JP2010127698A - Apparatus and method for estimation of radiated electromagnetic wave frequency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiated electromagnetic wave frequency estimation apparatus that estimates the radiation of an unnecessary electromagnetic wave with a frequency to be addressed from a change in a current passing through a wire. <P>SOLUTION: The apparatus includes an A/D conversion unit 15 which obtains an analog signal indicating a current passing through the wire 12 of an electrical circuit and converts it into a digital time-series signal and an analyzer 13 which calculates and estimates the frequency of an electromagnetic wave radiated in accordance with a temporal change in the current passing through the wire from the temporal change in the current on the basis of the time-series signal from the A/D conversion unit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiated electromagnetic wave frequency estimation device and a radiated electromagnetic wave frequency estimation method for analyzing the frequency of an electromagnetic wave radiated from an electric circuit formed on a printed circuit board or the like.

  Conventionally, various techniques are known for analyzing the frequency of an electromagnetic wave radiated from an electric circuit formed on a printed circuit board or the like. For example, Patent Document 1 discloses a noise source search device for a printed circuit board that can reduce the number of measurements and easily perform noise intensity distribution analysis by changing the frequency in a short time.

In the noise source search apparatus disclosed in Patent Document 1, image data of a printed circuit board to be measured is taken into a personal computer, and a scanning unit scans a minute antenna probe along a two-dimensional plane of the printed circuit board to be radiated. Detect noise, perform frequency analysis of radiated noise with a spectrum analyzer, capture the intensity level and position information of each measurement section into a personal computer, store it in memory, create map data, and overlay map data on image data Also display on the display.
JP 2000-19204 A

  However, in the conventional technology described above, it is possible to obtain only the time average information of the radiated electromagnetic wave, and information regarding the timing of the unnecessary electromagnetic wave of the frequency to be dealt with at which timing of the current change on the wiring, It was inconvenient because it was impossible to obtain information on which wiring current change radiated unnecessary electromagnetic waves.

  The present invention has been made to solve the above-mentioned inconvenience, and the problem is that an unnecessary electromagnetic wave having a frequency to be counteracted is estimated from a change in current flowing on the wiring and formed on a printed circuit board or the like. Another object of the present invention is to provide a radiated electromagnetic wave frequency estimation device and a radiated electromagnetic wave frequency estimation method capable of providing a guideline for improving the configuration of an electric circuit.

  In order to solve the above-mentioned problem, the radiated electromagnetic wave frequency estimation apparatus according to claim 1 includes an A / D converter that takes in an analog signal indicating a current flowing through a wiring of an electric circuit and converts it into a digital time-series signal; An analysis device is provided that calculates and estimates the frequency of an electromagnetic wave radiated with the time change of the current flowing through the wiring based on the time series signal from the D conversion unit from the time change of the current.

  The radiated electromagnetic wave frequency estimation device according to claim 2 is the radiated electromagnetic wave frequency estimation device according to claim 1, wherein the analysis device uses a time series signal from the A / D conversion unit to perform linear prediction analysis, and a signal A frequency estimation unit is provided that estimates a frequency of an electromagnetic wave radiated with time change of a current flowing through the wiring using a prediction coefficient obtained by linear prediction analysis in the analysis unit.

  The radiated electromagnetic wave frequency estimation apparatus according to claim 3 is the radiated electromagnetic wave frequency estimation apparatus according to claim 2, wherein the signal analysis unit performs linear prediction analysis using an autocorrelation matrix when the power of the time series signal is stationary in time. It is characterized by performing.

  The radiated electromagnetic wave frequency estimation apparatus according to claim 4 is characterized in that, in the radiated electromagnetic wave frequency estimation apparatus according to claim 2, linear prediction analysis is performed using an autocorrelation matrix when the power of the time series signal is not temporally stationary. To do.

  The method of estimating a frequency of radiated electromagnetic wave according to claim 5 includes a step of taking an analog signal indicating a current flowing through the wiring of the electric circuit and converting it into a digital time series signal, and a time change of the current flowing through the wiring based on the time series signal. An analysis step of calculating and estimating the frequency of the electromagnetic wave radiated from the time change of the current is provided.

  The radiated electromagnetic wave frequency estimation method according to claim 6 is the radiated electromagnetic wave frequency estimation method according to claim 5, wherein the analysis step includes a signal analysis step of performing linear prediction analysis using a time series signal, and a prediction obtained by linear prediction analysis. A frequency estimation step for estimating the frequency of an electromagnetic wave radiated with a time change of the current flowing through the wiring using a coefficient is provided.

  The radiated electromagnetic wave frequency estimation method according to claim 7 is the radiated electromagnetic wave frequency estimation method according to claim 6, wherein in the signal analysis step, linear prediction analysis is performed using an autocorrelation matrix when the power of the time series signal is stationary in time. Is performed.

  The radiated electromagnetic wave frequency estimation method according to claim 8 is the radiated electromagnetic wave frequency estimation method according to claim 6, wherein in the signal analysis step, linear prediction analysis is performed using an autocorrelation matrix when the power of the time series signal is not temporally stationary. It is performed.

  ADVANTAGE OF THE INVENTION According to this invention, the frequency of the electromagnetic waves radiated | emitted with the time change of the electric current which flows through the wiring on the electric circuit formed in the printed circuit board etc. can be estimated from the time change of an electric current. As a result, it is possible to provide a guideline for improving the configuration of an electric circuit formed on a printed circuit board or the like.

  Hereinafter, embodiments of a radiated electromagnetic wave frequency estimation apparatus and a radiated electromagnetic wave frequency estimation method of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a radiated electromagnetic wave frequency estimation apparatus according to Embodiment 1 of the present invention. This radiated electromagnetic wave frequency estimation device is composed of a printed circuit board 11 and an analysis device 13. The printed circuit board 11 is provided with a wiring 12 constituting an electric circuit, and a current flows through the wiring 12.

  The analysis device 13 includes a probe 14, an A / D conversion unit 15, a signal analysis unit 16, a frequency estimation unit 17, and a display unit 18.

  The probe 14 measures the time change of the current flowing through the wiring 12 by contacting the wiring 12 provided on the printed circuit board 11. Specifically, the probe 14 continuously takes in an analog signal indicating the magnitude of the current flowing through the wiring 12 and sends it to the A / D converter 15.

The A / D converter 15 converts the analog signal sent from the probe 14 into a digital signal. Digital signal obtained by conversion in the A / D converter 15 is sent as a time-series signal S _n to the signal analyzing unit 16 and a display unit 18.

Signal analyzing section 16 performs linear prediction analysis using the time-series signal S _n, for example, a CPU is configured by a program executed (Central Processing Unit), sent from the A / D converter 15. In this linear prediction analysis, the number of parameters (prediction coefficients) included in the linear prediction formula is M (the value of M is preferably selected from about 3 to 10 if necessary), and M prediction coefficients are set. as a _m, denote the linear prediction equation in equation (1) below.

To determine the value of the prediction coefficients a _m included in the equation (1), shall be given the condition that prediction residual represented by the following equation (2) is minimized.

Here, N + 1 is the number of time-series signal S _n which is used for one analysis, if necessary, be given a large arbitrary value from M. M estimated frequencies f _m (details will be described later) are calculated for each analysis section.

In order to minimize the prediction residual to obtain the value of the prediction coefficients a _m that satisfies the M simultaneous equations relating m 'shown in the following equation (3).

In solving this simultaneous equation, the autocorrelation coefficient (the value of the coefficient does not depend on how to take the constant n ₀ ) when the power of the time-series signal is temporally steady as shown in the following equation (4). This is equivalent to assuming that λ _m that is secondarily calculated by the frequency estimation unit 17 is zero.

Based on this assumption, the autocorrelation coefficient is newly expressed as the following equation (5).

The autocorrelation matrix when the power of the time series signal is stationary in time using the autocorrelation coefficient shown in the equation (5) is shown in the following equation (6). By diagonalized autocorrelation matrix shown in equation (6), conveniently prediction coefficient a _m is obtained. The prediction coefficients a _m obtained is sent to the frequency estimation unit 17.

Frequency estimation unit 17, for example, is constituted by a program executed by a CPU, a using the prediction coefficients a _m sent from the signal analyzer section 16, is radiated with the time variation of the current flowing through the wiring 12 Estimate the frequency of electromagnetic waves. Specifically, the following equation (7) is factored with respect to X in the X using prediction coefficients a _m.

By this factorization, M coefficients b _m shown in the following equation (8) are obtained.

ここで、△ＴはＡ／Ｄ変換部１５におけるサンプリング間隔である。 By using M coefficients b _m obtained by this factorization and solving for X, f _m and λ _m shown in equation (9) are obtained. Since this solution is generally a complex number, λ _m appears. However, in calculating the autocorrelation matrix in the signal analysis unit 16, since an approximation assuming λ _m to be zero is implicitly used, λ _m is used. Not. The (9) and f _m is the estimated frequency in the expression, are sent to the display unit 18.

Here, ΔT is a sampling interval in the A / D converter 15.

Display unit 18, the M estimated frequency f _m which is sent from the frequency estimation unit 17, as shown in FIG. 2 (b), at the same time is plotted over a plurality of sections, from the A / D converter 15 the time series signal S _n, as shown in FIG. 2 (a), and displays the alongside plotted. Thus, for each plot of one section (N + 1) time-series signal S _n, so that the estimated frequency f _m of the M set is plotted.

  FIG. 3 is a flowchart showing the operation of the radiated electromagnetic wave frequency estimating apparatus according to the first embodiment of the present invention, centering on the radiated electromagnetic wave frequency estimating process.

  In this radiation electromagnetic wave frequency estimation process, first, a current flowing through the wiring is captured (step S11). That is, the probe 14 continuously takes in an analog signal indicating the magnitude of the current flowing through the wiring 12 and sends it to the A / D converter 15.

Next, A / D conversion is performed (step S12). That, A / D converter 15, an analog signal sent from the probe 14 into a digital signal, when sent to the signal analyzer 16 and a display unit 18 as a sequence signal S _n.

Next, linear prediction analysis is performed (step S13). That is, the signal analyzing unit 16, a linear predictive analysis using autocorrelation matrix when to time-series signal S _n sent from the A / D converter 15, the power of the time series signal is temporally constant It is executed, and sends the prediction coefficients a _m obtained by linear prediction analysis to the frequency estimation unit 17.

Next, frequency estimation is performed (step S14). That is, the frequency estimation unit 17 uses the prediction coefficients a _m sent from the signal analyzer section 16, it estimates the frequency of the electromagnetic waves radiated with time changes in the current flowing through the wiring 12. Estimated frequency f _m estimated by the frequency estimation unit 17 is sent to the display unit 18.

Next, display is performed (step S15). That is, the display unit 18, as shown in FIG. 2, at the same time is plotted across the M estimated frequency f _m which is sent from the frequency estimation unit 17 in plurality of sections, when the A / D converter 15 sequence It plotted to display side-by-side signal S _n. Thereafter, the radiated electromagnetic wave frequency estimation process ends.

As described above, according to the radiated electromagnetic wave frequency estimating apparatus according to the first embodiment of the present invention, it is unnecessary to take measures from the power spectrum separately obtained by using the spectrum analyzer by the method described in Patent Document 1. to obtain frequency information of the electromagnetic wave, the estimated frequency f _m is, to check the time that matches the frequency on the plot. The time series signal S _n of the waveform (current change on the electric circuit) at the time before and after, unnecessary electromagnetic waves are radiated. The waveform of this timing can be improved by changing the configuration of the electric circuit, and the emission of unnecessary electromagnetic waves can be suppressed.

  FIG. 4 is a block diagram showing the configuration of the radiated electromagnetic wave frequency estimation apparatus according to Embodiment 2 of the present invention. This radiated electromagnetic wave frequency estimation device is configured by changing the function of the signal analysis unit 16 included in the analysis device 13 of the radiated electromagnetic wave frequency estimation device according to the first embodiment and replacing it with another signal analysis unit 21.

  In the following, the same components as those in the radiated electromagnetic wave frequency estimation apparatus according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and the description thereof will be omitted or simplified, and different portions will be mainly described. .

Signal analyzer 21, for example, is constituted by a program executed by the CPU, and performs linear prediction analysis using the time-series signal S _n sent from the A / D converter 15. In this linear prediction analysis, the number of parameters (prediction coefficients) included in the linear prediction formula is M (the value of M is preferably selected from about 3 to 10 if necessary), and M prediction coefficients are set. as a _m, denote the linear prediction equation in equation (1).

To determine the value of the prediction coefficients a _m included in the equation (1), shall be given the condition that prediction residual represented by the formula (2) is minimized. (2) the number of time-series signal S _n to be used for N + 1 is one of analysis used in the formula, if necessary, give a large arbitrary value from M. M estimated frequencies f _m are calculated for each analysis section.

In order to minimize the prediction residual to obtain the value of the prediction coefficients a _m that satisfies the M simultaneous equations relating m 'shown in the above (3). In solving this simultaneous equation, the autocorrelation coefficient (hereinafter referred to as “time-dependent autocorrelation coefficient”) when the power of the time series signal shown in the following equation (10) is not temporally steady (with divergence and attenuation) ), That is, an autocorrelation matrix (hereinafter referred to as “time-dependent autocorrelation matrix”) when the power of the time-series signal is not temporally steady, as shown in the following equation (11). .

By diagonalizing the time-dependent autocorrelation matrix, the prediction coefficient a _m is obtained. By using the time-dependent autocorrelation matrix, it is possible to more accurately estimate the frequency f _m. Prediction coefficients a _m obtained by the signal analyzer 21 as described above is sent to the frequency estimation unit 17.

Frequency estimation unit 17, as described in Example 1, using the prediction coefficients a _m sent from the signal analyzer section 16, the frequency of the electromagnetic waves radiated with time changes in the current flowing through the wiring 12 presume. Specifically, factoring in the X above (7) about the X using prediction coefficients a _m. By this factorization, M coefficients b _m shown in the above equation (8) are obtained.

Using M coefficients b _m obtained by this factorization and solving for X, f _m and λ _m shown in the above equation (9) are obtained. Since this solution is generally complex, λ _m appears. λ _m corresponds to the attenuation rate of the radiated wave, and the higher the attenuation rate, the broader the spectrum. The (9) and f _m is the estimated frequency in the expression, are sent to the display unit 18.

  FIG. 5 is a flowchart showing the operation of the radiated electromagnetic wave frequency estimation apparatus according to the second embodiment of the present invention, focusing on the radiated electromagnetic wave frequency estimation process. In the following, the same reference numerals as those used in FIG. 3 are attached to the steps for performing the same processing as the radiated electromagnetic wave frequency estimation process of the radiated electromagnetic wave frequency estimation apparatus according to the first embodiment shown in the flowchart of FIG. The explanation will be focused on the different parts.

In this radiation electromagnetic wave frequency estimation process, first, a current flowing through the wiring is captured (step S11). Next, A / D conversion is performed (step S12). Next, linear prediction analysis is performed (step S21). That is, the signal analyzing unit 16, with respect to the time-series signal S _n sent from the A / D converter 15, the autocorrelation matrix when the power of the time-series signal is not stationary in time (time-dependent autocorrelation matrix) performs linear predictive analysis using sends the prediction coefficients a _m obtained by the linear predictive analysis to the frequency estimation unit 17.

  Next, frequency estimation is performed (step S14). Next, display is performed (step S15). Thereafter, the radiated electromagnetic wave frequency estimation process ends.

As described above, according to the radiated electromagnetic wave frequency estimation apparatus according to the second embodiment of the present invention, it is unnecessary to take countermeasures from the power spectrum separately obtained by using the spectrum analyzer by the method described in Patent Document 1. to obtain frequency information of the electromagnetic wave, the estimated frequency f _m is, to check the time that matches the frequency on the plot. The time series signal S _n of the waveform (current change on the electric circuit) at the time before and after, unnecessary electromagnetic waves are radiated. The waveform of this timing can be improved by changing the configuration of the electric circuit, and the emission of unnecessary electromagnetic waves can be suppressed.

  The present invention is applicable to various devices that are required to suppress electromagnetic waves radiated from an electric circuit.

It is a block diagram which shows the structure of the radiation electromagnetic wave frequency estimation apparatus which concerns on Example 1 of this invention. It is a figure which shows the example of a display of the time series signal and estimated frequency which are displayed on the display part of the radiation electromagnetic wave frequency estimation apparatus which concerns on Example 1 of this invention. It is a flowchart which shows operation | movement of the radiation electromagnetic wave frequency estimation apparatus which concerns on Example 1 of this invention. It is a block diagram which shows the structure of the radiation electromagnetic wave frequency estimation apparatus which concerns on Example 2 of this invention. It is a flowchart which shows operation | movement of the radiation electromagnetic wave frequency estimation apparatus which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Printed circuit board 12 Wiring 13 Analysis apparatus 14 Probe 15 A / D conversion part 16, 21 Signal analysis part 17 Frequency estimation part 18 Display part

Claims (8)

An A / D converter that takes in an analog signal indicating the current flowing through the wiring of the electric circuit and converts it into a digital time-series signal;
Based on the time-series signal from the A / D conversion unit, an analysis device that calculates and estimates the frequency of the electromagnetic wave radiated with time change of the current flowing through the wiring from the time change of current,
A radiated electromagnetic wave frequency estimation device comprising: The analysis device includes:
A signal analysis unit that performs linear prediction analysis using a time-series signal from the A / D conversion unit;
A frequency estimation unit that estimates a frequency of an electromagnetic wave radiated with a time change of a current flowing through the wiring using a prediction coefficient obtained by linear prediction analysis in the signal analysis unit;
The radiated electromagnetic wave frequency estimation apparatus according to claim 1, comprising:   The radiated electromagnetic wave frequency estimation apparatus according to claim 2, wherein the signal analysis unit performs linear prediction analysis using an autocorrelation matrix when the power of the time series signal is stationary in time.   The radiated electromagnetic wave frequency estimation apparatus according to claim 2, wherein the signal analysis unit performs linear prediction analysis using an autocorrelation matrix when the power of the time series signal is not stationary in time. Taking an analog signal indicating the current flowing through the wiring of the electric circuit and converting it into a digital time-series signal;
Based on the time series signal, an analysis step for calculating and estimating the frequency of the electromagnetic wave radiated with the time change of the current flowing through the wiring from the time change of the current;
A method for estimating the frequency of radiated electromagnetic waves, comprising: The analysis step includes
A signal analysis step of performing linear prediction analysis using the time series signal;
A frequency estimation step for estimating a frequency of an electromagnetic wave radiated with a time change of a current flowing through the wiring using a prediction coefficient obtained by the linear prediction analysis;
The radiated electromagnetic wave frequency estimation method according to claim 5, further comprising:   7. The method of estimating a radiated electromagnetic wave frequency according to claim 6, wherein in the signal analysis step, linear prediction analysis is performed using an autocorrelation matrix when the power of the time series signal is stationary in time.   7. The method of estimating a radiated electromagnetic wave frequency according to claim 6, wherein, in the signal analysis step, linear prediction analysis is performed using an autocorrelation matrix when the power of the time series signal is not temporally stationary.

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