JP3112214B2 - Noise audible immunity evaluation tester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a common mode test signal containing a high frequency component to a line such as a communication line or a power line connected to a device under test such as a telephone so as to determine whether noise is heard from a receiver. The present invention relates to a noise-audible immunity evaluation tester for measuring and evaluating a noise-audible immunity characteristic, which is a tolerance limit of the test.

[0002]

2. Description of the Related Art Noise may be generated from a telephone receiver by the influence of an external electromagnetic interference wave. This is a so-called audible disorder. The main foreign electromagnetic disturbance that generates an audible failure, there is the waveform shown by V ₀ in FIG. 7 (a) ~ (d) . In FIG. 7, (a) shows a case of an amplitude modulation (AM modulation) sine wave, (b) shows a case of a power supply synchronous pulse wave, and (c)
Indicates a case of a damped vibration wave, and (d) indicates a case of an intermittent sine wave.

When these extraneous electromagnetic interference waves are induced in a telephone communication line, a common mode (longitudinal) current penetrates into the telephone equipment connected to the communication line. Then, noise often occurs from the receiver due to the unbalanced impedance of the equipment circuit, the detection characteristics of the entire equipment circuit due to the use of a large number of semiconductor circuit elements, and the like. The handset-pin when this waveform is generated as V _R shown in FIG. 7 (a) ~ (d) , which is the noise sound pressure by driving the receiver diaphragm is generated.

It is to be noted that V ₀ is an AM as shown in FIG.
V _{R in} the case of a modulated sine wave is, for example, a VH waveform composed of a carrier component obtained by reducing the V ₀ waveform as it is, as described in the Transactions of the Institute of Electronics, Information and Communication Engineers Spring Meeting, 1992, SB-3-2. It is known that a modulated wave is a waveform superimposed on a voice modulated wave waveform such as a VL waveform detected by the entire telephone circuit.

FIG. 8 is a block diagram showing a conventional configuration of a noise audible immunity test system for applying such an AM modulated sine wave to a device under test to evaluate the presence or absence of noise audibility from a receiver. is there. As shown in the figure, a device under test (EUT) 51 such as a telephone is supported at a constant height h from above the pseudo ground by an insulating support base 52. EUT
The receiver of the transmitter / receiver 53 of 51 is fitted into the microphone 54 via the acoustic coupler 55. The noise from the earpiece converted by the microphone 54 into an electric signal is a level meter 5 that indicates the electric signal output of the microphone 54.
6 is displayed. That is, the audible noise sound pressure P from the receiver
Can be recognized by the level meter 56.

The handset 53 has a pseudo hand circuit 57 equivalent to the impedance to ground when a handset is held by a hand.
Is connected. Handset 53 and microphone 54
Is a sound insulation box 58 for preventing surrounding noise other than audible noise from the receiver from entering the microphone 54.
Is stored in.

A communication line between the EUT 51 and an opposing communication device 61 such as a pseudo-switch is connected to a test signal applicator 60A for applying a test AM modulated sine wave (test signal) to the EUT 51 in a common mode. . Test signal applicator 60
A is a test signal generator (SG) 59 for generating a test signal.
And a common mode choke coil 62 for allowing the applied test signal to be applied only to the EUT side without being applied to the opposing communication device 61 side. Note that E
A line opening switch 63 is provided between the UT 51 and the test signal applicator 60A.

In such a test system, when an AM modulated sine wave such as V ₀ shown in FIG. 7A is applied to a communication line in a common mode as a test signal, a common mode current iv flows through the communication line. To enter the EUT 51. Then, the common mode current is converted and detected by an unbalanced impedance in the circuit of the EUT 51, a semiconductor circuit, or the like, and generates an audible noise in the receiver. Audible noise from the handset enters microphone 54 where it is converted to an electrical signal. Since the level meter 56 fluctuates according to the electric signal, the measurer can know the noise sound pressure P from the vibration. Thus, the noise sound pressure from the receiver is extracted by acoustic coupling.

The audible immunity of the EUT 51 is obtained as an open-end common mode voltage when the line opening switch 63 is opened by applying an applied voltage when a sound pressure P (= P ₀ ) occurs at a limit where noise starts to be heard. . Therefore, if the open-end common mode voltage is measured while changing the carrier frequency f of the test signal from the SG 59 and the measured value is plotted, the noise audible immunity characteristic of the EUT 51 can be obtained.

FIG. 9 shows a case where one test signal applicator 60A is connected to a system including a plurality of EUTs. In a system such as a key telephone device or a business phone, slave phones S ₁ , S ₂ ,..., _SM are connected to the main device (M) 70 via an extension such as a home bus line. On the opposite communication line side, the opposite telephone S _N 71
Is connected. Then, the audible immunity of such a system is evaluated using the test signal from the test signal applicator 60A.

[0011]

To evaluate the noise audible immunity characteristics of various telephones using the characteristic evaluation tester shown in FIG. 8, it is necessary to swing the level meter 56 properly corresponding to the noise sound pressure. become. However, the shape of the earpiece varies depending on the receiver. When the earpieces having different shapes are attached to the acoustic coupler 55, the fitting condition between the receiver and the acoustic coupler 55 changes, and the acoustic coupler 55 may not be properly coupled to the microphone 54 in some cases. In such a case, there is a problem that the swing of the level meter 56 is unstable especially near the audible sound pressure limit, and it is difficult to detect an appropriate sound pressure level.

Further, the evaluation based on the noise sound pressure targets only an AM-modulated sine wave as shown in FIG. FIG.
(B) ~ For the audible electromagnetic disturbance (d), the because correspondence between V _R wave and the noise sound pressure generated between handset terminals is not clear. Therefore, there is a problem that the characteristics cannot be evaluated for the audible electromagnetic interference waves shown in FIGS. 7B to 7D.

[0013] With the configuration shown in FIG. 9 to evaluate the audible immunity of the entire system, the child telephone S ₁ is a receiver and the EUT of the main apparatus 70, S _2, · · ·, to S _M and the opposite telephone S _N Noise sound pressure (P
₁ , P ₂ ,..., P _N ) to determine which one corresponds to the smallest audible immunity. However, if the test system shown in FIG. 8 is used for such a plurality of EUTs, an acoustic coupler 55 and a sound insulation box 58 corresponding to each EUT are required. Therefore, there is a problem that the equipment becomes enormous, and a considerable time is required for the test system arrangement work such as coupling.

The present invention provides a noise audible immunity evaluation tester for evaluating a noise audible immunity characteristic by measuring a noise signal generated between receiver terminals, instead of the noise sound pressure measurement by such an acoustic coupling method. The purpose is to:

[0015]

According to a first aspect of the present invention, there is provided a noise audible immunity evaluation tester for applying a test signal to an EUT in a common mode. Application level setting means for resetting to zero, audible signal detection means having high-frequency common mode high impedance characteristics and detecting a noise audible signal generated between the receiver terminals of the EUT, and a level of the noise audible signal by the audible signal detection means Is provided with an applied signal detecting means for measuring an applied signal level when a predetermined limit level is exceeded in accordance with a noise audible sound pressure from the receiver.

According to a second aspect of the present invention, there is provided a noise audible immunity evaluation tester for applying a test signal to an EUT in a common mode, wherein an applied level for increasing, stopping, and returning to zero the output level of the test signal. Setting means and a high frequency common mode high impedance characteristic,
Audible signal detecting means for detecting a noise audible signal generated between the receiver terminals of T, applied signal detecting means for measuring the level of the applied signal of the device under test by the applied level setting means,
The level of the noise audible signal detected by the audible signal detection means and E
And a characteristic evaluation means for obtaining a ratio with respect to the applied signal level of the UT.

According to a third aspect of the present invention, there is provided the noise audible immunity evaluation tester according to the first or second aspect of the invention, wherein the application level setting means receives an amplitude-modulated sine wave as a test signal. This is to be applied to the test equipment.

According to a fourth aspect of the present invention, in the noise audible immunity evaluation tester according to the first or second aspect of the present invention, the application level setting means includes a test signal other than an amplitude-modulated sine wave. A signal and a signal having a repetition frequency within an audible band shall be applied to the device under test, and an audible signal detection unit and a noise audible signal
The input is detected as a spectrum or a waveform.

[0019]

According to the present invention, the applied level setting means converts a test signal containing a high frequency such as an AM modulated sine wave into a common mode E signal.
Apply to the UT line. The applied signal detection means measures an applied signal level when the level of the noise audible signal detected between the receiver terminals exceeds a predetermined limit level of the noise audible signal corresponding to the noise audible sound pressure, Enables testing of high-frequency unbalance characteristics without using acoustic coupling.

The characteristic evaluation means obtains a noise audible immunity characteristic by a ratio between a level of the noise audible signal detected between the receiver terminals and a signal level applied to the EUT.

[0021]

FIG. 1 is a block diagram showing a configuration of a noise-audible immunity evaluation tester according to one embodiment of the present invention. Here, a case is shown in which noise audible immunity characteristics of two EUTs (EUTA, EUTB) 1A and 1B each having a handset 3A (or handset 3B) are shown. As shown in the figure, EUTA and EUTB are installed via a pseudo switch 61 between them.

A test signal applicator 60 is inserted between EUTA and EUTB. Between the receiver terminals R1 and R2 of both EUTs, an audible signal detecting means (hereinafter referred to as audible signal detecting means) 4 between the receiver terminals such as a differential probe.
A and 4B come into contact. The audible signal detection means 4A, 4B
The audible noise signals V _Ra and V _Rb generated between the terminals are detected. The audible signal detecting means 4A, 4B is connected to the receiver terminal R
1 and R2, a high impedance is provided between each contact terminal and the frame ground so that the high frequency common mode signal generated at these terminals does not flow to the frame ground side.

The applied signal detector 5 is constituted by a high impedance probe or the like, and introduces the voltage at the open end after the line opening switch 63 is opened. The applied signal measuring circuit 6
Level of the introduced voltage, i.e., measures the open end common mode voltage level V _0.

The BPF section 7 comprising a band-pass filter (BPF) corresponding to each audible signal detecting means passes only audible signals in the audio band among the signals detected by the audible signal detecting means 4A and 4B. Each BPF is switched and selected by the channel selection switch 8. Note that the channel selection switch 8 has a switching number n. Therefore, measurement can be performed for n EUTs.

The audible band signal measuring circuit 9 receives the output of the channel selection switch 8 and measures the level of the audible signal in the audio band. The audible signal comparison circuit 10 compares the output level of the channel selection switch 8 with a predetermined level. The operation storage circuit 11 receives the output of the applied signal measurement circuit 6 and the output of the audible band signal measurement circuit 9, performs an operation on them, and stores the operation result. Also,
Necessary information is displayed on the display unit 12.

The test signal generator 13 has a carrier frequency setting circuit 131 for setting a carrier frequency, and an AM modulation circuit 132 for amplitude modulating a carrier wave, and generates a test signal. The programmable attenuator 14 includes an attenuator (ATT) 141 for attenuating the test signal and an ATT 14
An application level setting circuit 142 for instructing an attenuation amount to 1;
It has a level holding circuit 143 for giving a level holding instruction to the applied level setting circuit 142, and a zero recovery circuit 144 for making the output of the ATT 141 zero, and controls the level of the test signal. The output of the programmable attenuator 14, that is, the output of the ATT 141, is amplified by the amplifier 16 and then supplied to the test signal applicator 60.

The channel selector switch 8 and the line release switch 63 are switched by the switch selector 15. That is, in the switch switching section 15, the channel selection switch 8 and the line opening switch 63 are operated by driving the magnets M1 and M2. The audible signal comparison circuit 10 includes an LE for display.
D17 is provided. Manual setting units 18, 19 and 20 are connected to the test signal generator 13, the programmable attenuator 14 and the switch switching unit 15, respectively.

Therefore, in the present embodiment, the application level setting means comprises the test signal generator 13 and the programmable attenuator 14. The audible signal detecting means includes audible signal detecting means 4A and 4B. The applied signal detecting means includes an applied signal detecting unit 5 and an applied signal measuring circuit 6. In addition, the characteristic evaluation means includes an operation storage circuit 1
1.

Hereinafter, in the configuration shown in FIG. 1, FIG.
When an AM modulated sine wave is applied as shown in
A, The operation | movement for obtaining the noise audible immunity characteristic of EUTB is demonstrated.

First, the measurer operates the manual setting section 20 to give an instruction to the switch switching section 15 to set the line opening switch 63 to the short-circuit state, and to set a BPF (for example, BPF) corresponding to one of the EUTs. An instruction is given to connect the channel selection switch 8 to the BPF of CH1). Further, the user operates the manual setting section 19 to set the applied frequency band and the step-up width of the frequency. The carrier frequency setting circuit 131 generates a carrier of the first frequency (for example, the minimum frequency) in the set application frequency band. The AM modulation circuit 132 converts the carrier into an audio band signal of a predetermined frequency (for example, f = 1 kHz
) Is output.

Further, the measurer operates the manual setting section 18 to set the step-up width of the applied signal level.
Alternatively, the level is set to be continuously variable. In the programmable attenuator 14, an application level setting circuit 14
2 is ATT at the set step width or continuously variable
The ATT 141 is controlled so that the output of the 141 changes. Therefore, an AM modulated wave whose level changes sequentially is output from the programmable attenuator 14, and the AM modulated wave is supplied to the test signal applicator 60 through the amplifier 16.
The test signal applicator 60 applies the AM modulated wave as a test signal to EUTA.

On the other hand, the audible signal detection means 4A is
Audible noise signal V _Ra generated between the receiver terminals (FIG. 7 (a)
VH and VL shown in FIG. ) Is detected. Then, the detected audible noise signal is sent to the connected BPF.
The BPF passes only audible signals in the audio band. The audible signal in the audio band is supplied to the audible band signal measurement circuit 9 and the audible signal comparison circuit 1 via the channel selection switch 5.
Input to 0.

The audio signal comparison circuit 10 compares the level of the input audio signal with a predetermined signal level V _R0 . The signal level V _R0, the level of the voice band signal corresponding to the occurrence of limit audible pressure P ₀ VL (i.e., VL ₀₎ is. Note that the relationship between V _R0 and P ₀ is A
It is known that when an M-modulated wave is applied, it is almost determined according to the type of the receiver (for example, a piezoelectric type or an electrostatic type). Then, when the level of the audible signal exceeds V _R0 , the audible signal comparison circuit 10 turns on the LED 17 and instructs the level holding circuit 143 of the programmable attenuator 14 to fix the output level of the ATT 141. . At that time, the audible signal comparison circuit 10 sends the line opening switch 6 to the switch switching unit 15.
3 is instructed to open. The switch switching unit 15 opens the line release switch 63 accordingly.

The applied signal detector 5 includes a test signal applicator 60
Output voltage is detected. Therefore, at this time, the open-end common mode voltage is input to the applied signal detection unit 5. The applied signal measurement circuit 6 measures the open-end common mode voltage level V ₀ and sends it to the operation storage circuit 11. The operation storage circuit 11 has its open-end common mode voltage level V ₀
Is stored and plotted on the frequency axis of the display unit 12. The arithmetic storage circuit 11 may be configured to take the ratio between the open-end common mode voltage level V ₀ and the level VL of the audio band signal output from the audible band signal measuring circuit 9 and plot the ratio.

Next, the arithmetic storage circuit 11 drives the zero recovery circuit 144 of the programmable attenuator 14 and
The output level of 1 is set to zero. The zero recovery circuit 144
When the control to make the output level of the TT141 zero is completed,
An instruction is given to the switch switching unit 15 so that the line release switch 63 is set to the short-circuit state. The switch switching unit 15
After performing the switch switching process, it notifies the carrier frequency setting circuit 131 of the test signal generator 13 to that effect. Then
The carrier frequency setting circuit 131 generates a carrier of the next frequency in the set applied frequency band. Then, each circuit executes the above operation again.

With the above processing, the open-end common mode voltage level (applied voltage level) V ₀ is measured for all frequencies in the set applied frequency band, and noise audible immunity characteristics are obtained. Next, the magnet M2 of the switch switching unit 15 is driven, and the channel selection switch 8 is switched to the CH2 side. Then, the noise audible immunity characteristic of EUTB is obtained by the same processing as the above processing.

As described above, the threshold level V _RO (= VL ₀ ) in the audible signal comparison circuit 10, the step-up width or continuously variable width of the applied signal level by the programmable attenuator 14, and the test signal generator 13 By setting the step-up width or the continuously variable width of the frequency in advance in advance and performing the above-described processing, noise audible immunity characteristics of a plurality of EUTs are automatically obtained. In the above embodiment, the measurement is automatically executed when the step-up width of the applied signal level and the step-up width of the frequency are set first, but the applied signal level and the frequency are manually set each time. It is also possible to adopt a configuration in which

FIG. 2 shows the EU obtained as described above.
It shows an example of noise audible immunity characteristics of TA and EUTB. The vertical axis represents the applied signal level V ₀ , or V ₀ and the level of the audio band signal when the level VL of the audio band signal of the audible noise signal V _Ra or V _Rb exceeds a threshold level V _R0 which is an audible limit value. V _{L and} a conversion attenuation amount (α _L = 20 log (V ₀ / V
L), is an _{α L '= 20log (V 0} / VL'), may be any of that. In the figure, Vh or α _L0 is an evaluation level value of noise audible immunity (a recommended value by a standardization organization such as IEC).

In the case of this example, the evaluation level value Vh (or the conversion attenuation evaluation value α for noise audible immunity evaluation)
_L0, EUT from EUTB for alpha EUTA satisfying the _L0 ^'), and that the frequency range of EUTB is below f1 and f2 less, respectively, the same applied signal level V ₀
It can be easily determined that the immunity level of A is small.

That is, the noise audible immunity of the EUT can be easily and quickly evaluated from the obtained noise audible immunity characteristics and the evaluation level value Vh. In addition, according to the present invention, an electric signal between the receiver terminals is extracted and evaluated without using the conventional acoustic coupling method, so that an acoustic coupler, a sound insulation box, and the like are not required. Therefore, even when many EUTs are connected to the home bus line as in the configuration shown in FIG. 9, noise audibility immunity evaluation and the like can be easily performed. In addition, it is possible to easily evaluate the audible noise immunity of the main device and the opposing communication device due to an increase in the imbalance of the extension circuit generated when the number of connected EUTs is sequentially increased.

In the above embodiment, the measurement of V _Ra and V _Rb for the two EUTs is performed by the channel selection switch 8.
Are executed by switching the audible signal comparison circuit 10. The output of each BPF is input to the audible signal comparison circuit 10, and the audible signal comparison circuit 1
0 may select one input.

In the operation of the above embodiment, FIG.
Although the case where the AM modulated sine wave as shown in FIG. 7A is used has been described, the waveforms shown in FIGS. 7B to 7D can be evaluated. When such a waveform is evaluated, for example, the audible noise signals V _Ra and V _Rb generated between terminals and the applied voltage are captured as either a spectrum or a waveform. In the case of using a spectrum, the audible band signal measuring circuit 9 and the applied voltage detecting circuit 6 are constituted by a spectrum analyzer. When capturing waveforms, configure them using a waveform analyzer such as a memory scope. Further, the threshold level V _RO in the audible signal comparison circuit 10 is set to a spectrum level or a waveform level corresponding to the limit audible sound pressure. In this way, the noise audible immunity evaluation can be performed on the waveforms shown in FIGS. Therefore, it is possible to perform noise audible immunity evaluation on a continuous pulse waveform or the like that cannot be performed by the conventional acoustic coupling method.

FIG. 3 is a configuration diagram showing a configuration of a test system in which EUTA is terminated by an equivalent impedance of a transmitter / receiver circuit. Its equivalent impedance is EUTA in FIG.
This corresponds to the transmitter / receiver load system. In FIG. 3 (a), Z _T is transmitter terminals T1, T2 viewed from transmitter equivalent impedance of EUT, Z _R is receiver terminals R1, R2 viewed from handset equivalent impedance, Zhg the handset terminal T
It is an equivalent impedance between 1, T2, R1, R2, and pseudo earth. FIG. 3 (b) shows a configuration in which the EUT is terminated with these equivalent impedances instead of the handset in the handset load system arrangement. Thereby, the arrangement of the EUT can be simplified.

FIG. 4 is a configuration diagram showing a configuration example of the audible signal detection means 4A, 4B using a differential probe. In the figure, reference numeral 21 denotes a contact for contacting the receiver terminals R1 and R2 to capture the signal level between the receiver terminals. Reference numeral 22 denotes a common mode having a large common mode attenuation over a wide band and a small or constant differential mode attenuation. A choke coil, 23 is an attenuating element, 26 is a metal differential probe member having a built-in differential signal detecting element 24 such as an FET and an amplifier 25, and 27 is a differential probe member 26.
Is the outer conductor of the connected coaxial cable.

The contact 21 detects a signal between the receiver terminals by touching the receiver terminals R1 and R2 of the EUT to which a test signal having a high frequency component such as a common mode AM modulated sine wave or a continuous pulse waveform is applied. I do. In that case,
Assuming that the common mode choke 22 and the attenuation element 23 are not provided, the high frequency component of the common mode signal generated at the receiver terminals R1 and R2 becomes the stray capacitance Cg between the differential signal detection element 24 and the differential probe member 26. Through the outer conductor 27 of the coaxial cable. Therefore, the signal between receiver terminals fluctuates greatly before and after contact with the differential probe. However, if the common mode choke 22 and the attenuating element 23 are inserted, they prevent high frequency components of the common mode signal. Therefore, according to the configuration shown in FIG. 4, even if the differential probe is brought into contact with the receiver terminals R1 and R2, the signal between the receiver terminals does not fluctuate, and proper measurement can be performed.

FIG. 5 is a configuration diagram showing another example of the configuration of the audible signal detection means 4A, 4B. As shown in the figure, a photoelectric conversion probe 34 as an audible signal detecting means is provided with an optical modulator 3
1, a light source 32 such as a laser, and an OE converter 33 for converting an optical signal into an electric signal.

The photoelectric conversion probe 34 uses two antenna elements of a dipole antenna disclosed in, for example, JP-A-2-275370 as contacts. When detecting an inter-terminal signal from the EUT, the intensity of the optical signal from the light source 31 is modulated by the inter-terminal signal in the optical modulator 31. Then, the OE converter 33 returns the optical signal to an electric signal. In such a probe, only the contact portion is made of metal, and the detected inter-terminal signal is converted into light by the optical modulator 31, so that the receiver terminal R
Even if a common mode high-frequency signal exists in R1 and R2, the signal between terminals does not fluctuate due to probe contact.

FIG. 6 is a block diagram showing a configuration of a noise-audible immunity evaluation tester according to another embodiment of the present invention. FIG. 6 shows a more automated process using a personal computer or the like. That is, a measurement control unit 40 and a storage unit 41 using a personal computer or the like are provided instead of the arithmetic and storage circuit 11.
Further, a setting unit 42 connected to the measurement control unit 40 is provided instead of the manual setting units 18, 19, and 20.

The applied signal measuring circuit 6, audible band signal measuring circuit 9, audible signal comparing circuit 10, test signal generator 1
3. The programmable attenuator 14 and the switch switching unit 15 are connected to the measurement control unit 40 via a GPIB bus.

With such a configuration, the noise-audible immunity characteristic can be obtained by the same processing as that for obtaining the noise-audible immunity characteristic by the configuration of the above embodiment. That is, according to the setting of the setting unit 42, the measurement control unit 40 sets the applied voltage level, the frequency, and the like for the switch switching unit 15, the programmable attenuator 14, and the test signal generator 13. Then, the measurement control unit 40
The outputs of the applied signal measurement circuit 6, audible band signal measurement circuit 9, and audible signal comparison circuit 10 are input, and the same processing as that of the arithmetic storage circuit 11 in FIG. 1 is performed.

[0051]

As described above, according to the present invention, the noise audible immunity evaluation tester generates a noise sound pressure by the audible signal detecting means which is less affected even if it comes into contact with the receiver terminal. Since the configuration is such that the inter-signal is measured electrically, it eliminates problems such as difficulty in mounting the handset during acoustic coupling due to the shape of the earpiece and instability of the detection level due to improper mounting. Many EUTs
When the audible immunity is measured at the same time, there is an effect that it is possible to provide a device capable of performing the measurement with high reproducibility in a short time.

Further, if the audible signal detecting means and the applied signal detecting means detect the input as a spectrum or a waveform, the audible immunity to a test signal for an external electromagnetic interference wave other than the AM modulated sine wave can be improved. There is an advantage that characteristics can be evaluated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a noise audible immunity evaluation tester according to one embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an example of a noise audible immunity characteristic.

FIG. 3 is a configuration diagram showing a configuration of a test system in which an EUT is terminated by an equivalent impedance of a handset circuit.

FIG. 4 is a configuration diagram illustrating a configuration example of an audible signal detection unit.

FIG. 5 is a configuration diagram showing another configuration example of the audible signal detection means.

FIG. 6 is a block diagram showing a configuration of a noise audible immunity evaluation tester according to another embodiment of the present invention.

FIG. 7 is a waveform diagram showing an external electromagnetic interference wave and a noise waveform from a receiver.

FIG. 8 is a configuration diagram showing a configuration of a conventional noise audible immunity test system.

FIG. 9 is a configuration diagram showing a configuration in which one test signal applicator is connected to a system including a plurality of EUTs.

[Explanation of symbols]

 1A, 1B EUT 4A, 4B Audible signal detection means 5 Applied signal detection unit 6 Applied signal measurement circuit 7 BPF unit 8 Channel selection switch 9 Audible band signal measurement circuit 10 Audible signal comparison circuit 11 Operation storage circuit 12 Display unit 13 Test signal generation Instrument 14 Programmable attenuator 15 Switch switching unit 16 Amplifier 40 Measurement controller 41 Storage unit 42 Setting unit

Claims (4)

(57) [Claims] A noise-audible immunity evaluation tester for evaluating a noise-audible immunity by applying a test signal containing a high-frequency component from a line of a device under test, wherein the test signal is applied to the device under test in a common mode. An application level setting means for increasing, stopping, and returning to zero the output level of a test signal; and a high frequency common mode high impedance characteristic for detecting a noise audible signal generated between receiver terminals of the equipment under test. Audible signal detecting means for detecting the level of an applied signal when the level of the noise audible signal exceeds a predetermined limit level corresponding to the noise audible sound pressure from the receiver. And a means for evaluating audible noise immunity. 2. A noise-audible immunity evaluation tester for evaluating a noise-audible immunity by applying a test signal containing a high-frequency component from a line of a device under test, wherein the test signal is applied to the device under test in a common mode. An application level setting means for increasing, stopping, and returning to zero the output level of a test signal; and a high frequency common mode high impedance characteristic for detecting a noise audible signal generated between receiver terminals of the equipment under test. An audible signal detecting unit, an applied signal detecting unit that measures a level of an applied signal of the device under test by the applied level setting unit, and a noise audible signal level detected by the audible signal detecting unit and a level of the applied signal. A noise audible immunity evaluation tester comprising: a characteristic evaluation means for obtaining a ratio. 3. An application level setting means for applying an amplitude-modulated sine wave as a test signal to a device under test, and an audible signal detection means detecting a modulation wave generated between receiver terminals of the device under test. 3. The noise audible immunity evaluation tester according to claim 1 or 2. 4. An application level setting means for applying a signal other than an amplitude-modulated sine wave and having a repetition frequency within an audible band to a device under test as a test signal, wherein the audible signal detection means comprises: 3. The noise-audible immunity evaluation tester according to claim 1, wherein the noise-audible signal is detected as a spectrum or a waveform, and the applied signal detecting means detects the applied signal as a spectrum or a waveform.