JPH083506B2 - Signal remover - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a signal removing device that can be used, for example, when measuring a distortion factor of an amplifier, a filter, a signal transmission path, or the like.

Background of the Invention A spectrum analyzer is available as a signal frequency analysis means. According to the spectrum analyzer, it is possible to measure the ratio of the high frequency component to the fundamental wave of the signal.

In addition, by using a two-input type spectrum analyzer, it is possible to compare the excitation given to the subject (there are electrical excitation and mechanical excitation) and its response output,
By looking at the correlation between the excitation signal and the response output signal, the response characteristic of the subject, that is, the transfer function and the like can be known.

At present, a digital spectrum analyzer equipped with an FFT (Fast Fourier Transform) and various arithmetic processing functions has been developed and put into practical use due to the spread of microcomputers. According to this digital spectrum analyzer, the frequency of the signal under measurement is analyzed by FFT to calculate the ratio of each harmonic to the fundamental wave, that is, each distortion factor,
Alternatively, the excitation signal and the response output signal given to the subject are frequency-analyzed by FFT, and the transfer function of the subject can be calculated from the amplitude characteristic and the amount of phase rotation of the response output signal. .

On the other hand, a signal generator is an element necessary for making these various measurements. A signal generator is generally configured by including a ROM that stores various waveform data and a reading means for the same, and has a desired waveform and frequency by reading the desired waveform data into the ROM at a desired speed. Output a signal.

That is, as shown in FIG. 7, a signal 2 to which conditions such as desired frequency, waveform, and amplitude are given is output from the signal generator 1, and the signal 2 is given to the subject 3. The two-input spectrum analyzer 4 takes in the signal 2 given to the subject 3 and the response output signal 5 output from the subject 3, frequency-analyzes both signals, and displays the frequency spectrum on the display unit 4A. In addition to displaying, the frequency analysis results of both are tested, for example, from the amplitude ratio of the fundamental wave of the excitation signal 2 to the fundamental wave included in the response output signal 5, the phase difference, and the fundamental ratio of the response output and the amplitude ratio of each harmonic. The transfer function and distortion rate of the body 3 can be obtained.

"Problems to be Solved by the Invention" By way of example, in order to measure the distortion rate generated in the test object 3, a sine wave signal with a distortion rate as small as possible is used as an excitation signal, and this sine wave signal is used as the test object 3 The distortion ratio is calculated by calculating the ratio of the fundamental wave component generated at the output side to the higher harmonic wave.

Therefore, the test subject 3 is an audio amplifier, a speaker, a video amplifier, etc., and these test subjects are products whose distortion rate is preferably as small as possible. As described above, the level of the harmonic component output from the subject 3 having a small distortion rate is extremely small, whereas the level of the fundamental wave is large, whereas it is difficult to measure the level of the harmonic component with high accuracy. .

Therefore, it is conceivable to insert a high-pass filter on the output side of the subject 3 and remove the fundamental wave by this high-pass filter. However, if a filter or the like is inserted in series with the subject 3, the two-input type spectrum analyzer 4 will be used. The amplitude characteristic and the phase characteristic of the two input signals are obtained by adding the amplitude characteristic and the phase characteristic of the filter.
It has the drawback that it cannot measure the true strain rate of.

An object of the present invention is to provide a signal removing device that can output a reverse phase signal of a fundamental wave in a response output signal output from a subject and remove a fundamental wave component included in the response output signal. is there.

"Means for Solving Problems" In the first invention of this application, A. a signal generator for giving a signal to a subject, and B. a signal given to the subject from this signal generator and output from the subject Two-input measuring means for measuring in advance the phase difference between the fundamental frequencies of the signals to be measured and their respective amplitude values, and C. The waveform data written in the waveform memory by the supply of the clock pulse is read, and the digital-analog A waveform reading means for generating an analog signal by a converter, and a fundamental wave of a signal output from the subject by changing the reading speed of the waveform memory to measure the frequency of the analog signal using the measurement result of the measuring means. Frequency setting means for setting a frequency that matches the frequency of the above, and the read start address of the waveform storage device is shifted to determine the phase of the analog signal using the measurement result of the measuring means. Phase setting means for setting the phase that matches the phase of the fundamental wave of the signal output from the subject, and provided in the transmission path of the analog signal, the amplitude of the analog signal using the measurement result of the measuring means Amplitude setting means for setting an amplitude that matches the amplitude of the fundamental wave of the signal output from the subject, and a removal signal generating means configured by, D. the signal output from the removal signal generating means and the subject The signal removing device is configured by adding means for adding the output signal and removing the fundamental wave contained in the output signal of the subject.

In the second invention of this application, A. a two-input type measuring means for measuring the phase difference between the frequencies of the fundamental waves of the signal given to the subject and the signal output from the subject, and the respective amplitude values, B. The removal signal generation condition memory that stores the removal signal generation condition consisting of the frequency, the amplitude value, and the phase difference of the fundamental wave measured by the two-input type measuring means, and C. The conditions read out from the removal signal generation condition storage device. D. signal removing means having frequency setting means, phase setting means, and amplitude setting means to be set, and D. the signal output from the signal removing means and the output signal of the subject are added, and the output of the subject is output. The signal removing device is configured by adding means for removing the fundamental wave included in the signal.

According to the configuration of the first invention of this application, a signal is given to the subject from the signal generator, and an input signal given to the subject and a response output signal outputted from the subject are given to the measuring means.

The measuring means obtains the phase difference between the frequencies of the fundamental waves of the input signal and the output signal given to the subject and the respective amplitude values from the input signal given to the subject and the response output signal.

The frequency, amplitude value and phase difference obtained by the measuring means are set in the removal signal generating means. In other words, the removal signal generation means has the same frequency and the same amplitude as the fundamental wave included in the response output signal output from the subject by setting the frequency, the amplitude value and the phase difference in the setting means, which is the exact opposite. Generates a phase remove signal.

This removing signal is given to the adding means provided on the output side of the subject, and an unnecessary signal included in the response output signal output from the subject, that is, the fundamental wave is removed in the case of distortion rate measurement,
Only the harmonic component from which the fundamental wave has been removed can be given to the distortion factor measuring means.

According to the second invention of this application, since the measurement result of the two-input type measuring means is captured and stored in the removal signal generation condition storage means, the generation condition of the removal signal generation means can be automatically set. As a result, the removal signal can be automatically generated.

As described above, according to the first invention and the second invention of the present application, since the fundamental wave component having a large level can be removed from the response output signal output from the subject, the measuring unit uses the harmonics having a small level. Only the wave component can be processed as the measurement target.

That is, since the signal with a large level is removed and the harmonic signal with a small level is frequency-analyzed to measure the level, even a signal with a small level can be measured with a sufficiently good SN ratio.

Therefore, by using the signal removing device of the present invention, the distortion rate can be accurately measured even when the amplitude ratio of the fundamental wave and the harmonic wave is large.

In addition, as another measurement method, so-called cross-modulation distortion can be measured by inputting two signals having frequencies close to each other to the test object and determining the ratio between the harmonic component and the fundamental wave generated at the output side. .

Further, according to the second aspect of the invention, the removal signal generating means automatically generates the removal signal when the measurement value of the measuring means is taken in, so that the distortion rate and the like can be measured in a short time.

"Embodiment" FIG. 1 shows an embodiment of the first and second inventions of the application. In the figure, 100 is a signal generator, 3 is a subject, 200 is a removal signal generating means, 300 is an adding means, and 400 is a measuring means.

The main configuration of the signal generator 100 is a fixed waveform generating section 101 that outputs prestored waveform data, and an arbitrary waveform generating section 102 that outputs by writing arbitrary waveform data from the outside and reading the waveform data. , These fixed waveform generator 1
01 or a low-pass filter 103 that filters the signal output from the arbitrary waveform generation unit 102, an amplifier 104 that amplifies the signal output from the low-pass filter 103 to an arbitrary level,
Further, it is constituted by a variable attenuator 105 which attenuates a signal to a desired level as needed. Reference numeral 106 denotes a DC offset generating means for superimposing a DC voltage on the output signal as required. The offset voltage output from the DC offset generating means 106 is superimposed on the signal by the adder circuit 107.

The fixed waveform generator 101 is a waveform storage unit composed of a ROM.
101A and a waveform reading means for supplying an address signal to the waveform memory 101A and for defining an initial value of the signal generated by setting an initial value of the address signal and a reading speed of the waveform memory.
101B, a variable frequency divider 101C, a latch circuit 101D that latches the waveform data read from the waveform storage unit 101A, and DA conversion means 101E that sequentially DA-converts the waveform data latched by the latch circuit 101D. can do.

Waveform memory 101A can be configured by ROM, R
The inside of the OM is divided into a plurality of storage areas, various waveform data such as sine waves and triangular waves are stored in each storage area, and waveforms are stored via the microcomputer 111 by designating a desired area from the key board 108. Arbitrary waveform data stored in the device 101A can be read.

On the other hand, the reading means 101B includes, for example, an accumulator 121, a center frequency setting device 122, and a phase setting device as shown in FIG.
It can be composed of 123 and.

Variable frequency divider 1 for clock terminal CK of accumulator 121
Give clock pulse from 01C. Whenever a clock pulse is given, the accumulator 121 is the center frequency setter 1
The numerical value set to 22 is cumulatively added, and the cumulative added value is given to the waveform memory 101A as an address signal. Therefore, when the numerical value "1" is set in the center frequency setting unit 122, the address signal output from the accumulator 121 is incremented by 1 every time the clock pulse is supplied, and all the addresses of the storage unit 101A are accessed to specify the specified storage. The waveform data stored in the area is read. The memory 101A stores the desired waveform data of 1
A cycle is stored, and a waveform of a constant frequency can be generated by repeatedly reading the waveform data for one cycle at a constant speed.

When "2" is set in the center frequency setting unit 122, the address signal output from the accumulator 121 changes by +2, and the address signal is written in the storage unit 121 in half the time when the address changes by "+1". The stored waveform data is read.

That is, the frequency f of the waveform read from the storage unit 101A changes by n · f according to the numerical value n set in the center frequency setting unit 122.

On the other hand, the phase setter 123 has a function of giving an initial value to the accumulator 121 and shifting the read address of the waveform data to an arbitrary position. Therefore, the accumulator 121 starts reading from the address by setting the address of the position where the waveform data is advanced by 90 °, for example, in the phase setter 123, and
Read the waveform data with the phase advanced by 0 °.

In this way, the structure is such that the frequency and phase of the waveform data read from the memory device 101A can be set freely. The variable frequency divider 101C significantly changes the reading speed of the memory 101A,
It is used as a range switch that greatly changes the frequency of a signal.

Arbitrary waveform generating section 102 is the same as fixed waveform generating section 101 except for the fact that a RAM that can be written and read as needed in memory device 102A is used. The arbitrary waveform generator 102 is used to freely write desired waveform data from the outside, read the waveform data, and generate an arbitrary waveform.

The clock pulse given to the fixed waveform generating section 101 and the arbitrary waveform generating section 102 is the basis of the acquisition clock (sampling clock) of the signals of the input terminals A and B of the measuring means 400. It is given and supplied to the frequency conversion means 125. The frequency conversion means 125 is composed of a phase-locked loop, so-called PLL, which converts the input clock signal into a clock signal having a frequency higher than this, for example, four times the frequency, and the frequency-converted clock signal. Is supplied to the fixed waveform generator 101 and the arbitrary waveform generator 102 through the frequency divider 126.

The waveform data read from the respective waveform storages 101A or 102A in the fixed waveform generation unit 101 and the arbitrary waveform generation unit 102 is latched in the latch circuits 101D and 102D, for example, at every rising edge of the clock pulse, and the latch output is the DA converter. 101E
And 102E and converted into an analog signal and applied to the low pass filter 103. The analog signal that has passed through the low-pass filter 103 is amplified or attenuated to a desired level by the amplifier 104 or the variable attenuator 105 and output to the output terminal 127.

The analog signal output to output terminal 127 is a switch SW.
-S is supplied to the contact 3 of the subject 3 and the switch SW-F.

The switch SW-F has contacts 1 and 2, and connects the contact 1 to the output side of the subject 3 and the contact 2 to the input side of the subject 3. The switching contact of the switch SW-F is connected to one terminal A of the measuring means 400, and the contact 1 is connected to the other input terminal B of the measuring means 400 through the adding means 300.

A switch SW− is provided at the other input terminal of the adding means 300.
The output terminal 128 of the removal signal generating means 200 is connected through N.

The signal removal means 200 is a signal generation means for the key board 108.
Except for the point that it is shared with 100 and is also coupled to the measuring means 400 through the interface 500, and that the condition storage section 129 for storing the generation condition of the removal signal is provided, it is completely different from the signal generator 100. It has the same structure.

The condition storage unit 129 is used to store the condition of a signal reproduced from a reproducing device such as a compact disc described later. As the storage unit 129, a part of RAM (not shown in the figure) built in the microcomputer 131 can be used. The condition storage unit 129 has a plurality of areas A, B, ... N, and stores a plurality of removal signal generation conditions in the plurality of areas A to N, respectively.

Reference numeral 132 represents a clock counter. The clock counter 132 starts counting when a start signal ST is given, and every time the count value matches the number of clocks stored in the condition storage unit 129, the count value is changed from the area A in the condition storage unit 129.
B, C, ... Are read sequentially, the removal signal generation conditions written therein are read by the microcomputer 131, and the removal signal generation conditions are sequentially switched.

“Explanation of Operation of Example” A case of measuring the strain rate of the subject 3 in the above-described configuration will be described. This measurement operation is executed by the configuration of the first invention of this application.

When measuring the strain rate of the subject 3, switch SW-
C to contact 1, switch SW-S to contact 1, switch SW
Set -F to contact 2 and switch SW-N to off. In this setting state, the fixed waveform generator 101 of the signal generator 100 generates a sine wave signal of frequency F through the interface 600, and the sine wave signal is given to the subject 3.

At the same time, the input signal of the subject 3 is input to the input terminal A of the measuring means 400, and the subject 3 is input to the input terminal B of the measuring means 400.
Input the output signal of.

The measuring means 400 uses a two-input type spectrum analyzer, and obtains the transfer function of the subject 3 from the correlation between the input signal and the output signal by taking in the input signal and the output signal of the subject 3. The calculation for obtaining this transfer function is performed by the microcomputer built in the measuring means 400.

From the transfer function calculated by the measuring means 400, the amplitude value A _p of the fundamental wave component output by the subject 3 and the phase rotation amount θ are obtained.

The amplitude value A _p of the fundamental wave component, the phase rotation amount θ, and the frequency F value obtained by the measuring means 400 control the removal signal generator 200 through the interface 500.
Be taken into. The microcomputer 131 sets a gain or an attenuation amount for generating a removal signal having an amplitude value A _p in the amplifier 104 and the variable attenuator 105 of the removal signal generator 200, and a fixed waveform generation unit of the removal signal generator 200. 101 waveform reading means 10
A phase rotation amount θ and a frequency value F are set in 1B, and a removal signal having a phase delayed by the phase angle θ at the same frequency as the signal output from the first signal generator 100 is generated.

In this way, by turning on the switch SW-N while the removal signal generator 200 outputs the removal signal, the addition signal is given to the adding means 300 and the fundamental wave component is removed from the output signal of the subject 3. Measuring means 400 for harmonic components only
Can be input to the input terminal B of.

Since only the harmonic wave from which the fundamental wave component having a large level is removed is input to the measuring means 400, the harmonic wave level can be accurately measured.

In other words, as shown in FIG. 3, when the frequency analysis is performed by the spectrum analyzer with the fundamental wave F ₀ included, there is a limit to the dynamic range of the frequency analyzer, so the harmonic wave F whose level is smaller than that of the fundamental wave F _{0. 1} , F ₂ , F ₃ … is leaked into the noise NS and its level cannot be measured accurately.

On the other hand, when the fundamental wave F ₀ is removed, the harmonics F ₁ , F ₂ , F _3, ... Can be sufficiently expanded and measured within the dynamic range of the frequency analyzer as shown in FIG. As a result, the level of each harmonic F ₁ , F ₂ , F _3, ... Can be measured with high accuracy without being influenced by the noise component NS or the like.

Therefore, the switch SW-F is switched to the contact 1 and the signal output from the subject 3 is applied to the input terminal A of the measuring means 400 to measure the level of the fundamental wave F ₀ of the signal in the channel on the input terminal A side. Thus, the strain rate of the subject 3 can be measured accurately.

On the other hand, according to the configuration of the present invention, cross modulation distortion can also be measured. That is, the fixed waveform generator 101 and the arbitrary waveform generator 102 of the signal generator 100 generate two sine wave signals F ₀₁ and F ₀₂ (FIG. 5A) whose frequencies are close to each other, and the two sine wave signals are generated. Assuming that sideband wave signals F ₁₁ , F ₁₂ and F ₂₁ , F ₂₂ are generated on the output side of the subject 3 as shown in FIG. 5B when the signal is given to the subject 3, the fundamental wave F ₀₁ or By obtaining the ratio of the level of F ₀₂ and each sideband signal F ₁₁ , F ₁₂ and F ₂₁ , F ₂₂ , the cross modulation distortion of the subject 3 can be measured.

Even in such a case, according to the present invention, the removal signal generator 200
Has a fixed waveform generator 101 and an arbitrary waveform generator 102, it is possible to generate a removal signal for canceling the fundamental waves F ₀₁ and F ₀₂ . Therefore, the levels of the sideband signals F ₁₁ , F ₁₂ and F ₂₁ , F ₂₂ can be accurately measured with the fundamental waves F ₀₁ and F ₀₂ removed, and intermodulation distortion can also be accurately measured.

On the other hand, in the second invention of this application, the removal signal generation condition storage unit 12
Since 9 is provided, distortion of a signal output from a recording / reproducing device such as a compact disc or a VTR can be measured. The measuring method will be described below.

A test subject 3'is connected to the input terminal 133 shown in FIG. 1, and a sinusoidal reproduction signal _Sc is input from the test subject 3 '.

The switch SW-S contacts the contact 2. Therefore, the signal generator 100 is controlled in the idle state. The above-mentioned part of the subject 3 is short-circuited, and the adding means 300
The reproduction signal S _c is directly supplied to.

The switches SW-S and SW-F are brought into contact with the contact 2, and in that state the reproduction signal from the subject 3'is input terminal A of the measuring means 400.
To enter. The measuring means 400 measures the frequency F, the amplitude value A, and the phase angle θ of the signal output from the subject 3 '.
The phase angle θ is the phase angle of the reproduction signal corresponding to the number of clock pulses P _c oscillated by the subject 3 ′ and output together with the reproduction signal S _c . The clock pulse P _c output from the subject 3'is applied to the terminal 134 and is applied as a clock pulse to the expulsion signal generator 200 through the switch SW-C.

In other words, the test object 3'records a signal and a synchronizing signal whose frequencies are sequentially changed in the used frequency band in advance,
This shall be reproduced. Taking a compact disc as an example, as shown in FIG. 6, the recording medium 135 has 4Hz, 8Hz, 17Hz,
The signals S _c1 , S _c2 , S _c3 , S _c4, ... Of 31 Hz, 61 Hz, 127 Hz, 251 Hz ... Are recorded, and at the same time, the synchronization signal P _s is recorded.

The signals S _c1 , S _c2 , S _c3 , S _c4, ... And the synchronization signal P _s are reproduced at the same time, and the signals S _c1 , S _c2 , S _c3, ... _Are given to one input terminal A of the measuring means 400, and synchronized with them. The signal P _s is supplied to the reference clock generator provided in the compact disc reproducing device 3 ', and the reference clock generator is synchronized. The clock pulse P _c synchronized with the sync signal reproduced in this manner is measured.
It is given to the external synchronizing terminal C of 400, and the signals S _c1 , S _c2 ... _Are sequentially AD-converted and _fetched in synchronization with the clock pulse P _c .

The frequency F of the signals S _c1 , S _c2 ...
Then, the amplitude value A and the phase θ with respect to the clock pulse P _c are measured in advance.

The measured value is transferred to the microcomputer 131 separately for each of the signals S _c1 , S _c2 , S _c3 ... And recorded in the condition storage unit 129 of the microcomputer 131.

The condition storage unit 129 also records the number of clocks K ₁ , K ₂ , K ₃ , ... At the joints of the signals S _c1 , S _c2 , S _c3 . The number of clocks K ₁ , K ₂ , K ₃ , ... Can be known by counting the number of clock pulses P _c given to the external synchronization input terminal C of the measuring means 40. The counter 132 can be used for this purpose. When the measuring means 400 detects that the frequency F of the reproduction signal S _c has changed while the counter 132 is counting the clock pulses P _c reproduced from the subject 3 ′, the count value of the counter 132 is calculated at that time. The storage area A of the condition storage unit 129 is read by the microcomputer 131 and, for example, the joint position of the signals S _c1 and S _c2 is set as the clock number K _1.
To record. Thus the seam between the signals S _c2 and S _c3 ,
The position of the seam between S _c3 and S _c4 is the number of sequential clock pulses.
.. N are sequentially recorded in the storage areas B, C, ... N of the condition storage unit 129 as K ₂ , K ₃ .

Next, the recording medium is returned to the initial state, and the signals S _c1 , S _c2 , S _c3 ...
To play again. In this case turns on the switch SW-N, the dividing signal generated by dividing the signal generator 200 is supplied to the addition means 300 to remove the fundamental wave component from the reproduced signal S _c.

That is, while the signal S _c1 is being reproduced, the microcomputer 131 reads the condition stored in the area A of the condition storage means 129, sets the condition in each of the frequency setting means, the amplitude setting means, and the phase setting means and reproduces it. The signal S _c1 having the same frequency and the same amplitude, and having a phase opposite to that of the signal S _c1 , is generated, and the signal is supplied to the adding means 300 to reproduce the signal S _c1.
The fundamental wave is removed and the signal from which the fundamental wave is removed is measured 40
Input to 0 input terminal B.

Therefore, the harmonic component of the signal S _c1 reproduced from the subject 3'on the B channel side of the measuring means 400 is frequency-analyzed and each level of each harmonic, that is, each level of the second harmonic and the third harmonic is indicated in each part. Can be measured.

The reproduction signal S _c1 is directly supplied to the input terminal A of the measuring means 400 through the switch SW-F. Therefore, the measuring unit 400 can separately measure the distortion rate determined by the ratio of the fundamental wave and the second harmonic, the distortion rate determined by the ratio of the fundamental wave and the third harmonic, and so on.

When the count value of the counter 132 reaches the number of clocks K ₁ corresponding to the joint position of the signals S _c1 and S _c2 , the microcomputer
Reference numeral 131 indicates a removal signal generation condition for the signal S _c2 stored in the storage area B of the condition storage unit 129, sets the generation condition in each setting section, and generates a removal signal for removing the fundamental wave of the signal S _c2. To do.

In this way, the signals S _c1 , S reproduced from the subject 3 ′ are
Each time _c2 , S _c3 ... Is reproduced, the removal signal generation condition is changed to generate a removal signal for removing the fundamental wave of each signal S _c1 , S _c2 , S _c3 . It is possible to supply to the input terminal B only the harmonic component with the fundamental wave removed.

Therefore, the measuring means 400 can measure each level in a state where the harmonics included in each of the signals S _c1 , S _c2 , S _c3 ... _Are sufficiently expanded within the range of the dynamic range, so that the level of the harmonic can be accurately measured. . As a result, it is possible to accurately measure the distortion rate of the signal reproduced from the subject 3 '.

[Advantageous Effects of the Invention] As described above, according to the signal removing apparatus of the present invention, the two signal generators 100 and 200 which operate by the same clock pulse are provided, while the excitation signal is applied to the subject 3.
The other generator 200 generates a removal signal to remove the fundamental wave output from the subject 3, and the removal signal is added by adding means.
Since the 300 has a structure that removes the fundamental wave in addition to the signal output from the subject, the signals output from the two signal generators 100 and 200 are synchronized, and the initial setting state is kept stable. Be drunk Therefore, since the state in which the fundamental wave is removed can be stably maintained, the residual component of the fundamental wave does not occur, and also in this respect, highly accurate measurement can be performed.

Further, since the condition storage unit 129 for storing the condition for generating the removal signal is provided in the removal signal generator 200, the fundamental wave of the signal given from the outside can be removed with high accuracy. As a result, the distortion of the signal reproduced from a reproducing device such as a compact disc or a VTR can be measured by changing the frequency.

Further, according to the present invention, the fundamental wave is removed and only the harmonic component is given to the measuring means 400, and only the harmonic component is subjected to frequency analysis to measure its frequency and level. It is possible to measure the level with high accuracy even for higher harmonics. Therefore, at this point, the strain rate can be measured with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram for explaining a reading means of the embodiment shown in FIG. 1, and FIG. 3 is a spectrum of a response output signal of a subject. 4 is a graph showing an example, FIG. 4 is a graph showing a state in which the fundamental wave in the spectrum shown in FIG. 3 is removed,
FIG. A is a graph showing an example of an excitation signal for measuring intermodulation distortion, FIG. 5B is a graph for explaining a method for measuring intermodulation distortion, and FIG. 6 is distortion of a subject that generates a signal. FIG. 7 is a front view for explaining a recording state of a signal recorded on a recording medium used for measurement, and FIG. 7 is a connection diagram for explaining a conventional technique. 3, 3 ′: subject, 100: signal generator, 101: fixed waveform generator, 102: arbitrary waveform generator, 101A: storage device, 101B: waveform reading means, 200: removal signal generating means, 300: adding means , 400: Measuring means, 500: Interface.

Claims (2)

[Claims] 1. A signal generator for giving a signal to a subject, and B. a frequency of a fundamental wave of a signal given to the subject from this signal generator and a signal output from the subject, a phase difference between them, and Two-input type measuring means for measuring each amplitude value in advance, and C. Waveform reading means for reading the waveform data written in the waveform memory by supplying the clock pulse and generating an analog signal by the digital-analog converter. A frequency setting means for changing the reading speed of the waveform memory and setting the frequency of the analog signal to a frequency that matches the frequency of the fundamental wave of the signal output from the subject using the measurement result of the measuring means. And the phase of the analog signal by shifting the read start address of the waveform memory and the phase of the fundamental wave of the signal output from the subject using the measurement result of the measuring means. The phase setting means for setting the phase to be adjusted, and the amplitude of the fundamental wave of the signal output from the subject by using the measurement result of the measurement means of the analog signal provided in the transmission path of the analog signal. The signal output from the removing signal generating means configured by the amplitude setting means for setting the amplitude matching with D. and the output signal of the subject are added and included in the output signal of the subject. A signal removing device comprising: an adding unit that removes the fundamental wave that is generated. 2. A. two-input type measuring means for measuring the frequency of the fundamental wave of the signal given to the subject and the signal output from the subject, the mutual phase difference and the respective amplitude values, and B. these two inputs. A signal-removal condition generation memory that stores the signal-removal signal generation conditions that consist of the frequency, phase difference, and amplitude value of the fundamental wave measured by the shape measurement means; A removal signal generating means having a frequency setting means, a phase setting means and an amplitude setting means, and D. The signal output from this removal signal generating means and the output signal of the subject are added to obtain the output signal of the subject. A signal removing device comprising an adding means for removing the fundamental wave included therein.