JP2009236818A - Frequency characteristic measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for measuring frequency characteristics without being affected by noise even in the case of high frequency region. <P>SOLUTION: A generator 2 receives a command which generates sine wave by which frequency sweep is carried out to step-like at intervals of predetermined frequency from an analyzer 4, and supplies a measured signal to an object to be measured 3 by generating sine wave of indicated frequency, whenever frequency which should be generated by this command is indicated. The analyzer 4 measures and displays the frequency characteristics of the object to be measured 3, by FFT-analyzing the measured signal output from the object to be measured 3 for sine wave of each step of step-like frequency sweep. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a frequency characteristic measuring apparatus that measures a frequency characteristic by a module plugged into an application program installed in a computer.

  Conventionally, application software installed in a personal computer (hereinafter referred to as “personal computer”) called DAW (Digital Audio Warkstation) is known. A personal computer equipped with a DAW can operate as a music processing apparatus, and can perform a series of music processing such as recording / playback, editing, and mixing of MIDI events and audio signals. In this music processing apparatus, for each music file, a MIDI track for recording a MIDI event, an audio track for recording an audio signal, and a bus for mixing the audio signal are created and recorded on each track. A MIDI channel strip and an audio channel strip are created corresponding to each track. The MIDI channel strip is provided with an operator, and the volume (expression) and localization (pan) of a MIDI event reproduced on the corresponding MIDI track are controlled according to the operation of the operator. . In addition, the frequency characteristics, volume, and localization of the audio signal are controlled in accordance with the operation of an operator provided in the audio channel strip. Such various signal processing of the audio signal is executed by a signal processing module prepared in the DAW. In addition, a program for providing an additional function to the application software can be plugged in.

  In the signal processing module, there are effect modules such as an equalizer and a compressor. When developing such an effect module, for example, an effect algorithm is plugged into the DAW, and audition and verification thereof are performed. In this case, when measuring the frequency characteristics, etc. of the plugged-in effect module, the measurement signal is given to the effect module plugged into the DAW, and the output waveform file is analyzed by a separate measuring device, and the frequency characteristics are analyzed. I was trying to measure. As described above, since the work of measuring the frequency characteristics and the like of the effect module is complicated, it is conceivable to plug an analyzer module capable of measuring the frequency characteristics of the effect module into the DAW. In this way, the frequency characteristics of the effect module can be easily measured by simply connecting the effect module to be measured and the analyzer module on the DAW. Furthermore, the measurement signal from the DAW is supplied to the external effect device, the output is returned to the DAW again, and the analysis is performed by the plugged-in analyzer module. Can also be measured.

FIG. 12 shows an outline of the configuration of the frequency characteristic measuring apparatus 101 that can be realized on a personal computer on which a conventional DAW is installed.
The frequency characteristic measuring apparatus 101 shown in FIG. 12 inputs a measurement signal such as white noise generated by the generator 102 to a measurement target 103 such as an effect, and the analyzer 104 outputs the measurement signal output from the measurement target 103 to the FFT (Fast The frequency characteristic of the measuring object 103 is measured by performing Fourier transform. The analyzer 104 is realized by an analyzer module plugged into the DAW, and the generator 102 and the measurement target 103 can also be a generator module and an effect module plugged into the DAW.
As a measurement signal to be applied to the effect module of the measurement object 103, either a DAW playback sound or a measurement signal generated by the generator 102 can be selected. When the generator 102 is configured by a generator module plugged in, a user interface for setting parameters of the generator 102 is prepared, and a user interface screen can be opened to select whether the measurement signal is a sine wave or white noise. The amplitude of the measurement signal can be set. Furthermore, when a sine wave is selected, the frequency of the sine wave can also be set.

  Further, a user interface (UI) for setting the analyzer 104 is prepared, and an example of the analyzer UI screen 140 is shown in FIG. In the analyzer UI screen 140 shown in FIG. 13, a frequency characteristic display region 140 a that displays the frequency characteristic of the measurement target 103 in which the horizontal axis is a logarithmic scale frequency and the vertical axis is an amplitude in decibels, Setting fields for the first setting unit 140b and the second setting unit 140c for setting parameters are provided. In the first setting unit 140b, a time window used when performing FFT in the Type column a is selected. The time window can be selected from a rectangular window, Hanning window, Hamming window, Blackman window, Blackman-Harris window, and flat top window. When the measurement signal is a periodic signal, a flat top window is preferable. In the Size column b, the window length of the time window that determines the frequency resolution can be set by the number of samples that can sample the measurement signal within the time window. The second setting unit 140c sets the number of additions for synchronous addition in order to relatively reduce the noise component included in the signal by adding the FFT results under the same condition in the Num column c. The number of additions is determined in the Num column c, and the addition is started with the Start button.

In FIG. 13, an example of frequency characteristics when the measurement target 103 is an equalizer is displayed in the frequency characteristic display area 140a. Referring to this frequency characteristic, the frequency characteristic is increased in the high range, unlike the original characteristic of the equalizer. This is because white noise including a wideband frequency component is generated as a measurement signal in the generator 102 and supplied to the measurement target 103, and the analyzer 104 performs FFT on the entire frequency band, so This is because it is easily affected by noise components. Thus, the conventional frequency characteristic measuring apparatus 101 has a problem that it is easily affected by noise components.
In addition, when the measurement target 103 has nonlinear characteristics with different responses depending on the frequency of the input signal, even if a measurement signal including a broadband frequency component such as white noise is input to the measurement target 103, the input There is a problem that it is impossible to measure nonlinear characteristics having different responses depending on the frequency of the signal to be generated.

  Therefore, the present invention provides a frequency characteristic measuring apparatus that can measure frequency characteristics that are not affected by noise even when the frequency becomes high, and that can measure nonlinear characteristics having different responses depending on the frequency of an input signal. It is intended to provide.

  In order to achieve the above object, the frequency characteristic measuring apparatus of the present invention receives a command from the analyzer module for generating a sine wave swept in steps at predetermined frequency intervals, and indicates the frequency to be generated by the command. Each time, a sine wave of the instructed frequency is generated and supplied as a measurement signal to the module to be measured, and a sine wave for each step generated from the generator module is swept in steps. The most important feature is to measure and display the frequency characteristics of the measurement target module by analyzing the spectrum information of the measurement signal output from the measurement target module.

According to the present invention, each time a command to generate a sine wave that is swept in steps at predetermined frequency intervals is received from the analyzer module and the frequency to be generated is indicated by the command, the sine of the indicated frequency is indicated. A wave is generated and supplied as a measurement signal to a module to be measured, and is output from the module to be measured for a sine wave generated at each step and swept in steps. By analyzing the spectrum information of the measurement signal, the frequency characteristic of the module to be measured is measured and displayed. As a result, the frequency characteristic can be measured without using white noise having a broadband frequency component as a measurement signal, so that the frequency characteristic can be measured without being affected by noise even in a high frequency range.
In addition, since a sine wave swept in steps at predetermined frequency intervals is supplied as a measurement signal to a module to be measured, it is possible to measure nonlinear characteristics having different responses depending on the frequency of the input signal. become.

A frequency characteristic measuring apparatus according to an embodiment of the present invention includes a module plugged into application software installed in a personal computer (hereinafter referred to as a “personal computer”). A UI screen is shown in FIG.
A measurement apparatus UI screen 1a shown in FIG. 1 is a user interface screen displayed when the frequency characteristic measurement apparatus 1 according to the embodiment of the present invention is activated. The application software on which the frequency characteristic measuring apparatus 1 operates can be, for example, a DAW (Digital Audio Warkstation) that can execute a series of music processing such as recording / playback, editing, and mixing of MIDI events and audio signals. . In the frequency characteristic measuring apparatus 1 shown in FIG. 1, a measurement signal generated by a generator 2 is input to a measurement target 3 such as an effect, and the measurement signal output from the measurement target 3 is subjected to FFT (Fast Fourier Transform) in the analyzer 4. As a result, the frequency characteristic of the measuring object 3 is measured. The generator 2 is a generator module plugged into the application software, and the analyzer 4 is also realized by an analyzer module plugged into the application software. The measurement object 3 can be an effect externally connected to the personal computer or an effect module plugged into the application software.

  As shown in FIG. 1, the output port 2 a of the generator 2 is logically connected to the input port 3 a of the measurement target 3, and the measurement signal generated in the generator 2 is supplied to the measurement target 3. Further, the output port 3b of the measurement object 3 is logically connected to the input port 4a of the analyzer 4, and the measurement signal output from the measurement object 3 is input to the analyzer 4 and subjected to FFT so that the frequency characteristic of the measurement object 3 is obtained. Is measured. Further, the command output port 4b of the analyzer 4 is logically connected to the command input port 2b of the generator 2, so that the analyzer 4 can instruct the frequency and amplitude of the measurement signal generated by the generator 2. . Then, the analyzer 4 sends a command including information on the frequency and amplitude of the sine wave for each frequency swept to the generator 2 so that the generator 2 generates a sine wave that is swept in steps at predetermined frequency intervals. sending. The generator 2 that has received a command for each step that is frequency swept generates a sine wave having the frequency and amplitude specified by the command, and supplies it to the measurement object 3 as a measurement signal for each step that is swept in frequency. In this case, FIG. 5A shows an example of a sine wave (Stepped Sine) frequency-swept in a step shape generated by the generator 2. The horizontal axis of the graph shown in FIG. 5A is time, the vertical axis is the frequency of the sine wave, and the generator 2 can generate and output a sine wave that rises stepwise at a predetermined frequency interval. I understand.

  The analyzer 4 performs FFT on the measurement signal output from the measurement object 3 for each step in which the frequency is swept, and analyzes the amplitude value of the peak frequency in the FFT result. As a result, when the frequency sweep of the measurement signal is completed in the generator 2 and the FFT of the measurement signal by the analyzer 4 is completed, the frequency characteristic of the measurement object 3 is measured by the analyzer 4. The measurement result of the frequency characteristic is displayed as a graph. FIG. 5B shows an example of a graph of frequency characteristics obtained by FFT analysis using the analyzer 4. In FIG. 5B, the horizontal axis is the frequency, and the vertical axis is the amplitude value of the peak frequency in the FFT result. As an example, two steps of the sine wave frequency-swept in the step generated by the generator 2 are shown. Corresponding frequencies are shown in FIG. 5 (b) by broken lines from FIG. 5 (a).

Here, an example of the measurement target UI screen 30 on which the parameter setting of the measurement target 3 can be performed is shown in FIG.
The measurement target UI screen 30 shown in FIG. 2 is an example of a four-band equalizer, and has four bands A, B, C, and D, and gain (G), frequency (F), and selectivity in each band. A total of twelve operators 30a for setting (Q) are provided. Each time the desired operating element 30a of these 12 operating elements 30a is operated to set an equalizer characteristic, the frequency characteristic measuring apparatus 1 measures the frequency characteristic to obtain an equalizer having a desired frequency characteristic. Can be set.

Next, an analyzer UI screen 40 on which the parameters of the analyzer 4 can be set is shown in FIG.
As shown in FIG. 3, the analyzer UI screen 40 has a frequency characteristic display area 40a for displaying the frequency characteristic of the measuring object 3 with the horizontal axis representing the logarithmic scale frequency and the vertical axis representing the amplitude in decibels. is doing. When plotting the FFT result value on the graph in the frequency characteristic display area 40a, when a plurality of values correspond to one graph plot point, for example, the frequency at which the peak value is plotted among the plurality of values. The characteristics are displayed. The first setting unit 40b and the second setting unit 40c for setting the parameters of the generator 2 are provided, and the settings of the third setting unit 40d and the fourth setting unit 40e for setting the parameters of the analyzer 4 are provided. A column is provided. Details of the analyzer UI screen 40 are shown in FIG. 8, and each column will be described with reference to FIG. In the Gain column a in the Generator column of the first setting unit 40b, the unit of the amplitude of the measurement signal supplied to the measurement object 3 is set in dB. In the illustrated example, the amplitude value is set to 0.00 dB. In the From column b in the Frequency column, the start frequency when the frequency of the sine wave as the measurement signal is swept in steps is set, the end frequency is set in the To column c, and the frequency dividing step in the Step column d Set the number. For example, if the From column b is 10 Hz, the To column c is 22.05 kHz, and the Step column d is 1/24 Oct, the sine wave used as the measurement signal is divided into 10 octaves by 24 steps from 10 Hz to 22.05 kHz. The frequency is swept up in steps.

  Furthermore, in the Time column e in the Duration column of the second setting unit 40c, the duration of the measurement signal at each step when the frequency of the sine wave is swept in steps is set. In the illustrated example, it is set to 0.29 sec. In the silent time column f, a silent time between steps when the frequency of the sine wave is swept in steps is set. As shown in the figure, when Silent time is set to 1.00 sec, the signal is faded out to zero amplitude at each step, and after the silent time is set for Silent time (1 sec), the next frequency is set. Fade in the sine wave. When the Silent time is set to 0.00 sec, the frequency is changed stepwise without changing the amplitude. At this time, however, the phases are connected even when the frequency is switched. Thus, the parameters of the generator 2 can be set on the analyzer UI screen 40.

  In the third setting unit 40d, a time window used when performing FFT in the Type column g in the Analyzer column is selected. The time window can be selected from a rectangular window, Hanning window, Hamming window, Blackman window, Blackman-Harris window, and flat top window. In the illustrated case, the flat top window (FlatTop) is selected because the measurement signal is a periodic signal. In the Size column h, the window length of the time window that determines the frequency resolution can be set by the number of samples that can sample the measurement signal within the window length. In the illustrated example, the window length is set to 8192 samples. The fourth setting unit 40e sets the number of additions to be added synchronously in order to relatively reduce the noise component included in the signal by adding the FFT results under the same conditions in the Num column i. In the Type column j, a synchronous addition method is selected from normal and correlation. In the illustrated example, the number of additions is set to 10, and the synchronous addition method is set to normal.

By the way, the window length of the time window for determining the resolution of the frequency is assumed to be Ss / Fs, where Ts is the window length, Ss is the number of samples that can be sampled within the window length, and Fs is the sampling frequency. It is represented by For example, if Fs = 44.1 kHz and Ss = 8192, the window length Td is about 185.76 ms. In this case, when FFT is performed, Ss / 2 frequency bins arranged at equal intervals in the frequency band from 0 Hz to the Nyquist frequency Fn (= Fs / 2 = 22.05 kHz) of the sampling frequency are obtained. This frequency bin becomes a frequency component (spectrum) obtained when the measurement signal sampled by multiplying by the time window is FFTed. That is, the frequency resolution in FFT is
Fn / (Ss / 2) = 2 Fn / Ss = Fs / Ss
It becomes. For example, if Fs = 44.1 kHz and Ss = 8192, the frequency resolution is about 5.38 Hz. The end frequency when the frequency of the sine wave is swept stepwise is set to be equal to or lower than the Nyquist frequency Fn so as not to exceed the Nyquist frequency Fn.

Here, in the frequency characteristic measuring apparatus 1 shown in FIG. 1, when the measurement signal from the generator 2 is directly input to the analyzer 4 without passing through the measurement object 3, the frequency characteristic measured by the analyzer 4 is not completely flat. It started to shake slightly. Therefore, when this cause was examined, the difference between the frequency of the sine wave that was swept in a stepwise manner as the measurement signal and the frequency bin obtained when performing the FFT analysis was different depending on the step during the frequency sweep. I understood. Therefore, in order to eliminate fluctuations in the frequency characteristics as much as possible, as the frequency of the sine wave to be swept in steps, the nearest frequency among the frequency bins obtained by FFT analysis is set as the frequency to be generated in the step. The analyzer 4 instructs the generator 2 to acquire the frequency every time and generate the frequency in that step.
Further, the relationship between the frequency interval Fd for each step during frequency sweep and the sampling number Ss in the window length Td satisfying a predetermined frequency resolution is expressed as Fd ≧ Fs / Ss,
Ss ≧ Fs / Fd (1)
It becomes. The window length Td that satisfies the sampling number Ss of the equation (1) is set.

  Further, since the horizontal axis in the frequency characteristic display area 40a is a logarithmic scale frequency, if the frequency of the sine wave to be swept in steps is increased at equal intervals, one graph plot point as the frequency increases. The value for will increase. Therefore, the frequency of each step of the sine wave to be swept in steps is set to a logarithmic scale frequency, and the value for one graph plot point is reduced by coarsening the frequency resolution according to the size of the frequency interval Fd. You may make it make it. That is, if the frequency of each step of the sine wave that is swept in steps is a logarithmic scale, the frequency interval Fd in each step is different. Even in this case, the window length Td satisfying the sampling number Ss of the above equation (1) is set, but the window length Td is changed so that the window length Td becomes shorter (the sample number decreases) as the frequency interval Fd becomes larger. FFT is performed.

Next, FIG. 4 is a block diagram showing a configuration of a personal computer in which the frequency characteristic measuring apparatus 1 according to the embodiment of the present invention is realized.
In FIG. 4, a CPU (Central Processing Unit) 10 controls the overall operation of the personal computer and executes operation software such as a plug-in generator module and analyzer module program and a control program. A ROM (Read Only Memory) 11 stores operation software such as a control program executed by the CPU 10, and a RAM (Random Access Memory) 12 stores a work area of the CPU 10 and read scene data. An area is set. By making this ROM 11 a rewritable ROM such as a flash memory, the operation software can be rewritten, and the version of the operation software can be easily upgraded. Although not shown, a large-capacity storage device such as a hard disk device is provided, and application software such as DAW installed in the large-capacity storage device and generator module and analyzer module programs to be plugged in are stored.

  The detection circuit 14 detects an event of the operation element 13 by scanning an operation element 13 such as a keyboard or a mouse provided in the personal computer, and outputs an event output corresponding to the operation element 13 having the event. Yes. The operator 13 includes an operator for setting parameters such as the operator 30a provided on the user interface screen. The display circuit 16 includes a display 15 such as a liquid crystal display (LCD), and a user interface screen or the like is displayed on the display 15. Various operations can be performed using a GUI (Graphical User Interface) on the user interface screen. The communication interface (I / F) 18 is an interface for connecting an external device 17 such as an external effect, and the personal computer and the external device 17 are logically connected through this interface. These units are connected to a communication bus 19 and exchange data via the communication bus 19.

Next, FIG. 6 shows a flowchart of analysis processing executed in the frequency characteristic measuring apparatus 1 according to the present invention.
After setting the connection on the measurement device UI screen 1a and setting the parameters on the measurement target UI screen 30 and the analyzer UI screen 40, the analysis process is started when the frequency measurement is started by operating the frequency measurement start button. In step S10, the start frequency, the end frequency, the output level, and the frequency division step number when the frequency of the sine wave set on the analyzer UI screen 40 is swept in steps are acquired. Next, in step S11, the frequency resolution is calculated from the sampling frequency Fs and the sampling number Ss which is the window length of the time window set on the analyzer UI screen 40. Further, the frequency of each step that is swept in frequency is calculated for each step from the start frequency, end frequency, and number of division steps acquired in step S10, and the frequency of each step calculated among the frequencies in the frequency bin is the largest. The near frequency is determined as the frequency of the measurement signal supplied to the measurement object 3, and the determined frequency information of each step is stored in the register in step S12. In this case, the frequency of each step to be swept is calculated as a logarithmic scale frequency, and the frequency of the measurement signal that supplies the frequency closest to the calculated frequency of each step among the frequencies of the frequency bins to the measurement object 3 You may make it determine as a frequency.

  Next, a window length Td that satisfies the sampling number Ss of the above equation (1) is calculated for each step according to the frequency interval Fd between the steps obtained from the determined frequency of each step, and stored in the register in step S13. Saved. In this case, when the frequency of each step to be swept is a logarithmic scale frequency, the calculated window length Td is shortened because the frequency interval Fd is increased as the measurement frequency is increased. The number of samples to be sampled decreases. Next, in step S14, it is determined whether or not the frequency of all the steps stored in the register is supplied from the generator 2 to the measurement object 3 and measurement is performed by the analyzer 4. In this case, it is the first time. It is determined that the measurement has not been performed yet, and the process proceeds to step S15. In step S15, sound generation setting information including the frequency information of the sine wave of the first step stored in the register and the output level acquired in step S10 is acquired, and the sine wave to be generated in step S16 is acquired. A sound generation instruction command including frequency information and output level information is transmitted to the generator 2. Receiving the sound generation instruction command, the generator 2 outputs a measurement signal of a sine wave having the frequency of the instructed frequency information at the instructed output level and supplies it to the measurement object 3.

  The measurement signal output from the measurement object 3 is input to the analyzer 4, and the measurement signal input to the analyzer 4 is subjected to FFT analysis in step S17. The frequency bin and its amplitude are obtained by performing the FFT analysis, and drawing based on the obtained peak frequency bin and its amplitude value is performed in the frequency characteristic display area 40a of the analyzer UI screen 40 in step S18. When the process of step S18 is completed, the process returns to step S14, and the process of steps S14 to S18 is repeatedly performed, so that the FFT analysis and the drawing process of the measurement signal at the frequency of the sine wave of the second step are performed, and then When the FFT analysis and the drawing process of the measurement signal at the frequency of the sine wave of step 3 are sequentially performed, and the FFT analysis and the drawing process of the measurement signal at the frequency of the sine wave of the Nth step as the final step are finished, the analyzer The frequency characteristic of the measuring object 3 is displayed in the frequency characteristic display area 40a of the UI screen 40. And it is judged that all the frequencies were measured in step S14, and an analysis process is complete | finished. When plotting the FFT analysis result on the graph in the frequency characteristic display area 40a, if a plurality of values correspond to one graph plot point, the frequency at which the peak value of the plurality of values is plotted. The characteristics are displayed. FIG. 8 shows an example of the frequency characteristic of the measuring object 3 displayed in the frequency characteristic display area 40a of the analyzer UI screen 40 by executing this analysis process. In this case, it can be seen that the measurement object 3 is an equalizer effect, and has a frequency characteristic in which about 700 Hz is a peak of attenuation and attenuates by about 38 dB.

Next, FIG. 7 shows a sequence diagram showing a sequence of communication performed between the analyzer 4 and the generator 2 when the processing from step S14 to step S18 is repeatedly performed in the analysis processing.
When the processing from step S14 to step S18 is repeatedly performed in the analysis processing, the analyzer 4 first reads the frequency F1 Hz and the amplitude L1 dB of the sine wave of the first step from the register, and generates a sine wave output command including this information as a generator. Send to 2. Receiving this sine wave output command, the generator 2 generates a first step sine wave having a frequency of F1 Hz and an amplitude of L1 dB in step S20 and outputs the sine wave to the measuring object 3. The sine wave of the first step is generated by fading in so that the amplitude gradually increases. Then, the analyzer 4 is notified that the first step sine wave instructed by the sine wave output command has been generated and output. Receiving the output notification in the first step, the analyzer 4 performs an FFT analysis of the measurement signal output from the measurement object 3, and performs drawing based on the obtained peak frequency bin and its amplitude value in step S21.

  Next, the analyzer 4 reads out the frequency F2 Hz and the amplitude L2 dB of the sine wave in the second step from the register, and sends a sine wave output command including this information to the generator 2. Receiving this sine wave output command, the generator 2 generates a sine wave of the second step having a frequency of F2 Hz and an amplitude of L2 dB in step S22 and outputs the sine wave to the measurement object 3. Then, the analyzer 4 is notified that the sine wave of the second step designated by the sine wave output command has been generated and output. Receiving the output notification in the second step, the analyzer 4 performs an FFT analysis of the measurement signal output from the measurement object 3, and performs drawing based on the obtained peak frequency bin and its amplitude value in step S23.

  A similar sequence is performed for each step of frequency sweeping the sine wave. In the final step, the analyzer 4 reads the frequency FNHz and amplitude LNdB of the sine wave of the final step from the register, and outputs a sine wave output command including this information. Send to generator 2. Receiving this sine wave output command, the generator 2 generates a sine wave of the final step having a frequency of FN Hz and an amplitude of LN dB in step S24 and outputs the sine wave to the measuring object 3. Then, the analyzer 4 is notified that the sine wave of the final step designated by the sine wave output command has been generated and output. Receiving the output notification of the final step, the analyzer 4 performs an FFT analysis of the measurement signal output from the measurement target 3, and performs drawing based on the obtained peak frequency bin and its amplitude value in step S25. Next, a sine wave output stop command for stopping the generation of the sine wave is sent to the generator 2. Receiving this sine wave output stop command, the generator 2 gradually decreases the amplitude of the sine wave and fades out to stop the sine wave. As a result, the frequency characteristic of the measurement object 3 as shown in FIG. 8 is displayed in the frequency characteristic display area 40 a of the analyzer UI screen 40.

Next, FIG. 9 to FIG. 11 show measurement signals obtained by stepping the frequency sweep of the sine wave generated by the generator 2.
The measurement signal shown in FIG. 9 is a measurement signal when a significant Silent time is set in the Silent time column f in the second setting unit 40c of the analyzer UI screen 40 shown in FIG. In this case, in response to the first step sine wave output command received from the analyzer 4, the generator 2 generates a first step sine wave having a frequency of F1 Hz and an amplitude of L1 dB, and fades in and outputs the sine wave. The duration of this sine wave after fade-in is the time set in the Time column e in the Duration column. When this time elapses, the sine wave fades out and stops. When Silent time, which is the silent time, has passed, the generator 2 generates a second step sine wave having a frequency of F2 Hz and an amplitude of L2 dB according to the second step sine wave output command received from the analyzer 4 and fades. Output. The duration of this sine wave after fade-in is the time set in the Time column e in the Duration column. When this time elapses, the sine wave fades out and stops. Thereafter, the same operation is repeated, and a sine wave having a final step frequency of FN Hz and an amplitude of LN dB is generated, faded in and output, and after the time set in the Time column e has elapsed, the sine wave is faded out. Stopped.

Further, the measurement signal shown in FIG. 10 is a measurement signal when the time is not set in the Silent time column f in the second setting unit 40c of the analyzer UI screen 40 shown in FIG. It is said that. In this case, in response to the first step sine wave output command received from the analyzer 4, the generator 2 generates a first step sine wave having a frequency of F1 Hz and an amplitude of L1 dB, and fades in and outputs the sine wave. The duration of this sine wave after fade-in is the time set in the Time column e in the Duration column. When this time elapses, the generator 2 generates a second-step sine wave having a frequency of F2 Hz and an amplitude of L2 dB according to the second-step sine wave output command received from the analyzer 4, and outputs the sine wave. However, the phase is connected even when the frequency is switched. Thereafter, the same operation is repeated, and a sine wave having a frequency of FN Hz and an amplitude of LN dB is generated and output after fading in, but after the time set in the Time column e has elapsed, the sine wave Is faded out and stopped.
Delay is a delay time for correcting the delay of the measurement object 3, and the analyzer 4 starts sampling the measurement signal after the set delay time.

  FIG. 11 shows an aspect in which the analyzer 4 performs FFT analysis on the measurement signal output from the measurement object 3 when the measurement signal shown in FIG. 10 is obtained. When analyzing the measurement signal in the second step, FIG. When the measurement is started at time t0 after the set Start time has elapsed after the frequency is switched to the frequency F2 Hz, the portion of the window length in the measurement signal is FFTed, and the amplitude value of the peak frequency in the FFT result is Analyzed. This FFT analysis is performed in the Duration period as many times as set in the num column i of the time t1, time t2, time t3,... And the fourth setting unit 40e, and the FFT analysis results are synchronously added. Such FFT analysis is performed in all steps including the second step.

In the present invention described above, the application software is DAW. However, the present invention is not limited to this and can be applied to application software that handles audio signals. In this case, the generator and analyzer programs may be plugged into the application software.
In addition, the measurement signal generated from the generator is supplied to the measurement target and the analyzer, and the transfer function of the measurement target is measured by using the measurement signal output from the measurement target in the analyzer and the measurement signal directly supplied from the generator. You may make it do.

It is a user interface (UI) screen which shows the structure of the outline | summary of the frequency characteristic measuring apparatus concerning the Example of this invention. It is an example of the measuring object UI screen which can perform the parameter setting of the measuring object in the frequency characteristic measuring apparatus concerning the Example of this invention. It is the analyzer UI screen which can perform the parameter setting of the analyzer in the frequency characteristic measuring apparatus concerning the Example of this invention. It is a block diagram which shows the structure of the personal computer by which the frequency characteristic measuring apparatus concerning the Example of this invention is implement | achieved. It is a figure which shows the graph of the measurement result of the frequency characteristic by which FFT analysis was carried out by the sine wave frequency-swept by the generator which the generator in the frequency characteristic measuring apparatus concerning the Example of this invention generated in the step shape. It is a flowchart of the analysis process performed in the frequency characteristic measuring apparatus concerning this invention. It is a sequence diagram which shows the sequence of the communication performed between an analyzer and a generator in the frequency characteristic measuring apparatus concerning the Example of this invention. It is a figure which shows the detail of the analyzer UI screen in the frequency characteristic measuring apparatus concerning the Example of this invention. It is a figure which shows the measurement signal at the time of setting silence time in the frequency characteristic measuring apparatus concerning the Example of this invention. It is a figure which shows the measurement signal when not setting silence time in the frequency characteristic measuring apparatus concerning the Example of this invention. It is a figure which shows the aspect which FFT-analyzes the measurement signal when it is set as the measurement signal shown in FIG. 10 in the frequency characteristic measuring apparatus concerning the Example of this invention. It is a figure which shows the outline | summary of a structure of the frequency characteristic measuring apparatus realizable on the personal computer in which the conventional DAW was installed. It is an analyzer UI screen in the conventional frequency characteristic measuring apparatus.

Explanation of symbols

1 Frequency characteristic measuring device, 1a measuring device UI screen, 2 generator, 2a output port, 2b command input port, 3 measurement object, 3a input port, 3b output port, 4 analyzer, 4a input port, 4b command output port, 10 CPU 11 ROM, 12 RAM, 13 operator, 14 detection circuit, 15 display, 16 display circuit, 17 external device, 18 communication I / F, 19 communication bus, 30 measurement target UI screen, 30a operator, 40 analyzer UI Screen, 40a frequency characteristic display area, 40b first setting unit, 40c second setting unit, 40d third setting unit, 40e fourth setting unit, 101 frequency characteristic measuring device, 102 generator, 103 measuring object, 104 analyzer, 140 analyzer UI screen, 140a Frequency characteristics display area 140b first setting unit, 140c second setting unit

Claims (4)

A frequency characteristic measuring device in which a generator module capable of generating a sine wave and an analyzer module capable of measuring a frequency characteristic are plugged into an application program installed in a computer,
Each time a command to generate a sine wave that is swept in steps at predetermined frequency intervals is received from the analyzer module, a sine wave of the specified frequency is generated every time a frequency to be generated is specified by the command. The generator module that supplies the measurement target module as a measurement signal;
The command information is supplied to the generator module, and the spectrum information of the measurement signal output from the module to be measured with respect to the sine wave for each step generated by the generator module in a stepwise manner is obtained. By analyzing, the analyzer module that measures and displays the frequency characteristics of the module to be measured, and
A frequency characteristic measuring apparatus comprising:   The frequency characteristic measuring apparatus according to claim 1, wherein the module to be measured is a signal processing module capable of executing signal processing included in an application program. In the analyzer module, the measurement signal output from the module to be measured is sampled at a predetermined sampling rate and spectrum information of the measurement signal multiplied by a time window having a predetermined window length is analyzed. And
In the command, the frequency component obtained when analyzing the spectrum information of the measurement signal and the frequency closest to the frequency to be generated in the step among the plurality of frequency bins determined by the sampling rate and the window length The frequency characteristic measuring apparatus according to claim 1, wherein The generator module is instructed by the command to generate a sine wave that is swept in steps at logarithmic scale frequency intervals,
In the analyzer module, the window length of the time window multiplied by the measurement signal output from the module to be measured is set to a predetermined frequency resolution corresponding to the frequency interval between steps in the frequency swept sine wave. 4. The frequency characteristic measuring apparatus according to claim 3, wherein the window length to be satisfied is changed for each step.

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