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

Abstract

The receiving array antenna device includes a plurality of element antennas (11) to (1 N A plurality of element antennas (11) to (1) in an array antenna (1) having N ) each transmits a digital reception signal based on the received signal to a plurality of element antennas (11) to (1 N ) for each corresponding receiving system, and each of the excitation coefficient multipliers (411) to (412) multiplies the received digital received signal by a corrected excitation coefficient to obtain a corrected digital received signal. N ) and a plurality of excitation coefficient multiplication units (411) to (41 N a complex adder (42) that adds the corrected digital received signals obtained by the respective antennas (11) to (1) to form a receiving beam; N ) transmits digital calibration signals based on the calibration signals received by the plurality of element antennas (11) to (1 N a correlation detection unit (46) for receiving the digital calibration signal for each of the plurality of receiving systems corresponding to the digital calibration signal for the reference receiving system, which is one of the plurality of receiving systems, and for obtaining a cross-correlation value for each of the plurality of receiving systems with respect to the digital calibration signal for the reference receiving system; n an inter-element system error calculation unit (47) that subtracts a noise correlation value for noise of a reference receiving system from the noise correlation value calculation unit (47) to a correlation detection unit (46) to obtain a corrected autocorrelation value, and obtains, for each of the plurality of receiving systems, an inter-element system error that is a relative difference in the cross-correlation value for each receiving system obtained by the correlation detection unit (46) using the corrected autocorrelation value for each receiving system as a reference, and obtains a correction coefficient using the obtained inter-element system error; and an excitation coefficient correction unit (48) that obtains, for each of the plurality of receiving systems, a corrected excitation coefficient to be sent to the excitation coefficient multiplication unit using the correction coefficient obtained by the inter-element system error calculation unit (47) for each receiving system and a preset excitation coefficient for each receiving system.

Description

[Technical Field]

[0001] The present disclosure relates to a receiving array antenna device that receives an analog received signal using an array antenna having a plurality of antenna elements and converts the signal into a digital received signal for processing, a calibration method for the receiving array antenna device, a receiving array antenna system, a calibration program, and a recording medium. [Background technology]

[0002] Patent Document 1 shows a satellite receiver that uses digital beam forming (DBF) to receive signals using an array antenna, convert the received analog signals into digital signals, and control excitation coefficients through digital signal processing. Patent Document 1 discloses a satellite receiver that can improve communication efficiency by calibrating errors between element systems that occur within the device, that is, gain error, delay error, and phase error.

[0003] Specifically, Patent Document 1 discloses a satellite receiver that includes N demultiplexing sections that demultiplex digital received signals obtained by converting calibration signals received by each of N receiving antenna elements into digital signals, into multiple subchannel signals of a predetermined band, N excitation coefficient multipliers that multiply each of the multiple subchannel signals by an excitation coefficient, and a complex adder that adds together the multiple subchannel signals after being multiplied by the excitation coefficients for each subchannel signal of the same band, one of the N demultiplexing sections being a reference demultiplexing section, a correlation detection section that calculates a cross-correlation value for each subchannel signal output from each demultiplexing section different from the reference demultiplexing section, with respect to a subchannel signal of the same band output from the reference demultiplexing section, and an excitation coefficient generation section that generates corrected excitation coefficients that are excitation coefficients to be multiplied by the subchannel signals by the excitation coefficient multipliers, based on the cross-correlation value calculated by the correlation detection section and excitation coefficients that are prepared in advance to form a desired receiving beam. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 152660 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors further studied the calibration that generates corrected excitation coefficients using cross-correlation values ​​and found that when the noise input to the correlation detection unit in response to the received calibration signal is large, for example, when the noise superimposed on the calibration signal is large due to the surrounding environment and the state of the equipment from the receiving antenna element to the correlation detection unit, that is, when the power ratio of the calibration signal to noise (S / N ratio) is small, a large error occurs in the amplitude estimation value between the systems. As a result, when the calibration signal-to-noise power ratio is small, the accuracy of the excitation coefficients after correction by calibration is low.

[0006] The present disclosure has been made in consideration of the above-mentioned points, and aims to provide a receiving array antenna device in which the accuracy of excitation coefficients after correction by calibration is high even when the power ratio of the calibration signal to noise is small. [Means for solving the problem]

[0007] A receiving array antenna device according to the present disclosure includes a plurality of excitation coefficient multipliers that receive digital reception signals from reception signals received by each of a plurality of element antennas in an array antenna having a plurality of element antennas, each of which receives a digital reception signal for each of the plurality of element antennas, and multiplies the received digital reception signal by a corrected excitation coefficient to obtain a corrected digital reception signal; a complex adder that adds the corrected digital reception signals obtained by the plurality of excitation coefficient multipliers to form a reception beam; a correlation detector that receives digital calibration signals from calibration signals received by each of the plurality of element antennas for each of the reception systems corresponding to the plurality of element antennas, and obtains a cross-correlation value for each reception system for the digital calibration signals in the plurality of reception systems relative to a digital calibration signal in a reference reception system that is one of the plurality of reception systems; From the autocorrelation value, The system is provided with an inter-element system error calculation unit that obtains a corrected autocorrelation value by subtracting a noise correlation value for noise of a reference receiving system extending from the element antenna to the correlation detection unit, and obtains, for each of the plurality of receiving systems, an inter-element system error which is a relative difference in the cross-correlation value for each receiving system obtained by the correlation detection unit using the corrected autocorrelation value for each receiving system as a reference, and obtains a correction coefficient using the obtained inter-element system error, and an excitation coefficient correction unit that obtains, for each of the plurality of receiving systems, a corrected excitation coefficient to be sent to the excitation coefficient multiplication unit using the correction coefficient obtained by the inter-element system error calculation unit for each receiving system and a preset excitation coefficient for each receiving system. [Effects of the Invention]

[0008] According to the present disclosure, the cross-correlation value is corrected using a noise correlation value for noise in the reference system, so even if the power ratio of the calibration signal to the noise is small, the accuracy of the excitation coefficient corrected by calibration is high, and calibration can be achieved with high precision. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram showing a receiving array antenna apparatus according to a first embodiment. [Figure 2] 5 is a flowchart showing a calibration method in the receiving array antenna apparatus according to the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating a hardware configuration of a DBF receiving section in the receiving array antenna apparatus according to the first embodiment. [Figure 4] FIG. 10 is a configuration diagram showing a receiving array antenna apparatus according to a second embodiment. [Figure 5] FIG. 10 is a configuration diagram showing a receiving array antenna apparatus according to a third embodiment. [Figure 6] FIG. 11 is a diagram for explaining sequence control in a receiving array antenna apparatus according to a third embodiment. [Figure 7] FIG. 10 is a configuration diagram showing a receiving array antenna apparatus according to a fourth embodiment. [Figure 8] FIG. 11 is a diagram showing signals after demultiplexing into subchannels in a digital calibration signal in a receiving array antenna apparatus according to a fourth embodiment. [Figure 9] FIG. 10 is a configuration diagram showing a receiving array antenna apparatus according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiment 1 A receiving array antenna apparatus according to a first embodiment will be described with reference to FIGS. 1 to 3. FIG. The receiving array antenna apparatus according to the first embodiment is used as a satellite repeater in a satellite communication system. The receiving array antenna apparatus according to the first embodiment includes a plurality of element antennas 11 to 1 N and a plurality of receivers 21-2. N and a plurality of analog-to-digital converters (ADCs) 31 to 33. N and a digital beam forming (DBF) receiving unit 4.

[0011] The DBF receiver 4 includes a plurality of excitation coefficient multipliers 411 to 41 Na complex adder 42, a noise correlation value storage unit 43, a correction coefficient storage unit 44, an excitation coefficient storage unit 45, a correlation detection unit 46, an element-system error calculation unit 47, and complex multipliers 481 to 48 N and an excitation coefficient correction unit 48 having: N represents a natural number greater than or equal to 2.

[0012] In the following description, 1 to N respectively represent a plurality of element antennas 11 to 1 N Each of these indicates one corresponding receiving system. n indicates receiving systems 1 to N, and m indicates a reference receiving system selected from the receiving systems 1 to N. In the first embodiment, the reference receiving system is the receiving system with the maximum received power, but any reference receiving system can be selected. When there is no need to explain each component individually, the component will be explained using n.

[0013] First, before describing each component, the error between element systems will be described. First, a plurality of element antennas 11-1 N The reception patterns received by each of the element antennas 11 to 1 N This is an error between element systems due to the characteristic difference between element antennas (hereinafter referred to as "error between element systems due to the characteristic difference between element antennas"), which indicates the difference in power and phase determined by the positional relationship between each antenna and the ground station and the calibration ground station.

[0014] The second type is inter-element system errors that occur within the device, that is, inter-element system errors due to gain error, delay error, and phase error (hereinafter referred to as inter-element system errors that occur within the device). Third, noise that occurs inside the device and affects the estimation of the error between element systems, such as the surrounding environment and the element antennas 11 to 1 N This is a noise component that is superimposed on the digital calibration signal depending on the state of the equipment from the calibration unit 41 to the correlation detection unit 46.

[0015] The receiving array antenna apparatus according to the first embodiment eliminates errors between element systems due to differences in characteristics between element antennas by using excitation coefficients that are set in advance for each receiving system. Furthermore, errors between element systems that occur within the device are eliminated by obtaining a cross-correlation value between the digital calibration signal for each receiving system and the reference calibration signal for the digital calibration signal for each receiving system. Furthermore, when calculating the inter-element system error that occurs inside the device, noise components are removed, thereby improving the accuracy of the calculated inter-element system error.

[0016] Multiple element antennas 11-1 N Each (hereinafter, unless there is a need to distinguish between them, they will be referred to as element antenna 1 n The calibration ground station 100 receives a received signal, which is an actual communication signal (transmitted signal) consisting of radio waves (in the radio frequency (RF) band) from a ground station (not shown), and a calibration signal 110 consisting of radio waves from the calibration ground station 100.

[0017] Multiple element antennas 11-1 N Since the received signal and the calibration signal 110 have spatial spread, each of the element antennas receives the same received signal and the calibration signal 110. n The power and phase of the received signal and calibration signal 110 at element antenna 1 n The reception pattern is determined by the positional relationship between the ground station and the calibration ground station 100. The difference in power and phase determined by the receiving pattern and positional relationship is n This is called the difference in characteristics between the two.

[0018] Although the expressions "received signal" and "calibration signal" are used, this does not mean that the received signal and calibration signal are simultaneously received and processed, but simply means that the received signal and calibration signal are received. This also applies to the following explanation.

[0019] Multiple receivers 21~2 N Each (hereinafter, unless there is a need to distinguish between them, n (explained as follows) is a plurality of element antennas 11 to 1 for each receiving system n. N Each is provided correspondingly. Receiver 2n is the corresponding element antenna 1 n The RF band received signal and calibration signal from the receiver 2 are frequency converted and converted into an electrical signal, and then converted into an analog received signal in the baseband frequency band suitable for subsequent processing. n adjusts the power of the analog received signal to an appropriate value.

[0020] Multiple ADC31~3 N Each (hereinafter, unless there is a need to distinguish between them, ADC3 n (explained as) includes a plurality of receivers 21 to 22 for each receiving system n. N They are electrically connected to each other. ADC3 n corresponds to the receiver 2 n The analog reception signal and analog calibration signal from the DBF receiver 4 are converted into digital signals, and the digital reception signal and digital calibration signal are output to the DBF receiver 4.

[0021] The receiver group 2 and the ADC group 3 convert the received signals and calibration signals, which are radio waves received by the array antenna 1, into baseband frequency bands, and then digitally convert the analog received signals and analog calibration signals, which are electrical signals, and then transmit the digitally converted digital received signals and digital calibration signals to the plurality of element antennas 11 to 11 in the array antenna 1. N A received signal preprocessing unit is configured to output to the DBF receiving unit 4 for each of the corresponding receiving systems n.

[0022] The DBF receiver 4 has a function of forming a receiving beam (beam forming unit) and a function of obtaining corrected excitation coefficients (excitation coefficient generating unit). The beam forming section in the DBF receiver 4 receives a received signal consisting of an actual communication signal from a ground station received by the array antenna 1, and uses the digital received signals output from the received signal pre-processing section for each of n receiving systems to obtain corrected digital received signals using corrected excitation coefficients.The beam forming section then adds up the corrected digital received signals obtained for each of n receiving systems to form a calibrated receive beam. The receive beam formed by the beam forming unit is a receive beam in which errors between element systems due to differences in characteristics between element antennas and errors between element systems that occur inside the device based on the hardware characteristics of the receive signal preprocessing unit have been calibrated by using the corrected excitation coefficients.

[0023] For calibration signal 110 received by array antenna 1 from calibration ground station 100, the excitation coefficient generation section in DBF receiver 4 first determines one of the multiple reception systems 1 to N as reference reception system m, and determines the digital calibration signal output from the reception signal pre-processing section in reference reception system m as the reference calibration signal, and obtains a cross-correlation value for the digital calibration signal for each of reception systems n with respect to the reference calibration signal for the digital calibration signal for each of reception systems n output from the reception signal pre-processing section. The correlation value in the digital calibration signal of the reference receiving system m with respect to the reference calibration signal is also called a cross-correlation value, and when it is necessary to distinguish it, it is called an auto-correlation value.

[0024] Next, the excitation coefficient generating unit subtracts the noise correlation value for the noise of the reference receiving system m from the autocorrelation value in the reference receiving system m to obtain a corrected autocorrelation value. Furthermore, the excitation coefficient generator obtains an error between element systems, which is a relative difference between the cross-correlation values ​​of each receiving system based on the corrected autocorrelation value for each receiving system n, and obtains a correction coefficient using the obtained error between element systems.

[0025] The excitation coefficient generator obtains the relative difference in cross-correlation values ​​using a corrected autocorrelation value obtained by subtracting the noise correlation value for the noise of the reference receiving system m. Therefore, even when the noise component is large and the power ratio of the calibration signal to noise is small, the relative difference in cross-correlation values ​​can be calculated with high accuracy, and as a result, the error between element systems can be obtained with high accuracy.

[0026] The excitation coefficient generator obtains corrected excitation coefficients for each of the n receiving systems for the beamformer using the correction coefficients for each of the n receiving systems and preset excitation coefficients for each of the n receiving systems. The preset excitation coefficients are excitation coefficients for forming a receiving beam, and are excitation coefficients that will result in a desired receiving beam from the beam forming section when it is assumed that there is no error between the receiving systems in the received signal preprocessing section.

[0027] The preset excitation coefficient is n The receiving pattern received by element antenna 1 n The element antenna 1 shows the difference in power and phase determined by the positional relationship between the ground station and the calibration ground station 100. n Based on the characteristic differences between The correction coefficient for each n-th receiving system is a coefficient that can calibrate the error between element systems that occurs inside the device, which is the difference in characteristics between n-th receiving systems in the received signal pre-processing unit. The inter-element system error, which is the relative difference in cross-correlation values, includes the inter-element system error due to the characteristic differences between the element antennas and the inter-element system error generated inside the device, and the excitation coefficient generation unit removes the inter-element system error due to the characteristic differences between the element antennas before obtaining the correction coefficients.

[0028] The beam forming unit in the DBF receiver 4 includes a plurality of excitation coefficient multipliers 411 to 41 N and a complex adder 42. The excitation coefficient generation unit in the DBF receiver 4 includes a correlation detection unit 46, an element-to-system error calculation unit 47, and an excitation coefficient correction unit 48.

[0029] A plurality of excitation coefficient multiplication units 411 to 41 N Each of them (hereinafter, unless there is a need to distinguish between them, they will be referred to as excitation coefficient multiplication units 41 n ) corresponds to the ADC3 in the ADC group 3 that constitutes the received signal pre-processing section. n and the corrected excitation coefficients of the corresponding receiving system n from the excitation coefficient generating unit in the DBF receiving unit 4. The corrected excitation coefficients are complex numbers.

[0030] Excitation coefficient multiplication unit 41 n multiplies the corresponding digital received signal by the corrected excitation coefficient to obtain a corrected digital received signal for each receiving system n. The complex adder 42 includes a plurality of excitation coefficient multipliers 411 to 41 N The corrected digital received signals for each receiving system n obtained by each are added together, that is, the corrected digital received signals are vector-synthesized to form a receiving beam.

[0031] The correlation detector 46 detects the correlation between the corresponding ADC 3 in the ADC group 3 that constitutes the received signal pre-processing unit. n The digital calibration signal from the reference receiving system m is received for each of the n receiving systems, one of the multiple receiving systems 1 to N is designated as the reference receiving system m, the digital calibration signal in the reference receiving system m is designated as the reference calibration signal, and a cross-correlation value for each of the n receiving systems with respect to the reference calibration signal for the digital calibration signal in the receiving system n is obtained.

[0032] The correlation detection unit 46 selects the reception system with the greatest reception power among the reception powers of the digital calibration signals in each of the reception systems n as the reference reception system m. The correlation detector 46 may use a digital calibration signal in a reception system that has been set in advance as the reference reception system m as the reference calibration signal. The cross-correlation value obtained by the correlation detector 46 is obtained by calculating a correlation vector between the digital calibration signal of the receiving system n and the reference calibration signal.

[0033] The element-to-element system error calculation unit 47 has the following functions. The first function is to read out the noise correlation value for the reference receiving system stored in the noise correlation value storage unit 43, and to obtain a corrected autocorrelation value by subtracting the read-out noise correlation value from the autocorrelation value for the reference receiving system m obtained by the correlation detection unit 46.

[0034] The noise correlation value for the reference receiving system is m 46 to the correlation detector 46 is a noise correlation value (correlation value due to noise power) of the noise of each receiving system n with respect to the noise of the reference receiving system m. The noise correlation value is a value obtained by measuring or calculating the noise component, in the first embodiment, the noise power (amplitude of the noise component) in advance.

[0035] The second function is a function for obtaining, for each of a plurality of receiving systems n, an error between element systems, which is the relative difference between the cross-correlation values ​​for each receiving system n obtained by the correlation detection unit 46 using the corrected autocorrelation value for the reference receiving system m obtained by the first function for each receiving system n as a reference. The inter-element system error, which is the relative difference in the cross-correlation value for each receiving system n obtained by the correlation detection unit 46 using the autocorrelation value for the reference receiving system m as a reference, includes inter-element system errors due to characteristic differences between element antennas and inter-element system errors generated inside the device. Furthermore, since the relative difference in the cross-correlation values ​​is obtained using the corrected autocorrelation values, even when the noise component is large and the power ratio of the calibration signal to noise is small, the relative difference in the cross-correlation values ​​can be calculated with high accuracy, and as a result, the error between the element systems can be obtained with high accuracy.

[0036] The third function is a function for calculating the final inter-element system error by removing the inter-element system error due to the characteristic difference between the element antennas from the inter-element system error obtained by the second function. The final inter-element system amplitude error in the inter-element system error is a value obtained by dividing the inter-element system amplitude error for each receiving system n in the inter-element system error obtained by the second function by the amplitude difference between the amplitude of the digital calibration signal in the reference receiving system m and the amplitude of the digital calibration signal in the receiving system n, which is taken as the reference.

[0037] The final inter-element system phase error in the inter-element system error is a value obtained by subtracting the phase difference between the phase of the digital calibration signal in the receiving system n, which is based on the phase of the digital calibration signal in the reference receiving system m, from the inter-element system phase error for each receiving system n in the inter-element system error obtained by the second function. When there is no need to distinguish between the amplitude error between element systems and the phase error between element systems, both will be referred to as the error between element systems.

[0038] The fourth function is to calculate a correction coefficient for correcting the inter-element system error that occurs inside the device using the final inter-element system error. The correction coefficients for each of the n receiving systems calculated by the element-to-system error calculation unit 47 are stored in the correction coefficient storage unit 44. The correction coefficients obtained by the element system error calculation unit 47 are less susceptible to noise, highly accurate, and capable of canceling out element system errors occurring within the device.

[0039] Complex multipliers 481 to 48 N (Hereinafter, unless there is a need to distinguish between them, the complex multiplier 48 n The excitation coefficient correction unit 48 having the excitation coefficients for the n receiving systems stored in the excitation coefficient storage unit 45 calculates excitation coefficients for the n receiving systems stored in the correction coefficient storage unit 44 by multiplying the excitation coefficients by the excitation coefficient multipliers 411 to 414. N The corrected excitation coefficients for each receiving system n are obtained.

[0040] Complex Multiplier 48 n is multiplied by the excitation coefficient of the receiving system n stored in the corresponding excitation coefficient storage unit 45 by the correction coefficient of the receiving system n stored in the correction coefficient storage unit 44, and outputs the corresponding excitation coefficient multiplication unit 41. n is given the corrected excitation coefficient of receiving system n. The corrected excitation coefficients obtained by the excitation coefficient correction unit 48 using the correction coefficients obtained by the inter-element system error calculation unit 47 are also less susceptible to noise, have high accuracy, and are coefficients that can cancel out inter-element system errors due to characteristic differences between element antennas and inter-element system errors that occur inside the device.

[0041] Next, a calibration method for the receiving array antenna apparatus according to the first embodiment will be described with reference to FIG. The excitation coefficients for n receiving systems are stored in advance in the excitation coefficient storage unit 45, and the noise correlation value storage unit 43 stores the noise correlation values ​​(correlation values ​​due to noise power) of the noise for n receiving systems.

[0042] The array antenna 1 receives a calibration signal 110 from the calibration ground station 100, and the received signal pre-processing unit, which is composed of a receiver group 2 and an ADC group 3, outputs the calibration signal to the element antenna 1. nWhen the correlation detection unit 46 in the DBF receiving unit 4 receives the digital calibration signals for n receiving systems corresponding to the above, the following process is performed in step ST1.

[0043] The correlation detector 46 receives the digital calibration signal R n [k] is expressed by the following equation (1). TIFF0007770619000001.tif13166

[0044] In the above equation (1), k is the frequency (subchannel number), A n [k] is the amplitude of the calibration signal of receiving system n, φ n [k] is the phase of the calibration signal for receiving system n, N n [k] indicates the noise component of the calibration signal of receiving system n.

[0045] The correlation detector 46 receives the calibration signal R in the reference receiving system m of the receiving systems n. m [k] is expressed by the following equation (2). The reference receiving system m is one of the receiving systems n. In the first embodiment, the receiving system with the maximum received power among the receiving systems n is taken as the reference receiving system m, and the calibration signal R m [k] is the calibration signal for the receiving system with the maximum received power.

[0046] TIFF0007770619000002.tif14166In the above equation (2), k is the frequency (subchannel number), A m [k] is the amplitude of the calibration signal of the reference receiving system m, φ m [k] is the phase of the calibration signal of the reference receiving system m, N m [k] denotes the noise component of the calibration signal of the reference receiving system m.

[0047] In step ST1, the correlation detector 46 calculates the correlation signal R m [k] and the digital calibration signal R in the receiving system n shown in equation (1) above. n [k] is used to calculate the cross-correlation value (correlation vector) in the receiving system n.

[0048] The cross-correlation value in the receiving system n calculated by the correlation detector 46 and expressed by the following equation (3) is expressed by the following equation (4). TIFF0007770619000003.tif13166 TIFF0007770619000004.tif19166

[0049] In the cross-correlation value in the receiving system n expressed by the above equation (4), the cross-correlation value in the reference receiving system m is an auto-correlation value, and the auto-correlation value in the reference receiving system m shown by the following equation (5) is expressed by the following equation (6). TIFF0007770619000005.tif12166 TIFF0007770619000006.tif12166

[0050] Step ST1 is a step in which the correlation detection unit 46 obtains the cross-correlation value in the receiving system n shown by the above equation (4) and the auto-correlation value in the reference receiving system m shown by the above equation (6). In short, step ST1 is a step in which the correlation detection unit 46 obtains (calculates) a cross-correlation value for each of the multiple receiving systems n with respect to the digital calibration signal in the reference receiving system m, which is one of the multiple receiving systems.

[0051] The cross-correlation value in the receiving system n and the auto-correlation value in the reference receiving system m are ensemble averages, and correlation components between signals and noise components with low correlation and correlation components between noises in different systems can be ignored. Therefore, the relative difference (left side of the following equation (7)) between the amplitude of the cross-correlation value in the receiving system n and the amplitude of the auto-correlation value in the reference receiving system m is calculated as shown in the following equation (7). Furthermore, the relative difference in phase of the cross-correlation value in the receiving system n with respect to the phase of the auto-correlation value in the reference receiving system m (the left side of the following equation (8)) is calculated as shown in the following equation (8).

[0052] TIFF0007770619000007.tif20166 TIFF0007770619000008.tif13166

[0053] The relative difference in the amplitude of the cross-correlation value in receiving system n with respect to the amplitude of the auto-correlation value in the reference receiving system m indicates the amplitude error between the element systems. The relative difference in phase of the cross-correlation value in receiving system n with respect to the phase of the auto-correlation value in the reference receiving system m indicates the phase error between the element systems.

[0054] Here, in the ideal case where there is no noise component, the noise component N m [k] is 0, and the relative difference in the amplitude of the cross-correlation value in the receiving system n with respect to the amplitude of the auto-correlation value in the reference receiving system m is calculated as follows: Furthermore, the phase of the relative difference in phase between the cross-correlation value in the nth receiving system with the auto-correlation value in the reference mth receiving system as the reference is calculated and expressed by the following equation (10).

[0055] TIFF0007770619000009.tif20166 TIFF0007770619000010.tif13166

[0056] However, in reality, noise components (noise power) are superimposed in the received signal preprocessing section, so the relative difference in the amplitude of the cross-correlation value in receiving system n, based on the amplitude of the auto-correlation value in reference receiving system m, is calculated by adding the noise component N of the digital calibration signal in reference receiving system m to the denominator, as shown in equation (7) above. m [k] (the amplitude (power value) of the noise component) exists.

[0057] Therefore, the cross-correlation value for each receiving system n with respect to the reference calibration signal for the digital calibration signal in the receiving system n calculated by the correlation detection unit 46 is calculated by adding the noise component N of the calibration signal in the reference receiving system m. m [k] will exist as an error component. When the noise superimposed on the signal is large and the signal-to-noise power ratio (S / N ratio) is small, the effect becomes significant and can result in a large error.

[0058] In step ST2, the element-to-element system error calculation unit 47 calculates the noise correlation value N' for the reference receiving system stored in the noise correlation value storage unit 43. m [k] is read out, and the noise correlation value N for the reference receiving system m is read out from the autocorrelation value for the reference receiving system m obtained by the correlation detection unit 46. m Subtract [k] to get the corrected autocorrelation value. The element system error calculation unit 47 obtain The corrected autocorrelation value (the left side of the following equation (11)) is expressed by the following equation (11).

[0059] TIFF0007770619000011.tif13166

[0060] In step ST3, the element-system error calculation unit 47 calculates the relative difference in amplitude of the cross-correlation value in the receiving system n based on the amplitude of the corrected autocorrelation value in the reference receiving system m, which is expressed by the following equation (12). Furthermore, the relative difference in phase of the cross-correlation value in the receiving system n with respect to the phase of the corrected autocorrelation value in the reference receiving system m is calculated as follows:

[0061] TIFF0007770619000012.tif19166 TIFF0007770619000013.tif14166

[0062] The relative difference in the amplitude of the cross-correlation value in receiving system n with reference to the amplitude of the corrected autocorrelation value in the reference receiving system m indicates the amplitude error between the element systems with the noise component of the amplitude reduced. The relative difference in phase of the cross-correlation value in receiving system n with respect to the phase of the corrected auto-correlation value in the reference receiving system m indicates the phase error between the element systems. Note that the noise component is mainly noise power, which affects the amplitude but not the phase, so the phase error between element systems shown by the above equation (13) is the same as the phase error between element systems when there is no noise component, shown by the above equation (10).

[0063] In the above equation (12), Δ is the error of the noise component in the digital calibration signal in the reference receiving system m. Δ is the square of the noise correlation value of the autocorrelation value in the reference receiving system m |N m [k]| 2 The squared value of the noise correlation value of the corrected autocorrelation value in the reference receiving system m, |N´ m [k]| 2 is the value obtained by subtracting TIFF0007770619000014.tif13166

[0064] Although Δ is not 0 strictly speaking, if the settings of the components that make up the received signal pre-processing unit are not changed, the noise correlation value for the reference receiving system stored in the noise correlation value storage unit 43 can be approximated to be almost the same as the noise component (noise power) superimposed on the calibration signal in the reference receiving system m. As is clear from the above equations (12) and (13), the influence of noise components is reduced from the relative difference in the cross-correlation value of receiving system n based on the autocorrelation value in the reference receiving system m, that is, the error between element systems.

[0065] Step ST3 is a step in which the element-to-system error calculation unit 47 calculates a relative difference for each cross-correlation value for each of the n receiving systems, using the corrected autocorrelation value as a reference, to obtain an element-to-system error for each receiving system. In step ST4, the inter-element system error calculation unit 47 determines the final inter-element system error by removing the inter-element system error due to the characteristic difference between the element antennas from the inter-element system error obtained in step ST3, and obtains a correction coefficient due to the final inter-element system error. The correction coefficients obtained by the element system error calculation unit 47 are stored in the correction coefficient storage unit 44.

[0066] That is, the final inter-element system amplitude error is a value obtained by dividing the inter-element system amplitude error calculated by the above equation (12) by the amplitude difference (shown by the following equation (15)) between the amplitude of the digital calibration signal in the reference receiving system m and the amplitude of the digital calibration signal in the receiving system n, which is taken as the reference. TIFF0007770619000015.tif12166

[0067] The final inter-element system phase error is a value obtained by subtracting the phase difference (shown by the following equation (16)) between the phase of the digital calibration signal in the reference receiving system m and the phase of the digital calibration signal in the receiving system n, which is based on the phase of the digital calibration signal in the reference receiving system m, from the inter-element system phase error calculated by the above equation (13). TIFF0007770619000016.tif12166

[0068] Steps ST3 and ST4 are steps in which the element-to-element system error calculation unit 47 calculates the relative difference based on the corrected autocorrelation value for each cross-correlation value for each of the n receiving systems to obtain the element-to-element system errors for each receiving system, and then obtains a correction coefficient using the obtained element-to-element system errors.

[0069] In step ST5, the excitation coefficient correction unit 48 reads out the excitation coefficients for each of the n receiving systems stored in the excitation coefficient storage unit 45 and the correction coefficients for each of the n receiving systems obtained by the inter-element system error calculation unit 47 and stored in the correction coefficient storage unit 44, and multiplies each of the n receiving systems by the correction coefficients for each of the n receiving systems corresponding to the excitation coefficients for each of the n receiving systems to obtain corrected excitation coefficients.

[0070] The excitation coefficients after correction obtained by the excitation coefficient correction unit 48 are input to the excitation coefficient multiplication units 411 to 414. N is given to. Step ST5 is a step in which the excitation coefficient corrector 48 generates corrected excitation coefficients based on the correction coefficients for each of the reception systems n and the preset excitation coefficients.

[0071] Next, the hardware configuration of the DBF receiving unit 4 in the receiving array antenna apparatus according to the first embodiment will be described with reference to FIG. The DBF receiving unit 4 includes a CPU (Central Processing Unit) 401 , a ROM (Read Only Memory) 402 , a RAM (Random Access Memory) 403 , an input interface unit 404 , and an output interface unit 405 . The CPU 401, ROM 402, RAM 403, input interface unit 404, and output interface unit 405 are connected to a bus 406, and data, control signals, and the like are exchanged between them via the bus 406.

[0072] The CPU 401 temporarily loads a program recorded in the ROM 402 into the RAM 403, and executes processing according to the loaded program. The ROM 402 stores various data, programs for executing processes in the DBF receiving unit 4, processing programs required to start up the DBF receiving unit 4, and the like.

[0073] The ROM 402 stores a beamforming program for executing a function of forming a receiving beam (beam forming unit) and a calibration program for executing a function of obtaining corrected excitation coefficients (excitation coefficient generating unit). The RAM 403 has a noise correlation value storage unit 43, a correction coefficient storage unit 44, and an excitation coefficient storage unit 45, and also has a storage unit for temporarily storing the program recorded in the ROM 402.

[0074] The input interface unit 404 includes ADC31 to ADC33. N A digital received signal and a digital calibration signal are input from each of them. The output interface unit 405 outputs the reception beam.

[0075] When the functions of the excitation coefficient generation unit, which includes the correlation detection unit 46, the inter-element system error calculation unit 47, and the excitation coefficient correction unit 48, are realized by the CPU 401 and the RAM 403, the calibration program for the receiving array antenna apparatus, which is recorded in the ROM 402 and executed by the CPU 401, includes the following steps: for digital calibration signals received by a plurality of element antennas, to obtain cross-correlation values ​​for each of the plurality of receiving systems with respect to the digital calibration signals of the plurality of receiving systems relative to the digital calibration signal in a reference receiving system, which is one of a plurality of receiving systems corresponding to each of the plurality of element antennas; to obtain a corrected autocorrelation value by subtracting a noise correlation value for the reference receiving system from the autocorrelation value for the digital calibration signal in the reference receiving system; to calculate a relative difference for each of the cross-correlation values ​​for each of the receiving systems using the corrected autocorrelation value as a reference to obtain inter-element system errors for each of the receiving systems, and to obtain correction coefficients using the obtained inter-element system errors; and to generate corrected excitation coefficients based on the correction coefficients for each of the receiving systems and preset excitation coefficients.

[0076] As described above, the receiving array antenna apparatus according to the first embodiment has a plurality of element antennas 11 to 1 N The array antenna 1 has a plurality of element antennas 11 to 1 N The corrected excitation coefficients used to form receive beams for digital receive signals derived from receive signals received by each element are obtained by the inter-element system error calculation unit 47 subtracting the noise correlation value for the reference receive system m from the autocorrelation value in the reference receive system m to obtain a corrected autocorrelation value, and for each of the plurality of receive systems n, the inter-element system error is obtained, which is the relative difference in the cross-correlation value for each receive system n obtained by the correlation detection unit 46 using the corrected autocorrelation value for each receive system n as a reference, and a correction coefficient is obtained using the obtained inter-element system error, and the excitation coefficient correction unit 48 obtains a correction coefficient for each receive system from the correction coefficient obtained by the inter-element system error calculation unit 47 and a preset excitation coefficient.Therefore, even if the power ratio of the calibration signal to noise between the digital calibration signal and the noise component superimposed in the receive signal pre-processing unit is small, the inter-element system error generated inside the device, which is calculated from the relative difference between the receive systems with respect to the reference receive system m, can be obtained with high accuracy, and as a result, the receive beam can be calibrated with high accuracy.

[0077] Embodiment 2 A receiving array antenna apparatus according to the second embodiment will be described with reference to FIG. The receiving array antenna apparatus according to the second embodiment is a receiving array antenna apparatus that is compatible with an actual communication signal (transmission signal) transmitted from a ground station (not shown) in which multiple subchannels formed by subcarrier signals of multiple different frequencies are multiplexed, and a calibration signal 110 from a calibration ground station 100 in which multiple subchannels formed by subcarrier signals of multiple different frequencies are multiplexed.

[0078] The receiving array antenna apparatus according to the second embodiment differs from the receiving array antenna apparatus according to the first embodiment in that it basically has a plurality of demultiplexing sections 51 to 55 in the received signal pre-processing section. N The difference is that a demultiplexing unit group 5 having the above is arranged after the ADC group 3, but in other respects it has the same functions. Therefore, the following description will focus on the differences from the receiving array antenna apparatus according to the first embodiment. In FIG. 4, the same reference numerals as those in FIGS. 1 to 3 indicate the same or corresponding parts.

[0079] The receiving array antenna apparatus according to the second embodiment includes a plurality of branching sections 51 to 5 N The excitation coefficient generator in the DBF receiver 4 obtains corrected excitation coefficients for each sub-channel demultiplexed into the respective set bands. Multiple branching units 51 to 5 N (Hereinafter, unless there is a need to distinguish between them, the demultiplexing unit 5 n (explained as follows) are multiple ADCs 31 to 3 for each receiving system n. N They are electrically connected to each other.

[0080] Demultiplexer 5 n is the corresponding ADC3 n The digital reception signal and the digital calibration signal from the digital receiver 1 are each demultiplexed into predetermined frequency bands, that is, into the frequency bands of the plurality of sub-channels 1 to K, and the demultiplexed digital reception signals and digital calibration signals of the plurality of sub-channels 1 to K are output to the DBF receiver 4. 1 to K indicate the sub-channel numbers. k indicates the sub-channel number from 1 to K, and unless it is necessary to distinguish between the multiple sub-channels 1 to K, they will be described as sub-channel k. K represents a natural number greater than or equal to 2.

[0081] In FIG. 4, the demultiplexing units 51 to 5 N Each of them is connected to the DBF receiving unit 4 by a single line, but the demultiplexing units 51 to 5 N Digital received signals and digital calibration signals of multiple (K) sub-channels are input from each to the DBF receiver 4. In the second embodiment, the element antenna 1 n From branching section 5 n Each of the K branches distributed by the branching unit 5 is called a receiving branch. n The group of K receiving systems distributed by n This is called the receiving system that corresponds to this. That is, in the second embodiment, element antenna 1 n The receiving system n corresponding to element antenna 1 n Demultiplexing section 5 corresponding to n This means a group of K receiving systems distributed by

[0082] A plurality of excitation coefficient multiplication units 411 to 41 N Each is a branching section 5 n The excitation coefficient multiplication unit 41 corresponds to the K reception systems distributed by 11 ~41 1K、···、 41 N1 ~41 NK It consists of: Excitation coefficient multiplication unit 41 nk is the corresponding branching section 5 n The digital received signal from is multiplied by the corresponding corrected excitation coefficient to obtain the corrected digital received signal for each receiving system nk. Receiving system nk is element antenna 1 n Receiving system n to branching section 5 n is a receiving system that means a receiving system k distributed by

[0083] The complex adder 42 includes complex adders 421 to 422 corresponding to a plurality of sub-channels. K It consists of: Complex Adder 42 k is a plurality of excitation coefficient multipliers 41 for the corresponding sub-channel k. 1k ~41 Nk The corrected digital received signals obtained by each of the receiving systems nk are added together, that is, the corrected digital received signals are vector-combined to form a receiving beam for sub-channel k. That is, the complex adder 42 k adds corrected digital received signals of sub-channel k in the same frequency band in multiple receiving systems n.

[0084] The correlation detection unit 46 detects the correlation between the n The digital calibration signal is received for each of the plurality of receiving systems nk distributed by the above method, and for each sub-channel k, one receiving system from the plurality of receiving systems 11 to 1K, ..., N1 to NK is set as a reference receiving system mk, the digital calibration signal in the reference receiving system mk is set as a reference calibration signal, and a cross-correlation value for each receiving system nk with respect to the reference calibration signal for the digital calibration signal in the receiving system nk is obtained. The correlation detection unit 46 obtains, for each sub-channel k, a cross-correlation value in the reception system nk shown by the above equation (4) and an auto-correlation value in the reference reception system mk shown by the above equation (6).

[0085] The reference receiving system mk is a receiving system for the sub-channel k selected as the reference receiving system m. Although a reference reception system mk is selected for each sub-channel k, the reception system with the greatest reception power among the reception powers of the digital calibration signals in each of the multiple reception systems nk may be selected as the reference reception system, and the reference calibration signal in the reference reception system may be common to the digital calibration signals in all sub-channels k in reception system n.

[0086] That is, in the selected reference reception system m, the number of subchannels k may be set as the reference reception system mk, or one subchannel in the reference reception system m selected for all subchannels may be set as the reference reception system. In this case, one subchannel in the reference reception system m becomes the reference reception system mk.

[0087] The element-to-system error calculation unit 47 reads out the noise correlation value for the reference reception system mk stored in the noise correlation value storage unit 43 for each sub-channel k, and subtracts the read-out noise correlation value from the autocorrelation value for the reference reception system mk obtained by the correlation detection unit 46, as shown in the above equation (11), to obtain a corrected autocorrelation value (first function).

[0088] The element-system error calculation unit 47 obtains, for each sub-channel k, an element-system error, which is the relative difference between the cross-correlation values ​​for each receiving system n k obtained by the correlation detection unit 46 using the corrected autocorrelation value for the reference receiving system m k as a reference, as shown in the above equations (12) and (13) (second function).

[0089] The inter-element system error calculation unit 47 calculates the final inter-element system error for each sub-channel k by removing the inter-element system error due to the characteristic difference between the element antennas from the inter-element system error, which is the relative difference in cross-correlation value (third function). The element system error calculation unit 47 calculates, for each sub-channel k, a correction coefficient for correcting the element system error occurring within the device using the final element system error (fourth function). The correction coefficients for the respective receiving systems nk calculated by the inter-element system error calculation unit 47 are stored in the correction coefficient storage unit 44 .

[0090] A plurality of complex multipliers 481 to 488 constituting the excitation coefficient correction unit 48 N Each of the complex multipliers 48 corresponds to a sub-channel k. 11 ~48 1K、···、 48 N1 ~48 NK It consists of: Multiple complex multipliers 48 11 ~48 1K、···、 48N1 ~48 NK Each of the excitation coefficient multiplication units 41 calculates, for each sub-channel k, a predetermined excitation coefficient for each receiving system k stored in an excitation coefficient storage unit 45 and a correction coefficient for each receiving system k stored in a correction coefficient storage unit 44. 11 ~41 1K、···、 41 N1 ~41 NK The corrected excitation coefficients for each receiving system nk are obtained. Complex Multiplier 48 nk The excitation coefficient of the corresponding receiving system nk stored in the excitation coefficient storage unit 45 is multiplied by the correction coefficient of the corresponding receiving system nk stored in the correction coefficient storage unit 44 to generate the corresponding excitation coefficient multiplication unit 41. nk The corrected excitation coefficient of the receiving system nk corresponding to

[0091] In the receiving array antenna apparatus according to the second embodiment, the time delay in the time domain is expressed as follows: n Since this appears in the phase term in the frequency domain of the digital calibration signal distributed by

[0049] , the amount of delay can be estimated from the slope of the phase term in the frequency domain.

[0092] That is, the element-system error calculation unit 47 calculates the frequency response of the phase error between the systems using the error between the receiving systems for each sub-channel k obtained by the second function, calculates the delay amount in the time domain from the gradient of the phase with respect to the frequency, and applies the delay amount calculated for each receiving system n in the received signal pre-processing unit to perform temporal correction, thereby making it possible to correct the temporal delay difference in the time domain that occurs between the receiving systems n.

[0093] TIFF0007770619000017.tif15166

[0094] In the receiving array antenna apparatus according to the second embodiment, the inter-element system error calculation unit 47 obtains a corrected autocorrelation value by subtracting the noise correlation value for the reference receiving system mk from the autocorrelation value in the reference receiving system mk, and obtains an inter-element system error, which is the relative difference between the cross-correlation values ​​for each receiving system n obtained by the correlation detection unit 46 using the corrected autocorrelation value for each receiving system n as a reference, for each receiving system n, and obtains a correction coefficient by using the obtained inter-element system error, and the excitation coefficient correction unit 48 obtains a correction coefficient by using the correction coefficient obtained by the inter-element system error calculation unit 47 for each receiving system n and a preset excitation coefficient, so that even when the power ratio of the calibration signal to noise is small, the inter-element system error generated inside the apparatus, which is calculated from the relative difference between the receiving systems with respect to the reference receiving system mk, can be obtained with high accuracy, and as a result, the receiving beam for each sub-channel k can be calibrated with high accuracy.

[0095] Embodiment 3 A receiving array antenna apparatus according to the third embodiment will be described with reference to FIGS. The receiving array antenna apparatus according to the third embodiment differs from the receiving array antenna apparatus according to the first embodiment in that the noise correlation value |N' of the noise stored in the noise correlation value storage unit 43 is m [k]| 2 is acquired in advance by itself and stored in the noise correlation value storage unit 43, but in other respects it has the same functions.

[0096] That is, the receiving array antenna apparatus according to the third embodiment further comprises a calibration processing sequence control unit 6 in addition to the components of the receiving array antenna apparatus according to the first embodiment. Therefore, the following description will focus on the differences from the receiving array antenna apparatus according to the first embodiment. 5 and 6, the same reference numerals as those in FIGS. 1 to 3 indicate the same or corresponding parts.

[0097] The calibration processing sequence control unit 6 executes a noise power acquisition sequence for acquiring a noise correlation value before, or preferably immediately before, the DBF receiving unit 4 executes the calibration sequence, and obtains the noise correlation value |N' n [k]| 2is acquired and stored in the noise correlation value storage unit 43. The calibration sequence executed by the DBF receiver 4 includes a beamforming sequence and a corrected excitation coefficient generation sequence, similar to the receiving array antenna apparatus according to the first embodiment. The corrected excitation coefficient generation sequence is performed before the beamforming sequence.

[0098] The corrected excitation coefficient generation sequence is executed by the excitation coefficient generation unit in the DBF receiving unit 4 . The corrected excitation coefficient generation sequence is a cross-correlation value in the digital calibration signal for each receiving system n and a noise correlation value |N´ for the noise of receiving system n stored by the noise power acquisition sequence executed before the calibration sequence is executed. n [k]| 2 The noise correlation value |N' for the noise of the receiving system m selected by the correlation detection unit 46 as the reference receiving system is m [k]| 2 the inter-element system error which is the relative difference between the cross-correlation values ​​for each n-th receiving system using the inter-element system error, the correction coefficient for each n-th receiving system using the inter-element system error, and the corrected excitation coefficient for each n-th receiving system using the correction coefficient and a preset excitation coefficient for each n-th receiving system.

[0099] The beam forming sequence is a sequence in which corrected digital receive signals for n receiving systems are obtained using corrected excitation coefficients for n receiving systems obtained by the corrected excitation coefficient generation sequence, and a calibrated receive beam is formed by adding the obtained corrected digital receive signals for n receiving systems.

[0100] The noise power acquisition sequence is a sequence in which a noise power value is acquired, a noise correlation value of the noise is calculated based on the acquired noise power, and the calculated noise correlation value is stored in the noise correlation value storage unit 43 . The noise power is acquired by a plurality of element antennas 11 to 1 NIn a state where none of the receivers receives the actual communication signal (transmission signal) from the ground station and the calibration signal 110 from the calibration ground station 100, the receiving array antenna device is operated, and the power of the signal output from the received signal pre-processing unit, that is, the ADCs 31 to 3 N The power value of the signal output from each is obtained, and the obtained result is used as the noise power N' n Let [k].

[0101] The noise correlation value of noise is calculated by the noise power N' of each receiving system n. n The correlation value for [k], i.e., the noise correlation value |N´ n [k]| 2 This is the calculation. The noise correlation value |N' stored in the noise correlation value storage unit 43 n [k]| 2 is the noise correlation value |N' for the receiving system m selected as the reference receiving system by the correlation detection unit 46. m [k]| 2 is the noise correlation value |N' for the noise of the reference receiving system m read out to the element-to-system error calculation unit 47. m [k]| 2 This becomes:

[0102] Just before executing the calibration sequence, the noise power acquisition sequence is executed to acquire the power value of the signal output from the received signal pre-processing unit, and the acquired noise power N' n [k] gives the noise correlation value |N´ for each receiving system n n [k]| 2 and obtain the noise correlation value |N´ for the noise of the reference receiving system m. m [k]| 2 Since the noise correlation value is obtained in the ambient environment and in the state of the equipment in the received signal pre-processing unit immediately before the calibration sequence is executed, the error between element systems can be calculated with high accuracy by the error between element systems calculation unit 47, and as a result, the receive beam can be calibrated with higher accuracy.

[0103] The receiving array antenna apparatus according to the third embodiment has the same effects as the receiving array antenna apparatus according to the first embodiment. In addition, since the noise power acquisition sequence is executed to obtain a noise correlation value for each n receiving system before executing a calibration sequence including a corrected excitation coefficient generation sequence and a beam forming sequence, the inter-element system error calculation unit 47 can calculate the inter-element system error with high accuracy, and as a result, the calibration accuracy for the receiving beam is further improved.

[0104] The receiving array antenna apparatus according to the second embodiment may be configured to further include the calibration processing sequence control unit 6 in the receiving array antenna apparatus according to the third embodiment. That is, the receiving array antenna apparatus according to the second embodiment further includes a calibration processing sequence control unit 6, and the calibration processing sequence control unit 6 controls the DBF receiving unit 4 to perform the calibration sequence described in the second embodiment before, or preferably immediately before, the DBF receiving unit 4 executes the calibration sequence. N The noise correlation value |N' is obtained by executing the noise power acquisition sequence for acquiring the noise correlation value in a state where neither the actual communication signal (transmission signal) from the ground station nor the calibration signal 110 from the calibration ground station 100 is received. n [k]| 2 is stored in the noise correlation value storage unit 43.

[0105] Embodiment 4 A receiving array antenna apparatus according to the fourth embodiment will be described with reference to FIGS. The receiving array antenna apparatus according to the fourth embodiment differs from the receiving array antenna apparatus according to the second embodiment in that the DBF receiving section 4 further includes a sub-channel selecting section 410, but otherwise has the same functions. Therefore, the following description will focus on the differences from the receiving array antenna apparatus according to the second embodiment. 7 and 8, the same reference numerals as those in FIGS. 1 to 4 denote the same or corresponding parts.

[0106] As a representative example, the receiving array antenna apparatus according to the second embodiment stores the noise correlation value for the receiving system for each sub-channel k in the digital calibration signal in the noise correlation value storage unit 43 before the corrected excitation coefficient generation sequence in the calibration sequence. In contrast, the receiving array antenna apparatus according to the fourth embodiment performs the corrected excitation coefficient generation sequence simultaneously with the multiple element antennas 11 to 1 N The noise correlation value for the reference receiving system m selected by the correlation detection unit 46 from the corresponding receiving systems is stored in the noise correlation value storage unit 43 .

[0107] The sub-channel selector 410 selects the reference reception system m selected by the correlation detector 46, as shown in FIG. n The DBF receiver 4 receives a digital calibration signal having a plurality of (K) subchannels and an empty subchannel from which an empty subchannel is selected, obtains the power value of the selected empty subchannel, and calculates the obtained result as the noise power N' n [k], and the noise power is N' n The correlation value for [k], i.e., the noise correlation value |N´ n [k]| 2 Calculate the noise correlation value |N' in the reference receiving system m n [k]| 2 to the noise correlation value storage unit 43.

[0108] The empty sub-channel in the digital calibration signal selected by the sub-channel selector 410 is a sub-channel to which no calibration signal is input, and only the noise components in the received signal pre-processing section are input to the received signal pre-processing section, i.e., the demultiplexing section 5 n It is output from and can be obtained as a noise power value.

[0109] As shown in FIG. 8, the empty subchannel in the digital calibration signal selected by the subchannel selection unit 410 is either an empty subchannel of a frequency adjacent to the subchannel to which the digital calibration signal is input, or an empty subchannel of a frequency away from the subchannel to which the digital calibration signal is input, in order to take into account leakage of the digital calibration signal, and to position where there is no influence of leakage of the digital calibration signal.

[0110] The correlation detection unit 46 is connected to the branching unit 5 n The digital calibration signal distributed by the above is received by n receiving systems, and one of the n receiving systems is designated as the reference receiving system m. The correlation detection unit 46 uses each of the multiple subchannels of the receiving system selected as the reference receiving system m as a reference calibration signal in the reference receiving system mk, and obtains a cross-correlation value for each receiving system nk with respect to the reference calibration signal for the digital calibration signal in the receiving system nk.

[0111] The sub-channel selector 410 selects one empty sub-channel from the digital calibration signal in the reference reception system m selected by the correlation detector 46, and calculates the power value of the selected empty sub-channel as noise power N' n Obtained as [k]. The sub-channel selector 410 selects the acquired noise power N' n [k] to noise correlation value |N´ n [k]| 2 Calculate the noise correlation value |N' in the reference receiving system m n [k]| 2 to the noise correlation value storage unit 43.

[0112] The element-to-system error calculation unit 47 reads out the noise correlation value for the reference reception system m, which is obtained by the subchannel selection unit 410 and stored in the noise correlation value storage unit 43, and subtracts the read noise correlation value from the autocorrelation value in the reference reception system mk, obtained by the correlation detection unit 46, for each subchannel in the reference reception system m to obtain a corrected autocorrelation value (first function). For each sub-channel k in the reference receiving system m, the noise correlation value subtracted from the autocorrelation value in the reference receiving system mk is the same.

[0113] The element system error calculation unit 47 obtains, for each sub-channel k, an element system error, which is the relative difference between the cross-correlation values ​​for each receiving system nk obtained by the correlation detection unit 46 using the corrected autocorrelation value for the reference receiving system mk as a reference (second function).

[0114] The inter-element system error calculation unit 47 calculates the final inter-element system error by removing the inter-element system error due to the characteristic difference between the element antennas from the inter-element system error for each sub-channel k (third function). The element system-to-element system error calculation unit 47 calculates a correction coefficient for correcting the element system-to-element system error using the final element system-to-element system error for each sub-channel k (fourth function). The correction coefficients for the respective receiving systems nk calculated by the inter-element system error calculation unit 47 are stored in the correction coefficient storage unit 44 .

[0115] The excitation coefficient correction unit 48, like the excitation coefficient correction unit 48 in the receiving array antenna apparatus according to the second embodiment, calculates the excitation coefficient multiplication unit 41 for each sub-channel k using the preset excitation coefficient for each receiving system k stored in the excitation coefficient storage unit 45 and the correction coefficient for each receiving system k stored in the correction coefficient storage unit 44. nk The corrected excitation coefficients for each receiving system nk are obtained.

[0116] The receiving array antenna apparatus according to the fourth embodiment has the same effects as the receiving array antenna apparatus according to the second embodiment. In addition, the sub-channel selector 410 obtains the cross-correlation value for each receiving system n k by the correlation detector 46, and simultaneously acquires the noise correlation value in the reference receiving system m. Therefore, errors between element systems that occur inside the apparatus can be obtained more accurately, and as a result, the calibration accuracy for the receiving beam for each sub-channel k is further improved.

[0117] Embodiment 5 A receiving array antenna system according to the fifth embodiment will be described with reference to FIG. The receiving array antenna system according to the fifth embodiment includes a receiving array antenna device and a control station 200.

[0118] The receiving array antenna device in the receiving array antenna system according to embodiment 5 differs from the receiving array antenna device according to embodiment 2 in that it is provided with a tracking telemetry command device (hereinafter referred to as TTC) 7 instead of the inter-element system error calculation unit 47, but otherwise has the same functions. Therefore, the following description will focus on the differences from the receiving array antenna apparatus according to the second embodiment and control station 200. In FIG. 9, the same reference numerals as those in FIGS. 1 to 4 indicate the same or corresponding parts.

[0119] The received signal pre-processing unit including the receiver group 2, ADC group 3, and demultiplexer group 5 in the receiving array antenna apparatus is the same as the received signal pre-processing unit in the receiving array antenna apparatus according to the second embodiment, and therefore description thereof will be omitted. The function of the correlation detection section 46 of the DBF receiver 4 in the receiving array antenna apparatus is the same as the function of the correlation detection section 46 of the DBF receiver 4 in the receiving array antenna apparatus according to the second embodiment, and therefore description thereof will be omitted.

[0120] The TTC 7 in the receiving array antenna device transmits to the control station 200, which is equipped with an arithmetic unit 220 having an inter-element system error calculation unit 223, cross-correlation values ​​for each receiving system nk obtained by the correlation detection unit 46 of the DBF receiving unit 4 in the receiving array antenna device, receives correction coefficients calculated based on the cross-correlation values ​​transmitted from the control station 200, and provides the correction coefficients to the excitation coefficient correction unit 48 in the DBF receiving unit 4.

[0121] That is, the TTC 7 receives the cross-correlation value in the receiving system nk and the auto-correlation value in the reference receiving system mk for each sub-channel k in the digital calibration signal from the correlation detector 46 . The TTC 7 telemetrizes the cross-correlation value in the receiving system nk and the auto-correlation value in the reference receiving system mk for each sub-channel k, and transmits the telemetrized signal 310 to the control station 200 via the TTC transmitting / receiving antenna 8 .

[0122] The control station 200 receives the telemetrized signal 310 via the control station transmitting and receiving antenna 210, converts the telemetrized signal 310 into a digital signal indicating the cross-correlation value in the receiving system nk and the auto-correlation value in the reference receiving system mk, calculates a correction coefficient for each receiving system nk using the calculation device 220, telemetrizes the correction coefficient for each receiving system nk, and transmits the telemetrized signal 320 to the receiving array antenna device via the control station transmitting and receiving antenna 210. Upon receiving the telemetry signal 310, the control station 200 calculates a correction coefficient and transmits the telemetry signal 320 to the receiving array antenna device via the control station transmitting and receiving antenna 210.

[0123] The arithmetic unit 220 in the control station 200 includes a noise correlation value storage unit 221 , a correction coefficient storage unit 222 , and an element-to-system error calculation unit 223 . The noise correlation value storage unit 221 stores noise correlation values ​​(correlation values ​​due to noise power) for each sub-channel k in each receiving system n in a received signal pre-processing unit including the receiver group 2, ADC group 3, and demultiplexer group 5 in the receiving array antenna device. The noise correlation value is a value obtained by measuring or calculating the noise component, or in the fifth embodiment, the noise power (amplitude of the noise component) in advance.

[0124] The element-system error calculation unit 223 obtains the cross-correlation value in the received reception system nk and the autocorrelation value in the reference reception system mk, reads out the noise correlation value for the reference reception system mk stored in the noise correlation value storage unit 221 for each sub-channel k, and obtains a corrected autocorrelation value by subtracting the noise correlation value for the reference reception system mk from the autocorrelation value in the reference reception system mk, as shown in the above equation (11) (first function).

[0125] The element-system error calculation unit 223 obtains, for each sub-channel k, an element-system error, which is the relative difference in the cross-correlation value for each receiving system k using the corrected autocorrelation value for the reference receiving system mk as a reference, as shown in the above equations (12) and (13) (second function).

[0126] The inter-element system error calculation unit 223 calculates the final inter-element system error by removing the inter-element system error due to the characteristic difference between the element antennas from the inter-element system error for each sub-channel k (third function). The inter-element system error calculation unit 223 calculates, for each sub-channel k, a correction coefficient for correcting the inter-element system error using the final inter-element system error (fourth function).

[0127] The correction coefficients for the respective reception systems nk calculated by the inter-element system error calculation unit 223 are stored in the correction coefficient storage unit 222 . Inter-element system error calculation section 223 has substantially the same function as inter-element system error calculation section 47 of DBF receiver section 4 in the receiving array antenna apparatus according to the second embodiment.

[0128] The control station 200 converts the correction coefficients for each receiving system nk stored in the correction coefficient storage unit 222 into a telemetry signal 320 and transmits it to the receiving array antenna device via the control station transmitting and receiving antenna 210. When the TTC 7 receives the telemetry signal 320 via the TTC transmitting / receiving antenna 8, it converts the telemetry signal 320 into a digital signal indicating a correction coefficient for each receiving system nk, and provides it to the excitation coefficient correction unit 48 of the DBF receiving unit 4. The complex multiplier 48 corresponding to the sub-channel k constituting the excitation coefficient correction unit 48 11 ~48 1K、···、 48 N1 ~48 NK Each of them is multiplied by an excitation coefficient multiplier 41 using a preset excitation coefficient for each receiving system k stored in an excitation coefficient storage unit 45 and a correction coefficient for each receiving system k from the TTC 7 for each sub-channel k. 11 ~41 1K、···、 41 N1 ~41 NKThe corrected excitation coefficients for each receiving system nk are obtained.

[0129] Excitation coefficient multiplication unit 41 of DBF receiving unit 4 in the receiving array antenna device 11 ~41 1K、···、 41 N1 ~41 NK A plurality of excitation coefficient multiplication units 411 to 41 N Functions of complex adders 421-42 K The function of the complex adder 42 configured as above is the same as that of the excitation coefficient multiplication units 411 to 41 of the DBF receiving unit 4 in the receiving array antenna apparatus according to the second embodiment. N The function of the complex adder is the same as that of the complex adder, so the explanation will be omitted.

[0130] Although the TTC transmitting / receiving antenna 8 is an antenna for both transmission and reception, it may be a separate antenna for transmission and reception, i.e., a transmitting antenna and a receiving antenna. Furthermore, the control station transmitting / receiving antenna 210 is an antenna for both transmission and reception, but it may be a separate antenna for transmission and reception, i.e., a transmitting antenna and a receiving antenna.

[0131] The receiving array antenna system according to the fifth embodiment reduces the computational load of the DBF receiver 4 in the receiving array antenna device, and can accurately calculate the inter-element system error, which is the relative difference between the receiving systems with respect to the reference receiving system mk, even when the power ratio of the calibration signal to noise between the digital calibration signal and the noise component superimposed in the received signal pre-processing unit in the receiving array antenna device is small. As a result, the receiving beam for each sub-channel k can be calibrated with high accuracy.

[0132] Note that the receiving array antenna apparatus according to the first embodiment may be configured to include a TTC 7 instead of the inter-element system error calculation unit 47 in the receiving array antenna apparatus according to the first embodiment, similar to the receiving array antenna apparatus in the receiving array antenna system according to the fifth embodiment, and may be configured to transmit cross-correlation values ​​for each of the n receiving systems obtained by the correlation detection unit 46 of the DBF receiver 4 to the control station 200, and receive correction coefficients calculated based on the cross-correlation values ​​transmitted from the control station 200.

[0133] In this case, the noise correlation value stored in the noise correlation value storage unit 221 of the arithmetic device 220 in the control station 200 is the same as the noise correlation value stored in the noise correlation value storage unit 43 of the DBF receiver 4 in the receiving array antenna apparatus according to embodiment 1, the function of the inter-element system error calculation unit 223 of the arithmetic device 220 in the control station 200 is the same as the function of the inter-element system error calculation unit 47 of the DBF receiver 4 in the receiving array antenna apparatus according to embodiment 1, and the correction coefficient stored in the correction coefficient storage unit 222 of the arithmetic device 220 in the control station 200 is the same as the correction coefficient stored in the correction coefficient storage unit 44 of the DBF receiver 4 in the receiving array antenna apparatus according to embodiment 1.

[0134] It should be noted that the embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted. [Industrial Applicability]

[0135] A receiving array antenna device according to the present disclosure is suitable for a satellite repeater in a satellite communication system. [Explanation of symbols]

[0136] 1 Array antenna, 11~1 N Element antenna, 2 receiver group, 21~2 N Receiver, 3 ADC groups, 31~3 N ADC, 4 DBF receiver, 411-41 NExcitation coefficient multiplication unit, 42 complex adder, 43 noise correlation value memory unit, 44 correction coefficient memory unit, 45 excitation coefficient memory unit, 46 correlation detection unit, 47 element system error calculation unit, 48 excitation coefficient correction unit, 481 to 48 N Complex multiplier, 410 Sub-channel selector, 5 Demultiplexer group, 51~5 N Branching unit, 6 calibration processing sequence control unit, 7 TTC, 200 control station, 220 calculation unit.

Claims

1. a plurality of excitation coefficient multiplication units each receiving a digital received signal corresponding to a received signal received by each of the plurality of element antennas in an array antenna having a plurality of element antennas for each reception system corresponding to the plurality of element antennas, and each multiplying the received digital received signal by a corrected excitation coefficient to obtain a corrected digital received signal; a complex adder that adds the corrected digital received signals obtained by the plurality of excitation coefficient multipliers to form a received beam; a correlation detection unit that receives digital calibration signals based on calibration signals received by each of the plurality of element antennas for each of the plurality of element antennas, and obtains a cross-correlation value for each of the plurality of reception systems with respect to the digital calibration signal in the plurality of reception systems with respect to the digital calibration signal in a reference reception system that is one of the plurality of reception systems; an element-system error calculation unit that obtains a corrected autocorrelation value by subtracting a noise correlation value for noise in the reference reception system extending from an element antenna to a correlation detection unit from the autocorrelation value in the reference reception system, obtains an element-system error that is a relative difference between the cross-correlation values ​​for each reception system obtained by the correlation detection unit using the corrected autocorrelation value for each reception system for each of the plurality of reception systems, and obtains a correction coefficient using the obtained element-system error; an excitation coefficient correction unit that obtains a corrected excitation coefficient for the excitation coefficient multiplication unit using a correction coefficient obtained by the element-to-system error calculation unit for each of the plurality of reception systems and a preset excitation coefficient for each of the reception systems; A receiving array antenna device comprising:

2. the digital received signals received by the complex adder for each reception system are digital received signals having a plurality of sub-channels obtained by dividing the digital received signals for each reception system according to the received signals received by each of the plurality of element antennas into predetermined frequency bands, the digital calibration signals received by the correlation detection unit for each reception system are digital calibration signals of a plurality of sub-channels obtained by dividing the digital calibration signals for each reception system based on the calibration signals received by each of the plurality of element antennas into predetermined frequency bands; 2. The receiving array antenna device according to claim 1.

3. 3. The receiving array antenna apparatus according to claim 2, further comprising a subchannel selector that selects an empty subchannel from a digital calibration signal having a plurality of subchannels in a reference receiving system, and obtains a noise correlation value for noise in the reference receiving system, which is used by the inter-element system error calculator, from a power value of the selected empty subchannel.

4. 4. The receiving array antenna apparatus according to claim 3, wherein the selected empty sub-channel is an empty sub-channel of a frequency adjacent to a sub-channel to which a digital calibration signal is input.

5. 4. The receiving array antenna apparatus according to claim 3, wherein the selected empty subchannel is an empty subchannel at a frequency position where there is no influence of leakage of a digital calibration signal from a subchannel to which a digital calibration signal is input.

6. 6. The receiving array antenna device according to claim 1, wherein the correction coefficient for each receiving system obtained by the inter-element system error calculation unit using the inter-element system error is a correction coefficient obtained by using the inter-element system error obtained by removing the inter-element system error due to a characteristic difference between the plurality of element antennas from the inter-element system error, which is the relative difference between the cross-correlation values ​​for each receiving system obtained by the correlation detection unit using the corrected autocorrelation value for each receiving system as a reference.

7. 6. The receiving array antenna apparatus according to claim 1, further comprising: a calibration processing sequence control unit that executes a noise power acquisition sequence to acquire a noise correlation value based on noise power in the receiving systems corresponding to each of the plurality of element antennas in a state in which the plurality of element antennas do not receive a digital calibration signal and a digital calibration signal, before executing a calibration sequence including a corrected excitation coefficient generation sequence in which the correlation detection unit obtains a cross-correlation value, the inter-element system error calculation unit obtains a correction coefficient, and the excitation coefficient correction unit obtains a corrected excitation coefficient, and a beam forming sequence in which the plurality of excitation coefficient multiplication units obtain corrected digital received signals and the complex adder forms a receive beam.

8. 6. The receiving array antenna device according to claim 2, wherein the inter-element system error calculation unit calculates, for each sub-channel, a frequency response of the inter-element system error, which is a relative difference between the cross-correlation values ​​for each sub-channel obtained by the correlation detection unit with the corrected autocorrelation value as a reference, and calculates a delay amount in the time domain from a slope of the phase with respect to the frequency.

9. a received signal preprocessing unit that converts received signals and calibration signals, which are radio waves received by each of a plurality of element antennas in an array antenna having a plurality of element antennas, into a baseband frequency band, digitally converts the analog received signals and analog calibration signals, which are electrical signals, and then outputs the digitally converted digital received signals and digital calibration signals for each reception system corresponding to each of the plurality of element antennas; a beam forming unit that obtains corrected digital received signals by using corrected excitation coefficients for the corresponding receiving systems from the digital received signals for each receiving system output from the received signal preprocessing unit, and adds the obtained corrected digital received signals for each receiving system to form a receive beam; an excitation coefficient generation unit that obtains a cross-correlation value for each receiving system between the digital calibration signal for each receiving system output from the received signal pre-processing unit in a reference receiving system that is one of the plurality of receiving systems and the digital calibration signal for each receiving system output from the received signal pre-processing unit, obtains a corrected autocorrelation value by subtracting a noise correlation value for noise in the reference receiving system from the autocorrelation value in the reference receiving system, obtains an inter-element system error that is a relative difference in the cross-correlation value for each receiving system using the corrected autocorrelation value as a reference for each receiving system, obtains a correction coefficient using the obtained inter-element system error, and obtains the corrected excitation coefficient for each receiving system to be sent to the beam forming unit using the correction coefficient for each receiving system and a preset excitation coefficient for each receiving system; A receiving array antenna device comprising:

10. a plurality of excitation coefficient multipliers for receiving digital reception signals from reception signals received by each of the plurality of element antennas in an array antenna having a plurality of element antennas, each of which receives a digital reception signal for each of reception systems corresponding to the plurality of element antennas, and multiplying the received digital reception signal by a corrected excitation coefficient to obtain a corrected digital reception signal; a complex adder for adding the corrected digital reception signals obtained by the plurality of excitation coefficient multipliers to form a reception beam; and a reception system for receiving digital calibration signals from calibration signals received by each of the plurality of element antennas, each of which receives a digital calibration signal for each of the reception systems corresponding to the plurality of element antennas, and which receives the digital calibration signal for each of the reception systems corresponding to the plurality of element antennas, and which obtains a corrected digital reception signal; a correlation detection unit that obtains a cross-correlation value for each receiving system between a digital calibration signal in a reference receiving system and a digital calibration signal in the plurality of receiving systems; a tracking telemetry command device that transmits the cross-correlation value for each receiving system obtained by the correlation detection unit and the autocorrelation value in the reference receiving system via a TTC transmitting antenna and receives a correction coefficient for each receiving system via a TTC receiving antenna; and an excitation coefficient correction unit that obtains a corrected excitation coefficient for the excitation coefficient multiplier for each of the plurality of receiving systems using the correction coefficient received by the tracking telemetry command device and a preset excitation coefficient for each receiving system; a control station comprising a calculation device that receives cross-correlation values ​​for each receiving system from the tracking telemetry command device in the receiving array antenna device and auto-correlation values ​​for the reference receiving system via a control station receiving antenna, subtracts a noise correlation value for noise in the reference receiving system extending from an element antenna to a correlation detection unit from the received auto-correlation value in the reference receiving system to obtain a corrected auto-correlation value, obtains inter-element system errors that are relative differences in the received cross-correlation values ​​for each receiving system using the corrected auto-correlation value for each receiving system for each receiving system, and obtains correction coefficients using the obtained inter-element system errors, and transmits the correction coefficients for each receiving system obtained by the calculation device via a control station transmitting antenna; A receiving array antenna system comprising:

11. 1. A calibration method for a receiving array antenna device, comprising: multiplying digital received signals in a plurality of receiving systems corresponding to each of the plurality of element antennas in an array antenna by corrected excitation coefficients corresponding to the plurality of receiving systems, and then adding the multiplication results to obtain a receiving beam, the method comprising: a correlation detection unit obtaining a cross-correlation value for each of the plurality of receiving systems with respect to a digital calibration signal in a reference receiving system, which is one of the plurality of receiving systems, for the digital calibration signals received by the plurality of element antennas; an inter-element system error calculation unit subtracting a noise correlation value for the reference receiving system from an autocorrelation value for the digital calibration signal in the reference receiving system to obtain a corrected autocorrelation value; the element-system error calculation unit calculates a relative difference with respect to each cross-correlation value for each of the reception systems, using the corrected autocorrelation value as a reference, to obtain an element-system error for each of the reception systems, and obtains a correction coefficient based on the obtained element-system error; an excitation coefficient correction unit generating the corrected excitation coefficients based on correction coefficients for each receiving system and preset excitation coefficients; A method for calibrating a receiving array antenna apparatus comprising:

12. a step of obtaining a cross-correlation value for each of a plurality of receiving systems, for digital calibration signals received by a plurality of element antennas, between a digital calibration signal in a reference receiving system, which is one of a plurality of receiving systems corresponding to each of the plurality of element antennas; a step of subtracting a noise correlation value for the reference receiving system from an autocorrelation value for the digital calibration signal in the reference receiving system to obtain a corrected autocorrelation value; a step of calculating a relative difference based on the corrected autocorrelation value for each cross-correlation value for each receiving system to obtain an inter-element system error for each receiving system, and obtaining a correction coefficient based on the obtained inter-element system error; a step of generating corrected excitation coefficients based on correction coefficients for each receiving system and preset excitation coefficients; A calibration program for a receiving array antenna device that causes a computer to execute the above.

13. a step of obtaining a cross-correlation value for each of a plurality of receiving systems, for digital calibration signals received by a plurality of element antennas, between a digital calibration signal in a reference receiving system, which is one of a plurality of receiving systems corresponding to each of the plurality of element antennas; a step of subtracting a noise correlation value for the reference receiving system from an autocorrelation value for the digital calibration signal in the reference receiving system to obtain a corrected autocorrelation value; a step of calculating a relative difference based on the corrected autocorrelation value for each cross-correlation value for each receiving system to obtain an inter-element system error for each receiving system, and obtaining a correction coefficient based on the obtained inter-element system error; a step of generating corrected excitation coefficients based on correction coefficients for each receiving system and preset excitation coefficients; A recording medium storing a program that causes a computer to execute the above.

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