JP2853589B2 - Direction detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a sonar device or other device for detecting the direction of arrival of an acoustic signal. The present invention can be used for any of acoustic signals in water and other liquid media and acoustic signals in air and other gaseous media.

[0002]

2. Description of the Related Art When a signal emitted from the same object having a relatively small amount of movement or a reflected signal is received by a directional receiver and subjected to frequency analysis, the frequency of a signal source is stabilized. The azimuth of the frequency is often seen to be relatively small and scattered about the signal source.

For this reason, in the conventional apparatus, as shown in FIG. 3, for example, the frequency noise is removed and the signal is detected by time-integrating the amplitude of the same frequency in the frequency analysis result. That is, the frequency of the signal input from the sensor is analyzed by the frequency analysis circuit 21, the integration is performed on the time axis by the time integration circuit 22, and the signal is compared with the amplitude threshold set by the signal determination circuit 23. A method is used in which a judgment is made and the intensity of the amplitude is displayed in a sonagram represented by shading in the shading image drawing circuit 24.

[0004] As another example, as shown in FIG. 4, an azimuth noise is removed and a signal is detected by time-integrating the amplitude of the same azimuth in the frequency analysis result. That is, the signal input from the sensor is frequency-analyzed by the frequency analysis circuit 31, the azimuth for each frequency is calculated by the azimuth detection circuit 32, the azimuth integration circuit 33 integrates in the same azimuth, and the signal determination circuit 34 Noise and signal are determined by comparing with the set amplitude threshold.

Further, as another example, as shown in FIG.
2. Description of the Related Art Frequency noise and azimuth noise are removed by synthesizing directivity in a certain azimuth, analyzing the frequency of a received signal, and performing time integration. That is, the directivity is synthesized by the directivity synthesis circuit 41 of the signal input from the sensor,
After the frequency is analyzed by the frequency analysis circuit 42, integration is performed on the time axis by the time integration circuit 43, and the signal and noise are determined by comparing with a certain amplitude threshold set by the signal determination circuit 44. .

The prior art of the present invention is disclosed in Japanese Patent Application Laid-Open No. 3-29.
There is one disclosed in Japanese Patent No. 3575. Although this prior art is considered to be related to the present invention, there is a disclosure that weighting is performed on the frequency.However, it is clear that the variance of the signal direction in a time series is calculated and a load is applied to a signal having a small variance. There is no idea to execute the calculation n times in a time series with the passage of time. Further, there is no description that the load on the variance is multiplied by the reciprocal of the variance.

[0007]

As described above, when a signal emitted or reflected by an object is received by a directional receiver and frequency analysis and azimuth detection are performed, the azimuth of the signal from the object becomes A relatively small variance around a certain value,
The variance of the direction of the noise is very large. Therefore, if information on the variance of the azimuth is used for signal detection, a more accurate signal can be detected.

The present invention has been made based on such a background, and an object of the present invention is to provide an apparatus capable of emphasizing a signal having a small azimuth variance value and enabling detection of a weaker signal. I do.

According to the present invention, a signal source is detected based on information that an acoustic signal from a signal source has a frequency that is temporally more stable than noise, whereas a signal from a signal source is detected. It is an object of the present invention to provide a device which can improve the ability to detect a signal buried in noise by utilizing the fact that the azimuth other than the frequency is stable.

[0010]

SUMMARY OF THE INVENTION The present invention is characterized in that the direction of arrival of an acoustic signal can be detected even if the signal is weak.

That is, the present invention provides means (1, 11) for receiving an incoming audio signal in a plurality of directions, a frequency analysis circuit (2) for analyzing the frequency of the audio signal,
An azimuth detecting device including azimuth detecting means (3) for calculating a signal azimuth according to the amplitude of the frequency obtained as a result of the frequency analysis, wherein the arithmetic circuit comprises m frequencies (m is a positive number). Means (5) for calculating the signal direction for the integers and calculating the variance d of the signal direction from the respective calculation results for the m frequencies; a memory for temporarily storing the calculated signal direction and the variance d;
Means (6) for emphasizing and loading the signal azimuth having a small variance d
And characterized in that:

The arithmetic circuit causes the signal direction to be calculated n times (n is an integer of 2 or more) in a time series with respect to the m frequencies (a total of m × n times) and the calculation result and the variance d thereof are stored in the memory. The emphasis weighting means includes means for multiplying the signal amplitude of interest by the reciprocal (1 / d) of the variance d, and the arithmetic circuit comprises:
Means for performing noise removal processing on each of m frequencies appearing in the output of the frequency analysis circuit, or means for performing noise removal processing on each of the frequencies appearing n times in the output of the frequency analysis circuit; It is desirable to have a density modulation means for displaying the signal direction emphasized on the result on the grayscale image.

Here, the variance means that n data are represented by x
_1, x _2, ..., when the x _n, the average value [External 1]
Is

[0014]

(Equation 1) Where the difference between each data x _{i and} the average value [1] is squared, added and divided by n, and is represented by S ² .

[0015]

(Equation 2)

[0016]

[Outside 1] In the prior art (described in Japanese Patent Application Laid-Open No. 3-293575), the direction of a signal source is detected based on a delay in signal arrival time due to spatial arrangement of signals by receiving waves with a plurality of sensors. Whereas the calculation cannot be performed unless the arrangement is a grid, the present invention is a sensor that is not arranged in a grid,
In extreme cases, prediction calculations are performed using signals received by a single sensor, enabling the same azimuth calculation as those arranged in a grid, enabling the sensor to be arranged freely. .

[0017]

An incoming sound signal is received in a plurality of directions, and the frequency analysis circuit analyzes the frequency of the sound signal. For the frequency resulting from the frequency analysis, a signal azimuth calculation process is performed according to the amplitude.

In this arithmetic processing, an arithmetic circuit calculates a signal direction for m frequencies (m is a positive integer), and
The variance d of the signal direction is calculated for each of the frequencies from the respective calculation results, and the calculated signal direction and its variance d are calculated.
Is temporarily stored in a memory, and a signal direction having a small variance d is weighted.

The arithmetic circuit calculates the signal direction n times (n is an integer of 2 or more) in a time series with respect to the m frequencies (total m × n times), and accumulates the calculation results and the variance d in the memory. , The emphasis weight is the reciprocal of variance d (1
/ D).

The arithmetic circuit can also perform noise removal processing on m frequencies appearing in the output of the frequency analysis circuit, and perform noise removal processing on frequencies appearing n times in the output of the frequency analysis circuit.

With respect to the calculation result by the calculation circuit, the signal direction in which the weight is emphasized can be displayed in a dark and light image.

As described above, according to the present invention, when the azimuth variance value is small using the azimuth variance at a frequency before and after a certain frequency and / or the azimuth variance at a time before and after a certain frequency in the frequency analysis result of the signal, The amplitude can be weighted so that the signal is enhanced.

Thus, signal detection can be performed by emphasizing the amplitude of a signal having a small azimuth variance. Therefore, in the frequency analysis result, compared with the method of integrating the amplitude of the same frequency with time and the method of integrating the amplitude of the same azimuth with time. It is possible to detect a weaker signal. In addition, the processing amount is significantly reduced compared to the method of combining the directivity in a certain direction and frequency analyzing the signal received, and the processing result displayed for each direction combining direction in the conventional method is reduced. It can be displayed as an omnidirectional signal on the same screen.

[0024]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention.

In the embodiment of the present invention, a plurality of directional microphones 1 constituting means for receiving an incoming acoustic signal in a plurality of directions and an input section 11 for inputting the output thereof are provided.
And a frequency analysis circuit 2 for analyzing the frequency of the acoustic signal
And an arithmetic circuit 20 for calculating the signal direction, and a frequency domain auto gain control (FDAGC) for performing a moving average operation in the frequency direction to correct the level in the frequency domain.
A circuit 7, an integration circuit 8 for integrating the same frequency component from the time series data obtained by the moving average operation on the azimuth load result obtained for each unit time and removing noise, and an integration circuit 8 obtained for each unit time from the integration circuit 8 A signal judgment circuit 10 for judging the azimuth load result, a gradation image drawing circuit 9 for drawing the processed azimuth load result from the integration circuit 8 with a gradation image, a gradation image drawing circuit 9 and a signal judgment circuit 10
Density modulation circuit 17 which receives the output from and modulates the density
And a sonagram 16 which receives the output from the density modulation circuit 17 and displays the signal intensity in shades.

The frequency analysis circuit 2 includes a low-pass filter 12 for filtering an audio signal from the input unit 11, an A / D converter 13 for digitally converting the audio signal, and an A / D converter 13 for digitally converting the audio signal. A fast Fourier transform circuit (FFT) 14 for performing a fast Fourier transform.

The arithmetic circuit 20 includes an azimuth detecting circuit 3 as azimuth detecting means for calculating a signal azimuth in accordance with the amplitude of the frequency obtained as a result of the frequency analysis by the frequency analyzing circuit 2, and a frequency direction and a time direction. Each will score a few points. That is, the azimuth data is captured through a rectangular window. That is, the control unit 4 causes the signal direction to be calculated n times (n is an integer of 2 or more) in time series with respect to the m frequencies (a total of m × n times) and accumulates the calculation result and its variance d in the memory 15. And a direction variance calculation circuit 5 as means for calculating a signal direction for m frequencies (m is a positive integer) and calculating a signal direction variance d from the respective calculation results for the m frequencies. A memory 15 for temporarily storing the signal direction and its variance d,
An azimuth dispersion load circuit 6 as means for emphasizing and loading the signal azimuth having a small variance d is included.

The means for emphasizing and loading includes means for multiplying the amplitude of the target signal by the reciprocal (1 / d) of its variance d. It may include means for performing noise removal processing for each frequency, or may include means for performing noise removal processing for each of the frequencies appearing n times in the output of the frequency analysis circuit 2. Further, there is provided a density modulation means for displaying a signal direction in which the arithmetic result of the arithmetic circuit 20 is emphasized on a grayscale image, and an amplifier 18 is connected to the input unit 11, and a speaker 19 is connected to the amplifier 18. You.

FIG. 2 is a diagram showing a configuration example of a signal cutout window (rectangular window) provided in the control circuit in the embodiment of the present invention. This signal extraction window is configured in the same manner as a window for processing such as edge enhancement and smoothing performed in image processing and the like, and this example includes a 5 × 5 window and includes “1” to
The data of “13” is emphasized using the azimuth dispersion value of “25”. The optimal size of the window is set according to the direction of the sensor, the signal processing parameters, and the like.

Next, the operation of the embodiment of the present invention configured as described above will be described. The gist of the present invention is to calculate the signal azimuth in accordance with the result of the frequency analysis, obtain a variance value for the signal azimuth for each frequency, and emphasize those having a small variance value.

The directional microphone 1 receives an incoming acoustic signal in a plurality of directions. The input unit 11 sends the acoustic signal to the amplifier 18 and the frequency analysis circuit 2. The sound signal amplified by the amplifier 18 is output as sound from a speaker 19. On the other hand, in the frequency analysis circuit 2, the low-pass filter 12 performs a filtering process, the A / D converter 13 digitizes the processed acoustic signal, and the fast Fourier exchange circuit 14 performs a fast Fourier transform process.

The arithmetic circuit 20 receives the output, and the azimuth detecting circuit 3 calculates the signal azimuth of the frequency obtained as a result of the frequency analysis in accordance with the amplitude and stores it in the memory 15. The azimuth variance calculation circuit 5 receives the calculated value of the signal azimuth via the control means 4 and calculates the variance d of the signal azimuth from the calculation results for m frequencies. Next, the azimuth dispersion load circuit 6 emphasizes and loads the signal azimuth having the small variance d. In this processing, the control means 4 causes the signal direction to be calculated n times (n is an integer of 2 or more) for the m frequencies in a time series (total m × n times), and the calculation result and its variance d
Is accumulated in the memory 15, and the signal amplitude targeted by the azimuth dispersion load circuit 6 is multiplied by the reciprocal (1 / d) of the variance d.

In the arithmetic circuit 20, noise removal processing is performed for each of m frequencies appearing in the output of the frequency analysis circuit 2, or noise removal processing is performed for each of the frequencies appearing n times in the output of the frequency analysis circuit 2. it can.

The above processing is performed in the arithmetic circuit 20, and the output is output to the FDAGC circuit 7. The FDAGC circuit 7 performs a moving average operation in the frequency direction to perform level correction in the frequency domain. Next, the integration circuit 8 determines the azimuth load result acquired for each unit time by the FDAGC circuit 7.
The same frequency component is integrated from the time-series data by the moving average operation to remove noise. When the result of the azimuth load exceeds a predetermined amplitude threshold, the signal determination circuit 10 determines that the signal is a signal and outputs the determination result. In this way, the grayscale image drawing circuit 9 displays the signal direction subjected to the filtering process and the weighted emphasis on the grayscale image of the sonagram 16.

[0035]

As described above, according to the present invention, the amplitude of a signal whose azimuth is stable can be emphasized and detected by loading the signal amplitude with the reciprocal of the azimuth dispersion value. Therefore, the amplitude of the noise whose direction is unstable is reduced,
It is possible to increase the amplitude of a signal having a stable azimuth, and it is possible to reliably detect a signal even under a low S / N ratio where detection is difficult. Further, the processing amount can be reduced, and the processing result can be displayed on the same screen as an omnidirectional signal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a cutout window (rectangular window) provided in a control circuit according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration and a signal detection method of a conventional example.

FIG. 4 is a diagram illustrating a configuration and a signal detection method of a conventional example.

FIG. 5 is a diagram illustrating a configuration and a signal detection method of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 directional microphone 2, 21, 31, 42 frequency analysis circuit 3, 32 azimuth detection circuit 4 control means 5 azimuth dispersion calculation circuit 6 azimuth dispersion load circuit 7 FDAGC circuit 8 integration circuit 9, 24 grayscale image drawing circuit 10, 23, 34, 44 signal determination circuit 11 input unit 12 low-pass filter 13 A / D converter 14 fast Fourier exchange circuit 15 memory 16 sonagram 17 density modulation circuit 18 amplifier 19 speaker 20 arithmetic circuit 22, 43 time integration circuit 33 azimuth integration circuit 41 direction Sex synthesis circuit

Claims (5)

(57) [Claims] 1. A means for receiving an incoming sound signal in a plurality of directions, a frequency analysis circuit for performing frequency analysis of the sound signal, and calculating a signal direction according to the amplitude of a frequency obtained as a result of the frequency analysis. An azimuth detecting device comprising: an arithmetic circuit including azimuth detecting means, wherein the arithmetic circuit calculates a signal azimuth for m frequency-analyzed frequencies (m is a positive integer);
Imports the calculation result n times (n is an integer of 2 or more) in chronological order
Temporarily store azimuth data (total m × n times) in memory
Means and signal orientation data stored in the memory.
And calculates the variance d of the signal direction for m frequencies
And the variance d of the obtained signal direction is small.
Means for emphasizing and loading the signal direction . 2. The azimuth detecting device according to claim 1, wherein said emphasis weighting means includes means for multiplying a target signal amplitude by a reciprocal (1 / d) of its variance d. Wherein said operation circuit, azimuth detecting device according to claim 1 or 2 including means for performing each of the noise removal processing for the m frequency appearing at the output of the frequency analyzing circuit. 4. The azimuth detecting device according to claim 1, wherein said arithmetic circuit includes means for performing noise removal processing on each of the frequencies appearing n times in the output of said frequency analysis circuit. 5. The azimuth detecting device according to claim 1, further comprising a density modulation means for displaying a signal azimuth which is weighted with respect to a calculation result of the calculation circuit on a grayscale image.