JP2021039074A - Signal source estimation device - Google Patents

Abstract

To provide a signal source estimation device capable of quantitatively calculating a ratio of a power spectrum of a signal source signal to a power spectrum of a target signal.SOLUTION: A device includes a frequency conversion part 40 for calculating a frequency spectrum from a target signal and a detector signal, a power spectrum calculation part 50 for calculating a power spectrum of the target signal and a power spectrum of the detector signal, a cross spectrum calculation part 60 for calculating a cross spectrum of the frequency spectrum of the detector signal and the frequency spectrum of the target signal, an averaging processing part 70 for averaging them, and a coherence function calculation part 80 for calculating a value of the coherence function and outputting the calculated value as a value showing a ratio of the power spectrum of the signal source signal to the power spectrum of the target signal.SELECTED DRAWING: Figure 2

Description

The present invention relates to a device for estimating a signal source, and more particularly to a technique for quantitatively estimating a signal from a signal source and a technique for estimating the direction in which the signal source exists.

Various techniques for identifying the source of electromagnetic waves have been proposed. The measuring device disclosed in Patent Document 1 calculates the waiting time distribution of the measurement data and the correlation source data. Then, the degree of correlation between the measurement data and the measurement source data is calculated based on the value of the parameter of the waiting time distribution. Based on this degree of correlation, a place where an electromagnetic wave that becomes noise is generated for the measurement target portion is specified.

Japanese Patent No. 5445245

The degree of correlation disclosed in Patent Document 1 has no meaning other than expressing a vague closeness, and there is no physical quantity corresponding to the degree of correlation. Therefore, when the signal to be analyzed is the target signal and the signal generated by a certain signal source is the signal source signal, it is not possible to quantitatively calculate the ratio of the power spectrum of the signal source signal to the power spectrum of the target signal. Can not. Of course, the technique disclosed in Patent Document 1 cannot calculate the power spectrum of the component caused by the signal source signal included in the power spectrum of the target signal. Further, with the technique disclosed in Patent Document 1, it is also difficult to estimate the direction in which the signal source signal included in the target signal is generated.

The present disclosure has been made based on this circumstance, and the first object is a signal source estimation device capable of quantitatively calculating the ratio of the power spectrum of the signal source signal to the power spectrum of the target signal. Is to provide.

A second object is to provide a signal source estimation device capable of calculating a power spectrum of a component caused by a signal source signal included in the power spectrum of a target signal.

A third object is to provide a signal source estimation device capable of estimating the direction in which the signal source signal included in the target signal is generated.

The above object is achieved by a combination of the features described in the independent claims, and the sub-claims provide further advantageous specific examples. The reference numerals in parentheses described in the claims indicate, as one embodiment, the correspondence with the specific means described in the embodiments described later, and do not limit the disclosed technical scope.

One disclosure to achieve the first objective is
A signal source estimation device that calculates the ratio of the power spectrum of the signal source signal (x) generated by the target signal source to the power spectrum of the target signal (y), which is the signal to be analyzed.
A frequency converter (40) that acquires a target signal and a detector signal (z) that is a signal detected by the detector (14) and calculates a frequency spectrum from the target signal and the detector signal, respectively.
A power spectrum calculation unit (50) that calculates the power spectrum of the target signal from the frequency spectrum (Y) of the target signal and calculates the power spectrum of the detector signal from the frequency spectrum (Z) of the detector signal.
A cross spectrum calculation unit (60) that calculates a cross spectrum between the frequency spectrum of the detector signal and the frequency spectrum of the target signal, and
An averaging processing unit (70) that averages the power spectrum of the target signal, the power spectrum of the detector signal, and the cross spectrum, and
The value of the coherence function, which is the value obtained by dividing the square of the averaged cross spectrum by the product of the power spectrum of the averaged target signal and the power spectrum of the averaged detector signal, is calculated and calculated. Is provided as a coherence function calculation unit (80) that outputs as a value indicating the ratio of the power spectrum of the signal source signal to the power spectrum of the target signal.

This signal source estimator calculates the value of the coherence function of the target signal and the detector signal from the target signal and the detector signal. The value of this coherence function indicates the ratio of the power spectrum of the signal source signal to the power spectrum of the target signal, as will be described in detail later. Therefore, this signal source estimation device can quantitatively calculate the ratio of the power spectrum of the signal source signal to the power spectrum of the target signal.

One disclosure to achieve the second objective is
A signal source estimation device that calculates the power spectrum of the component caused by the signal source signal (x) generated by the target signal source, which is included in the power spectrum of the target signal (y), which is the signal to be analyzed. There,
A frequency converter (40) that acquires a target signal and a detector signal (z) that is a signal detected by the detector (14) and calculates a frequency spectrum from the target signal and the detector signal, respectively.
A power spectrum calculation unit (50) that calculates the power spectrum of the detector signal from the frequency spectrum of the detector signal, and
A cross spectrum calculation unit (60) that calculates a cross spectrum between the frequency spectrum of the detector signal and the frequency spectrum of the target signal, and
An averaging processing unit (70) that averages the power spectrum and cross spectrum of the detector signal,
A transfer function estimator (180) that calculates the value obtained by dividing the averaged cross spectrum by the power spectrum of the averaged detector signal, and
The value obtained by multiplying the squared value of the value calculated by the transfer function estimation unit by the power spectrum of the detector signal is calculated as the power spectrum of the component caused by the signal source signal included in the power spectrum of the target signal. A signal source-derived power spectrum calculation unit (184) is provided.

As described above, this signal source estimation device can calculate the power spectrum of the component caused by the signal source signal included in the power spectrum of the target signal from the target signal and the detector signal.

One disclosure to achieve the third objective is
A signal source estimation device that estimates the direction in which the target signal source signal (x) included in the target signal (y), which is the signal to be analyzed, is generated.
A frequency converter (40) that acquires a target signal and a detector signal (z) that is a signal detected by the detector (14) and calculates a frequency spectrum from the target signal and the detector signal, respectively.
A cross spectrum calculation unit (60) that calculates a cross spectrum between the frequency spectrum of the detector signal and the frequency spectrum of the target signal, and
An averaging processing unit (70) that averages the cross spectrum, and
Based on the averaged cross spectrum, the declination determination unit (92) that determines the declination equivalent amount, which is an amount indicating the declination of the averaged cross spectrum, and
It is provided with an output device (30) that outputs an amount equivalent to the declination.

The amount of declination equivalent calculated by this signal source estimation device changes in magnitude when the position where the detector detects the signal source signal approaches or separates from the signal source. Therefore, the direction in which the signal source signal included in the target signal is generated can be estimated by confirming the change in the amount equivalent to the declination while changing the position where the detector detects the signal source signal.

It is an overall block diagram of a signal source estimation system 10. It is a block diagram which shows the process which a processing apparatus 20 executes. It is a figure which modeled the measurement system as an example. It is the figure which generalized the measurement system. It is a figure which shows the simulated measurement system. It is a figure which shows the power spectrum W (x1), W (x2) of FIG. It is a figure which shows the transfer function G1 and the power spectrum W (y1) of FIG. It is a figure which shows the transfer function G2 and power spectrum W (y2) of FIG. It is a figure which shows the power spectrum W (y1 + y2) of FIG. It is a figure which shows the power spectrum W (z1), W (z2), and the transfer function H of FIG. It is a figure which shows the value C (z1, y1 + y2) of a coherence function. It is a figure which shows the value C (z2, y1 + y2) of a coherence function. It is a figure which compares the value which multiplied W (y1 + y2) by C (z1, y1 + y2), and W (y1). It is a figure which compares the value which multiplied W (y1 + y2) by C (z2, y1 + y2), and W (y2). It is a figure which shows the use example of the signal source estimation system 10 in the case of estimating a signal source. It is a diagram showing a display example of displaying a phase difference ∠W _ZY on the display device 30. It is a figure which shows the processing apparatus 120 of 2nd Embodiment.

Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of the signal source estimation system 10. The signal source estimation system 10 includes a target signal detection line 12, a probe 14, a processing device 20, and a display device 30.

The target signal detection line 12 is connected to a location where the target signal y is to be detected. The target signal y is a signal to be analyzed. The content to be analyzed is the ratio of the signal source signal x included in the target signal y. The signal source signal x is a signal generated by a certain target signal source.

If the signal source signal x is an unnecessary signal in the target signal y, the signal source signal x is noise, and the signal source is a noise source. When the signal source signal x is noise, it is necessary to analyze how much noise is contained in the target signal y. An example of a location where the target signal y is to be detected is an antenna.

In addition to detecting the target signal y using the target signal detection line 12, the target signal y can be detected using an electric field probe or a magnetic field probe, or can be detected by an antenna.

The probe 14 is a detector for detecting the probe signal z, which is a detector signal. The probe signal z is a signal detected to calculate the ratio of the power spectrum of the signal source signal x to the power spectrum _{WYY of the target signal y.} The probe signal z is different from the signal source signal x only by the influence of the transfer function H of the probe 14.

The probe 14 is held by the operator and brought close to the signal source. The probe signal z, that is, the detector signal may also be detected by using the antenna or may be directly detected. In FIG. 1, a plurality of electronic devices 18 included in the ECU 16 are signal sources, respectively. The target device for detecting the probe signal z and the target signal y is not limited to a small device such as the ECU 16, but may be a vehicle or the like.

The processing device 20 corresponds to a signal source estimation device, and can be realized by a configuration including at least one processor. For example, the processing device 20 can be realized by a computer including a CPU, a ROM, a RAM, an I / O, and a bus line connecting these configurations. A program for making a general-purpose computer function as a processing device 20 is stored in the ROM. The processing unit 20 executes the process shown in FIG. 2 by executing the program stored in the ROM while the CPU uses the temporary storage function of the RAM. When the process shown in FIG. 2 is executed, it means that the method corresponding to the program is executed. The processing device 20 may be realized by a dedicated hardware logic circuit in addition to being realized by a computer. Hardware logic circuits are, for example, ASICs and FPGAs. Further, the processing device 20 may be realized by a combination of a processor that executes a computer program and one or more hardware logic circuits.

The details of the processing executed by the processing device 20 will be described later, but the processing device 20 has a value indicating the ratio of the power spectrum of the signal source signal x to the target signal y, and the signal source signal included in the target signal y. _{The power spectrum WVV} of the component due to x is calculated.

The display device 30 is an example of an output device, and displays a value indicating the ratio of the power spectrum of the signal source signal x to the target signal y calculated by the processing device 20 toward the operator. This value is γ _ZY ² . The _{reason why γ ZZ} ² is a value indicating the ratio of the power spectrum of the signal source signal x to the target signal y will be described later. _{The display device 30 also displays the power spectrum WVV} caused by the signal source signal x included in the target signal y toward the operator.

The display device 30 may be a device capable of two-dimensional graphing, or may be a simpler device. For example, the number of lit display lamp such as a LED, may be displayed γ _ZY ^2, _{W VV.} The display device 30 may be a meter display device for displaying a gamma _ZY ^2, _{W VV} by guidelines. Further, 2 with the type of display device 30 may display a gamma _ZY ² and _{W VV} in different display device 30.

[Explanation of Processing Device 20]
The function executed by the processing apparatus 20 will be described with reference to FIG. The processing device 20 includes a frequency conversion unit 40, a power spectrum calculation unit 50, a cross spectrum calculation unit 60, an averaging processing unit 70, a coherence function calculation unit 80, a multiplication unit 90, and a declination determination unit 92.

The frequency conversion unit 40 includes two frame cutting units 41 and 42 and two discrete Fourier transform units (hereinafter, DFT units) 43 and 44. A target signal y converted into a digital value by an AD conversion circuit (not shown) is input to the frame cutting unit 41. The frame cutting unit 41 cuts out a signal for the time used for one processing in the DFT unit 43 from the sequentially input target signal y, and multiplies the window function. Then, the cut-out signal is input to the DFT unit 43.

A probe signal z converted into a digital value by an AD conversion circuit (not shown) is input to the other frame cutting unit 42. The frame cutting unit 42 cuts out a signal for the time used for one processing in the DFT unit 44 from the probe signal z that is sequentially input. Then, the cut-out signal is input to the DFT unit 44.

The DFT unit 43 performs a discrete Fourier transform on the input target signal y. The signal after Fourier transform is a signal in which the target signal y is converted into a frequency spectrum. Let the converted signal be the target signal spectrum Y.

The DFT unit 44 performs a discrete Fourier transform on the input probe signal z. The signal after Fourier transform is a signal obtained by converting the probe signal z into a frequency spectrum. Let the converted signal be the probe signal spectrum Z.

The power spectrum calculation unit 50 includes a first power spectrum calculation unit 51 to which the target signal spectrum Y is input and a second power spectrum calculation unit 52 to which the probe signal spectrum Z is input. The first power spectrum calculation unit 51 calculates the power spectrum of the target signal spectrum Y, that is, | Y | ² . The second power spectrum calculation unit 52 calculates the power spectrum of the probe signal spectrum Z, that is, | Z | ² .

The cross spectrum calculation unit 60 calculates the cross spectrum of the probe signal spectrum Z and the target signal spectrum Y. Specifically, in the present embodiment ^{, the product of the conjugate complex number Z *} of the probe signal spectrum Z and the target signal spectrum Y is calculated.

The averaging processing unit 70 includes a first averaging processing unit 71, a second averaging processing unit 72, and a third averaging processing unit 73. The first averaging processing unit 71 averages the power spectrum of the target signal spectrum Y. _{Let WYY be} the average value of the power spectrum of the target signal spectrum Y. The second averaging processing unit 72 averages the power spectrum of the probe signal spectrum Z. The average value of the power spectrum of the probe signal spectrum Z and W _ZZ. The third averaging processing unit 73 averages the cross spectrum. _{Let W ZZ be} the average value of the cross spectrum. Hereinafter, the value indicated by the symbol W shall mean the value after the averaging process even if it is not indicated that it is an average, and the “average” is omitted.

The time for averaging the spectra in the averaging processing unit 70 can be arbitrarily set. The time for averaging the spectra can be, for example, about several tens of milliseconds. Further, the time for averaging the spectra may be about several seconds. The averaging times of the three averaging processing units 71, 72, and 73 can be the same as each other. As the averaging method, various averaging methods such as an n-term moving average and an exponential moving average can be adopted.

The coherence function calculation unit 80 calculates the value γ _ZZ ² of the coherence function shown in the equation (1). The coherence function calculation unit 80 causes the display device 30 to display the _{calculated value γ ZY} ^{2 of the coherence function.} The value of the coherence function γ _ZZ ² indicates the ratio of the power spectrum of the signal source signal x to the target signal y, as will be described later.

乗算部９０は、コヒーレンス関数の値γ_ＺＹ ^２に、ターゲット信号スペクトルＹのパワースペクトルＷ_ＹＹを乗じる。乗じた値は、次に詳しく説明するように、ターゲット信号ｙに含まれている信号源信号ｘに起因する成分のパワースペクトルＷ_ＶＶになる。乗算部９０は、信号源起因パワースペクトル算出部に相当する。また、乗算部９０は、パワースペクトルＷ_ＶＶを表示装置３０に表示させる。なお、算出するパワースペクトルＷ_ＶＶは、推定値であることから、図２では、Ｗ_ＶＶの上に、推定値を意味する記号を付している。

The multiplication unit 90 multiplies the value of the coherence function γ _ZY ² _{by the power spectrum W YY} of the target signal spectrum Y. The multiplied value becomes _{the power spectrum WVV} of the component caused by the signal source signal x included in the target signal y, as will be described in detail below. The multiplication unit 90 corresponds to a signal source-derived power spectrum calculation unit. Further, the multiplication unit 90 causes the display device 30 to display _{the power spectrum WVV.} Since the power spectrum _{WVV to be} calculated is an estimated value, in FIG. 2, a symbol meaning the estimated value is added above the _WVV.

The declination determination unit 92 determines the declination of the cross spectrum W _ZZ . Since the cross spectrum is a complex number, the argument is determined from the size of the real part and the size of the imaginary part of the complex number. The declination means _{the phase difference ∠W ZY} between the probe signal spectrum Z and the target signal spectrum Y.

Argument determination unit 92 displays the phase difference ∠W _ZY on the display device 30. Further, the display device 30 can display any one or more kinds of values among the values calculated by the processing device 20. That is, the display device 30, the phase difference ∠W _ZY, power spectrum _{W VV,} the value gamma _ZY ² of coherence function, power spectrum _{W YY} target signal spectrum Y, the power spectrum _{W ZZ} of the probe signal spectrum Z, cross spectral W Display any one or more of _ZY.

[Mathematical explanation]
Next, the value of the coherence function γ _ZZ ² indicates the ratio of the power spectrum of the signal source signal x to the _{target signal y, and the WVV} is a component caused by the signal source signal x included in the target signal y. It is theoretically explained that the power spectrum of.

FIG. 3 shows a diagram modeling a measurement system as an example. In the measurement system shown in FIG. 3, three signal sources A, B, signal _x A from _C, x B, _{x C,} respectively, transfer gain _{G A,} G B, after being transmitted by _{G C,} are synthesized Is the target signal y.

It is assumed that each signal x _A , x _B , x _C is uncorrelated with each other. At this time, when focusing on one signal source, the other signal sources can be combined into one as noise n. Therefore, any complex measurement system, including the measurement system illustrated in FIG. 3, can be generalized in FIG.

From FIG. 4, the target signal spectrum Y, which is the frequency spectrum of the target signal y, can be represented by the equation (2). Further, the probe signal spectrum Z, which is the frequency spectrum of the probe signal z, can be expressed by the equation (3). G is a transfer function when the signal source signal x is transmitted to the observation point of the target signal y, and H is a transfer function of the probe. X is the frequency spectrum of the signal source signal x, and N is the frequency spectrum of noise.

Y = GX + N (2)
Z = HX (3)

(2), (3) from _{equation, W ZZ} can deform equation _{(4), W ZY} can deform equation (5). For the modification of equation (5), the fact that the noise n and the signal source signal x are uncorrelated was used.

これら（４）式と（５）式を（１）式に代入すると、（６）式が得られる。

By substituting these equations (4) and (5) into the equation (1), the equation (6) is obtained.

In equation (6), _WXX is the average value of the power spectrum of the signal source signal x. From Eq. (6), _{it was proved that the value of the coherence function γ ZY} ² indicates the ratio of the power spectrum of the signal source signal x to the target signal y.

The value γ _ZY ² of the coherence function is calculated using the probe signal z, and there is a difference in the influence of the transfer function H between the probe signal z and the signal source signal x. However, the proof using the above equation shows that the transfer function H does not affect _{the value γ ZY} ^{2 of the coherence function.}

Further, since V = GX, the equation (7) holds. Note that V is the frequency spectrum of the signal v, and the signal v is a signal in which the signal source signal x is transmitted to the observation point of the target signal y by the transfer function G.

Eq. (8) can be obtained by modifying Eq. (7).

In (8), the left side of the W _VV is the power spectrum of the component caused by the signal source signal x contained in the power spectrum of the target signal y. Therefore, the value gamma _ZY ² of coherence function, by multiplying the power spectrum W _YY target signal spectrum Y, the power spectrum of the component caused by the signal source signal x contained in the power spectrum of the target signal y can be calculated Was proved.

[simulation result]
Next, the simulation results are shown. The simulated measurement system is shown in FIG. The measurement system shown in FIG. 5 has two signal sources A and B. The signal output by the signal source A is x1, and the power spectrum of the signal x1 is W (x1). Further, the signal output by the signal source B is x2, and the power spectrum of the signal x2 is W (x2). The transfer function G1 is a transfer function when the signal x1 is transmitted until it is input to the processing device 20, the signal after being transmitted by the transfer function G1 is y1, and the power spectrum of the signal y1 is W (y1). And. The transfer function G2 is a transfer function when the signal x2 is transmitted until it is input to the processing device 20, the signal after being transmitted by the transfer function G2 is y2, and the power spectrum of the signal y2 is W (y2). And. The signal obtained by combining the signal y1 and the signal y2 is the target signal (y1 + y2). This target signal (y1 + y2) is input to the processing device 20. Let the power spectrum of the target signal (y1 + y2) be W (y1 + y2). H is the transfer function of the probe 14.

As the simulation software, MATLAB (registered trademark) was used. The simulation conditions are as follows.
・ Sampling rate 250MHz
・ Signal length 0.01s
-Signal x1, x2 Impulse sequence with a period of 0.2 μs. The periods of the two signals are offset by 0.004%.

FIG. 6 shows the power spectra W (x1) and W (x2). FIG. 7 shows the transfer function G1 and the power spectrum W (y1). FIG. 8 shows the transfer function G2 and the power spectrum W (y2). FIG. 9 shows the power spectrum W (y1 + y2). FIG. 10 shows the transfer function H, the power spectrum W (z1) when the signal x1 output by the signal source A is observed by the probe 14, and the power when the signal x2 output by the signal source B is observed by the probe 14. It is a figure which shows the spectrum W (z2).

As shown in FIG. 6, there is almost no difference between W (x1) and W (x2). As a result, there is almost no difference between W (z1) and W (z2) shown in FIG. Therefore, even if W (y1 + y2) shown in FIG. 9 is compared with W (z1) or W (z2), it is impossible to estimate the signal source of a certain frequency component included in the target signal.

FIG. 11 is a diagram showing the value C (z1, y1 + y2) of the coherence function of W (z1) and W (y1 + y2). FIG. 12 is a diagram showing the value C (z2, y1 + y2) of the coherence function of W (z2) and W (y1 + y2). Comparing FIGS. 11 and 7 and FIGS. 12 and 8, it can be seen that the value of the coherence function indicates the ratio of the signal source signal x to the target signal (y1 + y2) input to the processing device 20. ..

FIG. 13 shows a comparison between the value obtained by multiplying the value C (z1, y1 + y2) of the coherence function shown in FIG. 11 by the power spectrum W (y1 + y2) and the power spectrum W (y1). FIG. 14 shows a comparison between the value obtained by multiplying the value C (z2, y1 + y2) of the coherence function shown in FIG. 12 by the power spectrum W (y1 + y2) and the power spectrum W (y2).

From FIGS. 13 and 14, by multiplying the value of the coherence function by the power spectrum W (y1 + y2), it is caused by the signals x1 and x2 included in the power spectrum of the signal (that is, the target signal) input to the processing device 20. It can be seen that the power spectrum of the signal component can be estimated quantitatively and correctly. Specifically, it can be seen that the signal input to the processing device 20 has the signal source A as the signal source for frequencies of 50 MHz or less and the signal source B as the signal source for frequencies of 70 MHz or more.

In this way, since the power spectrum of the signal source signal can be extracted from the power spectrum of the target signal, it is also possible to extract the signal source signal that cannot be observed because it is masked by a strong signal.

[Estimation example of signal source direction]
FIG. 15 is a diagram showing a usage example of the signal source estimation system 10 when estimating a signal source. In the example shown in FIG. 15, the signal source estimation system 10 is used to estimate the signal source of the radio wave received by the antenna AT.

In FIG. 15, the signal sources A, B, and C are connected to each other via a wire harness. The signal sources A, B, and C are devices equipped with electronic components, respectively. The target signal y is a signal received by the antenna AT.

Here, it is assumed that the signal source of the signal received by the antenna AT is the signal source A. When the probe 14 is placed near the signal source A, the value of the coherence function approaches 1. In addition, if the value of the coherence function when the probe 14 is brought close to another signal source is low, the signal source of the radio wave received by the antenna AT can be identified as the signal source A by the value of the coherence function.

However, the signal from the signal source A may be transmitted near the signal source B as well. In this case, the value of the coherence function becomes close to 1 even when the probe 14 is placed near the signal source B. Therefore, it may not be possible to determine which of the signal source A and the signal source B is the signal source of the signal received by the antenna AT only from the value of the coherence function.

However, even in such a case, while moving the probe 14 along a wire harness connecting the signal source A and source B, and the display device 30 by displaying a phase difference ∠W _ZY, a signal source Can be estimated.

On the display device 30 in FIG. 16 shows a display example of displaying a phase difference ∠W _ZY. In the display example of FIG. 16, each point is displayed on the complex plane as a complex number in which the magnitude is the value of the amplitude squared coherence and the argument _{is the opposite of the argument of the cross spectrum WZY.} ing. In addition, each point corresponds to the frequency.

The arrow represents the movement of the point when the probe 14 is moved in the direction approaching the signal source. As the probe 14 approaches the signal source, each point rotates counterclockwise, that is, the phase advances. That is, when the phase advances, it can be seen that the probe 14 is approaching the signal source. If the phase is delayed when the probe 14 is moved, it is known that the probe 14 is moving away from the signal source. In this way, the direction of the signal source can be estimated by confirming the change in the declination while moving the probe 14.

Instead of the deflection angle of the cross-spectral W _ZY, the amount having the same argument as the cross-spectral W _ZY (hereinafter, the deflection angle equivalent) may be displayed on the display device 30. The argument equivalent amount includes the cross spectrum W _ZZ itself, the complex coherence function shown in Eq. (9), and the like. Further, the display mode of the amount equivalent to the declination is not limited to the example of displaying in two dimensions as shown in FIG. Any display mode may be used as long as the change in the declination angle due to the movement of the probe 14 is known.

[Summary of the first embodiment]
According to the signal source estimation system 10 of the first embodiment described above, the target signal y and the probe signal z are acquired, and the value γ _ZY ² of the coherence function is calculated from these signals. Despite the influence of the transfer function H on the probe signal z, the value of the coherence function γ _ZY ² is the signal source signal x that occupies the power spectrum of the target signal y, as shown by the mathematical explanation and simulation results described above. It represents the ratio of the power spectrum of.

_{Therefore, if the value γ ZY} ² of the coherence function is calculated while changing the detection position of the probe signal z by changing the position of the probe 14, the value of the coherence function y can be calculated from each signal source included in the power spectrum of the target signal y. You can know the ratio of the power spectrum of the signal.

Further, in the present embodiment, a value obtained by multiplying the value _{of the coherence function γ ZY} ² _{by the power spectrum W YY} of the target signal spectrum Y is also calculated. This value is a power spectrum of a component caused by the signal source signal x included in the power spectrum of the target signal y, as shown by the mathematical explanation and simulation results described above. Therefore, according to the present embodiment, it is possible to know the power spectrum of the component caused by the signal source signal x included in the power spectrum of the target signal y.

Further, in this embodiment, to display a phase difference ∠W _ZY of the probe signal spectrum Z and the target signal spectrum Y to the display device 30. Thus, as described with reference to FIG. 16, while moving the probe 14 by checking the changes i.e. changes in the polarization angle of the phase difference ∠W _ZY, it is possible to estimate the direction of the signal source.

<Second Embodiment>
Next, the second embodiment will be described. In the following description of the second embodiment, the elements having the same number as the codes used so far are the same as the elements having the same code in the previous embodiments, unless otherwise specified. Further, when only a part of the configuration is described, the embodiment described above can be applied to the other parts of the configuration.

FIG. 17 shows the processing apparatus 120 of the second embodiment. The processing device 120 can be used in place of the processing device 20.

The processing device 120 does not include the coherence function calculation unit 80 and the multiplication unit 90 included in the processing device 20. Instead, the processing device 120 includes a transfer function estimation unit 180, a square unit 182, a multiplication unit 184, and a coherence function calculation unit 190. Other configurations of the processing device 120 are the same as those of the processing device 20.

The transfer function estimation unit 180 applies transfer function estimation by the cross-spectral method to the transfer system from the probe signal z to the target signal y. That is, the cross-spectral _{W ZY,} averaged, dividing by a power spectrum _{W ZZ} of the probe signal spectrum Z. Transfer function estimating unit 180 _outputs a value obtained by dividing the _{W ZY} in _{W ZZ} to the square portion 182.

The square unit 182 squares the value obtained from the transfer function estimation unit 180. The multiplication unit 184 calculates the product of the value output by the square unit 182 and the power spectrum _WZZ of the probe signal spectrum Z, and displays the calculated value on the display device 30. _{The calculated value is the power spectrum WVV} of the component caused by the signal source signal x included in the power spectrum of the target signal y, as will be described next. Therefore, the multiplication unit 184 corresponds to the signal source-derived power spectrum calculation unit.

Next, it will be described that the value calculated by the multiplication unit 184 is the power spectrum _WVV. The following equation (10) is a modification of the equation when the cross spectrum method is applied to the probe signal spectrum Z and the target signal spectrum Y, and the equations (2) and (3) described above are further applied to the cross spectrum method. Is applied.

(10) squared type, and is multiplied by _{W ZZ,} can expression modifications shown in (11). In the equation (11), the first line is _{the equation obtained by squared both sides of the equation (10) and multiplied by W ZZ} , and the second line is the _reduction by W ZZ and the denominator numerator. It is an equation multiplied by W _YY.

From the equation (11), it was shown that the _{value calculated by the multiplication unit 184 means the power spectrum WVV.}

The coherence function calculation unit 190 divides _{the value calculated by the multiplication unit 184 by the power spectrum WYY} of the target signal spectrum Y averaged by the first averaging processing unit 71. As described above, the value calculated by the multiplication unit 184 means the _{power spectrum WVV.} The value obtained by dividing this by the power spectrum W _{YY is the value of the coherence function γ ZZ} ² from the above-mentioned equation (7). The coherence function calculation unit 190 displays the calculated value on the display device 30.

Although the calculation procedure is different in this second embodiment, the same various values as in the first embodiment can be calculated. Therefore, the same effect as that of the first embodiment can be obtained.

Although the embodiments have been described above, the disclosed technology is not limited to the above-described embodiments, and the following modifications are also included in the disclosed scope, and further, within a range other than the following that does not deviate from the gist. It can be implemented with various changes.

<Modification example 1>
In the embodiment, the display device 30 is shown as an example of the output device. However, the output device may be a speaker.

10: Signal source estimation system 12: Target signal detection line 14: Probe 16: ECU 18: Electronic equipment 20: Processing device 30: Display device (output device) 40: Frequency conversion unit 41: Frame cutting unit 42: Frame cutting unit 43 : DFT unit 44: DFT unit 50: Power spectrum calculation unit 51: First power spectrum calculation unit 52: Second power spectrum calculation unit 60: Cross spectrum calculation unit 70: Averization processing unit 71: First averaging processing unit 72 : 2nd averaging processing unit 73: 3rd averaging processing unit 80: Coherence function calculation unit 90: Multiplying unit (signal source-derived power spectrum calculation unit) 92: Deviation angle determination unit 120: Processing device 180: Transmission function estimation unit 184: Multiplying unit (power spectrum calculation unit caused by signal source) 190: Coherence function calculation unit AT: antenna x: signal source signal y: target signal z: probe signal

Claims (8)

A signal source estimation device that calculates the ratio of the power spectrum of the signal source signal (x) generated by the target signal source to the power spectrum of the target signal (y), which is the signal to be analyzed.
A frequency converter (40) that acquires the target signal and the detector signal (z), which is a signal detected by the detector (14), and calculates a frequency spectrum from the target signal and the detector signal, respectively. ,
A power spectrum calculation unit (50) that calculates the power spectrum of the target signal from the frequency spectrum (Y) of the target signal and calculates the power spectrum of the detector signal from the frequency spectrum (Z) of the detector signal.
A cross spectrum calculation unit (60) that calculates a cross spectrum between the frequency spectrum of the detector signal and the frequency spectrum of the target signal, and
An averaging processing unit (70) that averages the power spectrum of the target signal, the power spectrum of the detector signal, and the cross spectrum.
The value of the coherence function, which is the value obtained by dividing the square of the averaged cross spectrum by the product of the averaged power spectrum of the target signal and the averaged power spectrum of the detector signal, is calculated. A signal source estimation device including a coherence function calculation unit (80) that outputs the calculated value as a value indicating the ratio of the power spectrum of the signal source signal to the power spectrum of the target signal. A signal source calculated by multiplying the value of the coherence function by the averaged power spectrum of the target signal as a power spectrum of a component caused by the signal source signal included in the power spectrum of the target signal. The signal source estimation device according to claim 1, further comprising a power spectrum calculation unit (90). A signal source estimation device that calculates the power spectrum of the component caused by the signal source signal (x) generated by the target signal source, which is included in the power spectrum of the target signal (y), which is the signal to be analyzed. There,
A frequency converter (40) that acquires the target signal and the detector signal (z), which is a signal detected by the detector (14), and calculates a frequency spectrum from the target signal and the detector signal, respectively. ,
A power spectrum calculation unit (50) that calculates the power spectrum of the detector signal from the frequency spectrum of the detector signal, and
A cross spectrum calculation unit (60) for calculating a cross spectrum between the frequency spectrum of the detector signal and the frequency spectrum of the target signal, and
The power spectrum of the detector signal, the averaging processing unit (70) for averaging the cross spectrum, and
A transfer function estimation unit (180) that calculates a value obtained by dividing the averaged cross spectrum by the power spectrum of the averaged detector signal, and
The value obtained by multiplying the squared value of the value calculated by the transfer function estimation unit by the power spectrum of the detector signal is the power of the component caused by the signal source signal included in the power spectrum of the target signal. A signal source estimation device including a signal source-derived power spectrum calculation unit (184) for calculating as a spectrum. In addition to calculating the power spectrum of the detector signal, the power spectrum calculation unit calculates the power spectrum of the target signal from the frequency spectrum of the target signal.
The averaging processing unit also averages the power spectrum of the target signal.
The value of the coherence function, which is the value obtained by dividing the power spectrum of the component caused by the signal source signal included in the target signal by the averaged power spectrum of the target signal, is calculated, and the calculated value is used as described above. The signal source estimation device according to claim 3, further comprising a coherence function calculation unit (190) that outputs a value indicating the ratio of the power spectrum of the signal source signal to the power spectrum of the target signal. The first or fourth aspect of the present invention, wherein the output device (30) is provided with a value indicating the ratio of the power spectrum of the signal source signal to the power spectrum of the target signal to be output to the operator of the signal source estimation device. Signal source estimator. The signal according to claim 2 or 3, further comprising an output device (30) that outputs a power spectrum of a component caused by the signal source signal included in the target signal to an operator of the signal source estimation device. Source estimator. Based on the averaged cross spectrum, a declination equivalent amount that is an amount indicating the declination of the averaged cross spectrum is determined, and the declination equivalent amount is output to the output device. (92) The signal source estimation device according to claim 5 or 6. A signal source estimation device that estimates the direction in which the target signal source signal (x) included in the target signal (y), which is the signal to be analyzed, is generated.
A frequency converter (40) that acquires the target signal and the detector signal (z), which is a signal detected by the detector (14), and calculates a frequency spectrum from the target signal and the detector signal, respectively. ,
A cross spectrum calculation unit (60) for calculating a cross spectrum between the frequency spectrum of the detector signal and the frequency spectrum of the target signal, and
An averaging processing unit (70) for averaging the cross spectrum and
Based on the averaged cross spectrum, a declination determination unit (92) for determining an argument equivalent amount, which is an amount indicating the declination of the averaged cross spectrum,
A signal source estimation device including an output device (30) that outputs the declination equivalent amount.

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