Angle error detection device

Abstract

To provide a technique for automatically aligning a gain of an automatic gain control part for a sum signal and a differential signal provided in an angle error detection device for performing angle error detection of an antenna used for tracking reception.SOLUTION: In an angle error detection device 12 for detecting an angle error of a reception direction of a frequency signal from a tracked object, first automatic gain control parts 32a, 432a amplify a sum signal of frequency signals received at different positions of an antenna 11 to a preset signal level. Second automatic gain control parts 32b, 432b amplify a differential signal on the basis of a result after a sum signal is supplied temporarily and operation for aligning a gain to that of the first automatic gain control parts is performed. An angle error detection part 41 detects an angle error on the basis of the amplified differential signal. A signal switching part 36 switches a signal supplied to the second automatic gain control parts between the sum signal and the differential signal.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a technique for detecting an angular error of an antenna with respect to a tracking target.

Background Art

[0002] In a receiving system that receives a communication signal, which is a frequency signal output from a tracking target such as a communication satellite or an aircraft, based on the result of detecting a deviation (angular error) of the receiving direction of the communication signal with respect to the front direction of the antenna, there is a system (tracking receiving system) that can change the direction of the antenna so that the receiving direction of the communication signal aligns with the front direction of the antenna.

[0003] As a method for detecting an angular error, a method is known in which the amplitude difference of received communication signals is obtained at two openings (first receiving unit, second receiving unit) provided in the antenna and having different arrangement positions, and the angular error is obtained based on this amplitude difference. In this method, calculations for obtaining the angular error are performed using the sum signal A + B and the difference signal A - B of the communication signal A received by the first receiving unit and the communication signal B received by the second receiving unit.

[0004] On the other hand, the signal level of the signal received by the antenna changes due to factors such as the magnitude of the angular error and weather conditions. Therefore, the sum signal and the difference signal are amplified using an automatic gain control unit (hereinafter also referred to as AGC (Automatic Gain Controller)) and then used for detecting the angular error. However, when the sum signal and the difference signal are amplified using different AGCs, the difference in the amplification characteristics of each AGC may become a factor that hinders the accurate calculation of the angular error.

[0005] Here, Patent Document 1 describes a gain difference automatic correction circuit that automatically tracks a satellite using an antenna that receives radio waves transmitted from the satellite while receiving the radio waves. This gain difference automatic correction circuit uses the AGC voltage used for controlling the AGC amplifier for the sum signal as the AGC voltage used for controlling the AGC amplifier for the difference signal. At this time, based on the result of comparing the levels of the amplified sum signal and difference signal, the AGC voltage of the AGC amplifier for the difference signal is corrected.

[0006] However, the gain difference automatic correction circuit described in Patent Document 1 has a problem in that it is necessary to convert the comparison result of the above levels into a correction voltage using a level converter, which takes time and effort to grasp and manage the conversion characteristics of the level converter.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention has been made under such circumstances, and provides a technique for automatically aligning the gains of the automatic gain control units for the sum signal and the difference signal provided in an angle error detection device that detects the angle error of an antenna used for tracking reception.

Means for Solving the Problems

[0009] First An angle error detection device, based on a frequency signal from a tracking target, a first received signal received by a first receiving unit of an antenna, and a second received signal received by a second receiving unit having a different reception position in the antenna from the first receiving unit, in an angle error detection device that detects an angle error of a reception direction of the frequency signal with respect to a front direction of the antenna. A first variable amplifier and a first control unit that outputs a control value for controlling the signal level of a signal output from the first variable amplifier, and a first automatic gain control unit for amplifying a sum signal obtained from the first received signal and the second received signal to a preset signal level. A second variable amplifier and a second control unit that outputs a control value for controlling the signal level of a signal output from the second variable amplifier, and a second automatic gain control unit for amplifying a difference signal obtained from the first received signal and the second received signal with the same gain as the first automatic gain control unit. An angle error detection unit that detects the angle error based on the difference signal amplified by the second automatic gain control unit. An operation unit that performs an operation to align the gain of the second automatic gain control unit with the gain of the first automatic gain control unit based on the result of supplying the sum signal to the second automatic gain control unit. A signal switching unit that switches the signal supplied to the second automatic gain control unit so that the sum signal is supplied during a first period in which an operation for aligning the gain is performed, and the difference signal is supplied during a second period in which the angle error is detected. 、 The operation unit During the first period, the sum signal is supplied to the second automatic gain control unit, and is determined based on the sum signal output from the second variable amplifier and the preset signal level. The control value of the second control unit at which the signal level of the sum signal output from the second variable amplifier becomes the preset signal level, and the sum signal is supplied to the first automatic gain control unit. A correction value acquisition unit that acquires a correction value for correcting the deviation from the control value of the first control unit at which the signal level of the sum signal output from the first variable amplifier becomes the preset signal level; An addition unit that adds the correction value acquired by the correction value acquisition unit to the control value of the first control unit; During the first period, the second control unit is connected to the second variable amplifier, and during the second period, the addition unit is connected to the second variable amplifier to switch the control value input to the second variable amplifier. A control value switching unit; Characterized by the above.

[0010] In addition, the second angle error detection device is an angle error detection device that detects an angle error of the reception direction of the frequency signal with respect to the front direction of the antenna based on a first reception signal received by a first reception unit of the antenna and a second reception signal received by a second reception unit having a different reception position in the antenna from the first reception unit. In, A first variable amplifier and a first control unit that outputs a control value for controlling the signal level of the signal output from the first variable amplifier, and a first automatic gain for amplifying the sum signal obtained from the first reception signal and the second reception signal to a preset signal level. Control unit; A second variable amplifier and a second control unit that outputs a control value for controlling the signal level of the signal output from the second variable amplifier, and a second automatic gain for amplifying the difference signal obtained from the first reception signal and the second reception signal with the same gain as the first automatic gain control unit. Control unit; An angle error detection unit that detects the angle error based on the difference signal amplified by the second automatic gain control unit; An operation unit that performs an operation to align the gain of the second automatic gain control unit with the gain of the first automatic gain control unit based on the result of supplying the sum signal to the second automatic gain control unit; A signal switching unit that switches the signal supplied to the second automatic gain control unit so as to supply the sum signal during a first period in which an operation for equalizing the gains is performed and to supply the difference signal during a second period in which the angle error is detected. The operation unit is a disconnect switch that performs an operation of disconnecting the second control unit from the second variable amplifier. During the first period, when the sum signal is supplied to the second automatic gain control unit and the sum signal output from the second variable amplifier reaches the preset signal level, the signal switching unit switches the signal supplied to the second automatic gain control unit to the difference signal to start the second period. The operation unit performs an operation of aligning the gain of the second automatic gain control unit with the gain of the first automatic gain control unit when it is assumed that the level of the sum signal supplied when the preset signal level was output is maintained, by performing the disconnecting operation in accordance with the start of the second period to fix the gain of the second variable amplifier.

Advantages of the Invention

[0011] According to the present invention, when detecting an angle error while controlling the signal levels of a sum signal and a difference signal using mutually different automatic gain control units, an operation is performed to align with the gain of the automatic gain control unit on the sum signal side by supplying the sum signal to the automatic gain control unit on the difference signal side. As a result, the gains of the two different automatic gain control units can be automatically aligned.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0013] FIG. 1 shows a configuration example of a tracking reception system 1 equipped with an angle error detection device according to an embodiment of the present invention. The following distance - tracking reception system 1 includes an antenna 11 that receives a communication signal (frequency signal) output from a target to be tracked, an antenna drive mechanism 15 that changes the orientation of this antenna 11, an angle error detection device 12 that detects a deviation (angle error) in the reception direction of the communication signal with respect to the front direction of the antenna 11 based on the sum signal and difference signal of the communication signal acquired from the antenna 11, a distance - tracking control unit 13 that determines the drive direction and drive amount of the antenna 11 based on the angle error detected by the angle error detection device 12, and an antenna drive unit 14 that performs drive control of the antenna drive mechanism 15 based on the drive direction and drive amount determined by the distance - tracking control unit 13.

[0014] FIG. 2 is a block diagram showing the antenna 11 and the angle error detection device 12 included in the above - mentioned distance - tracking reception system 1. For example, the target 8 to be tracked shown in FIG. 2 outputs a communication signal having a preset frequency. This communication signal includes a baseband signal modulated by a carrier wave having the preset frequency.

[0015] The antenna 11 includes a first reception unit 2a and a second reception unit 2b with different reception positions. When performing azimuth - angle measurement, the first reception unit 2a and the second reception unit 2b are arranged at different positions in the horizontal direction. When performing elevation - angle measurement, the first reception unit 2a and the second reception unit 2b are arranged at different positions in the elevation direction.

[0016] The communication signals (first reception signal A, second reception signal B) received by these first and second reception units 2a, 2b are output as a sum signal A + B and a difference signal A - B respectively, for example, after passing through addition units 21, 22 provided on the antenna 11 side. In the example shown in FIG. 2, the case of obtaining the sum signal and difference signal on the antenna 11 side has been described. However, the addition units 21, 22 for obtaining these signals may be provided on the angle error detection device 12 side.

[0017] FIG. 3 shows a block diagram of an angle error detection device 12a according to a comparative form before applying the present invention. The angle error detection device 12a includes reception filters 31a and 31b that filter out unnecessary components, a reception processing unit 3 provided with a first variable amplifier 32a and a second variable amplifier 32b that amplify the filtered sum signal and difference signal, and a signal processing block 4.

[0018] The signal processing block 4 includes an A / D conversion unit 43 that performs A / D conversion on the sum signal and difference signal amplified by the reception processing unit 3, a demodulation unit 41 that demodulates the digitally converted sum signal and difference signal, and an angle error detection unit 42 that obtains an angle error based on the signal level of the demodulated difference signal.

[0019] The aforementioned first variable amplifier 32a and second variable amplifier 32b provided on the reception processing unit 3 side each constitute an AGC (automatic gain control unit) that operates in combination with an AGC control unit 432 provided on the A / D conversion unit 43 side.

[0020] In the angle error detection device 12a having the above-described configuration, for example, the demodulation unit 41 quadrature-demodulates the sum signal and difference signal output from the addition units 21 and 22 and amplified by the first variable amplifier 32a and the second variable amplifier 32b. The demodulated sum signal and difference signal have different signal levels, and these signal levels change according to the angle error. At this time, in a range where the angle error is small, there is a relationship (θ≒Δ / Σ) in which the ratio of the signal level of the difference signal (Δ) to the sum signal (Σ) approximately corresponds to the angle error (θ). The angle error detection unit 42 detects the angle error using this relationship.

[0021] On the other hand, in a communication facility or the like where the tracking reception system 1 is provided, since the sum signal is demodulated by a main demodulation system (not shown) and subsequent processing is performed, it is required that the signal level of the demodulated sum signal be constant.

[0022] Therefore, in the first variable amplifier 32a and the second variable amplifier 32b that amplify the sum signal and the difference signal, the first variable amplifier 32a on the sum signal side amplifies the sum signal so that the output signal level becomes constant. On the other hand, the second variable amplifier 32b on the difference signal side amplifies with the same gain as the first variable amplifier 32a on the sum signal side. As a result, the signal level (difference signal level) of the difference signal output from the second variable amplifier 32b becomes a value normalized by the signal level (constant value) of the sum signal output from the first variable amplifier 32a (a value corresponding to "Δ / Σ").

[0023] As described above, using different first variable amplifier 32a and second variable amplifier 32b to amplify the sum signal and the difference signal with the same gain is important for more accurately detecting the angle error. Therefore, in the angle error detection device 12a shown in FIG. 3, in order to amplify the sum signal to a preset signal level, an AGC control unit 432 that outputs a control voltage (control value) to the first variable amplifier 32a is provided, and the same control voltage output from the AGC control unit 432 is also supplied to the second variable amplifier 32b that amplifies the difference signal. By supplying a common control voltage to the first variable amplifier 32a and the second variable amplifier 32b, it is intended to equalize the gains of the sum signal and the difference signal.

[0024] However, the actual first variable amplifier 32a and second variable amplifier 32b have their own unique amplification characteristics, and even when the same control voltage is input, the gains of both may not always be equal. Therefore, the angle error detection device 12a shown in FIG. 3 is provided with a correction value acquisition unit 434 for correcting the control voltage input to the second variable amplifier 32b on the difference signal side. The correction value acquisition unit 434 stores, as a correction value, the difference (offset value) between the control voltages of the first variable amplifier 32a and the second variable amplifier 32b in order to obtain the same gain as the first variable amplifier 32a on the difference signal side of the second variable amplifier 32b.

[0025] In the angle error detection device 12a, when a control voltage is output from the AGC control unit 432, the control voltage is input to the first variable amplifier 32a on the sum signal side as it is. On the other hand, the control voltage of the AGC control unit 432 is also supplied to the second variable amplifier 32b on the difference signal side. An adder 34 is provided in the supply line of the control voltage to the difference signal side, and a correction value read from the correction value acquisition unit 434 according to the value of the control voltage is added to the control voltage. As a result, it becomes possible to equalize the gains between the first variable amplifier 32a that amplifies the sum signal and the second variable amplifier 32b that amplifies the difference signal.

[0026] On the other hand, as described above, each of the first variable amplifier 32a and the second variable amplifier 32b has unique amplification characteristics. Every time the angle error detection device 12a is manufactured, if the work of inspecting the amplification characteristics of the first variable amplifier 32a and the second variable amplifier 32b and storing the correction value corresponding to the offset value of the control voltage in the correction value acquisition unit 434 is performed, there is a problem that the amount of work becomes enormous.

[0027] To address such a problem, the angle error detection device 12 according to the embodiment shown in FIG. 4 is configured to be able to automatically equalize the gains of the first variable amplifier 32a and the second variable amplifier 32b. Hereinafter, the configuration of the angle error detection device 12 according to the embodiment will be described. In each of the angle error detection devices 12 and 12b shown in FIGS. 4 and 6, for the components common to the angle error detection device 12a according to the comparative form described with reference to FIG. 3, the same reference numerals as those in FIG. 4 are given, and the description will not be repeated.

[0028] In the angle error detection device 12 shown in FIG. 4, for the first variable amplifier 32a that amplifies the sum signal, a first AGC control unit 432a that outputs a control voltage for controlling the signal level of the signal output from the first variable amplifier 32a is provided. The first AGC control unit 432a adjusts the control voltage based on the result of detecting the signal level of the signal output from the first variable amplifier 32a so that the signal level of the sum signal becomes a preset signal level. The first AGC control unit 432a corresponds to the first control unit, and the first variable amplifier 32a and the first AGC control unit 432a constitute the first AGC (first automatic gain control unit) of this example.

[0029] On the other hand, in the angle error detection device 12 of this example, for the second variable amplifier 32b that amplifies the difference signal, a second AGC control unit 432b that outputs a control value for controlling the signal level of the signal output from the second variable amplifier 32b is separately provided. The second AGC control unit 432b corresponds to the second control unit, and the second variable amplifier 32b and the second AGC control unit 432b constitute the second AGC (second automatic gain control unit) of this example.

[0030] Furthermore, on the input side of the second variable amplifier 32b (specifically, on the input side of the reception filter 31b), a signal switching unit 36 configured by a switch that switches the signal input to the second variable amplifier 32b between the sum signal and the difference signal is provided. The signal switching unit 36 switches the signal input to the second variable amplifier 32b between the sum signal and the difference signal based on the control signal obtained from the switching control unit 435.

[0031] The second AGC control unit 432b is used only during the period when the sum signal is input to the second variable amplifier 32b. During this period, the second AGC control unit 432b adjusts the control voltage based on the result of detecting the signal level of the signal output from the second variable amplifier 32b so that the signal level of the sum signal becomes a preset signal level common to the first variable amplifier 32a side.

[0032] In addition, the angle error detection device 12 is provided with a control value switching unit 35 configured by a switch that switches the output source of the control voltage supplied to the second variable amplifier 32b between the first AGC control unit 432a and the second AGC control unit 432b. The control value switching unit 35 switches the control voltage input to the second variable amplifier 32b based on the control signal acquired from the switching control unit 435.

[0033] Furthermore, in the angle error detection device 12, when supplying the control voltage output from the first AGC control unit 432a to the second variable amplifier 32b, an addition unit 34 that adds a correction value of the control voltage and a correction value acquisition unit 434 that acquires the correction value and outputs it to the addition unit 34 are provided.

[0034] The correction value acquisition unit 434 acquires a correction value for correcting the deviation between the control voltage of the first AGC control unit 432a and the control voltage of the second AGC control unit 432b in a state where the sum signal is input to the first variable amplifier 32a and the second variable amplifier 32b respectively and the outputs are at preset signal levels. For example, a case where the value obtained by subtracting the control voltage of the first AGC control unit 432a from the control voltage of the second AGC control unit 432b (offset value) is used as the correction value can be exemplified. The correction value acquisition unit 434, the addition unit 34, and the control value switching unit 35 constitute an operation unit that performs an operation to align the gain of the second variable amplifier 32b with the gain of the first variable amplifier 32a based on the result of inputting the sum signal to the second variable amplifier 32b.

[0035] The switching control unit 435 controls the signal switching unit 36 to switch the signal supplied to the second variable amplifier 32b between the sum signal and the difference signal during a first period in which an operation for aligning the gains of the first variable amplifier 32a and the second variable amplifier 32b is performed and a second period in which the angle error is detected. Furthermore, the switching control unit 435 performs switching control to switch the control voltage input to the second variable amplifier 32b between the first GC control unit 432a side and the second AGC control unit 432b side.

[0036] The operation of the angle error detection device 12 having the above configuration will be described with reference to the timing chart of FIG. 5. First, during the period when the antenna 11 is not receiving a communication signal from the tracking target 8, both the first AGC (the first variable amplifier 32a, the first AGC control unit 432a) and the second AGC (the second variable amplifier 32b, the second AGC control unit 432b) are stopped.

[0037] After that, at time t1, when the antenna 11 receives a communication signal from the tracking target 8, for a preset period, the switching control unit 435 connects the switch of the signal switching unit 36 to the contact A side, thereby supplying the sum signal to the second variable amplifier 32b as well. Also, during this period, the switching control unit 435 connects the switch of the control value switching unit 35 to contact A, thereby inputting the control voltage output from the second AGC control unit 432b to the second variable amplifier 32b.

[0038] Due to the settings of the signal switching unit 36 and the control value switching unit 35, a common sum signal is supplied to both the first variable amplifier 32a and the second variable amplifier 32b, and based on the control voltages output from the first AGC control unit 432a and the second AGC control unit 432b respectively, the signal level of the sum signal is amplified to a preset common signal level.

[0039] At this time, when the first variable amplifier 32a and the second variable amplifier 32b have different amplification characteristics, the control voltages output from the first AGC control unit 432a and the second AGC control unit 432b may be different from each other. The correction value acquisition unit 434 holds the difference value between these control voltages as a correction value for correcting the control voltage of the first AGC control unit 432a. The period during which the above operation is executed (the period from time t1 to time t2 in FIG. 5) corresponds to the first period for performing an operation to equalize the gains of the first variable amplifier 32a and the second variable amplifier 32b.

[0040] When a correction value for correcting the control voltage of the first AGC control unit 432a is obtained, at time t2, the switching control unit 435 connects the switch of the signal switching unit 36 to the contact B side. As a result, a difference signal is supplied to the second variable amplifier 32b. Also, in accordance with the above operation, the switching control unit 435 connects the switch of the control value switching unit 35 to the contact B side. As a result, a control value (corrected control voltage) obtained by adding the correction value to the control voltage output from the first AGC control unit 432a is input to the second variable amplifier 32b.

[0041] Here, the control voltage output from the first AGC control unit 432a is a value for amplifying the sum signal to a preset signal level. Also, the correction value output from the correction value acquisition unit 434 corrects the control voltage output from the first AGC control unit 432a so that when the sum signal is input to the second variable amplifier 32b, the signal level of the signal output from the second variable amplifier 32b matches the sum signal side.

[0042] When a difference signal is supplied to the second variable amplifier 32b under this condition and the corrected control voltage of the first AGC control unit 432a is input, the second variable amplifier 32b operates to amplify the difference signal with the same gain as the first variable amplifier 32a. By this operation, the signal level of the difference signal amplified with the same gain as the sum signal becomes a state normalized by the signal level of the sum signal (a level corresponding to the aforementioned "Δ / Σ").

[0043] By processing the normalized difference signal in the subsequent demodulation unit 41 and angle error detection unit 42, a correct angle error can be detected. The period after time t2 when the above operation is executed corresponds to a second period for detecting an angle error.

[0044] According to the angle error detection device 12 according to the embodiment described with reference to FIGS. 4 and 5, the following effects are obtained. When detecting the angle error while controlling the signal levels of the sum signal and the difference signal using the first and second AGCs that are different from each other, by supplying the sum signal to the second variable amplifier 32b on the difference signal side, an operation is performed to align it with the gain of the first variable amplifier 32a on the sum signal side. As a result, the gains of the two different first and second AGCs can be automatically aligned.

[0045] Here, the operation unit that supplies the sum signal to the second variable amplifier 32b on the difference signal side and aligns it with the gain of the first variable amplifier 32a on the sum signal side is not limited to the case where it is configured by the correction value acquisition unit 434, the addition unit 34, and the control value switching unit 35 described in FIG. 4. For example, FIG. 6 shows a block diagram of an angle error detection device 12b according to another embodiment.

[0046] The angle error detection device 12b shown in FIG. 6 is different from the angle error detection device 12 according to the first embodiment described with reference to FIG. 4 in that the correction value acquisition unit 434, the addition unit 34, and the control value switching unit 35 are not provided. Due to the difference in the above configuration, in the angle error detection device 12b of this example, the gain of the second variable amplifier 32b is adjusted only by the control voltage output from the second AGC control unit 432b. Furthermore, the angle error detection device 12b includes a disconnect switch 37 that performs an operation of disconnecting the second AGC control unit 432b from the second variable amplifier 32b. The disconnect switch 37 corresponds to an operation unit that performs an operation of aligning the gain of the second variable amplifier 32b with the gain of the first variable amplifier 32a.

[0047] The operation of the angle error detection device 12b having the above configuration will be described with reference to the timing chart of FIG. 7 as well. First, during the period when the antenna 11 is not receiving a communication signal from the tracking target 8, the fact that both the first AGC (the first variable amplifier 32a and the first AGC control unit 432a) and the second AGC (the second variable amplifier 32b and the second AGC control unit 432b) are stopped is the same as that of the angle error detection device 12 according to the first embodiment.

[0048] After that, at time t1, when the antenna 11 receives a communication signal from the tracking target 8, for a preset period, the switching control unit 435 connects the switch of the signal switching unit 36 to the contact A side, thereby supplying the sum signal to the second variable amplifier 32b as well. Also, during this period, the switching control unit 435 connects the disconnect switch 37 to the contact A, so that the control voltage output from the second AGC control unit 432b is input to the second variable amplifier 32b.

[0049] Due to the settings of the signal switching unit 36 and the control value switching unit 35, a sum signal common to both the first variable amplifier 32a and the second variable amplifier 32b is input, and based on the control voltages output from the first AGC control unit 432a and the second AGC control unit 432b respectively, a process of amplifying the signal level of the sum signal to a preset common signal level is performed.

[0050] At this time, when the first variable amplifier 32a and the second variable amplifier 32b have different amplification characteristics, the control voltages output from the first AGC control unit 432a and the second AGC control unit 432b may be different from each other. The first variable amplifier 32a and the second variable amplifier 32b adjust their gains based on these different control voltages so that the amplified sum signal becomes a common signal level. The period during which the above operation is executed (the period from time t1 to t2 in FIG. 7) corresponds to the first period for performing an operation to align the gains of the first variable amplifier 32a and the second variable amplifier 32b.

[0051] When the level of the sum signal output from the first variable amplifier 32a and the second variable amplifier 32b becomes stable (when the gains of the first variable amplifier 32a and the second variable amplifier 32b become stable), at time t2, the switching control unit 435 connects the switch of the signal switching unit 36 to the contact B side. As a result, a difference signal is supplied to the second variable amplifier 32b. Also, in accordance with the above operation, the switching control unit 435 disconnects the switch of the disconnect switch 37 from the contact A. As a result, the second variable amplifier 32b is in a state where the gain is fixed.

[0052] Here, the gain of the first variable amplifier 32a continues to be controlled by the first AGC control unit 432a, and the operation of amplifying the sum signal to a preset signal level continues. On the other hand, on the side of the second variable amplifier 32b, until immediately before time t2, the gain is adjusted so as to adjust the sum signal to the same signal level as the first variable amplifier 32a. After time t2, by disconnecting the second variable amplifier 32b and the second AGC control unit 432btp, the gain is fixed.

[0053] Therefore, when there is no significant fluctuation in the signal level of the sum signal supplied from the antenna 11 side around time t2, when a difference signal is supplied to the second variable amplifier 32b, the fixed gain of the second variable amplifier 32b operates to amplify the difference signal with the same gain as the first variable amplifier 32a. By this operation, the signal level of the difference signal amplified with the same gain as the sum signal becomes a state normalized by the signal level of the sum signal (a level corresponding to the aforementioned "Δ / Σ").

[0054] The period after time t2 when the above operation is executed corresponds to the second period for detecting the angle error. For example, in the case of receiving communication signals intermittently by several milliseconds at intervals of about one second from the tracking target 8, such as in TDD (Time Division Duplex) communication, a first period is set at the beginning of the reception timing of each communication signal, and then the angle error is detected in the second period. If it is a time of about several milliseconds, there is little possibility that the signal level will fluctuate greatly during the reception period of each received signal. Even if the gain of the second variable amplifier 32b is fixed, the gain can be made the same as that on the side of the first variable amplifier 32a.

[0055] By the above operation, also in the angle error detection device 12b shown in FIG. 6, the normalized difference signal can be processed by the demodulation unit 41 and the angle error detection unit 42 in the subsequent stage. As a result, the correct angle error can be detected.

[0056] Also in the angle error detection device 12b according to another embodiment described with reference to FIGS. 6 and 7, when controlling the signal levels of the sum signal and the difference signal using different first and second AGCs and detecting the angle error, an operation is performed of supplying the sum signal to the second variable amplifier 32b on the difference signal side to make it the same as the gain of the first variable amplifier 32a on the sum signal side. As a result, the gains of the two different first and second AGCs can be automatically made the same.

[0057] Here, the application of the angle error detection devices 12 and 12b according to each embodiment is not limited to a tracking reception system for communication. For example, the angle error detection devices 12 and 12b of the present invention may be provided in a radar system. In this case, the tracking target 8 becomes a detection target, and the frequency signal from the tracking target 8 irradiates the detection target with a frequency signal to become a reflected signal.

Explanation of Signs

[0058] 1 Tracking reception system 11 Antenna 12, 12a, 12b Angle error detection device 2a, 2b Receiving unit 21, 22 Adding unit 32a First variable amplifier 32b Second variable amplifier 36 Signal switching unit 42 Angle error detection unit 432a First AGC control unit 432b Second AGC control unit 8 Tracking target

Claims

1. In an angle error detection device that detects an angular error in the reception direction of a frequency signal with respect to the front direction of the antenna based on a first reception signal received by a first reception unit of the antenna and a second reception signal received by a second reception unit having a different reception position in the antenna from the first reception unit, a first variable amplifier and a first control unit that outputs a control value for controlling the signal level of a signal output from the first variable amplifier, and a first automatic gain control unit for amplifying a sum signal obtained from the first reception signal and the second reception signal to a preset signal level; a second variable amplifier and a second control unit that outputs a control value for controlling the signal level of a signal output from the second variable amplifier, and a second automatic gain control unit for amplifying a difference signal obtained from the first reception signal and the second reception signal with the same gain as the first automatic gain control unit; an angle error detection unit that detects the angle error based on the difference signal amplified by the second automatic gain control unit; an operation unit that performs an operation of aligning the gain of the second automatic gain control unit with the gain of the first automatic gain control unit based on a result of supplying the sum signal to the second automatic gain control unit; a signal switching unit that switches a signal supplied to the second automatic gain control unit so that the sum signal is supplied during a first period in which an operation for aligning the gains is performed, and the difference signal is supplied during a second period in which the angle error is detected; The operation unit is configured to: a correction value acquisition unit that determines, based on the sum signal supplied to the second automatic gain control unit during the first period and the signal level of the sum signal output from the second variable amplifier and the preset signal level, a control value of the second control unit at which the signal level of the sum signal output from the second variable amplifier becomes the preset signal level, and based on the sum signal supplied to the first automatic gain control unit and the signal level of the sum signal output from the first variable amplifier and the preset signal level, a control value of the first control unit at which the signal level of the sum signal output from the first variable amplifier becomes the preset signal level, and acquires a correction value for correcting a deviation therebetween; an addition unit that adds the correction value acquired by the correction value acquisition unit to the control value of the first control unit; During the first period, the second control unit is connected to the second variable amplifier, and during the second period, the adder is connected to the second variable amplifier, and a control value switching unit for switching the control value input to the second variable amplifier is provided. An angle error detection device characterized by that.

2. In an angle error detection device that detects an angle error in the reception direction of a frequency signal with respect to the front direction of the antenna based on a first reception signal received by a first reception unit of the antenna and a second reception signal received by a second reception unit whose reception position in the antenna is different from that of the first reception unit from a tracking target, A first variable amplifier and a first control unit that outputs a control value for controlling the signal level of the signal output from the first variable amplifier, and a first automatic gain control unit for amplifying the sum signal obtained from the first reception signal and the second reception signal to a preset signal level, A second variable amplifier and a second control unit that outputs a control value for controlling the signal level of the signal output from the second variable amplifier, and a second automatic gain control unit for amplifying the difference signal obtained from the first reception signal and the second reception signal with the same gain as the first automatic gain control unit, An angle error detection unit that detects the angle error based on the difference signal amplified by the second automatic gain control unit, An operation unit that performs an operation of aligning the gain of the second automatic gain control unit with the gain of the first automatic gain control unit based on the result of supplying the sum signal to the second automatic gain control unit, A signal switching unit that switches the signal supplied to the second automatic gain control unit so that the sum signal is supplied during the first period when the operation for aligning the gain is performed, and the difference signal is supplied during the second period when the angle error is detected, The operation unit is a disconnect switch that performs an operation of disconnecting the second control unit from the second variable amplifier, When the sum signal is supplied to the second automatic gain control unit during the first period and the sum signal output from the second variable amplifier reaches the preset signal level, the signal switching unit switches the signal supplied to the second automatic gain control unit to the difference signal to start the second period, The operation unit performs the disconnection operation in accordance with the start of the second period to fix the gain of the second variable amplifier, so that the gain of the second automatic gain control unit is made to match the gain of the first automatic gain control unit when the level of the sum signal supplied when the preset signal level was output is maintained. An angle error detection device characterized by performing such an operation.

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