JPH02280075A - Directivity combining method for wave receiving device - Google Patents

Abstract

PURPOSE:To obtain an optional characteristic of combined directivity independent of the arrangement and quantity of wave receiving device by obtaining weight coefficients to each wave receiving device by a space inverse Fourier transform and multiplying them by the output signals of each wave receiving device. CONSTITUTION:N pieces of the wave receiving device 12 with nondirectivity are arranged in a signal input part 11. At first, a desirable directivity characteristic function F(ktheta), arrangement r, theta of the wave receiving device, vector size of the number of incident wave and kr=2pi/lambda are set in an initial value setting part 13. Upon receipt of an output from the setting part 13, the weight coefficient is calculated by a calculating part 4. A space filter S(x,y) is obtained by performing the two-dimentional inverse Fourier transform to the directivity characteristic F(kx,ky) of each wave receiving device. Each weight coefficient constituting the space filter S(r,theta) is normalized with the total of entire weight coefficients to make a total power of the input signal equal to a combined signal power. The weight coefficient W is calculated by a coefficient calculating part 14, and a signal of the input part 11 is multiplied by W in a combining part 15 to obtain the total addition, which is outputted. An introduction of directivity characteristic function is made smooth and effective when a transfer function for BPF is used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for synthesizing the directivity of a receiver such as a microphone or a hydrophone in a sound source locating device, for example.

(Prior art) Conventional technology in this field includes, for example, "Marine Acoustics - Basics and Applications" edited by the Marine Acoustics Study Group (March 1, 1982).
) P, 166-167. The configuration will be explained below using figures.

FIG. 2 is a schematic diagram showing a directional synthesis method in horizontal beam scanning of a 360° sonar described in the above-mentioned document.

In the figure, a large number of transducers 2 are arranged around the circumference of a transducer 1 . These transducers 2 are set to function as a receiver 2 during reception. During reception, the output signal from each receiver 2 into which the sound wave is incident is switched by the analogue switch group 3 and guided to the delay circuit 4 while being shifted. The delay circuit 4 compensates for the phase delay of the output signal of each receiver 2 that occurs because the receivers 2 are arranged along the circumference, and prevents the directivity from spreading and side lobes from increasing. prevent. The output signals whose phase delays have been compensated for are added together by an adder circuit 5 and output.

In this way, this directional synthesis method increases the signal strength of the incident sound wave by matching the phases of the input waves of the receiver 2 whose direction of arrival of the incident sound wave is the front and the other receivers 2. This is what we are trying to do.

Following the above method, for example, 35 receivers 2 are arranged at a radius of 2 m.
Figure 3 (a) shows an example of the combined directivity characteristics when the antennas are placed at an angle of 5 degrees on the semicircle and receive a sound wave with a wavelength of 30 cm.
, shown in (b). Here, FIG. 3(a) shows the field pattern of the synthesized output obtained by rotating the sound source with respect to the receiver 2 and following the synthesis method described above, and FIG. 3(b) shows the upper semicircle of the field pattern. This is a composite output level curve in which the composite output is expressed logarithmically. From the figure, it can be seen that, for example, the main lobe 6 has a sharp shape.

(Problems to be Solved by the Invention) However, in the method for synthesizing the directivity of wave receivers having the above configuration, there is a problem that the synthesized directivity characteristics are determined by the placement position and number of wave receivers 2. The solution was difficult.

For example, as shown in FIG. 3(a), the shape of the main lobe 6 is fixed and the value of the half-width is also fixed. There was a risk that this would cause problems.

The present invention is a method for synthesizing directivity of wave receivers that solves the problem that the conventional technology had, in that the combined directivity characteristics of a plurality of wave receivers are determined by the arrangement position and number of wave receivers. It provides:

(Means for Solving the Problem) In order to solve the above problem, in the first invention, for a plurality of sound wave receivers installed at arbitrary positions, the installation position and number of the receivers are determined. The directional characteristic function and the magnitude of the wave number vector of the incident wave are set as initial values, and based on the initial values, respective weighting coefficients for each of the receivers are calculated by spatial inverse Fourier transform, and The receiver's directivity synthesis method is configured by outputting the sum of the products of each of the output signals and each of the molding coefficients.

In a second aspect of the invention, in the method for directional synthesis of wave receivers according to claim 1, a radio wave receiver is used in place of the acoustic wave receiver.

Furthermore, in a third invention, in the directivity synthesis method for a wave receiver according to claim 1 or 2, a transfer function for a frequency band limiting filter is used as the directivity characteristic function.

(Operation) According to the first invention, since the directivity synthesis method of the wave receivers is configured as described above, the weighting coefficient for each wave receiver is obtained by spatial inverse Fourier transform, and this is calculated from each wave receiver. Multiplying the output signal of the receiver makes it possible to obtain an arbitrary composite directivity characteristic without being restricted by the arrangement position or number of each receiver.

Furthermore, in the second invention, by replacing the first sonic wave receiver with a radio wave receiver, it is possible to obtain arbitrary composite directivity characteristics for radio waves that are not restricted by the arrangement or number of each receiver. do the work.

Furthermore, in the third invention, by using a frequency band limiting filter transfer function as the directional characteristic function, weighting coefficients can be calculated appropriately and reliably, and desired composite directional characteristics can be easily obtained.

Therefore, the above problem can be solved.

(Embodiment) FIG. 1 is a block diagram showing a method for combining directivity of a wave receiver in an embodiment of the present invention.

In the figure, a plurality of omnidirectional sound wave receivers 12 are installed at arbitrary positions in the signal input section 11. The initial value setting section 13 is for setting initial values regarding the wave receiver 12 and the like, and is connected to the coefficient calculation section 14.

The coefficient calculation unit 14 is for calculating a weighting coefficient to be applied to the output signal of each receiver 12.

The signal synthesis section 15 is for calculating the product of each output signal sent from the signal input section 11 and each weighting coefficient output from the coefficient calculation section 14, and outputting the sum thereof.

Directional synthesis by the directional synthesis device configured as described above is performed as follows.

First, in the initial value setting section 13, the desired directivity characteristic function F(ko), the installation position (r, θ) of each receiver 12, the total number n of receivers 12, and the size of the wave number vector of the incident wave are determined. k
=2π/λ (λ: wavelength) is set. For the directivity characteristic function F (K,), it is preferable to use a transfer function for a frequency band limiting filter, such as Butterworth's equation.

Next, the coefficient calculation unit 4 calculates the weighting coefficient as described below based on the input from the initial value setting unit 13.

The directional characteristic F (kX, ky) of the composite receiver is obtained by Fourier transforming the spatial filter S (x, y). Now, in the case of directivity on the same plane, it is sufficient to consider two-dimensional Fourier transformation, so F(kX, ky) (1). Therefore, the spatial filter S(x, y) to be obtained is an inverse Fourier transform of the directional characteristic, and S (x, y) = f f F (kx, ky) -ω-ω -J (Xk×+Yky) Xdk dk y ...(2) is given by. If this equation (2) is expressed in polar coordinates, it becomes the following equation.

S (r, θ) , Kr, the following equation is obtained.

S (r, θ) = δ(K, −, ) By normalizing each weighting coefficient constituting the spatial filter with the sum of all weighting coefficients, the input signal power delivered by each receiver 12 is can be made equal to the combined signal power obtained by this method.

For example, among the receivers 12 arranged at equal angles on the same circumference with radius r, the weighting coefficient W to be applied to the receiver 12 arranged at the angle θ is given by the following formula: shown.

k, δ(K, −, ) In this way, by performing the calculation according to equation (5), the coefficient calculation unit 14 calculates each weighting coefficient W... (
4) and output it to the signal synthesis section 15. On the other hand, in the signal input section 11, each receiver 12 is arranged at the position input by the initial value setting section 13, and each of these receivers 12 independently receives a sound wave and transmits the signal. The signal is sent to the signal combining section 15.

The signal synthesis section 15 multiplies each signal sent from the signal input section 11 by each weighting coefficient W output from the coefficient calculation section 14, calculates the total sum, and outputs the sum. This output becomes the output signal in the present directional synthesis method.

Examples of synthesized directivity characteristics when using the directivity synthesis method configured as described above are shown in Fig. 4(a), (b) and Fig. 5(
Shown in a) and (b). Figure 4(a).

(b) shows an example of the composite directional characteristic when using a certain directional characteristic relationship F (K,?), (a) shows the field pattern of the composite output, and (b) shows the upper part of the field pattern This is a composite output level curve that logarithmically represents the composite output of a semicircle. Further, FIGS. 5(a) and 5(b) show an example of the composite directional characteristic when another directional characteristic function F (Ke) is used.

This is shown using the same field pattern and composite output level curve as in (b).

In both Fig. 4 (a>, (b)) and Fig. 5 (a), (b), 35 receivers 12 are arranged at an angle of 5° on a semicircle with a radius of 2 m, This shows the case where a sound wave with a wavelength of 30 m is received.

First, the composite directivity characteristics shown in FIG. The figure shows the output of the signal obtained by rotating the sound source with respect to the receiver 12.

Next, for the composite directional characteristics of FIGS. 5(a) and 5(b), the directional characteristic function F(KO) given to the initial value setting section 13 is a Butterworth polynomial as shown in equation (7) below, and Kt: =-7, Kn =7. The results are shown when m=2.

As is clear from a comparison between FIGS. 4(a) and 5(b) and FIGS. 5(a) and (b), the composite directivity characteristics of the two are significantly different. That is, compared to the shape of the main lobe 16 in FIG. 4(a), the shape of the main lobe 17 in FIG. 5(a) has a large spread, especially at the tip, and the half width is also different. Furthermore, the appearance of each side lobe is also different. Therefore, there is a noticeable difference between the composite output level curves of FIG. 4(b) and FIG. 5(b).

In this way, according to this embodiment, an arbitrary composite directivity can be obtained by changing the number F (Ke) of directivity characteristics for the sound wave receiver 12 such as a microphone or a hydrophone placed at an arbitrary position. It becomes possible to hold it.

In the above embodiments, the method of directional synthesis of a wave receiver for sound waves has been described, but the present invention can be similarly applied to radio waves.

That is, a radio wave receiver is used in place of the sonic wave receiver 12,
The signal input section 11, initial value setting section 13, coefficient calculation section 14, signal synthesis section 15, etc. may be compatible with a radio wave receiver. By doing so, radio waves received by a radio wave receiver disposed at an arbitrary position, such as an array antenna, can be given an arbitrary composite directivity in the same way as sound waves.

Note that the present invention is not limited to the illustrated embodiment, and can be modified in various ways, such as the following modifications.

(i) A transducer may be used in place of the receiver 12 shown in FIG. In this case, the present invention is applied to the transducer switched to reception by the transmission/reception switching circuit.

(ii) For the frequency band-limiting filter transfer function used for the directivity characteristic function F (K#), it is possible to use not only the Butterworth equation described above but also various transfer relationships such as, for example, the Tievisiev equation.

(iii) The sound wave received by the receiver 12 in FIG. 1 means a sound wave in a broad sense. Therefore, the present invention can also be applied to ultrasonic waves.

(Effects of the Invention) As explained in detail above, according to the first invention, each weighting coefficient is calculated by inverse Fourier transform for a plurality of sound wave receivers installed at arbitrary positions, and Since the multiplication is made to match the output signal of each receiver, it is possible to obtain an arbitrary composite directivity characteristic. This makes it possible to support various sound sources and various uses without being restricted by the arrangement position or number of receivers.

According to the second invention, by replacing the sonic wave receiver with a radio wave receiver, the same effect as that of sound waves can be obtained for radio waves.

According to the third invention, by using the frequency band limiting filter transfer function, the directivity characteristic function can be introduced smoothly and effectively, and various composite directivity characteristics can be easily obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a method of combining directivity of a receiver in an embodiment of the present invention, FIG. 2 is a schematic diagram showing a method of combining directivity of a conventional receiver, and FIG. 3(a) , (b) show an example of the combined directivity characteristics according to the conventional method, (a) shows the field pattern of the combined output, and (b) shows the combined output level curve. ) shows an example of the synthesized directivity characteristic according to the method of the embodiment of the present invention, FIG. 5(a) shows the field pattern of the synthesized output, FIG. b) shows another example of synthetic directivity characteristics obtained by the method of the embodiment of the present invention;
) and (b) are a field pattern of a composite output and a diagram of a composite output level curve, respectively. 11... Signal input section, 12... Sonic wave receiver, 13... Initial value setting section, 14...
- Coefficient calculation unit, 15... Signal synthesis unit.

Claims (1)

[Claims] 1. For a plurality of sound wave receivers installed at arbitrary positions,
The installation position and number of the receivers, the directivity characteristic function, and the size of the wave number vector of the incident wave are set as initial values, and based on the initial values, the weighting coefficients for each receiver are calculated using the spatial inverse Fourier method. A method for combining directivity of a wave receiver, comprising: calculating by conversion, and outputting a sum of products of each signal output from each of the wave receivers and each of the weighting coefficients. 2. In the receiver directivity synthesis method according to claim 1,
A method for synthesizing the directivity of a wave receiver using a radio wave receiver instead of the acoustic wave receiver. 3. The method of synthesizing the directivity of a wave receiver according to claim 1 or 2, wherein a transfer function for a frequency band limiting filter is used as the directivity characteristic function.