JP3438527B2 - Signal wave arrival angle estimation device and array antenna control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for estimating a signal wave arrival angle using an array antenna used for various wireless communications, and a controller for this array antenna.

[0002]

2. Description of the Related Art An array antenna is an antenna composed of a plurality of antenna elements arranged at predetermined positions. By controlling the excitation of each element, a strong directivity is given only in a certain direction, or conversely. The sensitivity can be set to 0 (null) for a signal from a certain direction. Also,
When this array antenna is used as a receiving antenna,
Due to the difference in the physical position of each element antenna that is arranged, the phase of the received plane wave is different,
It is also possible to detect the phase difference and estimate the arrival direction of the signal.

An arrival angle estimation value of a signal obtained by using such an array antenna can be used as a reference signal when performing adaptive control of the array antenna. Conventionally, various arrival angle estimation methods have been used. Has been proposed, one of which is the MUSIC method. This MUSIC
The algorithm is, for example, “High-Resolutei
on Technologies in Signal P
processing Antenna ", Y. Ogaw
a, N.A. Nikuma, IEICE Transact
ions on Commun. vol. E78-B
No. 11 Nov. It is described in detail in 1995.

This MUSIC algorithm utilizes a signal correlation matrix obtained from the output of each element of the array antenna. The correlation matrix is expressed by the following equation. R _XX = E [X ^{* XT} ] Here, X is a column vector of the element antenna output, and E [] is the ensemble average (expected value), ^*
Let be the complex conjugate transpose and ^T the transpose. MUS
In the IC algorithm, first, the eigenvalue of this matrix is obtained. Then, the minimum eigenvalue matches the noise power, and the eigenvector corresponding to the minimum eigenvalue is orthogonal to the element output phase difference vector based on the signal arrival angle, which is referred to as a steering vector as described below. Here, the steering vector, for example, in the case of equally spaced one-dimensional array is represented as _{S = [s 1 s 2 ···} s m] T s m = 2 (m-1) πdsinθ / λ. Here, d is the element interval, λ is the wavelength of the received wave, and θ is the arrival angle.

Thus, the MUSIC algorithm is
After obtaining the eigenvector corresponding to the minimum eigenvalue of the signal correlation matrix, the steering vector θ is changed as a parameter, and the inner product of the eigenvector and steering vector in each case is calculated. It is a method to be an angle.

According to this method, the estimation accuracy of the arrival angle is considerably high, and even if there are a plurality of arrival signals, each arrival angle can be individually estimated, but the matrix eigenvalue decomposition is possible. There is a problem that the calculation load caused by is very large, and the arrival angle cannot be estimated in an environment where there are a plurality of strongly correlated signals such as a multipath environment. In such an environment, the MUSIC algorithm can reduce the influence of a signal having a strong correlation by performing a process called spatial smoothing, but such a process further increases the calculation load.

[0007]

In the above-mentioned conventional example,
It requires complicated calculations such as eigenvalue decomposition of covariance matrix, which is complicated. Although the direction of arrival of the signal wave obtained by such a method can be obtained with high accuracy under favorable conditions, control of the array antenna for application to mobile communications requires high accuracy in practice. Absent.

Considering the above points, the signal wave arrival direction can be estimated by a simple calculation even if the accuracy is sacrificed to some extent.
The ability of the computer should be used to speed up the calculation of the optimal weighting factor for that direction. Furthermore, considering the application to mobile satellite communication terminals, multipath environment is an unavoidable problem, and an estimation method that is durable to such environment is desirable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a simple arrival angle estimation device and array antenna control device having tolerance to a multipath environment in consideration of the above problems.

[0010]

SUMMARY OF THE INVENTION According to the invention, the known between the peak of one beam of a multi-beam and the null of the other beam realized with an array antenna having a plurality of antenna elements is known. There is provided a signal wave arrival angle estimation device and an array antenna control device configured to estimate a signal arrival angle and a control reference signal of an antenna using a positional relationship.

More specifically, the orthogonality of orthogonal multi-beams realized by using an array antenna having a plurality of antenna elements is utilized to estimate the signal wave arrival angle and the antenna control reference signal. A signal wave arrival angle estimation device and an array antenna control device are provided.

As described above, the method based on the eigenvalue decomposition of the signal correlation matrix has a property that the calculation load is large and the multipath environment is weak. In order to solve such a problem, the known spatial relationship between the peak and null of each beam of the multi-beam is used, and more specifically, the orthogonal multi-beam is used for the signal wave. The arrival angle is estimated. The orthogonal multi-beam is a Butler matrix or the like in an analog circuit, and can be configured by a spatial FFT in a digital circuit. At the position where one beam has a peak, the other beams are null. It refers to a beam whose constituent relationship holds at all peak positions. As an example, FIG. 1 shows a beam pattern of an orthogonal multi-beam that can be formed by a 4-element linear array. With the combination of this peak and null, it is possible to estimate with sufficient accuracy as the control reference signal of the array antenna.

Further, according to the present invention, analog / digital signal converting means for converting a plurality of signals respectively received by a plurality of antenna elements of the array antenna into digital signals at a predetermined sampling frequency, and analog / digital signal conversion. A complex signal converting means for converting the output of the means into a complex signal, and the output of the complex signal converting means multiplies the input signal by a plurality of weighting factors constrained by a predetermined relationship that is uniquely determined when the signal arrival direction is given. Weighting coefficient multiplication means, spatial FFT calculation means for performing spatial FFT on the output of the weighting coefficient multiplication means to form an orthogonal multi-beam, and maximum output beam selection means for selecting the maximum output among the outputs of the spatial FFT calculation means. , Is supplied with maximum beam selection information from the maximum output beam selection means, and is orthogonal to the selected maximum output beam. The null point is detected by using the frame, and the null detecting means for supplying a constant for shifting the orthogonal multi-beam to the weighting coefficient multiplying means, the orthogonal multi-beam shift information from the null detecting means and the maximum output beam selecting means. There is provided a signal wave arrival angle estimation device including signal arrival angle calculation means for obtaining information on a selected maximum output beam and calculating a signal arrival direction.

Furthermore, according to the present invention, a plurality of weighting factors constrained by a predetermined relationship uniquely determined when a signal arrival direction is given to a plurality of signals respectively received by a plurality of antenna elements of an array antenna are provided. A weighting factor multiplication means for multiplying an input signal, and an output of the weighting factor multiplication means, and a Butler matrix forming a multi-beam,
Of the outputs of the Butler matrix, the maximum output beam selecting means for selecting the maximum output and the maximum beam selection information are supplied from the maximum output beam selecting means, and the null point is determined using the beam orthogonal to the selected maximum output beam. Null detection means for detecting and supplying a constant for shifting the orthogonal multi-beams to the weighting coefficient multiplication means, orthogonal multi-beam shift information from the null detection means, and information on the maximum output beam selected from the maximum output beam selection means Therefore, there is provided a signal wave arrival angle estimation device including signal arrival angle calculation means for calculating a signal arrival direction.

Further, according to the present invention, the receiving section converts the plurality of signals respectively received by the plurality of antenna elements of the array antenna into digital signals at a predetermined sampling frequency, and analog / digital signal converting means. / A complex signal converting means for converting the output of the digital signal converting means into a complex signal, and a plurality of weighting factors constrained in a predetermined relationship uniquely determined when the signal arrival direction is given to the output of the complex signal converting means. Of the outputs of the reception weighting coefficient multiplication means for multiplying the signal, the reception weighting coefficient multiplication means, a spatial FFT is applied to the output of the reception weighting coefficient multiplication means to form an orthogonal multi-beam, and the maximum output beam among the outputs of the spatial FFT calculation means. And a maximum output beam selection means for outputting the selected maximum output beam as an array antenna output. Maximum beam selection information is supplied from the maximum output beam selection means, the null point is detected using a beam orthogonal to the selected maximum output beam, and a constant for shifting the orthogonal multi-beam is supplied to the reception weight coefficient multiplication means. And a null detecting means for
When maximum beam information is supplied from the maximum output beam selection means, a transmission beam changeover switch for connecting a transmitter to the maximum beam and a spatial inverse FFT calculation means for performing spatial inverse FFT on the value of each beam according to the information, Spatial inverse FFT
The output of the calculation means is multiplied by a weighting coefficient for transmission that multiplies a weighting coefficient constrained in a unique relationship based on a constant detected by the null detection means, and the output of the weighting coefficient multiplication means for transmission is output from a complex signal. Provided is an array antenna control device provided with a complex signal converting means for converting into a real signal, and a digital / analog signal converting means for converting an output from the complex signal converting means into an analog signal and supplying the analog signal to a plurality of antenna elements. It

Further, according to the present invention, the receiving unit converts the plurality of signals received by the plurality of antenna elements of the array antenna into a digital signal at a predetermined sampling frequency, and converts the plurality of signals into digital signals. Means, a complex signal converting means for converting the output of the analog / digital signal converting means into a complex signal, and a plurality of outputs constrained by a predetermined relationship uniquely determined when the signal arrival direction is given to the output of the complex signal converting means. Of the outputs of the receiving weight coefficient multiplying means for multiplying the input signal by the weighting coefficient, the spatial FFT calculating means for performing the spatial FFT on the output of the receiving weight coefficient multiplying means to form an orthogonal multi-beam, and the output of the spatial FFT calculating means. , Select the maximum output beam, and
Maximum output beam selection means for outputting the selected maximum output beam as an array antenna output, and maximum beam selection information supplied from the maximum output beam selection means, and a null point using the beam orthogonal to the selected maximum output beam And a null detection means for supplying a constant for shifting the orthogonal multi-beams to the reception weighting factor calculation means, a maximum output beam selection information from the maximum output beam selection means, and a constant for shifting the orthogonal multi-beams from the null detection means. And a signal which distributes the transmission signal to a number equal to the number of antenna elements, the transmission unit being supplied with a digital transmission signal from the transmitter. A transmission device that multiplies each transmission signal output from the distribution device and the signal distribution device by a predetermined transmission weighting coefficient. A complex signal conversion unit that converts the output of each digital signal of the weighting factor multiplication unit and the transmission weighting factor multiplication unit from a complex signal to an actual signal, and an output from the complex signal conversion unit is converted into an analog signal, and a plurality of signals are output. Of the digital / analog signal supplied to the antenna element, the signal arrival direction from the signal arrival angle calculation means, and the antenna element output from the analog / digital signal conversion means, and outputs the optimum weighting coefficient to transmit the weight. An array antenna control device is provided which comprises optimum weight calculation means for supplying to coefficient multiplication means.

Further, according to the present invention, the receiving unit constrains a plurality of signals respectively received by a plurality of antenna elements of the array antenna in a predetermined relationship that is uniquely determined when a signal arrival direction is given. Reception weight coefficient multiplication means for multiplying the input signal by the weight coefficient, a Butler matrix to which the output of the reception weight coefficient multiplication means is provided to form a multi-beam, the output of the Butler matrix, at the time of signal reception and transmission, The maximum output beam is selected from the output of the Butler matrix via the transmission / reception changeover switch that switches the subsequent device to the reception side and the transmission side, respectively, and the selected maximum output beam is used as the array antenna output. The maximum output beam selection means for outputting and the maximum beam selection information from the maximum output beam selection means. Is supplied, the null point is detected using a beam orthogonal to the selected maximum output beam, and a null detection means for supplying a constant for shifting the orthogonal multi-beam to the weighting coefficient multiplication means for reception is provided, When the maximum beam information is supplied from the maximum output beam selection unit, the transmission unit has a transmission beam changeover switch that connects the transmitter to the maximum beam output of the Butler matrix according to the information, and the output of the transmission beam changeover switch. Is supplied to the Butler matrix via the transmission / reception changeover switch, and the output thereof is multiplied by the weighting coefficient obtained at the reception in the weighting coefficient multiplication means for reception, and then is supplied to the plurality of antenna elements. An antenna controller is provided.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configurations of a signal wave arrival angle estimation device and an array antenna control device according to the present invention will be described below with reference to embodiments. Although the device according to the present invention can be applied to a two-dimensional array antenna, the following embodiment shows a case of application to a one-dimensional array for simplicity. Further, all of the embodiments described below make use of the known spatial positional relationship between the peak and null of each beam of the multi-beam, but as a special example thereof, the orthogonal multi-beam is used. It is related to the case. Therefore, it is clear that the exact same principle can be applied to non-orthogonal multi-beams.

First Embodiment FIG. 2 is a first embodiment of the present invention, which is an apparatus for estimating a signal arrival angle using an array antenna composed of a plurality of antenna elements 1-1 to 1-m. is there.

In the figure, 2 is an analog / digital converter (A / D), 3 is a complex signal converter, and 4-1 to 4-
m is a weighting coefficient multiplier, 5 is a spatial FFT calculator, 6 is a maximum output beam selector, 7 is a null detector, and 8 is a signal arrival angle calculator.

The output from each antenna element is analog /
After being sampled at a predetermined sampling rate by the digital converter 2 and converted into a digital signal, the complex signal converter 3 separates the signal into orthogonal components to form a complex signal. Each signal is multiplied by a corresponding weighting factor in weighting factor multipliers 4-1 to 4-m. The weighting factor is
Equal to the corresponding element of the steering vector S.
That is, the amplitude is fixed at 1, and the phase relationship between the elements is restricted by the following equation. _{S = [s 1 s 2 ···} s m] T s m = 2 (m-1) πdsinθ / λ where, d is the element spacing, lambda is the wavelength of the received waves, theta is the arrival angle.

In this embodiment, by substituting Δθ for θ in the above equation, a weighting factor equal to the number of elements is determined. This results in shifting the orthogonal multi-beam shown in FIG. 1 as it is on the horizontal axis.

Each element output multiplied by the weighting factor is subjected to spatial FFT by the spatial FFT calculation section 5 and an orthogonal multi-beam is output. Next, the maximum beam output of the orthogonal beam output is selected by the maximum output beam selector 6, and each beam output and maximum output beam selection information are output. The beam selected as the maximum beam, other beams, and maximum output beam selection information indicating which beam has been selected are supplied to the null detection unit 7 to detect θ, and the weight coefficient multipliers 4-1 to 4- supplied to m. The null detection unit 7 determines Δθ by gradually changing Δθ by using a route search method or a steepest descent method and detecting the dip of the null point of the orthogonal beam.

The arrival angle calculation unit 8 obtains information on the beam selected as the maximum output beam from the maximum output beam detection unit 6 and information on Δθ supplied to the steering vector as a weighting coefficient from the null detection unit 7. Then, the arrival direction of the maximum arrival signal in the environment where this antenna is present is calculated. In a multipath environment premised on mobile satellite communication terminals, it can be assumed that the direct wave from the satellite is the signal with the maximum power in that environment. Can be used as a method of estimating the arrival angle of.

Second Embodiment FIG. 3 shows a second embodiment of the present invention, which is a control device for controlling an array antenna composed of a plurality of antenna elements 1-1 to 1-m.

An analog / digital converter 2, a complex signal converter 3 and a (reception) weighting coefficient multiplier 4-in FIG.
The configurations of 1 to 4-m, the spatial FFT calculation unit 5, the maximum output beam selection unit 6, and the null detection unit 7 are the same as those in the first embodiment of FIG. In FIG. 3, 9 is a transmission beam changeover switch, 10 is a spatial inverse FFT calculation unit,
11-1 to 11-m are transmission weight coefficient multipliers, 12 is a complex signal conversion unit, and 13 is a digital / analog conversion unit (D
/ A) and 14 indicate antenna duplexers (diplexers), respectively.

In this embodiment, the array antennas 1-1 to 1-1
1-m is connected to the diplexer 14 and is commonly used for transmission and reception. The configuration and operation will be described below separately for reception and transmission.

First, at the time of reception, the diplexer 1
A plurality of received signals corresponding to the element antennas, which are output from 4, are sampled at a predetermined frequency by the analog / digital conversion unit 2, converted into digital signals, and then converted into complex signals by the complex signal conversion unit 3. To be done. The output of the complex signal converter 3 is multiplied by a weighting coefficient uniquely determined by a constant supplied from the null detector 7 by the reception weighting coefficient multipliers 4-1 to 4-m, and the spatial FF
An orthogonal multi-beam is formed by the T calculation unit 5.

The output of the spatial FFT calculator 5 is supplied to the maximum output beam selector 6 to select the maximum output beam. The output of the maximum power beam is fed to the receiver, while
Each beam output is supplied to the null detection unit 7 in the subsequent stage. Further, the maximum output beam selection unit 6 supplies the maximum output beam selection information indicating which beam has been selected to the null detection unit 7 and the transmission beam changeover switch 9. The null detection unit 7 supplied with each beam output and the above-mentioned maximum output beam selection information detects ΔN by using a path search method or a steepest descent method in order to detect a null point of a beam orthogonal to the maximum output beam. Δθ corresponding to the null point is detected as a parameter and supplied to the reception weighting coefficient multipliers 4-1 to 4-m and the transmission weighting coefficient multipliers 11-1 to 11-m.

With such a configuration, the output of the selected maximum beam is maximized by multiplying the weight coefficient based on the Δθ detected by the null detector 7. That is, although the maximum output beam selected first does not always direct the true peak in the signal arrival direction, the maximum peak is directed in the signal arrival direction by the weighting coefficient based on Δθ.

On the other hand, in the case of transmission, the maximum beam information selected at the time of reception is supplied from the maximum output beam selector 6 to the transmission beam changeover switch 9 so that the beam selected as the maximum beam at the time of reception is transmitted. Machine is connected. The transmission signal supplied is the spatial inverse FFT calculation unit 1
Applied to zero. The output is supplied with Δθ from the null detection unit 7, multiplied by the weighting factors in the transmission weighting factor multipliers 11-1 to 11-m, and converted into an actual signal by the complex signal converting unit 12, and finally. The signal is converted into an analog signal by the digital / analog converter 13 and is supplied to the array antenna via the diplexer 14, so that the signal is directed to the signal arrival direction at the time of reception, that is, the satellite direction in the case of mobile satellite communication. It becomes possible to supply signals to the antenna elements 1-1 to 1-m so as to form one of the orthogonal multi-beams.

By using the configuration as described above, the weighting coefficient obtained at the time of reception can be used as it is. In terms of hardware, the spatial FFT calculation unit 5 and the spatial inverse FFT calculation unit 10 further include the reception weighting coefficient multiplier 4
-1 to 4-m and transmission weight coefficient multipliers 11-1 to 11-
may be shared with m.

Third Embodiment FIG. 4 shows a third embodiment of the present invention, which is a control device for controlling an array antenna composed of a plurality of antenna elements 1-1 to 1-m.

The analog / digital converter 2, the complex signal converter 3 and the receiving weight coefficient multipliers 4-1 to 4-1 in FIG.
4-m, spatial FFT calculation unit 5, maximum output beam selection unit 6, null detection unit 7 and signal arrival angle calculation unit 8 have the following configurations:
Similar to the case of the first embodiment of FIG. 2, the transmission weighting coefficient multipliers 11-1 to 11-m, the complex signal converter 12,
The configurations of the digital / analog converter (D / A) 13 and the antenna duplexer (diplexer) 14 are the same as those in the second embodiment of FIG. In FIG. 4, further,
Reference numeral 15 is a signal distributor, and 16 is an optimum weighting coefficient calculation unit.

The configuration and operation of this embodiment will be described below separately for reception and transmission.

First, at the time of reception, the maximum output beam selected by the maximum output beam selector 6 is supplied to the receiver. In such a configuration, the output of the selected maximum beam is multiplied by the weighting coefficient based on Δθ detected by the null detection unit 7, so that the output is maximized.
As described above.

The signal arrival angle calculation unit 8 receives the maximum output beam selection information output from the maximum output beam selection unit 6 and the constant Δθ output from the null detection unit 7, and calculates the signal arrival angle θ. Output.

On the other hand, in the case of transmission, the digital signal from the transmitter is distributed by the signal distributor 15 into a number equal to the number of antenna elements. This output is multiplied by the transmission weight coefficient by the transmission weight coefficient multipliers 11-1 to 11-m. The outputs of the transmission weighting coefficient multipliers 11-1 to 11-m are converted into real signals by the complex signal conversion unit 12, and then converted into analog signals by the digital / analog signal conversion unit 13, and then the diplexer 14 is used. Is supplied to the array antenna via and is transmitted.

Transmission weighting coefficient multipliers 11-1 to 11-m
In, the weighting factors by which the transmitted signals are respectively multiplied are
The calculation is performed by the optimum weighting factor calculation unit 16 which uses the signal arrival direction output by the signal arrival angle calculation unit 8 as a reference signal.

In the present embodiment, the control algorithm used in the optimum weighting coefficient calculation unit 16 is HA (Howe).
lls-Applebaum) method is used. This algorithm is, for example, "Progress of adaptive antenna theory and future prospects", Ogawa and Kikuma, the journal of the Institute of Electronics, Information and Communication Engineers,
B-II Vol. J75-B-II No. 1119
It is explained in detail in November 1992.

The HA method is an algorithm that requires the signal arrival angle of the desired wave as a target reference value, and the optimum weighting coefficient W _opt is expressed as follows. W _opt = R _xx ^-1 S ^* or W _opt = R _uu ^-1 S ^* Here, the desired wave is X _s (t), the interference wave is X _i (t), and the noise is X _n (t). If represented by a column vector, R _xx = E [{X _s (t) + X _i (t) + X _n (t)} ^*
{X _s (t) + X _i (t) + X _n (t)} ^T ] R _uu = E [{X _i (t) + X _n (t)} ^* {X _i (t)
+ X _n (t)} ^T ], which are signal wave covariance matrices. The HA method includes a method of directly calculating optimum weights by performing a calculation including such an inverse matrix and an asymptotic solution method using a steepest descent method or the like. However, in order to perform real-time control of an array antenna, a direct solution method is used. Is preferable. This is because the asymptotic method affects the convergence speed of the radio wave environment, but the direct solution method avoids such a problem.
However, the load on the computer due to the inverse matrix calculation becomes considerably large.

Optimal weighting coefficient calculation section 16 based on this HA method
Receives the received signals from each of the antenna elements 1-1 to 1-m and the signal arrival direction from the signal arrival angle calculation unit 8 and outputs the optimum weighting coefficient W _opt .

Fourth Embodiment FIG. 5 is a fourth embodiment of the present invention, which is an apparatus for estimating a signal arrival angle using an array antenna composed of a plurality of antenna elements 1-1 to 1-m. is there.

Weighting coefficient multipliers 4-1 to 4- in FIG.
The configurations of m, the maximum output beam selection unit 6, the null detection unit 7, and the signal arrival angle calculation unit 8 are the same as those in the first embodiment of FIG. Further, in FIG. 5, 17 indicates a Butler matrix.

The present embodiment is a signal arrival direction estimating apparatus which estimates the signal arrival direction by using an array antenna as it is as an analog signal without using an analog / digital signal converter. The configuration and operation of this embodiment will be described below.

Antenna elements 1-1 to 1 of the array antenna
-M for the received signal, weighting factor multipliers 4-1 to 4
The weighting factors are each multiplied by -m. Here, the weighting factor is the same as in the case of the first embodiment.
Are constrained in a relationship uniquely determined by a constant Δθ, which indicates the spatial shift amount of the multi-beam. The outputs of the weight coefficient multipliers 4-1 to 4-m are input to the Butler matrix 17, and the multi-beam is output. The maximum beam output of the orthogonal beam output is selected by the maximum output beam selector 6, and each beam output and maximum output beam selection information is output. Further, the beam selected as the maximum beam and other beams, and the maximum output beam selection information are supplied to the null detection unit 7 to detect θ, and are supplied to the above-mentioned weight coefficient multipliers 4-1 to 4-m. It The null detection unit 7 determines Δθ by gradually changing Δθ by using a route search method or a steepest descent method and detecting the dip of the null point of the orthogonal beam.

The signal arrival angle calculation unit 8 obtains the beam information selected as the maximum output beam from the maximum output beam selection unit 6 and the Δθ information supplied from the null detection unit 7 to the steering vector as the weighting coefficient. Then, the arrival direction of the maximum arrival signal in the environment where this antenna is present is calculated, and θ is output.

Fifth Embodiment FIG. 6 shows a fifth embodiment of the present invention, which is a control device for controlling an array antenna composed of a plurality of antenna elements 1-1 to 1-m.

Reception weight coefficient multiplier 4-1 in FIG.
˜4-m, maximum output beam selector 6, null detector 7, transmission weighting coefficient multipliers 11-1 to 11-m, antenna duplexer (diplexer) 14, and transmission beam changeover switch 9 are configured as shown in FIG. Is the same as that of the second embodiment. In FIG. 6, reference numerals 17 and 18 denote Butler matrices.

The present embodiment is an array antenna control device that does not use an analog / digital signal converter but performs adaptive control of an array antenna as it is as an analog signal. The array antennas 1-1 to 1-m are connected to the diplexer 14 to be shared for transmission and reception. Hereinafter, the configuration and operation of this embodiment will be described separately for reception and transmission.

On the receiving side, the receiving weight coefficient multiplier 4-1
Each of the weighting factors is multiplied by ˜4-m. here,
Similar to the case of the first embodiment, the weighting factor is constrained in a uniquely determined relationship by a constant Δθ indicating the spatial shift amount of the multi-beam supplied from the null detection unit 7.
The outputs of the reception weight coefficient multipliers 4-1 to 4-m are input to the Butler matrix 17, and the multi-beam is output.

The output of the Butler matrix 17 is supplied to the maximum output beam selector 6 to select the maximum output beam. Further, the maximum output beam selection information indicating which beam has been selected is supplied to the null detection unit 7 and the transmission beam changeover switch 9, and the output of the selected beam is supplied to the receiver as the array antenna output. further,
Each beam output from the Butler matrix 17 is delivered as it is to the null detection unit 7 in the subsequent stage. The null detection unit 7 supplied with each beam output and the above-mentioned maximum output beam selection information detects the null point of the beam orthogonal to the maximum output beam, and therefore uses a path search method, a steepest descent method, or the like to calculate Δ
Δθ corresponding to the null point is detected using θ as a parameter, and is supplied to the reception weighting coefficient multipliers 4-1 to 4-m and the transmission weighting coefficient multipliers 11-1 to 11-m.

The output of the selected maximum beam is maximized by being multiplied by the weighting coefficient based on Δθ detected by the null detector 7. That is, the maximum output beam selected first does not always direct the true peak in the signal arrival direction, but the weighting coefficient based on Δθ causes the maximum peak to be directed in the signal arrival direction. Is as described above.

On the other hand, in the case of transmission, the maximum beam information selected at the time of reception is supplied from the maximum output beam selector 6 to the transmission beam changeover switch 9 so that the beam selected as the maximum beam at the time of reception is transmitted. Machine is connected. The supplied transmission signal is supplied to the Butler matrix 18, and the output thereof is multiplied by the weighting coefficient based on Δθ supplied from the null detection unit 7 by the transmission weighting coefficient multipliers 11-1 to 11-m. After that, diplexer 14
Antenna element so as to form one of the orthogonal multi-beams directed to the signal arrival direction at the time of reception, that is, the satellite direction in the case of mobile satellite communication, by supplying to the array antenna via It becomes possible to supply signals to 1-1 to 1-m. With the above configuration, the weighting coefficient obtained at the time of reception can be used as it is. In terms of hardware, the Butler matrix 17 and the Butler matrix 18 are shared by the reception weighting coefficient multipliers 4-1 to 4-m and the transmission weighting coefficient multipliers 11-1 to 11-m. It may be.

The embodiments described above are merely illustrative of the present invention and are not restrictive, and the present invention can be implemented in various other modified modes and modified modes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

[0056]

As described in detail above, according to the present invention, by utilizing the known spatial positional relationship between the peak and the null of each beam of the multi-beam, more specifically, The arrival angle of the signal wave is estimated using orthogonal multi-beams. The orthogonal multi-beam is a Butler matrix or the like in an analog circuit, and can be configured by a spatial FFT in a digital circuit. At the position where one beam has a peak, the other beams are null. It refers to a beam whose constituent relationship holds at all peak positions. With the combination of this peak and null, it is possible to estimate with sufficient accuracy as the control reference signal of the array antenna. Therefore, it is possible to obtain a simple arrival angle estimation device and array antenna control device having resistance to a multipath environment.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing an orthogonal multi-beam configured by applying spatial FFT to a 4-element linear array output.

FIG. 2 is a block diagram schematically illustrating the configuration of the first embodiment of the present invention.

FIG. 3 is a block diagram schematically illustrating a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a block diagram schematically illustrating a configuration of a third exemplary embodiment of the present invention.

FIG. 5 is a block diagram schematically illustrating a configuration of a fourth exemplary embodiment of the present invention.

FIG. 6 is a block diagram schematically illustrating a configuration of a fifth exemplary embodiment of the present invention.

[Explanation of symbols]

1-1 to 1-m array antenna 2 analog / digital converter 3, 12 Complex signal converter 4-1 to 4-m (for reception) weight coefficient multiplier 5 Spatial FFT calculator 6 Maximum output beam selector 7 Null detector 8 Signal arrival angle calculator 9 Transmit beam selector switch 10 Spatial inverse FFT calculator 11-1 to 11-m (for transmission) weighting coefficient multiplier 13 Digital / Analog converter 14 Antenna duplexer (diplexer) 15 Signal distributor 16 Optimal weighting factor calculator 17, 18 Butler Matrix

Continuation of front page (56) Reference JP-A-2-206776 (JP, A) JP-A-56-158504 (JP, A) JP-A-2-119302 (JP, A) JP-A-63-166305 (JP , A) JP-A-6-196921 (JP, A) JP-A-8-111651 (JP, A) JP-A-7-245526 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) H01Q 3/26

Claims (5)

(57) [Claims] 1. A signal wave arrival angle estimation apparatus using an array antenna having a plurality of antenna elements, wherein a plurality of signals respectively received by the plurality of antenna elements are converted into digital signals at a predetermined sampling frequency. Analog / digital signal converting means, a complex signal converting means for converting the output of the analog / digital signal converting means into a complex signal, and a predetermined value which is uniquely determined when the signal arrival direction is given to the output of the complex signal converting means. Weighting coefficient multiplication means for multiplying a plurality of weighting coefficients constrained by the relationship, spatial FFT calculation means for performing spatial FFT on the output of the weighting coefficient multiplication means to form an orthogonal multi-beam, and spatial FFT calculation means Among the outputs, the maximum output beam selection means for selecting the maximum output, and the maximum beam selection information from the maximum output beam selection means. And a null detecting means for detecting a null point of the selected maximum output beam by using a beam orthogonal to the selected maximum output beam, and supplying a constant for shifting the orthogonal multi-beam to the weighting coefficient multiplying means, and the null detecting means. From the maximum output beam selecting means and the information of the maximum output beam selected from the maximum output beam selecting means, and a signal arrival angle calculating means for calculating a signal arrival direction. Signal wave arrival angle estimation device. 2. A signal wave arrival angle estimation device using an array antenna having a plurality of antenna elements, wherein the signal arrival directions are uniquely given to a plurality of signals respectively received by the plurality of antenna elements. The weighting factor multiplication means for multiplying a plurality of weighting factors constrained in a predetermined relationship, the output of the weighting factor multiplication means, the Butler matrix forming the multi-beam, and the output of the Butler matrix Maximum output beam selection means for selecting an output, maximum beam selection information supplied from the maximum output beam selection means, the null point is detected using a beam orthogonal to the selected maximum output beam, and the weight coefficient multiplication is performed. Null detection means for supplying a constant to the means for shifting the orthogonal multi-beam, and orthogonal multi-beam shift from the null detection means Signal arrival angle estimation device for calculating a signal arrival direction by obtaining information and information about the maximum output beam selected from the maximum output beam selection device. . 3. An array antenna control device having a plurality of antenna elements, wherein a receiving section converts a plurality of signals respectively received by the plurality of antenna elements into digital signals at a predetermined sampling frequency. / Digital signal converting means, complex signal converting means for converting the output of the analog / digital signal converting means into a complex signal, and a predetermined relationship uniquely determined when a signal arrival direction is given to the output of the complex signal converting means Reception weight coefficient multiplication means for multiplying a plurality of weight coefficients constrained by, spatial FFT calculation means for performing spatial FFT on the output of the reception weight coefficient multiplication means to form an orthogonal multi-beam, and the spatial FFT calculation The maximum output beam is selected from the outputs of the means, and the selected maximum output beam is output as the array antenna output. Maximum output beam selection means and maximum beam selection information supplied from the maximum output beam selection means, the null point is detected using a beam orthogonal to the selected maximum output beam, and the reception weight coefficient multiplication means is provided. Null detection means for supplying a constant for shifting the orthogonal multi-beams, and the transmitter, when supplied with the maximum beam information from the maximum output beam selection means, connects the transmitter to the maximum beam according to the information. A transmission beam changeover switch, a spatial inverse FFT calculation means for performing a spatial inverse FFT on the value of each beam, and a relationship uniquely determined on the output of the spatial inverse FFT calculation means based on the constant detected by the null detection means. Weighting coefficient multiplication means for multiplying the weighting coefficient constrained by, and a complex weighting means for converting the output of the weighting coefficient multiplication means for transmission from a complex signal to an actual signal. Signal conversion means and array antenna control apparatus characterized by comprising a digital / analog signal conversion means supplying an output from the complex-signal converting means to said plurality of antenna elements is converted into an analog signal. 4. An array antenna control device having a plurality of antenna elements, wherein the receiving section digitally converts the plurality of signals respectively received by the plurality of antenna elements into a plurality of signals at a predetermined sampling frequency. To an analog / digital signal converting means, a complex signal converting means for converting the output of the analog / digital signal converting means into a complex signal, and a unique output when the signal arrival direction is given to the output of the complex signal converting means. A reception weighting coefficient multiplication means for multiplying a plurality of weighting coefficients constrained in a predetermined relationship, and a space FFT calculation means for forming an orthogonal multi-beam by applying a space FFT to the output of the reception weighting coefficient multiplication means, The space FF
A maximum output beam selection unit that selects the maximum output beam from the outputs of the T calculation unit and outputs the selected maximum output beam as an array antenna output, and maximum beam selection information from the maximum output beam selection unit Null detection means for detecting the null point using a beam orthogonal to the selected maximum output beam, and supplying a constant for shifting the orthogonal multi-beam to the reception weighting factor calculation means, and the maximum output beam selection The maximum output beam selection information from the means, each of which is supplied with a constant for shifting the orthogonal multi-beam from the null detection means, and comprises an arrival angle calculation means for calculating a signal arrival angle, and the transmission unit includes: A signal distribution device supplied with a digital transmission signal and distributing the transmission signal to a number equal to the number of antenna elements, and the signal distribution device Each of the transmission signals output from the transmission weight coefficient multiplication means for multiplying the transmission weight coefficient by a predetermined transmission weight coefficient, and the output of each digital signal of the transmission weight coefficient multiplication means is converted from a complex signal to an actual signal. Complex signal converting means, digital / analog signal converting means for converting an output from the complex signal converting means into an analog signal and supplying the analog signal to the plurality of antenna elements, and a signal arrival direction from the signal arrival angle calculating means, An array antenna control, comprising: optimum weight calculating means for receiving the antenna element outputs from the analog / digital signal converting means, outputting the optimum weight coefficients and supplying the optimum weight coefficients to the transmitting weight coefficient multiplying means. apparatus. 5. A control device for an array antenna having a plurality of antenna elements, wherein a receiving section is uniquely determined when a signal arrival direction is given to a plurality of signals respectively received by the plurality of antenna elements. A weighting factor multiplication means for reception that multiplies an input signal by a plurality of weighting factors constrained by the relationship, a butler matrix that is supplied with the output of the weighting factor multiplication means for reception and forms a multibeam, and a butler matrix of the butler matrix. Output, at the time of signal reception and transmission, a transmission / reception changeover switch for switching the subsequent device to the reception side and the transmission side, respectively, of the output of the Butler matrix via the transmission / reception changeover switch, the maximum output beam is selected, and
A maximum output beam selection means for outputting the selected maximum output beam as an array antenna output, and maximum beam selection information supplied from the maximum output beam selection means, and the null using the beam orthogonal to the selected maximum output beam Null detection means for detecting a point and supplying a constant for shifting the orthogonal multi-beams to the reception weighting coefficient multiplication means, and the transmitter is supplied with maximum beam information from the maximum output beam selector. According to the information, a transmission beam changeover switch for connecting the transmitter to the maximum beam output of the Butler matrix is provided, and the output of the transmission beam changeover switch is supplied to the Butler matrix through the transmission / reception changeover switch, and its output. Is multiplied by the weighting coefficient obtained at the time of reception by the receiving weighting coefficient multiplication means. After being calculated, the array antenna control device is configured to be supplied to the plurality of antenna elements.