2 is a diagram showing a configuration example of a subarray antenna according to the first embodiment; 4 is a diagram showing a configuration example of a receiving module according to the first embodiment; FIG. 4A and 4B are diagrams showing an example of division of an observation space in the first embodiment; FIG. 4 is a diagram showing sampling frequencies of an AD converter in the first embodiment; FIG. FIG. 4 is a diagram showing an example of orthogonal reception beams formed in divided observation spaces according to the first embodiment; 4A and 4B are diagrams showing processing of a space conversion unit in the first embodiment; FIG. The block diagram which shows the structural example of the radar system in 2nd Embodiment. The figure which shows the structural example of the subarray antenna in 2nd Embodiment. The figure which shows the structural example of the transmission/reception module in 2nd Embodiment. FIG. 8 is a diagram showing an example of transmission beams and reception beams formed by a subarray antenna according to the second embodiment;

Hereinafter, a receiving system, a radar system, and a signal processing method according to embodiments will be described with reference to the drawings. In the following embodiments, it is assumed that components denoted by the same reference numerals perform similar operations, and duplicate descriptions are omitted as appropriate.

[First Embodiment]
FIG. 1 is a block diagram showing a configuration example of a reception system according to the first embodiment. A receiving system receives, for example, a signal reflected at or emitted from an object. The receiving system includes an array antenna 10 , a frequency converter 12 , an AD converter 13 (sampling section), a multi-beam forming section 14 (beam forming section), a space converting section 15 (converting section) and a beam combining section 16 . The array antenna 10 has a plurality of antenna elements. A plurality of antenna elements are divided into M groups, and each group constitutes a subarray antenna 11 . In the following description, the number of antenna elements provided in array antenna 10 is represented by N, and the number of antenna elements forming subarray antenna 11 is represented by Ns (=N/M). The array antenna 10 may be configured with one subarray antenna 11 instead of multiple subarray antennas 11 . That is, M=1 may be set.

A frequency converter 12 , an AD converter 13 , a multi-beam former 14 and a space converter 15 are provided for each subarray antenna 11 . That is, the receiving system includes Ns receiving systems each composed of a subarray antenna 11 , a frequency converter 12 , an AD converter 13 , a multi-beam former 14 and a space converter 15 .

The frequency converter 12 converts the received signal obtained by the subarray antenna 11 into a baseband signal and supplies the baseband signal to the AD converter 13 . The frequency of the local signal (local oscillation signal) used for frequency conversion in the frequency converter 12 is determined according to the frequency of the signal to be detected. The AD converter 13 samples the baseband signal at a predetermined sampling frequency, which will be described later, and converts it into a digital signal. The multi-beam forming unit 14 controls the reception beams of the subarray antenna 11 and supplies digital signals for each reception beam to the space conversion unit 15 .

The space converter 15 converts the digital signal for each reception beam into an element signal which is a signal received by each antenna element provided in the subarray antenna 11 . The space transform unit 15 supplies the Ns element signals corresponding to the Ns antenna elements obtained by the transform to the beam combining unit 16 . The beam synthesizing unit 16 uses the Ns element signals supplied from each of the M space transforming units 15 to control the directivity direction of the reception beam and generate desired reception data. That is, the reception system forms reception beams of the full DBF method using element signals of all antenna elements of the array antenna 10, and generates reception data corresponding to the reception beams.

FIG. 2 is a diagram showing an arrangement example of the subarray antenna 11 in the array antenna 10 according to the first embodiment. Each sub-array antenna 11 is formed by dividing the antenna elements arranged in a matrix in the array antenna 10 in the row direction and the column direction. Although the subarray antenna 11 has a two-dimensional array in the example shown in FIG. 2, it may be a one-dimensional array.

FIG. 3 is a diagram showing a configuration example of the subarray antenna 11 in the first embodiment. The sub-array antenna 11 includes Ns reception modules 100 each including one antenna element, and a reception feeding circuit 42 . Each receiving module 100 amplifies a signal received by an antenna element, adds a predetermined phase to the amplified signal, and outputs the amplified signal. The receiving power supply circuit 42 synthesizes the signals output from the respective receiving modules 100 and outputs the synthesized result to the frequency converter 12 as a received signal.

FIG. 4 is a diagram showing a configuration example of the reception module 100 in the first embodiment. The receiver module 100 comprises an antenna element 54 , a low noise amplifier 55 and a phase shifter 56 . A signal received by the antenna element 54 is amplified by the low noise amplifier 55 and given a predetermined phase by the phase shifter 56 . The amplified and phase-shifted signal is supplied to the receiving/feeding circuit 42 . The phase that the phase shifter 56 adds to the signal is the phase for forming the desired reception beam in the subarray antenna 11 . Analog signal processing of the signals received by the Ns receiving modules 100 forms receiving subarray beams having desired directivity for each of the subarray antennas 11 . If the signal to be detected in the receiving system is a wideband signal, the phase shifter 56 may be configured using a time delay element in order to obtain uniform frequency characteristics.

In the receiving system, the observation space observable by the array antenna 10 is divided, and reception is performed by time division for each divided observation space. FIG. 5 is a diagram showing an example of dividing an observation space in the first embodiment. In the receiving system, the observation space represented by the sin Θ axis is divided into P sub-observation spaces, as shown in FIG. (Ns/P) orthogonal beam directions obtained by equally dividing each divided observation space with a spatial frequency sin Θ (AZ, EL) are the directions in which the receiving subarray beams are directed. When the spatial frequency sin Θ represents two dimensions of the azimuth axis and the elevation axis, PAZ×PEL is obtained by dividing the azimuth axis direction and the elevation axis direction into meshes at equal intervals. For simplicity, it is expressed as P (=PAZ×PEL) division.

FIG. 6 is a diagram explaining the sampling frequency of the AD converter 13 in the first embodiment. Normally, when the subarray antenna 11 forms the reception subarray beam, the signal received by the formed reception subarray beam is sampled at a sampling frequency corresponding to the bandwidth of the signal to be detected. The AD converter 13 in the first embodiment samples the received signal supplied from the sub-array antenna 11 at a frequency (Ns/P) times the sampling frequency corresponding to the bandwidth of the signal to be detected. The subarray antenna 11 time-divisionally forms (Ns/P) orthogonal reception beams with different directivity directions in the divided observation spaces as reception subarray beams for each of P divided observation spaces obtained by dividing the observation space.

FIG. 7 is a diagram showing an example of orthogonal reception beams formed in divided observation spaces according to the first embodiment. The orthogonal reception beams formed in the divided observation space are reception beams orthogonal to each other on the sin Θ axis. Orthogonal receive beams are formed in a time division manner so as to cover all regions of the divided observation space. Received signals obtained from each orthogonal receive beam are sampled at the aforementioned sampling frequency in the AD converter 13, and converted into element signals of all the antenna elements 54 in the subarray antenna 11 by inverse Fourier transform in the space transformer 15. .

The multi-beam forming unit 14 controls the phases applied by the phase shifters 56 provided in each receiving module 100 so that orthogonal receiving beams are formed in a time division manner. Orthogonal receive beams in the sin Θ axis are given by equation (1).

式（１）において、θｐは受信サブアレイビームの指向方向を表し、ｐ（＝１，２，…，Ｎｓ／Ｐ）は分割観測空間において受信サブアレイビームで覆われる領域を表す。なお、ｓｉｎΘ軸における２次元方向（ＡＺｐ，ＥＬｐ）をｐにて表現している。Ωは方位角軸及び仰角軸の２次元での観測空間を表す。Ｐは、観測空間の分割数を表す。

In equation (1), θp represents the pointing direction of the reception subarray beam, and p (=1, 2, . . . , Ns/P) represents the area covered by the reception subarray beam in the divided observation space. Note that the two-dimensional direction (AZp, ELp) on the sin Θ axis is expressed by p. Ω represents the observation space in two dimensions of the azimuth and elevation axes. P represents the number of divisions of the observation space.

The multi-beam forming unit 14 controls the phase of each phase shifter 56 of the subarray antenna 11, so that received signals by (Ns/P) orthogonal receive beams with different pointing directions are obtained for each divided observation area. The received signal is converted into a digital signal by the AD converter 13 . The multi-beam forming unit 14 associates the orthogonal receiving beams obtained when the received signals are obtained with the digital signals and supplies them to the space converting unit 15 .

The space transform unit 15 performs zero padding (zero padding).

式（２）において、Ｙ（ＡＺｐ，ＥＬｐ）は、ｐ（＝１，２，…，Ｎｓ／Ｐ）番目の直交受信ビームを用いた指向方向の受信に対応するディジタル信号が示すデータを表し、直交受信ビームの指向方向に対応する配列である。［・，・］はデータの連結を表す。ｚｅｒｏｓ（ｎ）は、ｎが示す数分のゼロを表す。

In equation (2), Y(AZp, ELp) represents data indicated by a digital signal corresponding to reception in a pointing direction using the p (=1, 2, . . . , Ns/P)-th orthogonal reception beam, It is an array corresponding to the directivity directions of the orthogonal reception beams. [・,・] represents concatenation of data. zeros(n) represents the number of zeros indicated by n.

The space transform unit 15 performs an inverse Fourier transform of the number of points Ns using the data Y(AZp, ELp) obtained by zero-filling in Equation (2). Element signals of Ns antenna elements 54 in the subarray antenna 11 are obtained by inverse Fourier transform. The Ns element signals X are represented by Equation (3).

式（３）において、ＩＦＦＴ［・］は逆フーリエ変換を表す。Ｙ（ＡＺｐ，ＥＬｐ）は、式（２）で得られたゼロ埋め後のデータを表す。Ｘは、アンテナ素子５４ごとの素子信号を要素とする配列である。配列Ｘは、サブアレイアンテナ１１におけるアンテナ素子５４の配置に対応する。例えば、配列Ｘは、大きさ［Ｘａｚ，Ｙａｚ］の２次元配列である。Ｘａｚは方位角軸方向のアンテナ素子５４の数であり、Ｙａｚは仰角軸方向のアンテナ素子５４の数である。

In Equation (3), IFFT[·] represents an inverse Fourier transform. Y(AZp, ELp) represents the data after zero padding obtained by the formula (2). X is an array whose elements are element signals for each antenna element 54 . Array X corresponds to the arrangement of antenna elements 54 in subarray antenna 11 . For example, array X is a two-dimensional array of size [Xaz, Yaz]. Xaz is the number of antenna elements 54 along the azimuth axis and Yaz is the number of antenna elements 54 along the elevation axis.

FIG. 8 is a diagram showing processing of the space conversion unit 15 in the first embodiment. As described above, the space transform unit 15 zero-fills the digital signal data obtained for each of the (Ns/P) orthogonal receiving beams (b1, b2, . . . do the conversion. The space transform unit 15 acquires the element signals X=[X1, X2, .

The element signal X of Equation (3) obtained for each space transforming section 15 is supplied to the beam synthesizing section 16 . That is, the element signals of all the antenna elements 54 included in the array antenna 10 are supplied to the beam combiner 16 . The beam synthesizing unit 16 generates desired reception data by controlling the directivity direction of the reception beam by full DBF using the supplied element signals. The beam combiner 16 multiplies the element signals by Taylor weights (Non-Patent Document 3) as weights for sidelobe reduction, further multiplies the complex weights for controlling the beam pointing direction, and then performs combining by addition. The beam synthesizing unit 16 acquires reception data from a reception beam in a desired direction using full DBF. Received data Y(AZp, ELp) is represented by Equation (4).

式（４）において、Ｘｎは、ｎ（＝１，２，…，Ｎｓ）番目のアンテナ素子の素子信号を表す。Ｗｎは、ｎ番目のアンテナ素子の素子信号に対するサイドローブ低減用のウェイトを表す。Ｗｐｎは、ｎ番目のアンテナ素子の素子信号に対するビーム指向方向を制御する複素ウェイトを表す。ビーム指向方向を制御する複素ウェイトＷｐｎは、式（５）で表される。

In Equation (4), Xn represents the element signal of the n (=1, 2,..., Ns)-th antenna element. Wn represents a side lobe reduction weight for the element signal of the n-th antenna element. Wpn represents a complex weight that controls the beam pointing direction for the element signal of the n-th antenna element. A complex weight Wpn that controls the beam pointing direction is represented by Equation (5).

式（５）において、ｘｎ，ｙｎ、ｚｎは、サブアレイアンテナ１１におけるアンテナ素子５４の位置座標を表す。基準位置は、サブアレイアンテナ１１の位相中心である。ｋｐｘ，ｋｐｙ，ｋｐｚは、式（６）で表される。

In equation (5), xn, yn, and zn represent position coordinates of antenna element 54 in subarray antenna 11 . The reference position is the phase center of subarray antenna 11 . kpx, kpy, and kpz are represented by Equation (6).

式（６）において、λは、検出対象の信号の波長である。ＡＺｐ及びＥＬｐは、サブアレイアンテナ１１の位相中心からみた方位角（Azimuth）軸及び仰角（Elevation）軸それぞれのビーム指向角である。

In equation (6), λ is the wavelength of the signal to be detected. AZp and ELp are the beam directivity angles of the azimuth (Azimuth) axis and the elevation (Elevation) axis viewed from the phase center of the subarray antenna 11, respectively.

By beam forming represented by equations (4) to (6), an arbitrary beam narrower than the interval of the subarray antennas 11 having Ns antenna elements (the interval of the phase centers between the subarray antennas 11) can be formed. . Also, even if the reception beam is formed in the divided observation space (Ω/P), it is possible to form an arbitrary beam in which the influence of the grating lobe is suppressed. That is, the receiving system can obtain element signals that can be used for full DBF. In this way, the receiving system can reduce the sidelobe level and form a high-quality antenna beam with high beam pointing accuracy and unwanted wave suppression performance by forming a reception beam using the full DBF. Since the receiving system can form a receiving beam with low side lobes and high directivity, it is possible to monitor the radio wave environment and accurately perform processing on the receiving side in a multistatic radar system.

The beamforming expressed by equations (4) to (6) is beamforming for each subarray antenna 11, but the composite number Ns is expanded to the number N of all antenna elements in the array antenna 10, and xn, yn, zn and By changing AZp and ELp to values according to the phase center of the array antenna 10, beamforming of the array antenna 10 is obtained.

According to the receiving system of the first embodiment, in the signal processing from the subarray antenna 11 to the space transforming unit 15, the reception beam can be formed using the full DBF method without using the signals of all the antenna elements 54. can be done. Analog and digital signal processing from the subarray antenna 11 to the space conversion unit 15 need not be performed for each signal of all the antenna elements 54, so even if the number of the antenna elements 54 is increased, the hardware is not increased. can be suppressed. That is, the receiving system in the first embodiment can improve observation performance by full DBF, suppress an increase in hardware scale, and facilitate system implementation.

In the receiving system of the first embodiment, an example of operation in which a plurality of orthogonal receiving beams (orthogonal multi-beams) are formed in a predetermined direction by subarrays was shown. A method other than the control of may be used. For example, the sub-array may have a configuration for forming orthogonal multi-beams in advance and switching between them.

[Second embodiment]
In the first embodiment, a reception system that forms arbitrary reception beams from signals received by the array antenna 10 has been described. In the second embodiment, a configuration in which the reception system is used for a radar system will be described.

FIG. 9 is a block diagram showing a configuration example of a radar system according to the second embodiment. The radar system comprises an array antenna 20 , a transmitter 30 and a receiver 40 . The array antenna 20 has a plurality of antenna elements. A plurality of antenna elements are divided into M groups, and each group constitutes a subarray antenna 11 . In the following description, as in the first embodiment, the number of antenna elements provided in the array antenna 20 is represented by N, and the number of antenna elements forming the subarray antenna 21 is represented by Ns (=N/M). Array antenna 20 may be configured with one subarray antenna 21 instead of multiple subarray antennas 21 . That is, M=1 may be set. The radar system according to the second embodiment has a configuration in which the receiving system according to the first embodiment and a transmitting section 30 (transmitting device) are combined.

The transmitter 30 comprises a signal generator 1 , a modulator 2 and a frequency converter 3 . A signal generator 1 generates a signal containing predetermined pulses and supplies the generated signal to a modulator 2 . The modulator 2 modulates pulses included in the supplied signal using a random code such as an M sequence, and supplies the modulated signal obtained by modulation to the frequency converter 3 . The frequency converter 3 frequency-converts the modulated signal with a predetermined carrier frequency, and supplies the transmission signal obtained by the conversion to each sub-array antenna 21 . A transmission signal supplied to each subarray antenna 21 is transmitted in the direction of the transmission beam formed in the subarray antenna 21 .

The receiver 40 includes a frequency converter 12 , an AD converter 13 , a multi-beam former 14 , a space converter 15 and a beam combiner 16 . The frequency converter 12, the AD converter 13, the multi-beam forming section 14, and the space converting section 15 are provided for each subarray antenna 21, as in the first embodiment. That is, the receiving section 40 has Ns receiving systems including the frequency converter 12 , the AD converter 13 , the multi-beam forming section 14 and the space converting section 15 . The frequency converter 12 of each receiving system converts the received signal obtained by the corresponding subarray antenna 21 into a baseband signal. The operation of each part in the receiving part 40 is the same as the operation in the first embodiment. The AD converter 13 performs sampling at a frequency (Ns/P) times the sampling frequency corresponding to the bandwidth of the transmission signal.

FIG. 10 is a diagram showing a configuration example of the subarray antenna 21 in the second embodiment. The sub-array antenna 21 includes Ns transmission/reception modules 200 each including one antenna element, a transmission feed circuit 41 and a reception feed circuit 42 . The transmission power supply circuit 41 distributes the transmission signal supplied from the transmission section 30 to each transmission/reception module 200 . The reception power supply circuit 42 synthesizes the signals output from each transmission/reception module 200 and outputs the synthesis result to the frequency converter 12 as a received signal.

FIG. 11 is a diagram showing a configuration example of the transmission/reception module 200 according to the second embodiment. The transceiver module 200 comprises a phase shifter 51 , a high power amplifier 52 , a circulator 53 , an antenna element 54 , a low noise amplifier 55 and a phase shifter 56 . The phase shifter 51 adds a predetermined phase to the supplied transmission signal and supplies the phase-added transmission signal to the high output amplifier 52 . The high-output amplifier 52 amplifies the transmission signal to which the predetermined phase has been added, and supplies the amplified transmission signal to the antenna element 54 via the circulator 53 . A transmission signal supplied to the antenna element 54 is transmitted from the antenna element 54 . Low noise amplifier 55 amplifies the signal received at antenna element 54 via circulator 53 and supplies the amplified signal to phase shifter 56 . The phase shifter 56 adds a predetermined phase to the amplified signal and supplies the signal to which the predetermined phase has been added to the receiving/feeding circuit 42 .

The phase added to the transmission signal in phase shifter 51 is a phase for forming a transmission beam in subarray antenna 21 when transmitting the transmission signal. Also, the phase added to the signal in the phase shifter 56 is the phase for forming the desired reception beam in the subarray antenna 21 . The subarray antenna 21 can form a transmission beam for transmitting a transmission signal and a reception beam for receiving a signal. If the transmission signal is a wideband signal, the phase shifter 51 may be configured using a time delay element in order to obtain uniform frequency characteristics.

FIG. 12 is a diagram showing an example of transmission beams and reception beams formed by the subarray antenna 21 in the second embodiment. The receiving beam (receiving sub-array beam) formed by the subarray antenna 21 may be a part of the direction in which the transmission beam is directed, or may be in the same direction as the direction in which the transmission beam is directed. The transmission/reception module 200 can independently control the transmission beam and the reception beam by including the phase shifter 51 for controlling the transmission beam and the phase shifter 56 for controlling the reception beam.

The radar system of the second embodiment forms a transmission beam in an observation space and transmits a transmission signal in the direction of the transmission beam. Furthermore, the radar system, like the receiving system of the first embodiment, forms a receiving beam using the full DBF method in the observation space, and generates receiving data in the direction in which the receiving beam is directed.

According to the radar system of the second embodiment, the reflection of the transmission signal transmitted in the desired observation direction is detected using a reception beam with low sidelobe and high directivity formed by full DBF, In addition to monitoring the radio wave environment, it is possible to detect and observe objects with high accuracy.

According to at least one embodiment described above, a received signal obtained in a time division manner using (Ns/P) orthogonal receiving beams is sampled at a sampling frequency corresponding to the bandwidth of the signal to be detected (Ns/ P) By having a sampling unit (AD converter 13) that performs sampling at a multiplied sampling frequency and a conversion unit that performs inverse Fourier transform on the sampled values, a frequency converter and an AD converter are provided for each antenna element. In addition, it is possible to obtain element signals, which are signals received by each antenna element of the array antenna, from the received signals obtained in time division, and DBF using element signals improves observation performance and reduces hardware scale. It is possible to suppress the increase and facilitate the implementation of the system.

The receiving system and the radar system in the above embodiments include a CPU (Central Processing Unit), a memory, an auxiliary storage device, etc., which are connected via a bus, and the CPU executes a program to perform signal processing on a digital signal. good too. The CPU may perform some or all of the operations in the transmitting device and some or all of the operations in the receiving device by executing programs stored in the auxiliary storage device. In addition, all or part of the operations in the receiving system and the radar system may be realized using hardware such as ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array), etc. . The program may be recorded on a computer-readable recording medium. Computer-readable recording media are portable media such as flexible disks, magneto-optical disks, ROMs and CD-ROMs, and non-temporary storage media such as hard disks built into computer systems. The program may be transmitted over telecommunications lines.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1... Signal generator, 2... Modulator, 3... Frequency converter, 10, 20... Array antenna, 11, 21... Sub array antenna, 12... Frequency converter, 13... AD converter, 14... Multi-beam former, DESCRIPTION OF SYMBOLS 15... Space conversion part 16... Beam combining part 30... Transmission part 40... Reception part 41... Transmission feed circuit 42... Reception feed circuit 51... Phase shifter 52... High output amplifier 53... Circulator, 54... Antenna element, 55... Low noise amplifier, 56... Phase shifter, 100... Receiving module, 200... Transmitting/receiving module

Claims (3)

The azimuth angles provided in the subarray antennas obtained by spatially dividing the observation space of an array antenna having one or more subarray antennas and dividing the azimuth axis direction and the elevation axis direction into meshes at equal intervals for each divided observation space. Forming a predetermined number of reception beams with directivity directions orthogonal to each other in the subarray antenna in a time division manner, which is obtained by dividing the number of antenna elements arranged in the axial direction and the elevation axis direction by the number of the divided observation spaces , a beam forming unit that controls a phase for forming a beam having an arbitrary pointing direction in an observation space;
a phaser that adds the phase to a signal received at the antenna element;
At a high sampling frequency obtained by multiplying the sampling frequency according to the bandwidth of the signal to be detected by the predetermined number, the signals output from the plurality of receiving modules including the antenna element and to which the phase has been added are combined and frequency-converted. a sampling unit that samples a received signal;
a transformation unit that performs zero padding on the sampled values obtained by the sampling unit and then performs an inverse Fourier transform on the space to obtain a transformation output of the number of the antenna elements;
a beam synthesizing unit that synthesizes the transformed outputs after multiplying the transformed outputs by a predetermined weight ;
A receiving system comprising: a transmission device that transmits a transmission signal toward the observation space;
a receiving system according to claim 1;
with
The transmission signal is included in the signal to be detected,
The beam synthesizing unit forms a beam in which the direction in which the transmission signal is transmitted is the arbitrary directional direction.
radar system. The azimuth angles provided in the subarray antennas obtained by spatially dividing the observation space of an array antenna having one or more subarray antennas and dividing the azimuth axis direction and the elevation axis direction into meshes at equal intervals for each divided observation space. Forming a predetermined number of reception beams with directivity directions orthogonal to each other in the subarray antenna in a time division manner, which is obtained by dividing the number of antenna elements arranged in the axial direction and the elevation axis direction by the number of the divided observation spaces , a beam forming step of controlling a phase for forming a beam having an arbitrary pointing direction in an observation space;
a phase addition step of adding the phase to a signal received at the antenna element;
At a high sampling frequency obtained by multiplying the sampling frequency according to the bandwidth of the signal to be detected by the predetermined number, the signals output from the plurality of receiving modules including the antenna element and to which the phase has been added are combined and frequency-converted. a sampling step for sampling the received signal;
a transformation step of obtaining a transformation output of the number of antenna elements by zero-filling the sampled values obtained by the sampling step and then performing an inverse Fourier transformation on the space;
a beam synthesizing step of synthesizing the transformed outputs after multiplying the transformed outputs by a predetermined weight ;
A signal processing method comprising:

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