JP4827595B2 - Impulse response detection device and impulse response detection program - Google Patents

Description

  The present application relates to a technical field such as an impulse response detection device that can efficiently and quickly detect an impulse response in an audio reproduction device that reproduces an audio signal.

  By measuring the impulse response from the object to be measured with respect to the impulse signal reproduced from the sound reproducing device for reproducing the audio signal, various acoustic characteristics such as the frequency characteristic of the object to be measured can be grasped.

  In recent years, due to the progress of various computer technologies including personal computers, D / A converters and computers built in CD players and the like have been built in instead of the previous expensive A / D converters and D / A converters. By using the A / D converter capability, a good measurement result of impulse response can be obtained.

  When an impulse signal actually output from a CD player is input into a computer using a microphone or the like and an impulse response is measured, the impulse signal reproduced by analog conversion from the CD player by a D / A converter is reproduced. Impulse after being emitted into the measurement room through an amplifier and a speaker, taken into a computer through a measurement object such as a microphone, and digitally converted by an A / D conversion processing unit provided in the computer The response will be measured.

  However, when the sampling cycle of the D / A converter of the CD player and the sampling cycle of the A / D conversion processing unit provided in the computer are asynchronous, the number of samplings representing the same waveform (sampling) Since the number) differs, beats and errors occur in the signal finally measured, and an accurate impulse response cannot be measured.

  As a method of correcting this synchronization shift, for example, there is a method using a pilot signal. In this case, however, a pilot signal generator for generating a pilot signal is required, and the apparatus configuration becomes complicated and the cost is increased. is there.

  The present application has been made in view of the circumstances described above. As an example of the problem, when detecting the impulse response of the measurement object to be measured, the D / A conversion and the A / D conversion are performed. It is an object of the present invention to accurately detect a good impulse response with a simple device configuration even when synchronization loss occurs.

  In order to solve the above-described problem, the invention according to claim 1 is characterized in that the first and second evaluation signals for measuring the impulse response are generated by a predetermined number of generated signals, and the generation is performed. A measurement signal acquisition means for acquiring the first evaluation signal as a measurement signal including a plurality of sampling signals via a measurement target system to be measured for an impulse response; and the generation signal for the acquired measurement signal. Periodic signal extracting means for extracting as at least two periodic signals including a number of the sampling signals, the extracted first periodic signal, and the cross-correlation of the second periodic signal following the first periodic signal A selection means for calculating a function and selecting a sampling number of a sampling signal having a maximum correlation value; and the second evaluation signal based on the selected sampling number Based on the correction means for correcting the number of generated signals, the measurement signal acquired by the measurement signal acquisition means, and the second evaluation signal in which the number of generated signals is corrected by the correction means, an impulse response And detecting means for detecting.

  In order to solve the above-described problem, the invention according to claim 7 is a signal generation means for generating a first evaluation signal and a second evaluation signal for measuring an impulse response with a predetermined number of generation signals. Measurement signal acquisition means for acquiring the generated first evaluation signal as a measurement signal including a plurality of sampling signals via a measurement target system for measuring an impulse response, and generating the acquired measurement signal A periodic signal extracting means for extracting as at least two periodic signals including the sampling signals of the number of signals, a cross-correlation function between the extracted first periodic signal and a second periodic signal following the first periodic signal Calculating means for selecting the sampling number of the sampling signal having the maximum correlation value, and the second evaluation signal based on the selected sampling number. Based on the correction means for correcting the number of generated signals, the measurement signal acquired by the measurement signal acquiring means, and the second evaluation signal in which the number of generated signals is corrected by the correction means It functions as a detecting means for detecting a response.

  Hereinafter, the best embodiment of the present application will be described with reference to the drawings. In the embodiment described below, the impulse response detection device of the present application is applied to a computer included in an impulse response detection system using a TSP signal as an example of a first evaluation signal for measuring an impulse response. This is an embodiment.

  First, the configuration and function of the impulse response detection system according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram of the impulse response detection system S.

  The outline of the impulse response detection system S will be described. The system S includes a control unit that functions as a signal generation unit, a measurement signal acquisition unit, a periodic signal extraction unit, a selection unit, a correction unit, a detection unit, and a synchronous addition processing unit. The computer 100 includes a CD (Compact Disc) player 200.

  First, the computer 100 generates a TSP (Time Stretched Pulse) signal So as a first evaluation signal and a reverse TSP signal Si as a second evaluation signal for measuring an impulse response, and the generated TSP signal The So is recorded on a recording medium such as a CD-R (hereinafter simply referred to as “CD”). Then, the CD on which the TSP signal So is recorded is loaded into the CD player 200, and the TSP signal So D / A (Digital / Analog) converted by the CD player 200 is connected to the CD player 200 via a connection cable. The sound is output through the speaker 201 as the measured object, and then the output sound propagates through the measurement chamber and is taken into the computer 100 through the microphone 101 as the measured object. A / D (Analog / Digital) conversion is performed to obtain the measurement signal Sm. Then, the computer 100 uses the measurement signal Sm to correct the inverse TSP signal so that the measured TSP signal So (measurement signal Sm (sy)) and the inverse TSP signal Si are synchronized, and then the impulse Detect response.

  Hereinafter, it demonstrates in detail using FIG.

This figure is an explanatory diagram of the structure and detection system of the impulse response detection system S, and the measurement target system in the present embodiment in which the frame surrounded by the alternate long and short dash line in FIG. A plurality of objects to be measured are included. Note that the object to be measured is a measurement object such as a component between the D / A conversion unit 204 of the CD player 200 and the A / D conversion unit 107 of the computer 100 and the measurement room environment. In this embodiment, the components between the D / A converter 204 of the CD player 200 and the A / D converter 107 of the computer 100 are connected to the amplifier 205, the speaker 201, the microphone 101, the microphone amplifier 106, and each member. Connection cable or bus.
<1. Configuration and function of computer>
The computer 100 includes an impulse generation unit 102, phase shifters 103o and 103i, a comparison measurement unit 104, a signal correction unit 105, a microphone amplifier 106, an A / D conversion unit 107, a synchronous addition processing unit 108, a superimposition processing unit 109, and an impulse measurement signal. The configuration includes a detection unit 110 and a control unit 111 that controls the entire computer, and each component is connected to each other via a cable or a bus (not shown).

  The impulse generator 102 functions as a signal generating unit together with the phase shifters 103o and 103i, and generates an impulse signal as a direct-current signal generated instantaneously. The generated impulse signal is output to the phase shifters 103o and 103i.

  The phase shifter 103o functions as a signal generating unit together with the impulse generator 102 and the phase shifter 103i, and changes the impulse signal generated by the impulse generator 102 in proportion to the square of the frequency, thereby changing the time axis direction. The TSP signal So having a TSP signal length (an example of the number of generated signals) (for example, 65536 samples) is generated as an example of the first evaluation signal by extending (shifting the phase). The generated TSP signal So is once recorded on a CD and then reproduced by the CD player 200.

  The phase shifter 103i functions as a signal generation unit together with the impulse generator 102 and the phase shifter 103o, and extends the impulse signal generated by the impulse generator 102 in the time axis direction (shifts the phase) in the same manner as the phase shifter 103o. After that, the reverse generation signal Si having the TSP signal length (number of generated signals) (for example, 65536 samples) is generated as an example of the second evaluation signal by being reversed on the time axis. Then, the generated inverse TSP signal Si is sent to the signal correction unit 105 and subjected to correction processing. Thereafter, the measurement signal Sm is superposed and an impulse response is detected.

  Note that TSP signal length data Dtsp indicating that the TSP signal length of the TSP signal So generated by the phase shifter 103o and the phase shifter 103i and the inverse TSP signal Si is 65536 samples is sent from the phase shifter 103i to the comparison measurement unit 104. The TSP signal length data Dtsp is stored in the comparison measurement unit 104.

  The comparison measurement unit 104 functions as a periodic signal extraction unit and a selection unit, takes in the measurement signal Sm from the measured system acquired through the A / D conversion unit 107, and uses the measurement signal Sm to perform the CD player 200. The difference between the signal length of the measurement signal Sm (hereinafter also referred to as the number of samplings) caused by the clock difference between the D / A conversion in FIG. 1 and the A / D conversion in the computer 100 is measured. The measured signal length of the measurement signal Sm is sent to the signal correction unit 105 and the synchronous addition processing unit 108, used for correcting the inverse TSP signal Si, and used for the synchronous addition processing of the measurement signal Sm. Become. Note that the measurement method of the signal length of the measurement signal Sm in the comparative measurement unit 104 and the synchronous addition processing method using the measured signal length will be described in detail later in “3. Specific processing procedure of impulse response detection processing”. Describe.

  The signal correction unit 105 functions as a correction unit and corrects the number of generated signals of the inverse TSP signal Si based on the signal length of the measurement signal Sm measured by the comparison measurement unit 104 described above to obtain the inverse TSP signal Su. . More specifically, the inverse TSP signal Si originally generated by the phase shifter 103i is a signal having a TSP signal length of 65536 samples. The inverse TSP signal Si is resampled based on the signal length of the measurement signal Sm measured by the comparison measurement unit 104 (correcting the number of generated signals), and the corrected inverse having a signal length equal to the measurement signal Sm. The TSP signal Su is configured to be acquired. The acquired corrected inverse TSP signal Su is sent to the superimposition processing unit 109 and superimposed on the measurement signal Sm.

  The microphone amplifier 106 functions as a measurement signal acquisition unit together with the microphone 101 and the A / D converter 107, and is one of the objects to be measured which are impulse response measurement targets included in the system to be measured. This is for amplifying the input signal. More specifically, the TSP signal So reproduced by the CD player 200 and output by sound from the speaker 201 is collected by the microphone 101 connected via a cable, and the collected TSP signal So is obtained. It is configured to be amplified and loaded into the computer 100.

  The A / D converter 107 is for converting the TSP signal So taken as an analog signal into the computer 100 via the microphone amplifier 106 into a digital signal. Further, it functions as a measurement signal acquisition unit together with the microphone 101 and the microphone amplifier 106, and acquires the measurement signal Sm as a plurality of sampling signals based on the sampling clock of the A / D conversion unit 107. The acquired measurement signal Sm is sent to the comparison measurement unit 104, and the comparison measurement unit 104 uses the sampling signal for the TSP signal length 65536 samples in the measurement signal Sm as one periodic signal. Based on the periodic signal corresponding to the period, the signal length of the measurement signal Sm is measured.

  The synchronous addition processing unit 108 functions as a synchronous addition processing unit, sequentially performs synchronous addition processing, and acquires a measurement signal Sm (sy) having a high S / N ratio.

  The superimposition processing unit 109 functions as a detection unit together with the impulse response detection unit 110, the measurement signal Sm (sy) subjected to the synchronous addition process, the corrected inverse TSP signal Su corrected by the signal correction unit 105, and The signal is for convolution.

  The impulse response detection unit 110 functions as a detection unit together with the superimposition processing unit 109, and based on the TSP response signal Stsp that is a result of the superimposition processing of the measurement signal Sm and the corrected inverse TSP signal Su by the superimposition processing unit 109. This is for detecting an impulse response.

In addition, the control unit 111 functions as a signal generation unit, a measurement signal acquisition unit, a periodic signal extraction unit, a selection unit, a correction unit, a detection unit, and a synchronous addition processing unit together with the above-described components, and an impulse response to a RAM (not shown) or the like. Store the detection program.
<2. Configuration and function of CD player>
The CD player 200 includes a CD loading unit 202, a reproduction processing unit 203, a D / A conversion unit 204, and an amplifier 205, and the respective components are connected to each other via a bus (not shown). .

  The CD loading unit 202 is for loading and operating a CD on which the TSP signal So generated by the computer 100 is recorded.

  The reproduction processing unit 203 is also for performing reproduction processing of recorded information recorded on the CD loaded in the CD loading unit 202. In this embodiment, the reproduction processing unit 203 reproduces the TSP signal So recorded on the CD. To do. The TSP signal So recorded on the CD is continuously played back. That is, when the TSP signal So is the TSP signal So once every 2 seconds (one cycle), the TSP signal So is reproduced five times (5 cycles) in 10 seconds. In order to detect the signal length of the measurement signal Sm, the measurement signal Sm corresponding to the TSP signal So corresponding to at least two periods is required. Therefore, the TSP signal So having two periods or more must be continuously reproduced. As described above, the TSP signal So recorded on the CD is continuously reproduced to reproduce as many TSP signals So as possible (with many cycles), and a large number of continuous TSP signals So are captured in the computer 100. In the synchronous addition process described in detail later, a measurement signal Sm having a higher S / N ratio can be acquired.

The D / A conversion unit 204 converts the TSP signal So read by the reproduction processing unit 203 as a digital signal into an analog signal and outputs the analog signal to the amplifier 205. The amplifier 205 is configured to amplify the output signal (here, the TSP signal So) from the D / A converter 204 and output the sound through the speaker 201.
<3. Specific procedure of impulse response detection processing>
Subsequently, a specific procedure of impulse response detection by the impulse response detection system S will be described with reference to FIGS. This process is performed based on an impulse response detection program stored in a RAM (not shown) of the control unit 111.

  First, the impulse generator 102 of the computer 100 generates an impulse signal as a DC signal that is instantaneously generated. The generated impulse signal is sent to the phase shifters 103o and 103i, the TSP signal So is generated by the phase shifter 103o, and the inverse TSP signal Si is generated by the phase shifter 103i. Note that the inverse TSP signal Si generated by the phase shifter 103i is performed after the description of the measurement signal Sm by the TSP signal So for convenience of explanation.

  The TSP signal So generated by the phase shifter 103o is once recorded on a CD. Subsequently, when the CD on which the TSP signal So is recorded is loaded into the CD loading unit 202 of the CD player 200 and operated, the reproduction processing unit 203 reads the TSP signal So recorded on the CD and performs reproduction processing. . As described above, the reproduction processing unit 203 is configured to continuously reproduce the TSP signal So recorded on the CD.

  The reproduced TSP signal So is converted from a digital signal to an analog signal via the D / A conversion unit 204 and output to the amplifier 205. The amplifier 205 is configured to amplify the output signal (here, the TSP signal So) from the D / A conversion unit 204 and output the amplified signal to the speaker 201.

  The TSP signal output from the speaker 201 propagates through the measurement chamber and is collected by the microphone 101, amplified by the microphone amplifier 106, and then taken into the computer 100 as the measurement signal Sm.

  The measurement signal Sm from the microphone amplifier 106 is converted from an analog signal to a digital signal by the A / D conversion unit 107. More specifically, the measurement signal Sm from the microphone amplifier 106 is acquired as a plurality of sampling signals based on the sampling clock of the A / D conversion unit 107.

  At this time, for example, the sampling frequency of the A / D conversion unit 107 is 44.1 kHz, and the synchronization between the A / D conversion unit 107 and the D / A conversion unit included in the CD player 200 described in detail later coincides. If the signal is synchronized (synchronized), the TSP signal length of the original TSP signal So is 65536 samples, and the signal length of the measurement signal Sm corresponding to one TSP signal So can be acquired as 65536 samples. Is calculated so that one measurement signal Sm is acquired at intervals of 65536 / 44100≈1.48 seconds, but in reality, the A / D conversion unit 107 and the D / A conversion unit of the CD player 200 are asynchronous. Since (not synchronized), the number of samples (signal length) of one measurement signal Sm is not always the same as the original TSP signal length 65536 samples.

  Accordingly, the measurement signal Sm from the A / D conversion unit 107 is divided into a plurality of periodic signals by the comparative measurement unit 104, and the two correlation signals are extracted to calculate a cross-correlation function. Measure the signal length.

  At this time, the comparison measurement unit 104 functions as an extraction unit, and for the sampling signal included in the measurement signal Sm sent from the A / D conversion unit 107, the sampling number of the first sampling signal is set to 1, and the original TSP A sampling signal up to a TSP signal length of 65536 of the signal So (and inverse TSP signal Si) is extracted as a periodic signal I1 of one cycle. It is assumed that the signal length of the original TSP signal So has been acquired in advance as the TSP signal length data Dtsp from the phase shifter 103i.

  3A and 3B, a sampling signal corresponding to sampling numbers 1 to 65536 is a periodic signal I1 (first periodic signal), and subsequent sampling numbers 65537 to 131072 are periodic signals I2 (first It is explanatory drawing at the time of extracting as a periodic signal).

  The comparison measurement unit 104 functions as a selection unit, calculates a cross-correlation function between the extracted periodic signal I1 and the extracted periodic signal I2, and selects a sampling number of a sampling signal that maximizes the correlation value.

  FIG. 3A shows an example in which the sampling number of the sampling signal with the maximum correlation value is 65536. In this case, correction instruction data Du for instructing to resample the inverse TSP signal Si as 65536 samples is sent from the comparison measurement unit 104 to the signal correction unit 105. As a result of calculating the cross-correlation function in this way, if the sampling number of the sampling signal having the maximum correlation value does not change from the original TSP signal length 65536 samples, the inverse TSP signal Si to be superposed later is Since the signal length (number of samples) is the same, there is no need to correct the inverse TSP signal Si. Accordingly, the correction instruction data Du indicating that correction is not necessary may be transmitted.

  On the other hand, FIG. 3B is an example in which the sampling number of the sampling signal with the maximum correlation value is 65556. In this case, the correction measurement data Du is sent from the comparison measurement unit 104 to the signal correction unit 105 to instruct re-sampling as the inverse TSP signal Si65556 samples.

  When the comparison measurement unit 104 selects the sampling number of the sampling signal with the maximum correlation value, the comparison measurement unit 104 performs the synchronous addition processing on the basis of the sampling number of the sampling signal with the maximum correlation value. Synchronous addition processing instruction data Dsy for instructing to perform is sent.

  The comparison measurement unit 104 sequentially extracts the periodic signal I from the measurement signal Sm received from the A / D conversion unit 107, calculates a cross-correlation function for each successive periodic signal, and maximizes the correlation value. The sampling number of the sampling signal is sequentially sent to the synchronous addition processing unit 108 as synchronous addition processing instruction data Dsy.

The synchronous addition processing unit 108 sequentially performs synchronous addition processing on the measurement signal Sm received from the A / D conversion unit 107 based on the synchronous addition processing instruction data Dsy.
(1) Embodiment of Synchronous Addition Processing As an example of the synchronous addition processing, a cross correlation function between the periodic signal In (n is a natural number) and the subsequent periodic signal In + 1 is calculated, and the correlation is maximized. The sampling signal corresponding to the sampling number next to the sampling number of the signal is the first sampling signal of the periodic signal In + 1 when the cross-correlation function of the next periodic signal In + 1 and the periodic signal In + 2 is calculated. And

  Specifically, the comparison measurement unit 104 first calculates the cross-correlation function between the periodic signal I1 and the periodic signal I2, and sets the sampling number 65556 of the sampling signal with the maximum correlation value. Pick out. Then, when extracting the periodic signal next, the sampling number 65557 obtained by adding 1 to the sampling number 65556 is used as the first sampling signal, and the sampling signals 65557 to 131092 (for the TSP signal length) are used as the periodic signal I2. Extract. Then, the sampling signal corresponding to the TPS signal length is extracted in the same way from the 131093 to the 196629 as the next periodic signal I3, and this is repeated.

  In this way, the S / N ratio can be improved by repeatedly reproducing and collecting the same TSP signal So, sequentially performing the synchronous addition process, and performing the measurement signal Sm (sy).

Further, according to the method of the synchronous addition process, the sampling clocks of the D / A conversion unit 204 of the CD player 200 and the A / D conversion unit 107 of the computer 100 are synchronized by synchronizing each of the preceding and following periodic signals. Can be dealt with even in the case of rocking with a relatively slow period.
(2) Modified example of synchronous addition process As another example of the synchronous addition process, a signal from the A / D conversion unit 107 is extracted as a plurality of periodic signals for each TSP signal length. Assuming that the number of extracted periods is F, by calculating a cross-correlation function between the first periodic signal I1 and the F-th periodic signal (that is, the last periodic signal IF), the total deviation of the signal length of the measurement signal Sm is calculated. There is a technique to grasp first.

  When the original TSP signal length is L and the sampling number of the sampling signal that maximizes the cross-correlation function correlation value between the first periodic signal I1 and the F-th periodic signal is Lc, a value that satisfies the following equation (1) A sampling signal having a value obtained by rounding off C as a sampling number is acquired as the first sampling signal of the S-th periodic signal IS.

周期信号を抽出する際に、上記式を用いることにより、最初に抽出すべきサンプリング番号が瞬時に算出できるので、演算量を節約することができ、より迅速なインパルス応答の検出が可能となる。

When extracting the periodic signal, the sampling number to be extracted first can be instantaneously calculated by using the above equation, so that the amount of calculation can be saved and the impulse response can be detected more quickly.

  Thus, the measurement signal Sm (sy) subjected to the synchronous addition processing by the synchronous addition processing unit 108 is sent to the superimposition processing unit 109.

  On the other hand, the inverse TSP signal Si generated by the phase shifter 103i is sent to the signal correction unit 105, where the signal correction unit 105 performs correction processing based on the correction instruction data Du from the comparison measurement unit 104, and corrects the correction. The inverted TSP signal Su is sent to the superimposition processing unit 109.

  The superimposition processing unit 109 functions as a detection unit together with the impulse response detection unit 110, and the measurement signal Sm (sy) subjected to the synchronous addition process and the corrected inverse TSP signal Su corrected by the signal correction unit 105. Are convolved and sent to the impulse response detector 110 as a TSP response signal Stsp. Then, the impulse response detector 110 detects the impulse response based on the TSP response signal Stsp.

  As described above, according to the present embodiment, in order to measure the impulse response, the TSP signal generated based on the impulse signal and the inverse TSP signal Si obtained by reversing the TSP signal So on the time axis , Are respectively generated at a TSP signal length 65536, and the generated TSP signal So is acquired as a measurement signal Sm including a plurality of sampling signals via a measurement target system to be measured for an impulse response. The signal Sm is extracted as at least two periodic signals including a sampling signal having a TSP signal length of 65536, their cross-correlation function is calculated, and based on the sampling number of the sampling signal having the maximum correlation value, the inverse TSP signal Si Since the number of generated signals is corrected, the corrected inverse TSP signal having the same sampling number as that of the measurement signal Sm is used. It is possible to obtain a Su. Since the impulse response is detected based on the corrected inverse TSP signal Su and the measurement signal Sm, there is a synchronization shift between the D / A converter 204 of the CD player 200 and the A / D converter 107 of the computer 100. Even if it occurs, it is possible to accurately detect a good impulse response with a simple device configuration.

  In addition, since the synchronous addition process is performed on the measurement signal Sm, the measurement signal Sm having a high S / N ratio can be acquired, and a more favorable impulse response can be detected.

  Further, since the preceding and following periodic signals are sequentially acquired based on the signal length of the measurement signal Sm during the synchronous addition process, the D / A conversion unit 204 of the CD player 200 and the A / D conversion unit 107 of the computer 100 are used. Even when the synchronization of the sampling clock fluctuates at a loose period, it can be dealt with.

Furthermore, as described in the modification of the synchronous addition process, the original TSP signal length is L, the number of extracted periods is F (F is a natural number of 2 or more), the extracted periodic signal I1, and the last When the cross-correlation function with the periodic signal IF, which is the period of the above, is calculated and the sampling number of the sampling signal with the maximum correlation value is Lc, when extracting the periodic signal IS, the above-described formula (1) Since the sampling signal having the value obtained by rounding off the value C satisfying the above as the sampling number is used as the first sampling signal, the sampling number to be extracted first can be calculated instantaneously, so that the calculation amount can be saved. Impulse response can be detected more quickly.
<4. Modification of periodic signal extraction method>
In the embodiment described above, the comparison measurement unit 104 performs the first sampling on the sampling signal included in the measurement signal Sm sent from the A / D conversion unit 107 based on the TSP signal length data Dtsp received from the phase shifter 103i. The sampling number of the signal is No. 1, and the sampling signal up to the TSP signal length 65536 of the original TSP signal So (and the inverse TSP signal Si) is extracted as one period signal I1, and thereafter the period signals I2 and I3. Although it is configured to extract, it is also possible to extract the number of samplings that is N times the TSP signal length as one periodic signal.

  This will be specifically described below with reference to FIG.

  In FIG. 5, sampling signals corresponding to the sampling numbers 1 to 131072 are extracted as the periodic signal I1 (first periodic signal) by extracting the sampling signals of the number twice the TSP signal (N = 2) as one periodic signal. And the subsequent sampling numbers 131072 to 262144 are extracted as the periodic signal I2 (second periodic signal).

  At this time, the comparison measurement unit 104 selects the sample number of the sampling signal that maximizes the correlation value by calculating the cross-correlation function in the same manner as described above. ) And sent out as the correction instruction data Du together with the selected sample number indicating whether the periodic signal has been acquired.

  In response to this, the signal correction unit 105 performs correction (re-sampling) after multiplying the inverse TSP signal Si once by N based on the correction instruction data Du, and performs correction (resampling) by 1 / N after the correction processing, thereby correcting the reverse TSP signal Su. To get.

  In this way, by oversampling (multiplying) the measurement signal Sm N times, it is possible to accurately measure even a deviation of less than one sample signal and obtain an impulse response with high accuracy.

<5. Variant>
In the above-described embodiment, the configuration using the TSP signal as the first evaluation signal for measuring the impulse response is employed. However, the evaluation signal used for measuring the impulse response is not limited to this. For example, an M-sequence signal may be used as the evaluation signal.

  FIG. 6 is an explanatory diagram of a configuration and a detection system of an impulse response detection system S when an M-sequence signal is used as an evaluation signal. An M-sequence signal generator 502 is provided instead of the impulse generator 102 and the phase shifters 103o and 103i functioning as signal generators in the above embodiment. Other configurations and functions of the impulse response detection system S are the same as those in the above-described embodiment.

  The M-sequence signal generator 502 functions as a signal generator and generates an M-sequence signal Sm-seq. The generated M-sequence signal Sm-seq. Is recorded on a CD and reproduced by the CD player 200, and is sent to the signal correction unit 105 to be corrected. That is, the M-sequence signal Sm-seq. Reproduced by the CD player 200 and acoustically output from the measured system having an impulse response is taken as an example of the first evaluation signal in the present application and superimposed on the measured signal Sm from the measured system. Therefore, the M-sequence signal Sm-seq. Sent to the signal correction unit 105 is taken as an example of the second evaluation signal in the present application.

  In addition, the M-sequence signal Sm-seq. Then, in the comparison measurement unit 104, an M-sequence signal length Dm-seq (not shown) indicating the M-sequence signal length (an example of the number of generated signals) is used for subsequent periodic signal extraction processing.

  Specific functions of other components such as the signal correction unit 105 are the same as those of the above-described embodiment.

1 is a schematic diagram of an impulse response detection system S. FIG. It is explanatory drawing of a structure and detection system of an impulse response detection system. It is an example of the extraction method of a periodic signal. It is an example of the extraction method of a periodic signal. It is a modification of the extraction method of a periodic signal. It is explanatory drawing of a structure and detection system of the impulse response detection system S at the time of using an M series signal as an evaluation signal.

Explanation of symbols

S ... Impulse response detection system S
DESCRIPTION OF SYMBOLS 100 ... Computer 101 ... Microphone 102 ... Impulse generation part 103o, 103i ... Phase shifter 104 ... Comparison measurement part 105 ... Signal correction part 106 ... Microphone amplifier 107 ... A / D conversion part 108 ... Synchronous addition process part 109 ... Superimposition process part 110 ... impulse response detection unit 111 ... control unit 200 ... CD player 201 ... speaker 202 ... CD loading unit 203 ... reproduction processing unit 204 ... D / A conversion unit 205 ... amplifier 502 ... M sequence signal generation unit So ... TSP signal Si ... reverse TSP signal Su ... corrected inverse TSP signal Sm, Sm (sy) ... measurement signal Stsp ... TSP response signal I (I1, I2, I3, ...) ... periodic signal Dtsp ... TSP signal length data Du ... correction instruction data Dsy ... Synchronous addition processing instruction data Sm-seq .... M sequence signal Dm-seq .... M sequence signal length data Smre ... M sequence response signal

Claims (12)

Signal generating means for generating first and second evaluation signals for measuring the impulse response with a predetermined number of generated signals;
Measurement signal acquisition means for acquiring the generated first evaluation signal as a measurement signal including a plurality of sampling signals via a measurement target system to be measured for an impulse response;
Periodic signal extraction means for extracting the acquired measurement signal as at least two periodic signals including the sampling signals of the number of generated signals;
Selecting means for calculating a cross-correlation function between the extracted first periodic signal and the second periodic signal following the first periodic signal, and selecting a sampling number of a sampling signal having a maximum correlation value;
Correction means for correcting the number of generated signals of the second evaluation signal based on the selected sampling number;
Detection means for detecting an impulse response based on the measurement signal acquired by the measurement signal acquisition means and the second evaluation signal in which the number of generated signals is corrected by the correction means;
An impulse response detecting device comprising: The impulse response detection device according to claim 1,
The periodic signal extraction means extracts the acquired measurement signal as the periodic signal including sampling signals that are N times the number of generated signals (N is a natural number of 2 or more),
The correction unit multiplies the second evaluation signal by N times, and then generates the second evaluation signal multiplied by the N times based on the sampling number selected by the selection unit. Correct the number,
The detection means detects an impulse response based on the measurement signal acquired by the measurement signal acquisition means and the second evaluation signal multiplied by N times corrected by the correction means. An impulse response detecting apparatus characterized by being used in the above. In the impulse response detecting device according to claim 1 or 2,
The periodic signal extraction means extracts a continuous periodic signal from the first periodic signal to the last periodic signal for the measurement signal acquired by the measurement signal acquisition means,
The selecting means calculates the cross-correlation function for each of the extracted successive periodic signals, selects the sampling number of the sampling signal that maximizes the correlation value, and
Further comprising synchronous addition processing means for sequentially performing synchronous addition processing on the measurement signal based on each selected sampling number;
The impulse response detection device, wherein the detection means detects the impulse response based on the measurement signal subjected to the synchronous addition process. In the impulse response detection device according to claim 3,
The periodic signal extraction unit is configured to obtain two periodic signals of the measurement signal acquired by the measurement signal acquisition unit, the first periodic signal and a second periodic signal following the first periodic signal. Extract and
The selecting means calculates the cross-correlation function of the extracted two periodic signals, and selects the sampling number of the sampling signal that maximizes the correlation value,
Further, the periodic signal extracting means outputs a sampling signal corresponding to the sampling number next to the sampling number selected by the selecting means, the second periodic signal, and the third periodic signal following the second periodic signal. An impulse response detecting device, wherein the first sampling signal of the second periodic signal is extracted as the two periodic signals. In the impulse response detection device according to claim 3,
The number of periods extracted by the periodic signal extraction means is F (F is a natural number of 2 or more),
The selecting means calculates a cross-correlation function between the first periodic signal extracted by the periodic signal extracting means and the F-th periodic signal that is the last period, and sampling that maximizes the correlation value Let the sampling number of the signal be Lc,
If the number of generated signals is L,
The periodic signal extracting means extracts a sampling signal having, as a sampling number, a value obtained by rounding off a value C satisfying the following expression (1) when extracting the Sth periodic signal (S is a natural number of 2 or more and F or less). Is an initial sampling signal of the S-th periodic signal.

In the impulse response detection device according to claim 1,
The first evaluation signal generated by the signal generation means is a TSP signal or an M-sequence signal,
When the first evaluation signal is a TSP signal, the second evaluation signal is an inverted TSP signal obtained by reversing the TSP signal on the time axis,
When the first evaluation signal is an M-sequence signal, the second evaluation signal is also the same M-sequence signal as the first evaluation signal. Computer
Signal generating means for generating the first and second evaluation signals for measuring the impulse response with a predetermined number of generated signals;
A measurement signal acquisition means for acquiring the generated first evaluation signal as a measurement signal including a plurality of sampling signals via a measurement target system to be measured for an impulse response;
Periodic signal extraction means for extracting the acquired measurement signal as at least two periodic signals including the sampling signals of the number of generated signals;
Selecting means for calculating a cross-correlation function between the extracted first periodic signal and the second periodic signal following the first periodic signal, and selecting a sampling number of a sampling signal having a maximum correlation value;
Correction means for correcting the number of generated signals of the second evaluation signal based on the selected sampling number;
Based on the measurement signal acquired by the measurement signal acquisition unit and the second evaluation signal in which the number of generated signals is corrected by the correction unit, function as a detection unit that detects an impulse response. Characteristic impulse response detection program. In the impulse response detection program according to claim 7,
The periodic signal extracting means functions to extract the acquired measurement signal as the periodic signal including sampling signals that are N times the number of generated signals (N is a natural number of 2 or more);
The generated signal of the second evaluation signal multiplied by N times based on the sampling number selected by the selection means after the correction means has multiplied the second evaluation signal by N times. Function to correct the number,
When the detection means detects an impulse response based on the measurement signal acquired by the measurement signal acquisition means and the second evaluation signal multiplied by N times corrected by the correction means. An impulse response detection program which is made to function for use. In the impulse response detection program according to claim 7 or 8,
The periodic signal extraction unit functions to extract a continuous periodic signal from the first periodic signal to the last periodic signal for the measurement signal acquired by the measurement signal acquisition unit,
The selecting means calculates the cross-correlation function for each of the extracted successive periodic signals, and functions to select the sampling number of the sampling signal having the maximum correlation value; and
Further causing the computer to function as synchronous addition processing means for sequentially performing synchronous addition processing on the measurement signal based on each selected sampling number;
An impulse response detection program for causing the detection means to detect the impulse response based on the measurement signal subjected to the synchronous addition process. In the impulse response detection program according to claim 9,
For the measurement signal acquired by the measurement signal acquisition unit, the periodic signal extraction unit calculates two periodic signals of the first periodic signal and a second periodic signal following the first periodic signal. Function to extract,
Calculating the cross-correlation function of the extracted two periodic signals, and selecting the sampling number of the sampling signal that maximizes the correlation value;
Further, the periodic signal extracting means, the sampling signal corresponding to the sampling number next to the sampling number selected by the selecting means, the second periodic signal next, and the third periodic signal following the second periodic signal. And an impulse response detection program that functions as a first sampling signal of the second periodic signal when extracted as the two periodic signals. In the impulse response detection program according to claim 9,
The number of periods extracted by the periodic signal extraction means is F (F is a natural number of 2 or more),
Causing the selecting means to function to calculate a cross-correlation function between the first periodic signal extracted by the periodic signal extracting means and the Fth periodic signal that is the last period; and
The sampling number of the sampling signal that maximizes the correlation value of the cross-correlation function is Lc,
If the number of generated signals is L,
When the periodic signal extraction means extracts an S-th periodic signal (S is a natural number not less than 2 and not more than F), a sampling signal having, as a sampling number, a value obtained by rounding off a value C satisfying the following expression (1) Is made to function as the first sampling signal of the S-th periodic signal.

In the impulse response detection program according to any one of claims 7 to 11,
The first evaluation signal generated by the signal generation means is a TSP signal or an M-sequence signal,
When the first evaluation signal is a TSP signal, the second evaluation signal is an inverted TSP signal obtained by reversing the TSP signal on the time axis,
An impulse response detection program characterized in that, when the first evaluation signal is an M-sequence signal, the second evaluation signal is also the same M-sequence signal as the first evaluation signal.

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