Calibration device for array antenna system, calibration method, array antenna system, calibration program, and recording medium

Abstract

A calibration device (100) for an array antenna device generates transmission signal calibration values for a plurality of distributed transmission signals that are output by a transmission signal distribution unit (3), are obtained by distributing a transmission signal from a signal processing unit (4-n), and are to be output to each of a plurality of antenna elements (1-n) via a plurality of signal processing systems (4-n) in which a calibration signal generated by a calibration signal generation unit (5) is superimposed. The calibration device (100) comprises: a pseudo transmission signal generation unit (110) that generates a pseudo transmission signal from a plurality of transmission signals distributed from the transmission signal distribution unit (3) and a plurality of transmission signals on which calibration signals from the plurality of signal processing systems (4-n) are superimposed; and a calibration value generation unit (120) that generates a loopback transmission signal from the plurality of transmission signals on which the calibration signals from the plurality of signal processing systems (4-n) are superimposed, generates a difference signal between the loopback transmission signal and the pseudo transmission signal generated by the pseudo transmission signal generation unit (110), and generates the transmission signal calibration values based on a correlation value between the difference signal and the calibration signal generated by the calibration signal generation unit (5).

Description

Calibration Device, Calibration Method, Array Antenna System, Calibration Program, and Recording Medium for Array Antenna System

[0001] The present disclosure relates to a calibration device, a calibration method, an array antenna system, a calibration program, and a recording medium for an array antenna system.

[0002] In the field of array antenna systems that radiate transmission waves into space, in order to reduce the amplitude-phase error, which is the characteristic variation between multiple transmission lines that transmit transmission signals to multiple antenna elements, a calibration technique for correcting the transmission signals transmitted through each of the multiple transmission lines is essential. An array antenna system including a calibration device for correcting the transmission signals transmitted through each of the multiple transmission lines is disclosed in Patent Document 1.

[0003] The calibration device in the array antenna system disclosed in Patent Document 1 is as follows. That is, the transmission signal from the transmitter in each transmission line is phase-controlled by the phase control unit, synthesized by the power combining unit, detected by the calibration signal receiver, and sent to the calibration signal analysis unit. The phase of the calibration signal generated by the calibration signal generation unit for each transmission line is offset by the calibration signal phase offset unit and sent to the calibration signal analysis unit. The calibration signal analysis unit uses the phase-offset calibration signal as a reference signal, performs a correlation process with the detected calibration signal to calculate the relative amplitude-phase error, and the relative amplitude-phase error is given to the DBF unit that distributes the transmission signal to each transmission line, and the amplitude and phase of the transmission signal are adjusted.

[0004] In short, the calibration device in the array antenna system disclosed in Patent Document 1 controls the phase of the transmission signal with the calibration signal superimposed on each transmission line, then synthesizes and detects it, thereby obtaining the calibration signal from the transmission signal with the calibration signal superimposed, and improving the extraction accuracy of the calibration signal.

[0005] WO2023 / 181972 publication

[0006] Although the array antenna device disclosed in Patent Document 1 is configured as described above to ensure calibration accuracy, in the field of array antenna systems, various calibration devices that can ensure calibration accuracy and improve the efficiency of calibration time are desired.

[0007] This disclosure has been made in view of the above-mentioned points, and aims to provide a calibration device for an array antenna system that can ensure calibration accuracy and improve the efficiency of calibration time.

[0008] The calibration apparatus for an array antenna device according to this disclosure is a calibration apparatus that generates calibration values ​​for transmission signals for multiple distributed transmission signals to be output to each of multiple antenna elements via multiple signal processing systems that distribute transmission signals from a signal processing unit output by a transmission signal distribution unit and superimpose calibration signals from a calibration signal generation unit, and comprises: a pseudo-transmission signal generation unit that generates pseudo-transmission signals from multiple transmission signals into which multiple transmission signals distributed from a transmission signal distribution unit and calibration signals from multiple signal processing systems are superimposed; and a calibration value generation unit that generates a folded transmission signal from multiple transmission signals into which calibration signals from multiple signal processing systems are superimposed, generates a difference signal between the folded transmission signal and the pseudo-transmission signal generated by the pseudo-transmission signal generation unit, and generates calibration values ​​for transmission signals based on the correlation value between the difference signal and the calibration signal from the calibration signal generation unit.

[0009] According to this disclosure, the system includes a pseudo-transmission signal generation unit that generates a pseudo-transmission signal from a plurality of transmission signals superimposed with a plurality of transmission signals distributed from a transmission signal distribution unit and calibration signals from a plurality of signal processing systems, and a calibration value generation unit that generates a loopback transmission signal from a plurality of transmission signals superimposed with calibration signals from a plurality of signal processing systems, generates a difference signal between the loopback transmission signal and the pseudo-transmission signal generated by the pseudo-transmission signal generation, and generates a calibration value for the transmission signal based on the correlation value between the difference signal and the calibration signal from the calibration signal generation unit. This makes it possible to ensure calibration accuracy and improve the efficiency of calibration time.

[0010] This is a block diagram showing an example configuration of an array antenna system according to Embodiment 1. This is a diagram showing an example of computer-based hardware configuration for the correlation value calculation unit and pseudo-transmission signal update unit in the pseudo-transmission signal generation unit and the calibration phase switching unit, subtraction unit and calibration processing unit 124 in the calibration value generation unit of the array antenna system calibration device according to Embodiment 1. This is a flowchart showing an example of operation for generating a pseudo-transmission signal during pre-shipment adjustment in the array antenna system calibration device according to Embodiment 1. This is a flowchart showing an example of operation for generating a pseudo-transmission signal at the start of operation of the array antenna system in the array antenna system calibration device according to Embodiment 1 and an example of operation for generating a pseudo-transmission signal when updating the pseudo-transmission signal during operation of the array antenna system. This is a flowchart showing an example of operation for generating a calibration value for the transmission signal in the array antenna system calibration device according to Embodiment 1. This is a block diagram showing an example configuration of an array antenna system according to Embodiment 2. This is a flowchart showing an example of operation for generating a calibration value for the transmission signal in the array antenna system calibration device according to Embodiment 2.

[0011] Embodiment 1. The array antenna system according to Embodiment 1 will be described with reference to Figures 1 to 5. The array antenna system according to Embodiment 1 is a beamforming antenna system for transmission in which transmitted waves are radiated into space from a plurality of antenna elements arranged at equal intervals in one dimension or at equal intervals in one direction and in another direction orthogonal to that direction in two dimensions. The calibration device and calibration method of the array antenna system according to Embodiment 1 can also be applied to the transmission system of an array antenna system for both transmission and reception.

[0012] As shown in Figure 1, the array antenna system according to Embodiment 1 comprises a plurality of antenna elements 1-1 to 1-N (where N is a natural number of 2 or more), a signal processing unit 2, a transmission signal distribution unit 3, a plurality of signal processing systems 4-1 to 4-N, a calibration signal generation unit 5, and a calibration device 100. Each of the plurality of signal processing systems 4-1 to 4-N corresponds to one of the plurality of antenna elements 1-1 to 1-N.

[0013] In the following explanation, if it is not necessary to distinguish between antenna elements 1-1 to 1-N, we will refer to them as antenna element 1-n (where n is 1 to N) to avoid complexity in the explanation. Similarly, if it is not necessary to distinguish between signal processing systems 4-1 to 4-N, we will refer to them as signal processing system 4-n (where n is 1 to N) to avoid complexity in the explanation.

[0014] Antenna element 1-n receives the transmission signal, which has been frequency-converted, i.e., modulated, by a carrier wave in the RF (Radio Frequency) band, and converts it into a transmission wave, which is then radiated into space. Signal processing unit 2 generates and outputs the transmission signal, which is a baseband signal representing the information to be transmitted. In Embodiment 1, the transmission signal, which is a baseband signal, is a digital signal.

[0015] The transmission signal generated by the signal processing unit 2 may be a digitally modulated signal obtained by modulating the baseband signal. In the following description, the term "baseband signal" is used as a general term for both the baseband signal and the digitally modulated signal obtained by modulating the baseband signal.

[0016] The signal processing unit 2 is composed of, for example, a semiconductor integrated circuit or a single-chip microcontroller that implements a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

[0017] The transmission signal distribution unit 3 receives the transmission signal, which is a baseband signal, from the signal processing unit 2, distributes it to correspond to a plurality of antenna elements 1-1 to 1-N, adjusts the amplitude and phase of the distributed transmission signals using excitation weights based on calibration values ​​for transmission signals from the calibration device 100, and outputs each of the distributed and adjusted transmission signals to the respective signal processing systems 4-1 to 4-N. In Embodiment 1, the transmission signal distribution unit 3 is configured using digital beamforming.

[0018] The transmitted signal distributed and adjusted from the transmitted signal distribution unit 3 is a baseband signal that reduces the amplitude phase difference, which is the characteristic variation between the signal processing systems 4-n corresponding to each of the multiple antenna elements 1-1 to 1-N. The calibration value for the transmitted signal from the calibration device 100 indicates the excitation weight for the distributed transmitted signal, and the excitation weight in the transmitted signal distribution unit 3 is updated by the calibration value for the transmitted signal from the calibration device 100.

[0019] The signal processing system 4-n superimposes a calibration signal from the calibration signal generation unit 5 onto the corresponding transmission signal distributed by the transmission signal distribution unit 3, and outputs the transmission signal modulated by the RF band carrier wave to the corresponding antenna element 1-n. The signal processing system 4-n includes an input-side extraction unit 41-n, a calibration signal injection unit 42-n, a transmitter 43-n, and an output-side extraction unit 44-n.

[0020] The input-side extraction unit 41-n receives the corresponding transmission signal distributed by the transmission signal distribution unit 3, outputs the input transmission signal as the main transmission signal to the calibration signal injection unit 42-n, and outputs it as a transmission signal for calibration to the calibration device 100. The input-side extraction unit 41-n is, for example, a directional coupler or a switch.

[0021] The calibration signal injection unit 42-n receives the main transmission signal from the input side extraction unit 41-n and the calibration signal from the calibration signal generation unit 5, injects the calibration signal into the transmission signal, and outputs the transmission signal with the calibration signal superimposed to the transmitter 43-n. The calibration signal injection unit 42-n is, for example, a directional coupler or a switch.

[0022] Furthermore, the calibration signal injection unit 42-n may perform digital processing using software such as a CPU without using dedicated hardware such as a directional coupler. In this case, the calibration signal injection unit 42-n obtains a transmission signal with the calibration signal superimposed by adding the transmission signal from the input side extraction unit 41-n and the calibration signal from the calibration signal generation unit 5.

[0023] Transmitter 43-n receives a transmission signal, which is a baseband signal superimposed with a calibration signal from calibration signal injection unit 42-n, and outputs the input baseband signal as a transmission signal modulated by an RF band carrier. The baseband signal is a digital signal, and the RF band modulated transmission signal is an analog signal. The RF band modulated transmission signal is power amplified by transmitter 43-n. The RF band modulated transmission signal is a data signal containing the information to be transmitted.

[0024] The output extraction unit 44-n receives the transmission signal modulated in the RF band by the transmitter 43-n, outputs the input transmission signal to the antenna element 1-n as the main transmission signal, and outputs it to the calibration device 100 as a transmission signal for calibration. The output extraction unit 44-n is, for example, a directional coupler or a switch.

[0025] The calibration signal generation unit 5 generates a calibration signal having a symbol pattern, separates the generated calibration signal as a corresponding calibration signal for each signal processing system 4-n, and provides the corresponding calibration signal to the calibration signal injection unit 42-n in the signal processing system 4-n. The calibration signal generation unit 5 generates the calibration signal according to a pre-designed specification. The calibration signal is an insertable signal that can be separated for each signal processing system 4-n, for example, a spread spectrum signal, or a code-division signal, frequency-division signal, or time-division signal.

[0026] The calibration signal may be a chirp pulse signal in which up chirps and down chirps appear randomly when viewed on the time axis. Furthermore, if the calibration signal injection unit 42-n is digitally processed by a CPU or the like, the functions of the calibration signal generation unit 5 may be digitally processed by a CPU or the like in conjunction with the functions of the calibration signal injection unit 42-n.

[0027] The calibration device 100 distributes the transmission signals from the signal processing unit 2, which are output by the transmission signal distribution unit (beamforming unit) 3, and generates multiple transmission signal calibration values ​​for each of the multiple antenna elements 1-n via multiple signal processing systems 4-n that superimpose calibration signals from the calibration signal generation unit 5.

[0028] The calibration device 100 generates a pseudo-transmission signal from a transmission signal in which multiple transmission signals distributed from the transmission signal distribution unit 3 and calibration signals from the calibration signal generation unit 5 output from multiple signal processing systems 4-n are superimposed. It then generates a calibration value for the transmission signal from the pseudo-transmission signal and the transmission signal in which the calibration signals from the calibration signal generation unit 5 output from multiple signal processing systems 4-n are superimposed, and provides the calibration value for the transmission signal to the transmission signal distribution unit 3.

[0029] As shown in Figure 1, the calibration device 100 includes a pseudo-transmission signal generation unit 110 and a calibration value generation unit 120. The pseudo-transmission signal generation unit 110 generates a pseudo-transmission signal from a plurality of transmission signals distributed from the transmission signal distribution unit 3 before the array antenna system is shipped (the phase in which the pseudo-transmission signal is obtained, hereinafter abbreviated as the pre-shipment phase).

[0030] The pseudo-transmit signal generation unit 110 generates a pseudo-transmit signal to update the previous pseudo-transmit signal from a transmission signal in which a plurality of transmission signals distributed from the transmission signal distribution unit 3 and calibration signals output from the calibration signal generation unit 5 from a plurality of signal processing systems 4-n are superimposed. This occurs during the phase in which a pseudo-transmit signal and pseudo-transmit signal correction values ​​are obtained when the array antenna system is first started to operate (hereinafter abbreviated as the operation start phase) and during the phase in which a pseudo-transmit signal and pseudo-transmit signal correction values ​​are obtained when the pseudo-transmit signal is updated (hereinafter abbreviated as the pseudo-transmit signal update phase).

[0031] The pseudo-transmission signal generation unit 110 includes a reference pseudo-transmission signal generation unit 111, a correlation value calculation unit 112, and a pseudo-transmission signal update unit 113. The calibration value generation unit 120 includes a loopback transmission signal generation unit 121, a calibration phase switching unit 122, a subtraction unit 123, and a calibration processing unit 124. The calibration processing unit 124 includes a calibration signal extraction unit 124a and a calibration value calculation unit 124b.

[0032] The pseudo-transmit signal generation unit 110 generates a pseudo-transmit signal from multiple transmission signals superimposed on multiple transmission signals distributed from the transmission signal distribution unit 3 and calibration signals output from multiple signal processing systems 4-n. The reference pseudo-transmit signal generation unit 111 has an input-side power combining unit and combines multiple transmission signals distributed from the transmission signal distribution unit 3 to generate a reference pseudo-transmit signal. The reference pseudo-transmit signal is a combined baseband signal.

[0033] The reference pseudo-transmission signal generation unit 111 provides the generated reference pseudo-transmission signal to the pseudo-transmission signal update unit 113 during the pre-shipment phase. The reference pseudo-transmission signal generation unit 111 predicts the transmission signal and generates a reference pseudo-transmission signal during the pre-shipment phase. The reference pseudo-transmission signal generation unit 111 provides the generated reference pseudo-transmission signal to the correlation value calculation unit 112 during the operation start phase (pre-processing phase).

[0034] The reference pseudo-transmission signal generation unit 111 provides the generated reference pseudo-transmission signal to the correlation value calculation unit 112 in order to update the pseudo-transmission signal stored in the pseudo-transmission signal update unit 113 during the pseudo-transmission signal update phase. The pseudo-transmission signal update phase is performed periodically based on a set period. The pre-shipment phase, the start-up phase, and the pseudo-transmission signal update phase are collectively referred to as the first calibration phase for obtaining the pseudo-transmission signal.

[0035] The correlation value calculation unit 112 receives the reference pseudo-transmission signal generated by the reference pseudo-transmission signal generation unit 111 and the loopback transmission signal generated by the loopback transmission signal generation unit 121 during the operation start phase and the pseudo-transmission signal update phase, and calculates the correlation value (phase vector) between the reference pseudo-transmission signal and the loopback transmission signal. The correlation value calculation unit 112 generates a pseudo-transmission signal correction value based on the calculated correlation value, and stores the generated pseudo-transmission signal correction value together with the reference pseudo-transmission signal and the loopback transmission signal in the storage unit.

[0036] The specific generation of the pseudo-transmitted signal correction value by the correlation value calculation unit 112 is performed as follows: First, the ensemble average of the product of the reference pseudo-transmitted signal and the complex conjugate signal of the reference pseudo-transmitted signal is calculated to obtain the first correlation vector. Next, the ensemble average of the product of the aliased transmitted signal and the complex conjugate signal of the reference pseudo-transmitted signal is calculated to obtain the second correlation vector. Finally, the second correlation vector is divided by the first correlation vector, and the divided value is stored in the storage unit as the pseudo-transmitted signal correction value.

[0037] In the pre-shipment phase, the pseudo-transmission signal update unit 113 stores the reference pseudo-transmission signal generated by the reference pseudo-transmission signal generation unit 111 as a pseudo-transmission signal in the storage unit. In the operation start phase and the pseudo-transmission signal update phase, the pseudo-transmission signal update unit 113 receives the reference pseudo-transmission signal generated by the reference pseudo-transmission signal generation unit 111, reads the pseudo-transmission signal correction value stored in the storage unit of the correlation value calculation unit 112, and generates a pseudo-transmission signal by correcting the reference pseudo-transmission signal with the pseudo-transmission signal correction value. The pseudo-transmission signal update unit 113 updates the pseudo-transmission signal stored in the storage unit to the generated pseudo-transmission signal and stores the generated pseudo-transmission signal in the storage unit.

[0038] The calibration value generation unit 120 generates a calibration value for the transmission signal from a transmission signal in which calibration signals from the calibration signal generation unit 5 output from multiple signal processing systems 4-n are superimposed, and a pseudo-transmission signal generated by the pseudo-transmission signal generation unit 110, and provides the calibration value for the transmission signal to the transmission signal distribution unit 3. The calibration value generation unit 120 generates a loopback transmission signal from multiple transmission signals in which calibration signals from multiple signal processing systems 4-n are superimposed, generates a difference signal between the loopback transmission signal and the pseudo-transmission signal generated by the pseudo-transmission signal generation unit 110, and generates a calibration value for the transmission signal based on the correlation value between the difference signal and the calibration signal from the calibration signal generation unit 5.

[0039] The calibration value generation phase in which the calibration value generation unit 120 generates calibration values ​​for the transmission signal is called the second calibration phase. The second calibration phase is performed periodically based on a set period during the operation of the array antenna system.

[0040] The aliasing transmission signal generation unit 121 has an output-side power combining unit and a demodulation unit (receiving circuit), and generates an aliasing transmission signal by combining multiple transmission signals from multiple signal processing systems 4-n, demodulating them, and converting them into a baseband signal. Specifically, the output-side power combining unit in the aliasing transmission signal generation unit 121 combines multiple transmission signals that have calibration signals from multiple signal processing systems 4-n superimposed on them and are modulated by an RF band carrier wave. The demodulation unit in the aliasing transmission signal generation unit 121 demodulates the combined transmission signal that has calibration signals superimposed on it and is modulated by an RF band carrier wave, and converts it into a baseband signal with calibration signals superimposed on it. The baseband signal with calibration signals superimposed on it is called the aliasing transmission signal.

[0041] The calibration phase switching unit 122 provides the loopback transmission signal generated by the loopback transmission signal generation unit 121 to the correlation value calculation unit 112 in the loopback transmission signal generation unit 110 during the operation start phase and the pseudo-transmission signal update phase of the first calibration phase, and provides the loopback transmission signal generated by the loopback transmission signal generation unit 121 to the subtraction unit 123 in the calibration processing unit 124 during the second calibration phase.

[0042] In the second calibration phase, the subtraction unit 123 reads out the pseudo-transmission signal stored in the storage unit of the pseudo-transmission signal update unit 113, subtracts the pseudo-transmission signal from the aliased transmission signal generated by the aliased transmission signal generation unit 121, and generates a difference signal.

[0043] The calibration processing unit 124 receives the calibration signal from the calibration signal generation unit 5 and the difference signal generated by the subtraction unit 123, calculates the amplitude phase difference from the correlation between the difference signal and the calibration signal, and generates a calibration value for the transmission signal based on the calculated amplitude phase difference. The calibration value for the transmission signal generated by the calibration processing unit 124 is provided to the transmission signal distribution unit 3, and the excitation weight in the transmission signal distribution unit 3 is updated according to the calibration value for the transmission signal.

[0044] The calibration signal extraction unit 124a calculates an amplitude phase difference from the correlation between the differential signal generated by the subtraction unit 123 and the calibration signal generated by the calibration signal generation unit 5. The amplitude phase difference corresponds to the relative amplitude phase error with respect to the calibration signal. When the calibration signal generated by the calibration signal generation unit 5 is a spread spectrum signal, for example, the calculation of the amplitude phase difference by the calibration signal extraction unit 124a is to perform a despreading process. It is possible to obtain the relative amplitude phase error with respect to the calibration signal generated by the calibration signal generation unit 5, separated into values for each of the plurality of signal processing systems 4-n.

[0045] The calibration value calculation unit 124b generates a calibration value for the transmission signal to be given to the transmission signal distribution unit 3 from the amplitude phase difference calculated by the calibration signal extraction unit 124a. The calibration value for the transmission signal generated by the calibration value calculation unit 124b is a calibration value for the transmission signal corresponding to each transmission signal distributed from the transmission signal distribution unit 3. The calibration value for the transmission signal generated by the calibration value calculation unit 124b corresponds to each transmission signal distributed from the transmission signal distribution unit 3 and is an excitation weight that cancels the amplitude phase difference calculated by the calibration signal extraction unit 124a.

[0046] In the first embodiment, the correlation value calculation unit 112 and the pseudo-transmission signal update unit 113 in the pseudo-transmission signal generation unit 110 and the calibration phase switching unit 122, the subtraction unit 123, and the calibration processing unit in the calibration value generation unit 120 are realized by a hardware configuration by a computer. As shown in FIG. 2, it is realized by including a CPU (Central Processing Unit) 1A, a large-capacity semiconductor memory (RAM: Random Access Memory) 1B, a storage device (ROM: Read only memory) such as a hard disk device or an SSD device and other non-volatile recording devices, an input interface unit 1D, an output interface unit 1E, and a signal path (bus) 1F.

[0047] The CPU 1A controls and manages the RAM 1B, the ROM 1C, the input interface unit 1D, and the output interface unit and the output interface unit 1E. The CPU 1A loads the program stored in the ROM 1C into the RAM 1B, and the CPU 1A executes various processes based on the program loaded into the RAM 1B.

[0048] A part of the memory area of the RAM 1B constitutes the memory part in the correlation value calculation unit 112 and the memory part of the pseudo transmission signal update unit 113. The functions of the correlation value calculation unit 112 and the pseudo transmission signal update unit 113, and the subtraction unit 123 and the calibration processing unit 124 are stored as programs in the ROM 1C.

[0049] The CPU 1A loads the program stored in the ROM 1C into the RAM 1B. Based on the program loaded by the CPU 1A into the RAM 1B, the CPU 1A stores a reference pseudo transmission signal in the RAM 1B, generates a pseudo transmission signal correction value, stores the pseudo transmission signal correction value together with the reference pseudo transmission signal and the folded transmission signal in the RAM 1B, generates a corrected pseudo transmission signal, updates the pseudo transmission signal stored in the RAM 1B with the generated pseudo transmission signal and stores it in the RAM 1B, generates a difference signal and a calibration value for the transmission signal, stores the calibration value for the transmission signal in the RAM 1B, and supplies it to the transmission signal distribution unit 3.

[0050] The signal path 1F is a bus that mutually connects the CPU 1A, the RAM 1B, the ROM 1C, the input interface unit 1D, and the output interface unit 1E. Note that the correlation value calculation unit 112 and the pseudo transmission signal update unit 113, and the calibration phase switching unit 122, the subtraction unit 123, and the calibration processing unit 124 are not realized by a hardware configuration by a computer, and each may be hardware such as a dedicated processing circuit.

[0051] Next, the calibration operation of the calibration device 100 in the array antenna system according to Embodiment 1 will be described using FIGS. 3 to 6. First, the operation in the pre-shipment phase in the first calibration phase will be described using FIG. 3.

[0052] In step ST01, the reference pseudo-transmit signal generation unit 111 acquires the baseband signals, which are the transmission signals, distributed from the transmission signal distribution unit 3 to a plurality of signal processing systems 4-n, via each of the plurality of input-side extraction units 41-n. Step ST01 is the step of acquiring the baseband signals. In step ST02, the reference pseudo-transmit signal generation unit 111 synthesizes the acquired plurality of transmission signals to generate a reference pseudo-transmit signal. Step ST02 is the step of generating a reference pseudo-transmit signal.

[0053] In step ST03, the pseudo-transmission signal update unit 113 stores the reference pseudo-transmission signal generated by the reference pseudo-transmission signal generation unit 111 as a pseudo-transmission signal in the storage unit. Step ST03 is a step in which a pseudo-transmission signal is obtained before the array antenna system is shipped and the pseudo-transmission signal is stored in the pseudo-transmission signal update unit 113. Through the operation of steps ST01 to ST03, a pseudo-transmission signal is generated by the pseudo-transmission signal generation unit 110 and the first pseudo-transmission signal is stored in the pseudo-transmission signal generation unit 110.

[0054] Next, the operation of the operation start phase (pre-processing phase) in the first calibration phase will be explained using Figure 4. In step ST10, the reference pseudo-transmission signal generation unit 111 determines whether or not it is necessary to update the pseudo-transmission signal stored in the storage unit of the pseudo-transmission signal update unit 113. This determination is based on whether or not a pseudo-transmission signal correction value is stored in the storage unit of the pseudo-transmission signal update unit 113, or whether or not it is time for an update. Step ST10 is a step in determining whether or not it is necessary to update the pseudo-transmission signal.

[0055] The operation start phase is the initial start of operation of the array antenna system, so since the pseudo-transmit signal correction value is not stored in the memory of the pseudo-transmit signal update unit 113, the process proceeds to steps ST11 and ST13. In other words, in the operation start phase, whether or not a memory update is necessary is determined by whether or not the pseudo-transmit signal correction value is stored in the memory of the pseudo-transmit signal update unit 113. In step ST11, the transmission signal, which is a baseband signal distributed from the transmission signal distribution unit 3 to a plurality of signal processing systems 4-n, is acquired by the reference pseudo-transmit signal generation unit (input-side power combining unit) 111 via each of the plurality of input-side extraction units 41-n. Step ST11 is the step of acquiring the baseband signal.

[0056] In step ST12, the reference pseudo-transmission signal generation unit 111 synthesizes multiple acquired transmission signals to generate a reference pseudo-transmission signal. Step ST12 is a step in which a reference pseudo-transmission signal is generated.

[0057] In step ST13, the transmission signal, which is modulated by multiple RF band carriers on which calibration signals from multiple signal processing systems 4-n are superimposed, is acquired by the aliasing transmission signal generation unit (output side power combining unit) 121 via each of the multiple output side extraction units 44-n. Step ST13 is a step in which the transmission signal on which the calibration signals are superimposed is acquired.

[0058] In step ST14, the aliasing transmission signal generation unit 121 converts each of the acquired transmission signals superimposed with the calibration signals into a baseband signal superimposed with the calibration signals, and then synthesizes the converted baseband signals to generate an aliasing transmission signal. Step ST14 is a step for generating an aliasing transmission signal.

[0059] In step ST15, the correlation value calculation unit 112 stores the reference pseudo-transmission signal generated by the reference pseudo-transmission signal generation unit 111 and the aliased transmission signal generated by the aliased transmission signal generation unit 121 in the storage unit. The correlation value calculation unit 112 calculates the correlation value (correlation vector) between the reference pseudo-transmission signal and the aliased transmission signal, generates a pseudo-transmission signal correction value based on the correlation value, and stores the pseudo-transmission signal correction value in the storage unit. Step ST15 is a step for generating a pseudo-transmission signal correction value.

[0060] In step ST16, the pseudo-transmit signal update unit 113 superimposes the pseudo-transmit signal correction value calculated by the correlation value calculation unit 112 onto the pseudo-transmit signal stored in the storage unit of the pseudo-transmit signal update unit 113 to generate a new pseudo-transmit signal. The pseudo-transmit signal update unit 113 updates the pseudo-transmit signal stored in the storage unit with the newly generated pseudo-transmit signal. Step ST16 is a step of generating a new pseudo-transmit signal and updating the pseudo-transmit signal.

[0061] Steps ST11 to ST16 are steps in which the pseudo-transmission signal generation unit 110 generates a pseudo-transmission signal from a plurality of transmission signals superimposed with a plurality of transmission signals distributed from the transmission signal distribution unit 3 and calibration signals from a plurality of signal processing systems 4-n. The method for updating the pseudo-transmission signal in steps ST12, ST15, and ST16 is performed by the CPU 1A executing processing according to a program stored in ROM 1C.

[0062] In other words, the program stored in ROM 1C includes the steps of: generating a reference pseudo-transmission signal by synthesizing the transmission signals, which are baseband signals distributed from the transmission signal distribution unit 3 to a plurality of signal processing systems 4-n; calculating the correlation value between the reference pseudo-transmission signal and a plurality of transmission signals, which are formed by superimposing calibration signals from the plurality of signal processing systems 4-n, and a folded transmission signal converted into a baseband signal, and generating a pseudo-transmission signal correction value based on the correlation value; and generating a new pseudo-transmission signal by superimposing the pseudo-transmission signal correction value onto the pseudo-transmission signal stored in the memory unit, thereby updating the pseudo-transmission signal.

[0063] Next, the operation of the pseudo-transmission signal update phase in the first calibration phase will be explained using Figure 4. In step ST10, the reference pseudo-transmission signal generation unit 111 determines whether or not it is necessary to update the pseudo-transmission signal stored in the storage unit of the pseudo-transmission signal update unit 113. Since it is the pseudo-transmission signal update phase, it is determined that an update of the pseudo-transmission signal is necessary, and the process proceeds to steps ST11 and ST13.

[0064] Steps ST11 to ST16 are the same as steps ST11 to ST16 in the operation start phase, so their explanation is omitted. During the operation of the pseudo-transmission signal update phase, the newly generated reference pseudo-transmission signal, the loopback transmission signal, and the pseudo-transmission signal correction value are stored in the storage unit of the correlation value calculation unit 112, and the newly generated pseudo-transmission signal is stored in the storage unit of the pseudo-transmission signal update unit 113. The program stored in ROM 1C at this time is the same as the program stored in ROM 1C in the operation start phase.

[0065] Next, the operation of the second calibration phase, which is the calibration value generation phase, will be explained using Figure 5. In step ST10, the reference pseudo-transmission signal generation unit 111 determines whether or not it is necessary to update the pseudo-transmission signal stored in the storage unit of the pseudo-transmission signal update unit 113. Since the calibration value generation phase is not the first calibration phase which occurs before shipment, at the start of operation, or during updates, it is determined that updating the pseudo-transmission signal is unnecessary, and the process proceeds to step ST21.

[0066] In step ST21, the aliasing transmission signal generation unit (output-side power combining unit) 121 acquires a transmission signal with a calibration signal superimposed on it via each of the multiple output-side extraction units 44-n. Step ST21 is the step of acquiring a transmission signal with a calibration signal superimposed on it. In step ST22, the aliasing transmission signal generation unit 121 converts each of the acquired multiple calibration signals into a baseband signal with a calibration signal superimposed on it, and combines the converted baseband signals to generate an aliasing transmission signal. Step ST22 is the step of generating an aliasing transmission signal.

[0067] In step ST23, the subtraction unit 123 reads the pseudo-transmission signal stored in the storage unit of the pseudo-transmission signal update unit 113, and subtracts the pseudo-transmission signal from the loopback transmission signal generated by the loopback transmission signal generation unit 121 to obtain a difference signal. Step ST23 is a step to generate a difference signal.

[0068] In step ST24, the calibration signal extraction unit 124a of the calibration processing unit 124 calculates the amplitude phase error from the correlation between the difference signal obtained by subtraction by the subtraction unit 123 and the calibration signal from the calibration signal generation unit 5. Step ST24 is a step for calculating the amplitude phase error.

[0069] In step ST25, the calibration value calculation unit 124b of the calibration processing unit 124 calculates a calibration value for the transmission signal to be given to each of the multiple signal processing systems 4-n from the amplitude phase error calculated by the calibration signal extraction unit 124a, and outputs the calculated calibration value for the transmission signal to the transmission signal distribution unit 3. Step ST25 is a step of calculating the calibration value for the transmission signal. Steps ST24 and ST25 are steps in which the calibration processing unit 124 calculates the amplitude phase error from the correlation between the difference signal and the calibration signal and generates a calibration value for the transmission signal to be given to each of the multiple signal processing systems 4-n.

[0070] Steps ST21 to ST25 are steps in which the calibration value generation unit 120 generates a folded transmission signal from multiple transmission signals on which calibration signals from multiple signal processing systems 4-n are superimposed, generates a difference signal between the folded transmission signal and the pseudo-transmission signal generated by the pseudo-transmission signal generation unit 110, and generates a calibration value for the transmission signal based on the correlation value between the difference signal and the calibration signal from the calibration signal generation unit 5.

[0071] The method for generating calibration values ​​for the transmission signal in steps ST23 to ST25 is performed by the CPU 1A executing processing according to a program stored in ROM 1C. Specifically, the program stored in ROM 1C includes a procedure for obtaining a difference signal by subtracting a pseudo-transmission signal generated by the pseudo-transmission signal generation unit 110 from a folded transmission signal obtained by synthesizing multiple transmission signals in which calibration signals from multiple signal processing systems are superimposed and converted into a baseband signal, and a procedure for calculating the amplitude phase error from the correlation between the difference signal and the calibration signal from the calibration signal generation unit 5, and generating calibration values ​​for the transmission signal to be given to each of the multiple signal processing systems 4-n.

[0072] The calibration device for the array antenna system according to Embodiment 1 includes a pseudo-transmission signal generation unit 110 that generates a pseudo-transmission signal from a plurality of transmission signals in which a plurality of transmission signals distributed from a transmission signal distribution unit 3 and calibration signals from a plurality of signal processing systems 4-n are superimposed, and a calibration value generation unit that generates a folded transmission signal from a plurality of transmission signals in which calibration signals from a plurality of signal processing systems 4-n are superimposed, generates a difference signal between the folded transmission signal and the pseudo-transmission signal generated by the pseudo-transmission signal generation unit 110, and generates a calibration value for the transmission signal based on the correlation value between the difference signal and the calibration signal from the calibration signal generation unit 5. Thus, calibration accuracy can be ensured and the calibration time can be made more efficient.

[0073] The calibration device for the array antenna system according to Embodiment 1 minimizes the influence of the transmitted signal on amplitude phase errors, which are characteristic variations between antenna elements, i.e., multiple signal processing systems 4-n, enabling efficient calibration processing and allowing simultaneous acquisition of calibration values ​​for the transmitted signal due to amplitude phase errors for all multiple signal processing systems 4-n.

[0074] The calibration device for the array antenna system according to Embodiment 1 can update the pseudo-transmission signal for obtaining calibration values ​​for the transmission signal not only in the pre-shipment phase and the start-up phase (pre-processing phase) of the first calibration phase, but also in the pseudo-transmission signal update phase. Therefore, in the second calibration phase, which is the calibration value generation phase, more reliable calibration, that is, a calibration value for the transmission signal with high accuracy can be obtained.

[0075] In the calibration device for the array antenna system according to Embodiment 1, if the correlation value calculation unit 112 and pseudo-transmission signal update unit 113, along with the reference pseudo-transmission signal generation unit 111 and the aliased transmission signal generation unit 121, and the calibration phase switching unit 122, subtraction unit 123, and calibration processing unit 124 are each configured with dedicated processing circuits or other hardware, then even if the number of signal processing systems 4-n increases, there is no need to increase the size of the dedicated processing circuits or other hardware.

[0076] Embodiment 2. The array antenna system according to Embodiment 2 will be described with reference to Figures 6 and 7. The array antenna system according to Embodiment 2 differs from the array antenna system according to Embodiment 1 in that, while the array antenna system according to Embodiment 1 periodically performs the pseudo-transmission signal update phase based on a set period, Embodiment 2 performs the pseudo-transmission signal update phase when the amplitude phase error calculated by the calibration signal extraction unit 124a in the calibration processing unit 124 exceeds a threshold. All other aspects are the same. In Figures 6 and 7, the same reference numerals as those used in Figures 1 to 5 indicate the same or corresponding parts.

[0077] As shown in Figure 6, the array antenna system according to Embodiment 2 comprises a plurality of antenna elements 1-1 to 1-N (where N is a natural number of 2 or more), a signal processing unit 2, a transmission signal distribution unit 3, a plurality of signal processing systems 4-1 to 4-N, a calibration signal generation unit 5, and a calibration device 100. The signal processing system 4-n has an input-side extraction unit 41-n, a calibration signal injection unit 42-n, a transmitter 43-n, and an output-side extraction unit 44-n.

[0078] The calibration device 100 has a pseudo-transmission signal generation unit 110 and a calibration value generation unit 120. The pseudo-transmission signal generation unit 110 has a reference pseudo-transmission signal generation unit 111, a correlation value calculation unit 112, a pseudo-transmission signal update unit 113, and an amplitude phase error determination unit 114. The calibration value generation unit 120 has a loopback transmission signal generation unit 121, a calibration phase switching unit 122, a subtraction unit 123, and a calibration processing unit 124. The calibration processing unit 124 has a calibration signal extraction unit 124a and a calibration value calculation unit 124b.

[0079] The amplitude-phase error determination unit 114 compares the amplitude-phase difference calculated by the calibration signal extraction unit 124a in the calibration processing unit 124 with a threshold value. If the amplitude-phase difference exceeds the threshold value, it issues a command to the reference pseudo-transmission signal generation unit 111 to perform the pseudo-transmission signal update phase, causing the pseudo-transmission signal generation unit 110 to start generating the pseudo-transmission signal.

[0080] The amplitude phase error determination unit 114 is implemented by a computer-based hardware configuration together with the correlation value calculation unit 112 and pseudo-transmission signal update unit 113 in the pseudo-transmission signal generation unit 110, and the calibration phase switching unit 122, subtraction unit 123 and calibration processing unit 124 in the calibration value generation unit 120.

[0081] Next, the calibration operation of the calibration device 100 in the array antenna system according to Embodiment 2 will be described. The operation of the pre-shipment phase in the first calibration phase is the same as the operation of the pre-shipment phase in the first calibration phase shown in Figure 3 of the calibration device 100 in the array antenna system according to Embodiment 1, so the explanation will be omitted.

[0082] The operation of the operation start phase (pre-processing phase) in the first calibration phase is the same as the operation of the operation start phase in the first calibration phase shown in Figure 4 of the calibration device 100 in the array antenna system according to Embodiment 1, so the explanation will be omitted.

[0083] The operation of the second calibration phase, which is the calibration value generation phase, will be explained using Figure 7. In step ST10, the reference pseudo-transmission signal generation unit 111 determines whether or not it is necessary to update the pseudo-transmission signal stored in the storage unit of the pseudo-transmission signal update unit 113. Since the calibration value generation phase is not the first calibration phase before shipment and at the start of operation, it is determined that updating the pseudo-transmission signal is unnecessary, and the process proceeds to step ST21. Steps ST21 to ST24 are the same as steps ST21 to ST24 shown in Figure 5 in the calibration device 100 in the array antenna system according to Embodiment 1, so the explanation will be omitted.

[0084] In step ST24a, the amplitude-phase error determination unit 114 determines whether the amplitude-phase error exceeds a threshold. If the amplitude-phase error is below the threshold, the process proceeds to step ST25. If the amplitude-phase error exceeds the threshold, the process proceeds to step ST11 in the pseudo-transmit signal update phase of the first calibration phase shown in Figure 4. Processing from step ST11 to step ST16 is performed to update the pseudo-transmit signal stored in the storage unit of the pseudo-transmit signal update unit 113, and the process returns to step ST23. Step ST24a is a step for determining the amplitude-phase error.

[0085] Steps ST23 and ST24 are processed, and the process proceeds to step T24a. Since the pseudo-transmission signal stored in the storage unit of the pseudo-transmission signal update unit 113 is generated by combining multiple transmission signals at the present time and using a reference pseudo-transmission signal and a loopback transmission signal, the difference signal calculated by the subtraction unit 123 in step ST23 becomes small, and the amplitude phase error calculated by the calibration signal extraction unit 124a in step ST24 becomes below the threshold. As a result, in step ST24a, it is determined that the amplitude phase error is below the threshold, and the process proceeds to step ST25.

[0086] In step ST25, the calibration value calculation unit 124b of the calibration processing unit 124 calculates a calibration value for the transmission signal to be given to each of the multiple signal processing systems 4-n from the amplitude phase error calculated by the calibration signal extraction unit 124a, and outputs the calculated calibration value for the transmission signal to the transmission signal distribution unit 3.

[0087] The calibration device for the array antenna system according to Embodiment 2 has the same effects as the calibration device for the array antenna system according to Embodiment 1. In addition, in the second calibration phase, which is the calibration value generation phase, if the amplitude phase error of the pseudo-transmitted signal for generating the calibration value exceeds a threshold, the pseudo-transmitted signal is updated and the calibration value for the transmitted signal is obtained, thus further improving the calibration accuracy.

[0088] Furthermore, it is possible to freely combine the embodiments, modify any component of each embodiment, or omit any component of each embodiment.

[0089] The calibration device for array antenna systems described herein is applicable to array antenna systems that radiate transmitted waves into space in the field of communication systems.

[0090] 1-1 to 1-N Antenna element. 2 Signal processing unit, 3 Beamforming unit, 4-1 to 4-N Signal processing system, 41-1 to 41-N Input side extraction unit, 42-1 to 42-N Calibration signal injection unit, 43-1 to 43-N Transmitter, 44-1 to 44-N Output side extraction unit, 5 Calibration signal generation unit, 100 Calibration device, 110 Pseudo-transmission signal generation unit, 111 Pseudo-transmission signal generation unit for reference, 112 Correlation value calculation unit, 113 Pseudo-transmission signal update unit, 114 Amplitude phase error determination unit, 120 Calibration value generation unit, 121 Folded transmission signal generation unit, 123 Subtraction unit, 124 Calibration processing unit, 124a Calibration signal extraction unit, 124b Calibration value calculation unit.

Claims

1. A calibration device for an array antenna system comprising: a transmission signal distribution unit that distributes transmission signals from a signal processing unit and generates calibration values ​​for transmission signals for output to each of a plurality of antenna elements via a plurality of signal processing systems that superimpose calibration signals from a calibration signal generation unit, the device comprising: a pseudo-transmission signal generation unit that generates pseudo-transmission signals from a plurality of transmission signals on which the plurality of transmission signals distributed from the transmission signal distribution unit and calibration signals from the plurality of signal processing systems are superimposed; and a calibration value generation unit that generates a folded transmission signal from a plurality of transmission signals on which calibration signals from the plurality of signal processing systems are superimposed, generates a difference signal between the folded transmission signal and the pseudo-transmission signal generated by the pseudo-transmission signal generation unit, and generates a calibration value for transmission signals based on the correlation value between the difference signal and the calibration signal from the calibration signal generation unit.

2. The calibration device for an array antenna system according to claim 1, comprising: a pseudo-transmission signal generation unit, a reference pseudo-transmission signal generation unit that synthesizes a plurality of transmission signals distributed from the transmission signal distribution unit to generate a reference pseudo-transmission signal; a correlation value calculation unit that generates a pseudo-transmission signal correction value based on the correlation value of a folded transmission signal generated by synthesizing a plurality of transmission signals in which the reference pseudo-transmission signal generated by the reference pseudo-transmission signal generation unit and calibration signals from the plurality of signal processing systems are superimposed by the folded transmission signal generation unit; and a pseudo-transmission signal update unit that generates a pseudo-transmission signal obtained by correcting the reference pseudo-transmission signal generated by the reference pseudo-transmission signal generation unit with the pseudo-transmission signal correction value generated by the correlation value calculation unit.

3. The calibration device for an array antenna system according to claim 2, wherein the generation of a pseudo-transmitted signal correction value by the correlation value calculation unit involves calculating a first correlation vector which is the ensemble average of the product of a reference pseudo-transmitted signal and the complex conjugate signal of the reference pseudo-transmitted signal, calculating a second correlation vector which is the ensemble average of the product of the aliased transmitted signal and the complex conjugate signal of the reference pseudo-transmitted signal, dividing the second correlation vector by the first correlation vector, and using the divided value as the pseudo-transmitted signal correction value.

4. The calibration device for an array antenna system according to any one of claims 1 to 3, comprising: a calibration value generation unit comprising: a reverse transmission signal generation unit that synthesizes a plurality of transmission signals in which calibration signals from a plurality of signal processing systems are superimposed to generate a reverse transmission signal; a subtraction unit that subtracts a pseudo-transmission signal generated by a pseudo-transmission signal generation unit from the reverse transmission signal generated by the reverse transmission signal generation unit to generate a difference signal; and a calibration processing unit that calculates an amplitude-phase difference from the correlation between the difference signal generated by the subtraction unit and the calibration signal from the calibration signal generation unit, and generates a calibration value for a transmission signal based on the calculated amplitude-phase difference.

5. The calibration processing unit comprises: a calibration signal extraction unit that calculates an amplitude phase difference indicating a relative amplitude phase error with respect to the calibration signal from the correlation between the difference signal generated by the subtraction unit and the calibration signal generated by the calibration signal generation unit; and a calibration value calculation unit that generates a calibration value for a transmission signal to be given to the transmission signal distribution unit for each transmission signal distributed from the transmission signal distribution unit from the amplitude phase difference calculated by the calibration signal extraction unit.

6. The calibration device for an array antenna system according to claim 4 or 5, wherein the calibration value generation unit has an amplitude-phase error determination unit that initiates the generation of a pseudo-transmission signal by the pseudo-transmission signal generation unit when the amplitude-phase difference exceeds a threshold.

7. The calibration device for an array antenna system according to any one of claims 1 to 6, wherein the calibration signal generated by the calibration signal generation unit is a spread spectrum signal.

8. An array antenna system comprising: a plurality of antenna elements; a signal processing unit that outputs a transmission signal which is a baseband signal; a calibration device according to any one of claims 1 to 7; a transmission signal distribution unit that outputs a transmission signal corresponding to the plurality of antenna elements, in which the amplitude phase difference is adjusted by an excitation weight based on a calibration value for the transmission signal from the calibration device; a calibration signal generation unit that generates a calibration signal; and a plurality of signal processing systems that each superimpose the calibration signal generated by the calibration signal generation unit onto the transmission signal distributed by the transmission signal distribution unit, and output a transmission signal modulated by an RF band carrier wave to each of the plurality of antenna elements.

9. A calibration method for an array antenna system, comprising: a transmission signal distribution unit outputting a transmission signal from a signal processing unit, distributing the transmission signal from the signal processing unit, and generating a calibration value for a transmission signal for output to each of a plurality of antenna elements via a plurality of signal processing systems that superimpose a calibration signal from a calibration signal generation unit, the method comprising: a pseudo-transmission signal generation unit in the calibration system generating a pseudo-transmission signal from a plurality of transmission signals superimposed with a plurality of transmission signals distributed from the transmission signal distribution unit and calibration signals from the plurality of signal processing systems; and a calibration value generation unit in the calibration system generating a folded transmission signal from a plurality of transmission signals superimposed with calibration signals from the plurality of signal processing systems, generating a difference signal between the folded transmission signal and the pseudo-transmission signal generated by the pseudo-transmission signal generation unit, and generating a calibration value for a transmission signal based on the correlation value between the difference signal and the calibration signal from the calibration signal generation unit.

10. A calibration program for an array antenna system that causes a computer to perform the following steps:

10. A procedure to generate a reference pseudo-transmission signal by synthesizing multiple transmission signals, which are baseband signals distributed from a transmission signal distribution unit to multiple signal processing systems; 10. A procedure to generate a folded transmission signal by synthesizing multiple transmission signals, on which calibration signals from the multiple signal processing systems are superimposed, and converting them to a baseband signal; 11. A procedure to generate a pseudo-transmission signal correction value by calculating the correlation value between the reference pseudo-transmission signal and the folded transmission signal; 22. A procedure to update the pseudo-transmission signal by superimposing the pseudo-transmission signal correction value on the previously generated pseudo-transmission signal; 33. A procedure to obtain a difference signal by subtracting the updated pseudo-transmission signal from the folded transmission signal; 44. A procedure to calculate the amplitude phase error from the correlation between the difference signal and the calibration signal from the calibration signal generation unit, and generate a calibration value for the transmission signal to be given to each of the multiple signal processing systems.

11. A recording medium storing a program that causes a computer to execute the following steps:

11. A procedure for generating a reference pseudo-transmission signal by synthesizing multiple transmission signals, which are baseband signals distributed from a transmission signal distribution unit to multiple signal processing systems; 2. A procedure for generating a loopback transmission signal by synthesizing multiple transmission signals, on which calibration signals from the multiple signal processing systems are superimposed, and converting them to a baseband signal; 3. A procedure for calculating the correlation value between the reference pseudo-transmission signal and the loopback transmission signal and generating a pseudo-transmission signal correction value; 4. A procedure for updating the pseudo-transmission signal by superimposing the pseudo-transmission signal correction value onto the pseudo-transmission signal; 5. A procedure for obtaining a difference signal by subtracting the updated pseudo-transmission signal from the loopback transmission signal; and 6. A procedure for calculating the amplitude phase error from the correlation between the difference signal and the calibration signal from the calibration signal generation unit and generating a calibration value for the transmission signal to be given to each of the multiple signal processing systems.

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