JPH05188105A - Impulse response measuring apparatus - Google Patents

Abstract

PURPOSE:To highly accurately measure the impulse response of an object to be measured. CONSTITUTION:A digital signal read from a digital source or the like is input from an input terminal 1. A response signal from an object to be measured to a signal wherein the digital signal has been converted into an analog signal is input from an input terminal 4. The analog signal input from the input terminal 4 is synchronized with the digital signal input from the input terminal 1 and converted into a digital signal by an A/D-converter 5. The time shift between the converted signal and the digital signal input from the input terminal 1 is corrected with the digital signal used as a reference, the ratio of the corrected signal to the digital signal is calculated in a frequency region by a calculator 11, and this is again converted into a time-base signal by a calculator 13 to be output. Since no impulse signal need not be used as a measuring signal, average power in a time-base direction of the signal is large, while use of a signal of a wide frequency range allows measurement of the output response at the rime of a large input of the object to be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impulse response measuring device for measuring the impulse response of an object to be measured.

[0002]

2. Description of the Related Art With the advent of digital audio represented by a compact disc (CD), the sound quality of a source has been remarkably improved. Along with this, each part is being studied to improve the sound quality of audio equipment. Moreover, in considering the improvement of the sound quality of such an audio device, not only is the auditory sense of the difference in the sound quality between the conventional audio device and the audio device aiming at the improvement of the sound quality, but also the difference in the sound quality is quantified. The measurement method for confirmation is also being studied. That is, as one of the measuring methods, a measuring method that multilaterally analyzes the transient response characteristics of the measured object based on the impulse response of the measured object has become the mainstream today.

Therefore, conventionally, the following impulse response measuring device has been known. Hereinafter, a conventional impulse response measuring device will be described with reference to FIG. In FIG. 8, 81 is a signal generator for generating a measurement signal, 82 is a DUT, 83 is an input terminal for inputting the output of the DUT 82, and 84 is a signal input from the input terminal 83 from an analog signal. An A / D converter (analog / digital converter) for converting into a digital signal, 85 is an arithmetic unit for synchronously adding the output of the A / D converter 84, and 86 is an output terminal for outputting the output of the arithmetic unit 85. 9 is an operation explanatory diagram of the signal generator 81, FIG. 10 is an operation explanatory diagram of the A / D converter 84, and FIG. 11 is an operation explanatory diagram of the arithmetic unit 85.
Reference numeral 12 is an operation flow of the arithmetic unit 85.

Next, the operation of this conventional example will be described. The signal generator 81 generates a pulse signal as shown in FIG. 9 (a). The response signal of the DUT 82 to this pulse signal is as shown in FIG. 9 (b). When this output signal is converted into a digital signal by the A / D converter 84, the converted signal becomes as shown in FIG. 9 (c). By the way, in this impulse response measuring device, a signal close to an impulse is generated from the signal generator 81, and the response signal of the DUT 82 to the output signal of the signal generator 81 is used as the impulse response of the DUT 82. This output signal is converted into a digital signal by the A / D converter 84. That is, the smaller the pulse width of the output pulse of the signal generator 81, the higher the accuracy of the impulse response of the DUT 82.

Moreover, in order to analyze the characteristics of the DUT 82 from various angles by using this impulse response, it is necessary to convert the impulse response into a digital signal and store it. Therefore, the impulse response signal of the DUT 82 is A /
The digital signal is converted by the D converter 84. However, A
Since the / D converter 84 samples the input signal at the sampling cycle interval, a signal having a small pulse width is converted into a digital signal as shown in FIG. That is, when the impulse response signal of the DUT 82 is A / D converted several times, different results are obtained depending on the start timing of the A / D conversion, and the reproducibility of the measurement data and the measurement accuracy are reduced. Therefore, measurement is performed a plurality of times on one object to be measured, and the arithmetic result is synchronously added to the measurement result to improve reproducibility and measurement accuracy.

Here, as a method of synchronous addition, for example, as shown in FIG. 11 (a), a sampling point (time) at which the input signal to the A / D converter 84 first reaches a predetermined voltage value,
That is, the data at the first sampling point (time) at which the data obtained by converting the input signal into a digital signal reaches a predetermined value is stored at a predetermined address in the memory in the calculator 85 shown in FIG. 11 (b). Place the measurement data in.

This will be explained according to the operation flow shown in FIG. 12. First, the impulse response signal to the output signal of the signal generator 81 is sent to the device under test 82 from the A / D converter 84.
Is converted into a digital signal by means of, and the first sampling point at which the data A / D converted by the arithmetic unit 85 exceeds a predetermined numerical value is found. Then, the measured data is stored such that the data at the sampling point is stored at a predetermined address of the memory in the calculator 85. Next, the impulse response is measured for the same DUT 82, and the digital data converted by the A / D converter 84 is judged by the calculator 85 as the first sampling point (time). Then, the data at the sampling point is made to correspond to a predetermined address of the memory in the arithmetic unit 85, added to the data already stored in the memory, and stored again in the memory. The above processing is performed a predetermined number of times and averaged.

The above synchronous addition is expressed by a mathematical expression. A / D
The impulse response signal converted into digital data by the converter 84 is x (i, j) (i = 1, 2, ..., Mj = 1,
2, ..., N: i is the number of measurements, j is a sampling number, m is the sampling point at which the arithmetic unit 85 first reaches a predetermined value, and M is the output of the arithmetic unit 85, where M is the number of synchronous additions.
(L) (l = 1, 2, ..., N) becomes (Equation 1). Also, if the data is added before the α sampling point (that is, i = m−α) before the sampling point m (that is, i = m), the relationship between i and l is (Equation 2).

[0009]

[Equation 1]

[0010]

[Equation 2]

The output of the calculator 85 is output from the output terminal 86. In this way, A / D
The influence on the reproducibility of the measured data due to the limitation of the sampling speed of the converter 84 or the unevenness of the sampling start timing is eliminated.

[0012]

However, in the above-mentioned conventional configuration, it is necessary to provide an A / D converter which is high speed and has a large quantization number in order to measure the impulse response of the object to be measured with high accuracy. The problem is that the measurement signal is originally an impulse, but in reality it is impossible to generate an impulse, so a pulsed signal is usually used as the measurement signal. Since it is small, for example, when an object to be measured that has different characteristics at large amplitude and small amplitude, such as a speaker, is difficult to measure when the vibration amplitude of the diaphragm of the speaker is large. Uses synchronous addition to obtain reproducibility of measured data, but in reality, it is the average value of data sampled at any time within one sampling period, that is, the sampling frequency. For the following time window is data subjected to smoothing processing of the data had problem that can not be accurately measured the impulse response of the object to be measured.

The present invention solves the above-mentioned conventional problems. Since it is not necessary to use an impulse for a measurement signal, the signal has a large average power in the time axis direction and a signal having a wide frequency range, for example, a signal. By using white noise, it is possible to measure the impulse response from a small amplitude to a large amplitude of the vibration amplitude of the speaker's diaphragm with respect to the measured object such as a speaker, and Since it is not necessary to use impulses and a digital signal read from a digital source is used, highly accurate measurement is possible by using an A / D converter that has characteristics equivalent to the sampling frequency and quantization number of the digital source. And the digital signal read from a digital source, etc. as a reference, and the sample generated during A / D conversion. By removing the unevenness of the starting point of the measurement, it is possible to remove the influence on the reproducibility of the measurement data and perform measurement, and convert the digital signal read from the digital source used during measurement into an analog signal. And an impulse response measuring device capable of performing measurement by removing the influence on the signal of the D / A converter and the A / D converter which converts the response output of the DUT into a digital signal. The purpose is that.

[0014]

In order to achieve this object, the impulse response measuring apparatus of the present invention has a first input of a digital signal recorded in a digital source or the like.
Input terminal, first storage means for storing a digital signal input to the first input terminal, and first signal generation for generating a reference signal synchronized with the digital signal input to the first input terminal. Means, a second input terminal for inputting a response output signal of the DUT to the analog signal obtained by converting the digital signal into the analog signal, and a second input terminal based on the reference signal generated by the first signal generating means. First conversion means for converting an input analog signal into a digital signal, second storage means for storing an output of the first conversion means, a signal stored in the second storage means, and a first storage means. First arithmetic means for detecting a time lag between signals stored in the storage means with reference to the signal stored in the first storage means and correcting the signal stored in the second storage means And the first performance A third storage means for storing the output of the means, a second calculation means for calculating the spectrum of the signal stored in the first storage means, and a spectrum of the signal stored in the third storage means. Third calculating means for calculating, fourth calculating means for dividing the output of the third calculating means by the output of the second calculating means, and fourth storing means for storing the output of the fourth calculating means , And is composed of a fifth arithmetic means for converting the signal stored in the fourth storage means into a time axis signal, and outputs the output of the fifth arithmetic means.

Further, in order to achieve this object, the impulse response measuring apparatus of the present invention is input to a third input terminal for inputting a digital signal recorded in a digital source or the like and a third input terminal. Fifth storage means for storing the digital signal, second signal generating means for generating the reference signal, and second means for converting the digital signal into an analog signal using the reference signal output by the second signal generating means as the operation reference. Conversion means, an output terminal for outputting the output signal of the second conversion means, a fourth input terminal for inputting a response output signal of the DUT to the analog signal output from the output terminal, and a fourth input The third conversion means for converting the analog signal input to the terminal into the digital signal using the reference signal output by the second signal generation means as the operation reference, and the output of the third conversion means are described. And a time difference between the signal stored in the sixth storage means and the signal stored in the fifth storage means is detected with reference to the signal stored in the fifth storage means. Then, the sixth calculation means for correcting the signal stored in the sixth storage means, the seventh storage means for storing the output of the sixth calculation means, and the fifth storage means are stored. The spectrum of a moving signal
Calculating means, eighth calculating means for calculating the spectrum of the signal stored in the seventh storing means, and ninth calculating means for dividing the output of the eighth calculating means by the output of the seventh calculating means. Comprising arithmetic means, eighth storage means for storing the output of the ninth arithmetic means, and tenth arithmetic means for converting the signal stored in the eighth storage means into a time axis signal. The output of the calculation means is output.

Further, in order to achieve this object, the impulse response measuring apparatus of the present invention has a fifth input terminal for inputting a digital signal read from a digital source or the like, and a digital signal input to the fifth input terminal. Ninth storage means for storing a signal, third signal generation means for generating a reference signal synchronized with the digital signal input to the fifth input terminal, and an analog signal obtained by converting the digital signal into an analog signal are input. A sixth input terminal for inputting the response output signal of the DUT to the analog signal obtained by converting the digital signal into the analog signal, and the sixth input terminal and the seventh input terminal. First signal switching means for selectively switching the analog signal to be switched,
Fourth conversion means for converting the output of the first signal switching means into a digital signal, and second signal switching means for switching and outputting the output of the fourth conversion means in synchronization with the first signal switching means, The fourth signal when the first signal switching means selects the analog signal input to the sixth input terminal
Storage means for storing the output of the converting means of No. 11 and storage means for storing the output of the fourth converting means when the first signal switching means selects the analog signal input to the seventh input terminal. And a time difference between the signal stored in the tenth storage means and the signal stored in the ninth storage means is detected with reference to the signal stored in the ninth storage means. Eleventh calculation means for correcting the signal stored in the tenth storage means, twelfth storage means for storing the output of the eleventh calculation means, and the signal stored in the eleventh storage means And a time difference between the signals stored in the ninth storage means is detected with reference to the signal stored in the ninth storage means, and the signal stored in the eleventh storage means is corrected. Twelve arithmetic means, thirteenth storage means for storing the output of the twelfth arithmetic means, A thirteenth calculation means for calculating a spectrum of the stored signal to the 9 storage means, the
Fourteenth calculation means for calculating the spectrum of the signal stored in the twelfth storage means, fifteenth calculation means for calculating the spectrum of the signal stored in the thirteenth storage means, and fourteenth
The output of the arithmetic means of is divided by the output of the thirteenth arithmetic means.
Sixteen arithmetic means and a fourteenth arithmetic means for storing the output of the sixteenth arithmetic means
Storage means, a seventeenth calculation means for dividing the output of the fifteenth calculation means by the output of the thirteenth calculation means, a fifteenth storage means for storing the output of the seventeenth calculation means, and a fifteenth Eighteenth arithmetic means for dividing the signal stored in the storage means by the signal stored in the fourteenth storage means, sixteenth storage means for storing the output of the eighteenth arithmetic means, and sixteenth It is composed of a nineteenth arithmetic means for converting the signal stored in the storage means into a time axis signal, and outputs the output of the nineteenth arithmetic means.

[0017]

The present invention has the following functions due to the above configuration. That is, a digital signal read from a digital source or the like is input to the first input terminal and stored in the first storage means. At that time, the first signal generating means generates a reference signal synchronized with the input digital signal and supplies it to the first converting means. When the response signal of the device under test to the signal obtained by converting the above digital signal into an analog signal is input to the second input terminal, the first converting means is based on the reference signal output from the first signal generating means. This analog signal is converted into a digital signal. The converted signal is stored in the second storage means. Next, the first calculation means calculates the time difference between the signal stored in the second storage means and the signal stored in the first storage means from the signal stored in the first storage means. Correct as a reference. Then, the correction output for the signal stored in the second storage means, which is the output of the first calculation means, is stored in the third storage means. Next, the second calculation means calculates the spectrum of the signal stored in the first storage means. Similarly, the third calculation means calculates the spectrum of the signal stored in the third storage means. Then, the fourth arithmetic means divides the output of the third arithmetic means by the output of the second arithmetic means. The output of the fourth calculation means is stored in the fourth storage means. Next, the fifth calculation means transforms the spectrum signal stored in the fourth storage means from the frequency domain into the time domain. Then, the output of the fifth calculation means is output. That is, the spectrum of the output signal of the DUT for the measurement signal is divided by the spectrum of the measurement signal in the frequency domain, and the division result is converted from the frequency domain into the time domain to calculate and output the impulse response. ing.

Further, the present invention having the above-described structure operates as follows. That is, a digital signal read from a digital source or the like is input to the third input terminal and stored in the fifth storage means. The second signal generating means generates a reference signal and supplies it to the second and third converting means. Further, the digital signal described above is converted into an analog signal based on the reference signal generated by the second signal generating means, and is output from the output terminal. The analog signal output from this output terminal is supplied to the DUT. When the response signal of the DUT to this signal is input to the fourth input terminal, the third converting means converts this analog signal into a digital signal based on the reference signal output from the second signal generating means.
The converted signal is stored in the sixth storage means. next,
The sixth arithmetic means corrects the time lag between the signal stored in the sixth storage means and the signal stored in the fifth storage means with reference to the signal stored in the fifth storage means. To do. The correction output for the signal stored in the sixth storage means, which is the output of the sixth arithmetic means, is the seventh output.
Is stored in the storage means. Next, the seventh calculation means is the fifth
The spectrum of the signal stored in the storage means is calculated. Similarly, the eighth calculation means calculates the spectrum of the signal stored in the seventh storage means. Then, the ninth arithmetic means divides the output of the eighth arithmetic means by the output of the seventh arithmetic means. The output of the ninth calculation means is stored in the eighth storage means. Next, the tenth calculation means transforms the spectrum signal stored in the eighth storage means from the frequency domain into the time domain. Then, the output of the tenth calculation means is output. That is, the spectrum of the output signal of the DUT for the measurement signal is divided by the spectrum of the measurement signal in the frequency domain, and the division result is converted from the frequency domain into the time domain to calculate and output the impulse response. ing.

Further, the present invention having the above-described structure operates as follows. That is, the digital signal read from a digital source or the like is input to the fifth input terminal and stored in the ninth storage means. At that time, the third signal generating means generates a reference signal synchronized with the inputted digital signal and supplies it to the fourth converting means. When the analog signal obtained by converting the digital signal into an analog signal is input to the sixth input terminal and the response signal of the DUT to the signal obtained by converting the digital signal into an analog signal is input to the seventh input terminal, The first signal switching means selectively switches the analog signals input to the sixth and seventh input terminals. The signal selected by the first signal switching means is input to the fourth conversion means. The fourth converting means converts the analog signal into a digital signal based on the reference signal output from the third signal generating means. The signal obtained by converting the signal input from the sixth input terminal is the second signal.
Is output to the tenth storage means by the signal switching means of
It is stored in the tenth storage means. The signal obtained by converting the signal input from the seventh input terminal is output to the eleventh storage means by the second signal switching means and stored in the eleventh storage means. Next, the eleventh calculation means calculates the time difference between the signal stored in the tenth storage means and the signal stored in the ninth storage means and calculates the signal stored in the ninth storage means. Correct as a reference. Then, the correction output for the signal stored in the tenth storage means, which is the output of the eleventh calculation means, is stored in the twelfth storage means. Similarly, the twelfth calculation means calculates the time difference between the signal stored in the eleventh storage means and the signal stored in the ninth storage means as the signal stored in the ninth storage means. Correct as a reference. The output of the twelfth calculation means,
The correction output for the signal stored in the eleventh storage means is stored in the thirteenth storage means. Next, the thirteenth calculation means calculates the spectrum of the signal stored in the ninth storage means. Similarly, the fourteenth calculation means calculates the spectrum of the signal stored in the twelfth storage means. And the
The fifteen arithmetic means calculates the spectrum of the signal stored in the thirteenth storage means. And the 16th computing means is the 14th
The output of the arithmetic means of is divided by the output of the thirteenth arithmetic means. The output of the sixteenth calculation means is stored in the fourteenth storage means. Similarly, the seventeenth calculating means divides the output of the sixteenth calculating means by the output of the fourteenth calculating means. The output of the seventeenth calculation means is stored in the fifteenth storage means. Next, the eighteenth calculation means divides the signal stored in the fifteenth storage means by the signal stored in the fourteenth storage means. And
The output is stored in the sixteenth storage means. And the 19th
The calculation means of converts the spectrum signal stored in the eighth storage means from the frequency domain to the time domain. Then, the output of the nineteenth calculation means is output. That is, the spectrum of the output signal of the DUT for the measurement signal is divided by the spectrum of the measurement signal in the frequency domain, and the division result is converted from the frequency domain into the time domain to calculate and output the impulse response. ing.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of an impulse response measuring apparatus in a first embodiment of the present invention. In FIG. 1, 1 is an input terminal for inputting a digital signal read from a digital source or the like, 2 is a memory for storing the digital signal input to the input terminal 1, and 3 is a synchronization with the digital signal input from the input terminal 1. To generate a reference signal, 4 is an input terminal for inputting the response output signal of the DUT to the signal obtained by converting the digital signal into an analog signal, and 5 is a digital signal for the analog signal input to the input terminal 4. A / D converter for converting to, 6 is A
A memory that stores the output of the / D converter 5, and 7 corrects the time lag between the signal stored in the memory 6 and the signal stored in the memory 2 with reference to the signal stored in the memory 2. An arithmetic unit that performs the operation, a memory 8 that stores the output of the arithmetic unit 7, an arithmetic unit that calculates the spectrum of the signal stored in the memory 2, and an arithmetic unit that calculates the spectrum of the signal stored in the memory 8. , 11 is an arithmetic unit that divides the output of the arithmetic unit 10 by the output of the arithmetic unit 9, 12 is a memory that stores the output of the arithmetic unit 11, 13 is the spectrum signal stored in the memory 12 is converted into a time axis signal Calculator, 14 is a calculator
It is an output terminal for outputting 13 output signals.

FIG. 2 is an explanatory diagram for explaining digital signals and analog signals input to the input terminals 1 and 4 of the impulse response measuring apparatus according to the first embodiment, and 21 is a compact disc (CD) and 22. Plays CD21 C
D player, 23 is an analog signal output terminal of the CD player 22, 24 is a digital signal output terminal of the CD player 22, 25
Is an object to be measured. 3 and 4 are operation explanatory diagrams of the calculator 7 in the impulse response measuring apparatus of the first embodiment.

The operation of the impulse response measuring apparatus of the first embodiment of the present invention thus constructed will be described below. For example, a predetermined track of the CD 21 on which white noise is recorded is reproduced by the CD player 22. From the digital signal output terminal 24, the CD player 22
The digital signal read from the CD 21 is output.
When this digital signal output terminal 24 is connected to the input terminal 1, the input digital signal is stored in the memory 2. At the same time, the signal generator 3 generates a reference signal synchronized with the digital signal input from the input terminal 1 and supplies the output signal to the A / D converter 5.

Further, at the same time, a signal obtained by converting the digital signal input to the input terminal 1 into an analog signal is output from the analog signal output terminal 23 of the CD player 22 and supplied to the DUT 25. Then, the device under test 25 outputs a response output signal corresponding to the input analog signal, and this output signal is input to the input terminal 4. The analog signal input from the input terminal 4 is input to the A / D converter 5. Then, the A / D converter 5 converts the input analog signal into a digital signal using the output signal of the signal generator 3 as an operation reference. The analog signal input from the input terminal 4 is converted into a digital signal by the A / D converter 5 and stored in the memory 6. That is, the analog signal input to the input terminal 4 is converted into a digital signal in synchronization with the digital signal input to the input terminal 1 and stored in the memory 6.

By the way, there is a time lag T ₀ as shown in FIG. 3 between the signals thus stored in the memories 2 and 6. That is, since the A / D converter 5 operates in synchronization with the digital signal input to the input terminal 1, there is no time lag between the signals originally stored in the memory 2 and the memory 6. However, since there is a limit to the operating speed of the actual device, time lag occurs. However, the deviation is constant. That is, the time shift ΔT (n) at the nth sample can be expressed by (Equation 3). ΔT (n) is shown in FIG.

[0025]

[Equation 3]

Then, the arithmetic unit 7 notes this time difference.
The signal stored in the memory 2 is removed as a reference. here
Then, the operation of the arithmetic unit 7 is detected when a time lag is detected,
It consists of two steps of correction of misalignment. This operation will be described.
First, the time between the signals stored in memory 2 and memory 6
The gap detection is the data for detecting the time shift from the memory 2.
Data of a predetermined number of samples is extracted mainly from the data. next,
The data corresponding to the data extracted from the memory 2 is stored in the memory
Also extract from 6. And extracted from this memory 6
K / N samples from the time the data was sampled
(K = 0, 1, 2, ..., N-1) N sets of data delayed
Data. One of the methods to generate this N sets of data
An example will be described below. Sampling period is T_s, Sampling
The function is S (m) (m = -N₀, ..., 0, ..., N₀) And
And time t corresponding to k / N samples _d(k) is (Equation 4)
Become.

[0027]

[Equation 4]

The data extracted from the memory 6 is x
(i) (i = 1, 2, ..., M), the data x _c (i, k) delayed by k / N sample time from x (i) becomes (Equation 5). This x _c (i, k) is shown in FIG. 4 (a).

[0029]

[Equation 5]

The N sets of data x _c (i, k) generated by the above processing and the data y (i) (i
= 1, 2, ..., M), the correlation coefficient C (k) is calculated based on (Equation 6).

[0031]

[Equation 6]

[0032] When the correlation coefficient calculated in this way becomes the maximum, the time lag t _d (k ₀₎ of the (k = k ₀₎ is the memory 2 and memory 6
There will be a time lag between the signals stored in. This C (k)
Is shown in Fig. 4 (b). Here, if N is increased, the accuracy of detecting the time shift is improved.

Next, the detected time lag is corrected for the signal stored in the memory 6 using (Equation 5). Then, the corrected signal is stored in the memory 8. By the above processing, the time lag between the signal stored in the memory 2 and the signal stored in the memory 8 is removed, and the signal stored in the memory 8 is stored in the CD player 22 of the DUT 25 of the DUT 25. Is a signal obtained by converting a response signal to an analog reproduction signal obtained by reproducing the same signal as the signal stored in the memory 2 into a digital signal.

Signal processing is performed on the data stored in the memories 2 and 8 to measure the impulse response of the DUT 25. First, the measurement principle will be described. The signals stored in the memories 2 and 8 are x (i) and y (i), and the impulse response of the DUT 25 is h (i) (i = 0, 1, ..., N−).
If 1), then (Equation 7) holds.

[0035]

[Equation 7]

Furthermore, when the expression (7) is described in the frequency domain, the expression (8) is obtained.

[0037]

[Equation 8]

However, the spectra of x (i), y (i) and h (i) are defined as X (k), Y (k) and H (k). From (Equation 8) to H
(k) can be calculated by (Equation 9).

[0039]

[Equation 9]

Therefore, h (i) can be calculated by converting H (k) from the frequency domain to the time domain. Next, the operation of each unit will be described. The computing units 9 and 10 obtain the spectra of the signals stored in the memories 2 and 8, respectively. Here, DFT is used as an example of a method of calculating a spectrum from a time discrete signal. The signals stored in the memory 2 and the memory 8 are represented by x (i) and y, respectively.
Given (i), X (k) and Y (k) of those spectra can be expressed by (Equation 10) and (Equation 11).

[0041]

[Equation 10]

[0042]

[Equation 11]

Next, the computing unit 11 calculates the spectrum ratio H (k) of the signals stored in the memories 2 and 8 thus calculated, based on (Equation 9). Then, the calculated ratio is stored in the memory 12. Next, the spectrum signal stored in the memory 12 is converted into the time axis signal h (i) again by the calculator 13 based on (Equation 12).

[0044]

[Equation 12]

The converted signal h (i) is output from the output terminal 14. Therefore, in the first embodiment of the present invention,
The digital signal read from a digital source and the analog signal that is the response output of the DUT to the signal obtained by converting the read digital signal into an analog signal are converted into digital signals in synchronization with the digital signal recorded in the source. After conversion to remove the time lag between them, the spectra of both signals are calculated. Then, the ratio between the two is taken in the frequency domain and converted again into a time axis signal. Through the above processing, the impulse response of the DUT can be measured.

In the first embodiment, when calculating the time shift between the signals stored in the memories 2 and 6 in the arithmetic unit 7, signals having a k / N sample time difference are generated. Although a sampling function was used for this generation, this can also be done using the following method. That is, the signal extracted from the memory 6 is subjected to DFT, and on the other hand, the transfer function G (k) (Equation 1) in which the amplitude is 1 and the phase P _h (k) is represented by (Equation 13)
Data having a k / N sample time delay can be generated by multiplying 4) and performing IDFT on the multiplication result.

[0047]

[Equation 13]

[0048]

[Numerical equation 14]

Further, in the first embodiment, when the time lag between the signal stored in the memory 2 and the signal stored in the memory 6 is detected in the arithmetic unit 7, it is stored in each memory. Although the signal processing is performed by extracting the data centering on one point of the signal, the time shift may be detected and corrected for a plurality of points.

Furthermore, in the first embodiment, the impulse response is measured only from the measurement data of one time. However, the measurement is performed a plurality of times to remove the external noise mixed in at the time of measurement, and the obtained result is You may add and average. Further, in the first embodiment, since the time lag such as the latch timing of the A / D conversion which occurs at the time of the A / D conversion is removed with the digital signal recorded in the digital source as a reference, it is different from the conventional one. The quality of the measurement data does not deteriorate due to the averaging. FIG. 5 shows a block diagram of an impulse response measuring apparatus according to the second embodiment of the present invention. In FIG. 5, reference numeral 51 is an input terminal for inputting a digital signal read from a digital source, 52 is a memory for storing the digital signal input to the input terminal 51, 53 is a signal generator for generating a reference signal, and 54 is A D / A converter for converting a digital signal input to the input terminal 51 into an analog signal, 55 is an output terminal for outputting the output of the D / A converter 54, 56
Is an input terminal for inputting the response output of the DUT to the analog signal output from the output terminal 55, 57 is an A / D converter for converting the analog signal input from the input terminal 56 into a digital signal, and 58 is an A / D converter. A memory that stores the output of the D converter 57, and 59 corrects the time lag between the signal stored in the memory 58 and the signal stored in the memory 52 with reference to the signal stored in the memory 52. Calculator, 510 is a memory that stores the output of the calculator 59, 511 is a calculator that calculates the spectrum of the signal stored in the memory 52, and 512 is a calculator that calculates the spectrum of the signal stored in the memory 510 , 513 is an arithmetic unit for dividing the output of the arithmetic unit 512 by the output of the arithmetic unit 511, 514 is a memory for storing the output of the arithmetic unit 513, and 515 is for converting the spectrum signal stored in the memory 514 into a time axis signal. Calculator, 516 This is an output terminal for outputting the output signal of the calculator 515.

The operation of the impulse response measuring apparatus of the second embodiment of the present invention thus constructed will be described below. First, the digital signal read from a digital source is input to the input terminal 51, and
Stored in 52. Here, for example, the digital signal input to the input terminal 51 is the digital signal output from the digital output terminal 24 of the CD player 22 as in the first embodiment or the digital signal stored in a certain memory. May be. The signal generator 53 is a D / A converter 54.
And a signal (sampling clock) that is the operation reference of the A / D converter 57 is generated, and the sampling clock is supplied to the D / A converter 54 and the A / D converter 57.

The D / A converter 54 receives the input terminal 51 according to the timing of the sampling signal output from the signal generator 53.
The digital signal input from is converted into an analog signal and output from the output terminal 55. When the analog signal output from the output terminal 55 is supplied to the device under test, the device under test outputs a response output signal corresponding to the input signal. This response output signal is input via the input terminal 56. Then A
The / D converter 57 converts the analog signal input from the input terminal 56 into a digital signal according to the timing of the sampling clock output from the signal generator 53. The converted digital signal is stored in the memory 58. That is, in principle, there is no time lag between the digital signals stored in the memories 52 and 58, but only a time lag due to the operating speed of the existing electronic device.

Hereinafter, the memory 52, the memory 58, the arithmetic unit 59, the memory 510, the arithmetic unit 511, the arithmetic unit 512, the arithmetic unit 513, the memory 514, the arithmetic unit 515, and the output terminal 516 are the memories of the first embodiment, respectively. 2, the memory 6, the arithmetic unit 7, the memory 8, the arithmetic unit 9, the arithmetic unit 10, the arithmetic unit 11, the memory 12, the arithmetic unit 13 and the output terminal 14 perform exactly the same operation, and therefore the explanation of the operation will be omitted.

Therefore, in the second embodiment of the present invention,
The digital signal read from a digital source or the like and the read digital signal are converted into an analog signal based on the reference signal generated by the signal generator, and the analog signal which is the response output of the DUT to this signal is converted to the above-mentioned reference. The signals are converted into digital signals based on the signals, the time lag between them is removed, and then the spectra of both signals are calculated.
Then, the ratio between the two is taken in the frequency domain and converted again into a time axis signal. Through the above processing, the impulse response of the DUT can be measured.

In the second embodiment, the D / A converter 54 converts the digital signal input from the input terminal 51 into an analog signal, but converts the digital signal stored in the memory 52 into an analog signal. Alternatively, the output may be output from the output terminal 55.

FIG. 6 shows a block diagram of an impulse response measuring apparatus according to the third embodiment of the present invention. In FIG. 6, 61 is an input terminal for inputting a digital signal read from a digital source, 62 is a memory for storing the digital signal input to the input terminal 61, 63 is a signal generator for generating a reference signal, and 64 is a An input terminal for inputting a signal obtained by converting a digital signal input to the input terminal 61 to an analog signal, 65 is an input terminal for inputting the output response signal of the DUT to the analog signal input to the input terminal 64, and 66 is an input A signal switcher for selectively switching the signals input from the terminal 64 and the input terminal 65, 67 is an A / D converter for converting the output of the signal switcher 66 into a digital signal, and 68 is an A / D converter.
A signal switcher that switches the output of the D converter 67 in synchronization with the signal switcher 66, and 69 is a signal switcher 66 is an input terminal.
A memory that stores the output of the signal switcher 68 that selectively switches the output of the A / D converter 67 when the signal input to 64 is selected, and 610 stores the signal that the signal switcher 66 inputs to the input terminal 65. A memory that stores the output of the signal switch 68 that selectively switches the output of the A / D converter 67 when selected, and 611 is the signal stored in the memory 69 and the memory 62.
The calculator that corrects the time lag between the signals stored in the memory 62 based on the signal stored in the memory 62, 612 is the memory that stores the output of the calculator 611, and 613 is the memory 610. A calculator that corrects the time difference between the signal and the signal stored in the memory 62 based on the signal stored in the memory 62, 614 is a memory that stores the output of the calculator 613, and 615 is a memory 62. An arithmetic unit for calculating the spectrum of the stored signal, 616 is an arithmetic unit for calculating the spectrum of the signal stored in the memory 612, 617 is an arithmetic unit for calculating the spectrum of the signal stored in the memory 614, 618 Is a calculator that divides the output of calculator 616 by the output of calculator 615, 619 is a calculator that divides the output of calculator 617 by the output of calculator 615, and 620 is the output of calculator 619 that is the output of calculator 618 621 is the calculator of 620 Memory for storing the force, 622 calculator for converting the spectrum signals stored in the memory 621 in the time axis signal, 623
Is an output terminal for outputting the output signal of the computing unit 622. FIG. 7 is an explanatory diagram for explaining the operation concept of the third embodiment.

The operation of the impulse response measuring apparatus of the third embodiment of the present invention thus constructed will be described below. First, the digital signal read from a digital source is input to the input terminal 61, and
It is stored in 62. Here, for example, the digital signal input to the input terminal 61 is the digital signal output from the digital output terminal 24 of the CD player 22 as in the first embodiment. Further, the signal generator 63 generates a signal (sampling clock) serving as an operation reference of the A / D converter 67 in synchronization with the digital signal input from the input terminal 61,
A sampling clock is supplied to the A / D converter 67.

A signal obtained by converting a digital signal input from the input terminal 61 into an analog signal, for example, an analog signal output from the analog output terminal 23 of the CD player 22 is input to the input terminal 64. This analog signal is selected by the signal switcher 66 and input to the A / D converter 67, which converts the analog signal input from the input terminal 64 into a digital signal in synchronization with the clock output from the signal generator 63. The signal switch 68 switches in synchronization with the signal switch 66, and the output of the A / D converter 67 is stored in the memory 69. Similarly, the response output of the DUT to the analog signal input from the input terminal 64, for example, the output signal of the DUT 25 is input to the input terminal 65. Then, the signal is selected by the signal switch 66, the analog signal is converted into a digital signal by the A / D converter 67 using the output clock of the signal generator 63 as an operation reference, and the signal is switched by the signal switch 68 and stored in the memory 610. ..

In principle, there is no time lag between the digital signals stored in the memory 62, the memory 69 and the memory 610, but only a time lag due to the operating speed of the existing electronic device. To do. Based on the signal stored in the memory 62 as the time difference, the calculator 61
At 1, the time lag between the signals stored in the memories 69 and 62 is detected, the time lag is corrected for the signals stored in the memory 69, and the output is stored in the memory 612. Similarly, using this time difference as a reference for the signal stored in the memory 62, the calculator 613 detects the time difference between the signals stored in the memory 610 and the memory 62 and stores it in the memory 610. The time shift is corrected for the signal, and the output is stored in the memory 613. The operation of the arithmetic units 611 and 613 is the same as that of the arithmetic unit 7 in the first embodiment.

Next, the spectra of the signals stored in the memories 62, 612 and 614 are calculated by the arithmetic units 615, 616 and 61, respectively.
Calculated as 7. The arithmetic units 615, 616 and 617 perform the same operations as the arithmetic unit 10 in the first embodiment. And
The calculator 618 divides the output of the calculator 616 by the output of the calculator 615. In addition, the calculator 619 outputs the output of the calculator 617 to the calculator.
Divide by the output of 615. The arithmetic units 618 and 619 operate in the same manner as the arithmetic unit 11 of the first embodiment. Next, the calculator 620 divides the output of the calculator 619 by the output of the calculator 618. The result is stored in the memory 621. Then, the computing unit 622 converts the spectrum signal stored in the memory 621 into a time axis signal. This arithmetic unit 622 performs the same operation as the arithmetic unit 13 in the first embodiment. Then, the output of the arithmetic unit 622 is output from the output terminal 623.

Next, the operating principle of the arithmetic units 618, 619 and 622 will be described with reference to FIG. For example, the transfer function 71 of the analog signal output portion of the CD player 22 is H ₁ (W), the transfer function 72 of the A / D converter 67 is H ₂ (w), the transfer function of the DUT 25.
If 73 is H ₃ (w), the transfer function of the signal input from the input terminal 64 to the signal input from the input terminal 61 is G
₁ (w), and if the transfer function of the signal input from the input terminal 65 to the signal input from the input terminal 61 is G ₂ (w), it is Each relationship can be expressed by (Equation 15) and (Equation 16).

[0062]

[Equation 15]

[0063]

[Equation 16]

However, the transfer function to be originally measured is H
_Since it is ₃ (w), H ₃ (w) can be calculated by using (Equation 17).

[0065]

[Numerical equation 17]

The impulse response of the object to be measured can be calculated by converting this H ₃ (w) into a time axis signal. Therefore, in the third embodiment of the present invention, a digital signal read from a digital source or the like and the read digital signal are converted into analog signals based on the generated reference signal, and the response of the DUT to this signal is converted. The analog signal that is the output is converted into a digital signal based on the above-mentioned reference signal, the time lag between the two signals is removed, the spectra of both signals are calculated, and the ratio of both signals is calculated in the frequency domain to determine the time again. Convert to axis signal. Through the above processing, the impulse response of the DUT can be measured.

That is, in the third embodiment of the present invention, the digital signal read from a digital source or the like, the signal obtained by converting the read digital signal into an analog signal, and the response output of the device under test to this analog signal. The analog signal is converted into a digital signal in a form synchronized with the digital signal recorded in the source to eliminate the time lag of the three, and then the spectra of the three signals are calculated. Then, in the frequency domain, the ratio of the digital signal read from a digital source or the like to the signal obtained by converting the signal into an analog signal and the ratio of the digital signal read from the digital source or the like to the signal obtained by converting the signal into an analog signal are detected. The ratio with the response output of the measured object is calculated, and the ratio between the two is calculated and converted into a time axis signal again. Through the above processing, the impulse response of the measured object can be measured without being affected by the characteristics of the measurement system.

[0068]

As described above, according to the present invention, the response output signal of the DUT to the signal obtained by converting the digital signal read from the digital source or the like into the analog signal is the digital signal read from the digital source or the like. Input in synchronization and convert to digital signal. The time lag between the converted input signal and the digital signal is corrected using the digital signal as a reference, the ratio between the corrected signal and the digital signal is calculated in the frequency domain, and the time-axis signal is converted again to obtain the impulse of the DUT. Calculate the response.

Therefore, in the present invention, since it is not necessary to use an impulse for the measurement signal, by using a signal having a large average power in the time axis direction and a wide frequency range of the signal, for example, white noise, With respect to an object to be measured such as a speaker, it is possible to obtain an effect that it is possible to measure an impulse response from when the vibration amplitude of the diaphragm of the speaker is small to when it is large. Also,
Since it is not necessary to use an impulse as a measurement signal and a signal recorded in a digital source is used, highly accurate measurement can be performed by using an A / D converter having characteristics equivalent to the sampling frequency and quantization number of the digital source. The possible effect is obtained. Further, by using the digital signal recorded in the digital source as a reference, it is possible to remove the influence on the reproducibility of the measurement data by removing the irregularity of the sampling start point that occurs at the time of A / D conversion. The effect is obtained. Furthermore, the analog signal input to the DUT, that is, the digital signal read from a digital source, etc., is converted into an analog signal, and the transfer function for the digital signal read from the digital source and the digital function of the DUT are read. By calculating the transfer function for the digital signal and calculating the ratio of the two, the part that converts the digital signal read from a digital source into an analog signal and the part that converts the input analog signal into a digital signal It is possible to obtain the effect of removing the influence on the measurement signal and measuring the impulse response of the DUT.

[Brief description of drawings]

FIG. 1 is a block diagram of an impulse response measuring device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a digital signal and an analog signal input to the impulse response measuring device according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a time shift in the impulse response measuring device according to the first embodiment of this invention.

FIG. 4 is an explanatory diagram illustrating an operation of a computing unit in the impulse response measuring device according to the first embodiment of the present invention.

FIG. 5 is a block diagram of an impulse response measuring device according to a second embodiment of the present invention.

FIG. 6 is a block diagram of an impulse response measuring device according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating an operation of the third exemplary embodiment of the present invention.

FIG. 8 is a conventional impulse response measuring device.

FIG. 9 is an operation explanatory diagram of a signal generator in the conventional impulse response measuring apparatus.

[FIG. 10] A / in the conventional impulse response measuring apparatus
It is operation | movement explanatory drawing of a D converter.

FIG. 11 is an operation explanatory diagram of a computing unit in the conventional impulse response measuring device.

FIG. 12 is an operation flow diagram of an arithmetic unit in the conventional impulse response measuring device.

[Explanation of symbols]

 1 input terminal 2 memory 3 input terminal 4 A / D converter 5 signal generator 6 memory 7 arithmetic unit 8 memory 9 arithmetic unit 10 arithmetic unit 11 arithmetic unit 12 memory 13 arithmetic unit 14 output terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04R 3/00 310 8622-5H

Claims (6)

[Claims] 1. A first input terminal for inputting a digital signal read from a digital source or the like, a first storage means for storing a digital signal input to the first input terminal, and the first input terminal. First signal generating means for generating a reference signal synchronized with a digital signal input to an input terminal, and second input for inputting a response output signal of the DUT to the analog signal obtained by converting the digital signal into an analog signal. A terminal, first conversion means for converting an analog signal input to the second input terminal into a digital signal, second storage means for storing an output of the first conversion means, and the second The time difference between the signal stored in the storage means and the signal stored in the first storage means is detected with reference to the signal stored in the first storage means, and the second storage is performed. A first arithmetic means for correcting the signal stored in the means, a third memory means for storing the output of the first arithmetic means, and a signal stored in the first memory means. Second calculation means for calculating the spectrum, third calculation means for calculating the spectrum of the signal stored in the third storage means, and output of the third calculation means for the second calculation means Calculating means for dividing by the output of the fourth calculating means, and a fourth calculating means for storing the output of the fourth calculating means.
And a fifth arithmetic means for converting the signal stored in the fourth memory means into a time axis signal, and the output of the fifth arithmetic means is output. Response measurement device. 2. The impulse response measuring device according to claim 1, wherein the first converting means operates based on a reference signal output from the first signal generating means. 3. A third input terminal for inputting a digital signal recorded in a digital source or the like, and the third input terminal.
Fifth storing the digital signal input to the input terminal of
Storage means, second signal generating means for generating a reference signal, and second signal converting the digital signal into an analog signal.
Converting means, an output terminal for outputting the output signal of the second converting means, a fourth input terminal for inputting a response output signal of the DUT to the analog signal output from the output terminal, Stored in the sixth storage means; and sixth storage means for storing the output of the third conversion means, the third conversion means for converting an analog signal input to the input terminal 4 of FIG. The time difference between the signal stored in the fifth storage means and the signal stored in the fifth storage means, and the signal stored in the sixth storage means with reference to the signal stored in the fifth storage means. To the sixth arithmetic means, a seventh memory means for storing the output of the sixth arithmetic means, and a seventh memory means for calculating the spectrum of the signal stored in the fifth memory means. Arithmetic means and the seventh storage means Eighth arithmetic means for calculating the spectrum of the stored signal, ninth arithmetic means for dividing the output of the eighth arithmetic means by the output of the seventh arithmetic means, and the ninth arithmetic means And an eighth storage means for storing the output of the second storage means and a tenth calculation means for converting the signal stored in the eighth storage means into a time axis signal, and outputs the output of the tenth calculation means. An impulse response measuring device characterized by: 4. The impulse response measuring device according to claim 3, wherein the second converting means and the third converting means operate based on a reference signal output from the second signal generating means. 5. A fifth input terminal for inputting a digital signal read from a digital source or the like, a ninth storage means for storing a digital signal input to the fifth input terminal, and the fifth Third signal generating means for generating a reference signal synchronized with a digital signal input to the input terminal, a sixth input terminal for inputting an analog signal obtained by converting the digital signal into an analog signal, and the digital signal as an analog signal A seventh input terminal for inputting a response output signal of the DUT to the analog signal converted into a signal;
First signal switching means for selectively switching analog signals input to the sixth input terminal and the seventh input terminal, and a fourth conversion for converting an output of the first signal switching means into a digital signal. Means, second signal switching means for switching and outputting the output of the fourth converting means in synchronization with the first signal switching means, and the first signal switching means is input to the sixth input terminal. A tenth storing the output of the fourth converting means output by the second signal switching means when the selected analog signal is selected.
Storage means and the first signal switching means are the seventh means.
Stored in the eleventh storage means and the tenth storage means for storing the output of the fourth conversion means output by the second signal switching means when the analog signal input to the input terminal of The time difference between the stored signal and the signal stored in the ninth storage means is detected based on the signal stored in the ninth storage means and stored in the tenth storage means. Eleventh calculation means for correcting a signal, twelfth storage means for storing an output of the eleventh calculation means, a signal stored in the eleventh storage means, and the ninth storage means Twelfth calculating means for detecting a time lag between the signals stored in the memory with reference to the signal stored in the ninth storing means and correcting the signal stored in the eleventh storing means And a thirteenth memory for storing the output of the twelfth arithmetic means Means, thirteenth calculation means for calculating the spectrum of the signal stored in the ninth storage means, and fourteenth calculation means for calculating the spectrum of the signal stored in the twelfth storage means Calculating the spectrum of the signal stored in the thirteenth storage means,
The output of the fifteenth calculation means and the fourteenth calculation means is converted into the thirteenth calculation means.
16th computing means for dividing by the output of the computing means of
Fourteenth storage means for storing the output of the sixteen calculation means, a seventeenth calculation means for dividing the output of the fifteenth calculation means by the output of the thirteenth calculation means, and the seventeenth calculation means A fifteenth storage means for storing an output, an eighteenth calculation means for dividing a signal stored in the fifteenth storage means by a signal stored in the fourteenth storage means, and the eighteenth storage means An output of the nineteenth calculation means is provided, which includes a sixteenth storage means for storing the output of the calculation means and a nineteenth calculation means for converting the signal stored in the sixteenth storage means into a time axis signal. And an impulse response measuring device. 6. The impulse response measuring apparatus according to claim 5, wherein the fourth converting means operates based on the reference signal output from the third signal generating means.