JP4288663B2 - Phase phasing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a phasing method and apparatus, and more particularly to a noise reduction technique for reducing noise in a sonar or the like.
[0002]
[Prior art]
It is necessary to reduce various noises mixed in a sonar or the like based on an ANC (Adaptive Noise Canceller) method and improve the S / N ratio. A general prior art for this will be described below with reference to FIG.
[0003]
As shown in FIG. 4, a general phasing device 10 includes an array 11 including a plurality of receivers, an adaptive filter 12, a multiplier 13, and an adder 14. A phasing beam B is formed by the array 11. In addition, a normal received signal (desired signal and various noise signals) obtained by beam steering in the direction of arrival of the target signal and a reference signal having only a signal highly correlated with various noise signals not including the desired signal are used. Then, the signal filtered by the adaptive filter 12 using an adaptive algorithm such as LMS (Least Mean Square) is subtracted from the normal received signal by the subtractor composed of the multiplier (multiplier) 13 and the adder 14. By doing so, noise contained in a normal received signal is reduced. As the reference signal, the output of the phasing beam C1 beam steered to a noise source or the output of a receiver C2 installed in the vicinity of the noise source is generally used.
[0004]
Here, as a conventional technique, in order to prevent a desired signal from leaking to the reference signal due to the influence of ship motion and the like, and the reduction effect due to ANC is reduced, the reference phasing beam is always used as the desired signal. A technique for controlling to form a null in the arrival direction is disclosed (for example, see Patent Document 1). In addition, a receiver is placed on the bottom of the stern side to receive various noise waves generated by the ship, and the signal is inverted and added to the signal from the transmitter and receiver to reduce the reception noise in the low frequency range. A sonar device is disclosed (for example, see Patent Document 2).
[0005]
[Patent Document 1]
JP-A-5-323017 (page 2-3, FIG. 1)
[Patent Document 2]
JP-A-5-142335 (page 2-3, FIG. 1)
[0006]
[Problems to be solved by the invention]
In the conventional method, when a single noise source is far away, the interference signal can be reduced. However, when there are multiple noise sources at a short distance, the correlation of the interference signal input to each receiver is possible. Since the range in which the noise can be obtained is limited, the correlation between noises is lowered in the conventional method in which processing is performed after beam synthesis and a sufficient noise reduction effect cannot be expected.
[0007]
In addition, if the number of receivers is small and the array is small, the directional width due to phasing increases, so it becomes difficult to form a phasing beam that measures only the interference signal from the noise source. There was a problem that the signal level was also reduced.
[0008]
OBJECT OF THE INVENTION
The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a phasing method and apparatus that eliminates or reduces such problems.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the phasing method and apparatus according to the present invention employ the following characteristic configuration.
[0010]
(1) In a phasing device that reduces various noise signals mixed in a sonar and the like and improves the S / N ratio by the ANC technique,
An array including a plurality of receivers arranged at the center and its periphery, a plurality of delay devices for delaying the output signal of each receiver of the array, a process including a plurality of adders and an adaptive filter calculator With
The adaptive filter calculator of the processing unit receives a difference signal between average values of the output signal of the central receiver and the output signals of the surrounding receivers ,
The processing unit outputs a difference signal of an average value of an output signal of the adaptive filter calculator and an output signal of all receivers of the array.
[0011]
(2) The phasing device according to ( 1) , wherein the processing unit divides the receivers of the array into a plurality of combinations in different directions, processes the combinations, and adds the processing results.
[0012]
(3) The phasing device according to the above (1) or (2) , wherein the array includes nine receivers arranged in a matrix.
[0013]
(4) The array is composed of nine receivers arranged in a matrix.
The phasing device according to (2) , wherein the plurality of combinations are four combinations of vertical and horizontal and diagonal including a central receiver.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration and operation of a preferred embodiment of the phasing method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0018]
First, FIG. 1 is an explanatory diagram of a first embodiment of a phasing method and apparatus according to the present invention. The present invention includes an array 100, delay units 121 to 129 that delay the output signals of a plurality of receivers 111 to 119 constituting the array 100 and adjust the phase, and a processing unit that processes the output signals of these delay units. Is done. As shown in FIG. 1A, the array 100 includes nine receivers 111 to 119 of 3 × 3 in a matrix so as to surround a central receiver 115. In addition, as shown in FIG. 1B, the array 100 includes four combinations 101 to 104 that sandwich the central receiver 115 between two receivers. That is, the first combination 101 includes the receivers 111, 115, and 119 in the diagonally downward direction. The second combination 102 is composed of vertical receivers 114, 115 and 116. The third combination 103 includes receivers 113, 115, and 117 in a diagonally upward direction. Finally, the fourth combination 104 is composed of horizontal receivers 112, 115 and 118.
[0019]
As shown in the block diagram of FIG. 1C, the outputs of the first combination 101 to the fourth combination 104 of the array 100 are processed by processing units each including a delay unit, an adder, an adaptive filter calculator, and the like. . As will be described in detail below, the output signals of the combinations 101 to 104 are added and averaged as will be described later with reference to FIG.
[0020]
The receivers 111, 115, and 119 of the first combination 101 receive reverberation sound from the target or radiated sound of the target by sound waves transmitted in water or in the air. Delay devices 121, 125, and 129 perform delay processing of the receiver output based on the propagation path difference caused by the phasing direction. An adder (first adder) 131 adds the outputs of the delay units 121 and 129. The averager (first averager) 141 multiplies the output of the adder 131 by 1/2 and averages the result. The multiplier (first multiplier) 151 multiplies the output of the delay device 125 by -1. An adder (second adder) 132 adds the outputs of the averager 141 and the multiplier 151. Here, the output of the adder 132 is referred to as a reference signal.
[0021]
Next, the adaptive filter calculator 160 performs reference signal filtering. The multiplier (second multiplier) 152 multiplies the output of the adaptive filter calculator 160 by -1. An adder (third adder) 133 adds the outputs of the delay units 121, 125, and 129. The averager (second averager) 142 multiplies the output of the adder 133 by 1/3 and averages. The output of the averager 142 is called a primary signal. An adder (fourth adder) 134 adds the primary signal and the output of the multiplier 152. The output of the adder 134 is called a canceled signal (or canceled signal). The adaptive filter calculator 160 updates the filter coefficient every sample from the reference signal and the canceled signal one sample before by an adaptive algorithm such as LMS.
[0022]
In FIG. 1C, although partially omitted, the second combination 102 by the receivers 114, 115 and 116, the third combination 103 by the receivers 117, 115 and 113, and the receivers 112, 115 and In each of the fourth combinations 104 by 118, the same processing as that of the first combination 101 described above is performed. Then, as shown in FIG. 1D, the adder 35 adds the canceled signals from the adders 134, 234, 334, and 434 of the combinations 101, 102, 103, and 104, respectively. The averager 43 multiplies the output of the adder 35 by ¼ and averages.
[0023]
Next, FIG. 2A shows the directivity characteristics of the primary signal described above, and FIG. 2B shows the directivity characteristics of the reference signal described above. The primary signal is a beam having directivity characteristics in the phasing direction. On the other hand, the reference signal is a dumpling beam having a minimum portion in the phasing direction. By adding the outputs of the first to fourth combinations 101 to 104 described above, the reference signal approximately forms a donut-shaped beam having a minimum portion in the phasing direction. The donut-shaped beam is used to capture an interference signal from an orientation different from the phasing orientation and remove the interference signal from the primary signal.
[0024]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the second embodiment of the phasing method and apparatus according to the present invention. In the second embodiment, for convenience of explanation, the same or similar reference numerals are used for the components corresponding to the first embodiment. The second embodiment includes nine receivers 111 to 119 arranged in a matrix, delay devices 121 to 129 connected to the output side of the receivers 111 to 119, a first adder 531, 2 adder 532, third adder 533, fourth adder 534, first averager 541, second averager 542, first multiplier 551, second multiplier 552, and adaptive filter calculator 560. Yes.
[0025]
The delay units 121 to 129 perform delay processing of output signals from the wave receivers 111 to 119 based on the propagation path difference caused by the phasing direction. The first adder 531 adds the output signals of the eight delay units 111 to 114 and 116 to 119 excluding the delay unit 125 of the central receiver 115. The first averager 541 multiplies the output signal of the first adder 531 by 1/8 and averages.
[0026]
The first multiplier 551 multiplies the output signal of the delay device 125 by -1. The second adder 532 adds the output signals of the first averager 541 and the first multiplier 551, and outputs a reference signal. The adaptive filter calculator 560 performs reference signal filtering. Second multiplier 552 multiplies the output signal of adaptive filter calculator 560 by -1. The third adder 533 adds the output signals of the first adder 531 and the center delay unit 125. The second averager 542 multiplies the output signal of the third adder 533 by 1/9 and outputs the primary signal. The fourth adder 534 adds the primary signal and the output signal of the second multiplier 552, and outputs a final canceled signal.
[0027]
Here, the adaptive filter calculator 560 updates the filter coefficient for each sample using an adaptive algorithm such as LMS from the reference signal and the canceled signal one sample before. The reference signal having such a configuration has a donut-shaped directivity having a minimal portion in the phasing direction. Therefore, by subtracting the output of the adaptive filter calculator 560 to which the reference signal is input from the primary signal, an effect equivalent to that of the first embodiment described above is exhibited. In addition, the configuration is simplified compared to the first embodiment.
[0028]
The configuration and operation of the preferred embodiment of the phasing method and apparatus according to the present invention have been described in detail above. However, it should be noted that such embodiments are merely examples of the present invention and do not limit the present invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention.
[0029]
【The invention's effect】
As is clear from the above description, according to the phasing method and apparatus of the present invention, the following remarkable effects in practical use can be obtained. That is, a directional reference signal having a minimum portion in the phasing direction is formed, and the signal subjected to adaptive filter processing so as to remove the component of the reference signal included in the primary signal is subtracted from the primary signal. The adaptive filter calculator updates the filter coefficient so that the reference signal component included in the primary signal is removed from the reference signal and the output signal one sample before the adder by an adaptive algorithm such as LMS. As a result, it is possible to effectively form a phasing beam for measuring only the interference signal from the noise source, to sufficiently reduce the noise signal, and to greatly improve the S / N ratio.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a first embodiment of a phasing method and apparatus according to the present invention.
FIGS. 2A and 2B are operation explanatory views of the first embodiment of the present invention shown in FIG. 1, wherein FIG. 2A shows the directivity of a primary signal, and FIG. 2B shows the directivity of a reference signal;
FIGS. 3A and 3B are explanatory diagrams of a second embodiment of the phasing method and apparatus according to the present invention, where FIG. 3A is an array composed of a plurality of receivers, and FIG. 3B is a process for processing an output signal of the array; It is a block diagram of a part.
FIG. 4 is an explanatory diagram of a general prior art.
[Explanation of symbols]
100 Array 111 to 119 Receiver 101 to 104 Receiver combination 121 to 129 Delay device 35, 131 to 134, 431 to 434, 531 to 534 Adder 43, 141, 142, 441, 442, 541, 542 Average 160, 460, 560 Adaptive filter calculator

Claims (4)

In a phasing device that reduces various noise signals mixed in a sonar and improves the S / N ratio by the ANC technique,
An array including a plurality of receivers arranged at the center and its periphery, a plurality of delay devices for delaying the output signal of each receiver of the array, a process including a plurality of adders and an adaptive filter calculator With
The adaptive filter calculator of the processing unit receives a difference signal between average values of the output signal of the central receiver and the output signals of the surrounding receivers ,
The phasing device is characterized in that the processing unit outputs a difference signal of an average value of output signals of the adaptive filter calculator and output signals of all receivers of the array. The phasing device according to claim 1 , wherein the processing unit divides the receivers of the array into a plurality of combinations in different directions, processes the combinations, and adds the processing results. . The phasing device according to claim 1 or 2, wherein the array includes nine receivers arranged in a matrix. The array is composed of nine receivers arranged in a matrix,
The phasing device according to claim 2 , wherein the plurality of combinations are four combinations of vertical and horizontal and diagonal including a central receiver.

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