JP2012242350A - Voltage probe and voltage measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage probe capable of accurately measuring voltage with a simple and inexpensive structure.SOLUTION: The voltage probe includes: a voltage measuring terminal 201 for obtaining a voltage signal V indicating voltage at an observation point; an attenuator 202 for attenuating the voltage signal V by a predetermined attenuation amount; a modulation part 203 for modulating the voltage signal V after the attenuation at frequency range of an electric wave area and outputting a modulated signal Vm; a transmission cable 204 for transmitting the modulated signal Vm; and a demodulation part 205 for outputting, to a voltage measuring device 106, the voltage signal V obtained by demodulating the modulated signal Vm having been transmitted by the transmission cable 204.

Description

  The present invention relates to a voltage probe used for voltage measurement.

  Conventionally, an unbalanced measuring instrument such as an oscilloscope, which is connected to a measuring object from an electric probe via a coaxial cable and distinguishes the point to be measured between the measuring instrument's ground and the signal line, has a different ground level from the measuring instrument. When observing a voltage waveform between two points that are not grounded or a circuit, it is difficult to accurately measure due to the influence of grounding or the influence of signals. Therefore, in Patent Document 1 below, in order to solve the problem that unnecessary information is measured, a voltage to be measured is applied to the electrode of the light modulation means, and the intensity of light changed depending on the voltage is converted into an electric signal. In addition, a technique for measuring a voltage using an unbalanced measuring instrument is disclosed.

JP-A-9-33572

  However, according to the above conventional technique, a calibration technique for correcting the characteristics of the electrical / optical conversion mechanism is necessary, and the voltage range (dynamic range) that can be sensed is narrow and the electrical / optical output signal is weak. There was a technical problem that it was difficult to ensure S / N. In addition, there is a problem in practical use in that component parts such as an electric / optical conversion mechanism of the voltage probe are expensive and many component parts are complicated.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a voltage probe capable of realizing accurate voltage measurement with a simple and inexpensive configuration.

  In order to solve the above-described problems and achieve the object, the present invention is a voltage probe connected to a voltage measuring device for measuring a voltage, a voltage measuring terminal for obtaining a voltage signal indicating a voltage at an observation point, Attenuating means for attenuating the voltage signal by the amount of attenuation, modulating means for modulating the attenuated voltage signal in the frequency range of the radio wave region and outputting a modulated signal, a transmission cable for transmitting the modulated signal, and the transmission Demodulating means for outputting the voltage signal obtained by demodulating the modulated signal transmitted by a cable to the voltage measuring device.

  According to the present invention, there is an effect that accurate voltage measurement can be realized with a simple and inexpensive configuration.

FIG. 1 is a diagram illustrating a configuration example of a general system for performing a noise injection test. FIG. 2 is a diagram illustrating a configuration example of the voltage probe according to the first embodiment. FIG. 3 is a diagram illustrating a configuration example of the voltage probe according to the second embodiment. FIG. 4 is a diagram illustrating a configuration example of the voltage probe according to the fourth embodiment. FIG. 5 is a diagram illustrating a configuration example of the voltage probe according to the fifth embodiment.

  Embodiments of a voltage probe according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a general system for performing a noise injection test. This system includes a noise test apparatus 101, a noise injection cable 102, an electronic device 103, a voltage probe 104, a transmission cable 105, and a voltage measurement apparatus 106. In a high-voltage noise test performed by the noise test apparatus 101, the noise injection cable 102, and the electronic device 103, the electronic device 103 is used by the voltage probe 104, the transmission cable 105, and the voltage measurement device 106 in an environment exposed to the strong electromagnetic field 107. Measure the voltage at any point in. In such a system, a configuration for suppressing noise entering the voltage measurement side will be described.

  FIG. 2 is a diagram illustrating a configuration example of the voltage probe 104a of the present embodiment. The voltage probe 104 a includes a voltage measurement terminal 201, an attenuator 202, a modulation unit 203, a transmission cable 204, and a demodulation unit 205. The voltage probe 104 a includes a transmission cable 204 corresponding to the transmission cable 105 and is directly connected to the voltage measurement device 106.

  The voltage measurement terminal 201 obtains a voltage signal indicating a voltage at an observation point to be measured. The attenuator 202 attenuates the voltage signal obtained at the voltage measurement terminal 201. Modulator 203 modulates and outputs the attenuated voltage signal. The transmission cable 204 is a transmission path for the modulated signal. The demodulator 205 demodulates the modulated signal and outputs it to the voltage measurement device 106.

  In the voltage probe 104a, the voltage measurement terminal 201 obtains the voltage signal V indicating the voltage at the point from the observation point, and the attenuator 202 attenuates the voltage signal V by a predetermined attenuation amount. Then, the modulation unit 203 modulates the attenuated voltage signal V on the frequency axis that is resistant to intrusion noise from the strong electromagnetic field 107 on the frequency axis in the radio wave region (up to 3 THz). To obtain the modulation signal Vm. Then, the modulation unit 203 outputs the modulation signal Vm to the demodulation unit 205 via the transmission cable 204 in the environment of the strong electromagnetic field 107. The demodulator 205 demodulates the modulation signal Vm to obtain a voltage signal V, and outputs it directly to the voltage measurement device 106. Then, the voltage measuring device 106 performs signal processing and provides a voltage waveform to the measurer.

  Here, it is important how the voltage signal V obtained from the voltage measurement terminal 201 can be transmitted to the voltage measurement device 106 while suppressing intrusion noise from the transmission cable 204. In the present embodiment, intrusion noise is suppressed by performing transmission by changing signal characteristics for transmission in the radio wave region.

  Although the intrusion noise from the strong electromagnetic field 107 superimposed from the transmission cable 204 is a large signal, if the noise waveform used in the high voltage noise standard test is fixed, it is locally from the viewpoint of frequency. Since it is unevenly distributed, it can be greatly suppressed by the demodulator 205 if modulation is performed while avoiding this frequency spectrum.

  The voltage measuring device 106 is a measuring device that analyzes a voltage signal in a time domain or a frequency domain, such as a general oscilloscope or a spectrum analyzer.

  Further, the transmission cable 204 can significantly reduce intrusion noise by using a coaxial cable having a shield structure.

  The modulation unit 203 may be an analog system that directly modulates the voltage signal V, or a digital signal system that modulates the digital signal Vd obtained by quantizing and encoding the voltage signal V. Either may be adopted. However, as is well known, the digital method is more resistant to noise.

  The voltage measurement terminal 201, the attenuator 202, and the modulation unit 203 should be about 1/10 square or less with respect to the wavelength λ size of the maximum frequency of the high voltage noise so as to reduce the influence of the strong electromagnetic field 107. Is desirable.

  In addition, although the case where the demodulation part 205 was comprised in the voltage probe 104a was demonstrated, it is not limited to this, It is also possible to take the structure which incorporates the demodulation part 205 in the voltage measurement part 106 inside. In this case, the configuration on the voltage measurement side is a system having three configurations: a voltage probe, a transmission cable, and a voltage measurement device, as in FIG. As a result, the same function can be obtained and the voltage probe can be miniaturized.

  As described above, in the present embodiment, the voltage probe 104a attenuates the voltage signal V obtained from the voltage measurement terminal 201, and then modulates the frequency spectrum to perform dispersion so that the nature of the signal for transmission in the radio wave region is reduced. Is transmitted via a transmission cable, demodulated before the voltage measuring device 106, and the voltage signal V is output to the voltage measuring device 106. Thus, as a technical point of view, the voltage signal V is prevented from deteriorating due to intrusion noise from the strong electromagnetic field 107 local to a specific frequency, rather than directly transmitting the voltage signal under the strong electromagnetic field 107. be able to. In addition, since the transmission path can be specified through the transmission cable 204, not only the antenna but also the space is not propagated, so that the C / N ratio (Carrier to Noise Ratio) is hardly deteriorated and a power amplifier is unnecessary. And as an economic effect, it can be downsized and can be configured at low cost. In addition, functional blocks including the modulation unit 203 are provided by devices such as ICs, and many are distributed in the market and can be easily obtained.

  In addition, although demonstrated using the example in a high voltage noise test environment, it cannot be overemphasized, and it cannot be overemphasized that it can measure also in a strong electromagnetic field other than having demonstrated in this Embodiment.

  Further, since the voltage probe 104a transmits a signal in the radio wave region instead of the optical region, the device processing accuracy required in the optical region is not required. In addition, general-purpose parts distributed in the market can be applied as circuit components.

Embodiment 2. FIG.
In the present embodiment, the modulation signal Vm is frequency-converted and transmitted via the transmission cable 204. A different part from Embodiment 1 is demonstrated.

  FIG. 3 is a diagram illustrating a configuration example of the voltage probe 104b according to the present embodiment. The voltage probe 104b includes a voltage measurement terminal 201, an attenuator 202, a modulation unit 203, a frequency conversion unit 306, a transmission cable 204, a frequency conversion unit 307, a high-pass filter 308, and a demodulation unit 205. Is done. As in the first embodiment, the voltage probe 104 b is directly connected to the voltage measurement device 106.

  The frequency conversion unit 306 moves the center frequency of the modulation signal Vm obtained by the modulation unit 203 to the high frequency region and outputs it to the transmission cable 204. For example, the frequency of the modulation signal Vm is converted from an AF (Audio Frequency) region through an IF (Intermediate Frequency) region to an RF (Radio Frequency) region. The frequency conversion unit 306 is a first frequency conversion unit. The frequency conversion unit 307 performs conversion for returning the modulation signal Vm input from the transmission cable 204 to the frequency before the frequency domain movement by the frequency conversion unit 306. For example, contrary to the frequency conversion unit 306, the frequency of the modulation signal Vm is converted from the RF region to the AF region through the IF region. The frequency conversion unit 307 is the second frequency conversion unit. The high pass filter 308 blocks noise that has entered the transmission cable 204 and outputs the modulation signal Vm to the demodulation unit 205.

  In the voltage probe 104b, the frequency conversion unit 306 moves the center frequency of the modulation signal Vm obtained from the modulation unit 203 to the high frequency region, thereby moving the modulation signal Vm away from the frequency band of intrusion noise from the strong electromagnetic field 107. The transmission cable 204 is transmitted under the magnetic field 107 environment. The frequency conversion unit 307 performs conversion to return the input modulation signal Vm to the frequency before the frequency domain movement by the frequency conversion unit 306, and the high-pass filter 308 blocks noise that has entered the transmission cable 204, and the modulation signal Vm is output to the demodulation unit 205. The processing in other configurations is the same as that in the first embodiment.

  In particular, in the frequency conversion unit 306, the conversion frequency is converted into a high frequency region in order to avoid the frequency band of intrusion noise. The central frequency fc is the maximum value fmax of the occupied band in which the energy of the intrusion noise occupies 90%. By setting as described above, it is possible to significantly suppress intrusion noise.

  As in the first embodiment, the frequency measuring unit 307, the high-pass filter 308, and the demodulating unit 205 may be included in the voltage measuring device 106 in order to reduce the size of the voltage probe 104b. Even in this case, the same function as described above can be obtained.

  As described above, in the present embodiment, in the voltage probe 104b, the frequency converter 306 moves the modulation signal Vm to the high frequency region avoiding the intrusion noise band and transmits the transmission cable 204. As a result, in Embodiment 1, there is a possibility that the modulation signal Vm from the modulation unit 203 exists in the vicinity of the intrusion noise band and gives an error to the measured voltage value. However, the frequency conversion unit 306 converts the modulation signal Vm into By moving to a high frequency region that avoids the intrusion noise band, the transmission cable 204 can be transmitted while avoiding intrusion noise.

Embodiment 3 FIG.
In the present embodiment, the modulation unit 203 applies spread spectrum modulation. A different part from Embodiment 1, 2 is demonstrated.

  The configurations of the voltage probes 104a and 104b are the same as those shown in FIGS. In the case of using spread spectrum modulation, the modulation unit 203 can improve noise resistance by increasing the spreading factor N. However, since the speed of hardware is required, it is desirable that the spreading factor N is as small as possible. Therefore, in the first and second embodiments, since the influence of intrusion noise is different, it is necessary to set an appropriate spreading factor N.

  The spreading factor is the ratio of the spreading code rate (chip rate) to the transmission data rate (bit rate: bit rate). In the first embodiment, there is a high possibility that the intrusion noise from the strong electromagnetic field is in the vicinity of the voltage signal band. Therefore, the influence of the intrusion noise can be further reduced by increasing the spreading factor N. On the other hand, in the second embodiment, the frequency converter 306 is far from the frequency band of the intrusion noise, and the influence of the intrusion noise is reduced. Therefore, the spreading factor N can be made smaller than that in the first embodiment.

Here, the maximum frequency f _r of the noise band, when the voltage signal band f _V and frequency converted frequency f _r, defines the relation between the spreading factor N as following equation (1). Thereby, it is possible to effectively suppress the intrusion noise by obtaining the spreading factor N.

N> (f _r −f _r ) / f _V (1)

  By applying the spreading factor N calculated as described above to the first embodiment, it is possible to effectively suppress intrusion noise from a strong electromagnetic field even in a frequency band that is easily affected by intrusion noise.

  Further, by applying the spreading factor N to the second embodiment, it is possible to reduce the influence of the intrusion noise by moving the modulation signal Vm away from the intrusion noise band, and to obtain the effect of suppressing the noise of the spread spectrum modulation. .

  Further, in the first and second embodiments, although there is an effect in suppressing the patterned noise defined by the high voltage noise test standard, noise having a random frequency band or level that is not defined by this standard has invaded. In some cases it was difficult to effectively suppress this. However, by using spread spectrum, an effect can also be obtained in suppressing random noise.

  Similar to the first and second embodiments, the demodulator 205, the frequency converter 307, the high-pass filter 308, and the demodulator 205 may be included in the voltage measurement device 106. Even in this case, the same function as described above can be obtained.

  As described above, in the present embodiment, spread spectrum modulation is applied in the modulation unit 203. As a result, when the influence of the intrusion noise is different as shown in the first and second embodiments, a different spreading factor N can be set for each, and a signal-to-noise ratio higher than a predetermined value can be ensured.

Embodiment 4 FIG.
In the present embodiment, the level of the voltage signal input to the frequency conversion unit 306 is attenuated according to the noise intensity. A different part from Embodiment 2 is demonstrated.

  FIG. 4 is a diagram illustrating a configuration example of the voltage probe 104c of the present embodiment. The voltage probe 104c includes a voltage measurement terminal 201, an attenuator 202, a modulator 203, an antenna 409, a detector 410, a voltage controller 411, a variable attenuator 412, a frequency converter 306, and a transmission cable. 204, a frequency conversion unit 307, a high-pass filter 308, and a demodulation unit 205. As in the second embodiment, the voltage probe 104c is directly connected to the voltage measurement device 106.

  The antenna 409 receives intrusion noise from the strong electromagnetic field 107. The detection unit 410 converts the intensity of noise received by the antenna 409 into a voltage value. The voltage control unit 411 determines the signal level of the modulation signal Vm transmitted through the transmission cable 204 based on the voltage value obtained by the detection unit 410, and outputs the attenuation level Vc. The variable attenuator 412 attenuates the modulation signal Vm according to the attenuation level Vc.

  In the voltage probe 104c, the antenna 409 receives intrusion noise from the strong electromagnetic field 107, and the detection unit 410 converts the intensity of this noise into a voltage value. The voltage control unit 411 determines the signal level of the modulation signal Vm transmitted through the transmission cable 204 based on this voltage value, and outputs the attenuation level Vc expressing the attenuation level to the variable attenuator 412. As a method for determining the signal level, for example, a table in which the signal level of the modulation signal Vm is determined in advance according to the voltage value output from the detection unit 410 is provided, and the intrusion noise ratio (C / N) is determined based on this table. ) Is a method for determining a signal level that can be a constant value, but is not limited thereto. Then, the variable attenuator 412 attenuates the modulation signal Vm according to the attenuation level Vc. As a result, signal transmission in accordance with the intrusion noise level of the strong electromagnetic field 107 becomes possible, and the C / N can be kept at a predetermined level or higher. The operation of the other configuration is as described above.

  Specifically, the voltage control unit 411 performs an operation of decreasing the attenuation amount of the variable attenuator 412 as the level of noise entering the transmission cable 204 increases. For example, when the intrusion noise increases by 3 dB, an operation of decreasing the attenuation amount by 3 dB is performed. The operation described above is to change the signal level and should be applied when the digital signal system is adopted.

  As in the second embodiment, the frequency measuring unit 307, the high-pass filter 308, and the demodulating unit 205 may be included in the voltage measuring device 106 in order to reduce the size of the voltage probe 104c. Even in this case, the same function as described above can be obtained.

  Moreover, although Embodiment 2 was demonstrated, it is not limited to this, It can apply also to Embodiment 1,3.

  As described above, in the present embodiment, the voltage control unit 411 attenuates the level of the modulation signal Vm according to the level of intrusion noise from the strong electromagnetic field 107. As a result, the ratio of the intrusion noise (C / N ratio) to the modulation signal Vm level can be made constant. Further, when the digital method is used, an effect that intrusion noise can be stably suppressed can be obtained.

Embodiment 5 FIG.
In the present embodiment, a case will be described in which voltage measurement is performed at a plurality of locations with one voltage probe. A different part from Embodiment 3 is demonstrated.

  FIG. 5 is a diagram illustrating a configuration example of the voltage probe 104d according to the present embodiment. The voltage probe 104d includes voltage measuring terminals 201-1 to 201, attenuators 202-1 to 202-1, modulators 203-1 to 203, a multiplexer 513, a frequency converter 306, a transmission cable 204, The frequency conversion unit 307, the high-pass filter 308, the signal distribution unit 514, and the demodulation units 205-1 to 205-3 are configured. Similarly in the present embodiment, the voltage probe 104d is directly connected to the voltage measuring device 106a. Here, as an example, a case where there are three measurement locations will be described, but this is not a limitation. The present invention can also be applied to the case of two places or four or more places. Note that the voltage measuring device 106a is configured to include a channel capable of inputting three or more signals as an example. However, like the voltage measuring device 106, the voltage measuring device 106a may be a measuring device having a general configuration.

  The voltage measurement terminals 201-1 to 20-3 are connected to the measurement object and obtain voltage signals V1 to V3 at the respective observation points. The attenuators 202-1 to 202-1 attenuate the voltage signals V1 to V3 obtained at the voltage measurement terminals 201-1 to 201-3, respectively. Modulation section 203-1 performs spread spectrum modulation using code A and outputs modulated signal Vm1. Modulation section 203-2 performs spread spectrum modulation using code B and outputs modulated signal Vm2. Modulator 203-3 performs spread spectrum modulation using code C and outputs modulated signal Vm3.

  The multiplexing unit 513 multiplexes the modulation signals Vm <b> 1 to Vm <b> 3 (code division multiplexing: CDM (Code Division Multiplex)) to generate the modulation signal Vm, and outputs the modulation signal Vm to the frequency conversion unit 306. The signal distribution unit 514 outputs the modulation signal Vm to each of the demodulation units 205-1 to 205-1.

  Demodulation section 205-1 performs despreading using code A to obtain demodulated signal V1, and outputs it to voltage measurement section 106a. Demodulation section 205-2 performs despreading using code B to obtain demodulated signal V2, and outputs it to voltage measurement section 106a. Demodulation section 205-3 despreads using code C to obtain demodulated signal V3, and outputs it to voltage measurement section 106a.

  Then, the voltage measuring device 106a performs signal processing on each of the input voltage signals V1 to V3, and provides a voltage waveform to the measurer.

  As in the first to fourth embodiments, in order to reduce the size of the voltage probe 104d, the frequency conversion unit 307, the high-pass filter 308, and the demodulation units 205-1 to 205-3 are provided inside the voltage measurement device 106a. It is also possible. Even in this case, the same function as described above can be obtained.

  As described above, in the present embodiment, when there are a plurality of voltage measurement locations, the voltage signals Vm obtained by modulating and multiplexing the voltage signals V1 to V3 obtained from the respective measurement locations using different codes. Is transmitted to a plurality of voltage signals Vm in front of the voltage measuring device 106a and demodulated using each code to obtain voltage signals V1 to V3 and input them to the voltage measuring device 106a. It was decided. As a result, even when there are a plurality of voltage measurement points, there is an effect that multiplexing can be performed without preparing a transmission cable and voltage signals can be transmitted without being affected by intrusion noise. That is, there is an effect that the configuration can be simplified without using a plurality of voltage probes.

DESCRIPTION OF SYMBOLS 101 Noise test apparatus 102 Noise injection cable 103 Electronic device 104,104a, 104b, 104c, 104d Voltage probe 105 Transmission cable 106,106a Voltage measurement apparatus 201, 201-1-3 Voltage measurement terminal 202, 202-1-3 Attenuator 203, 203-1 to 3 Modulator 204 Transmission cable 205, 205-1 to 3 Demodulator 306 Frequency converter 307 Frequency converter 308 High-pass filter 409 Antenna 410 Detector 411 Voltage controller 412 Variable attenuator 513 Multiplexer 514 Signal distributor

Claims (12)

A voltage probe connected to a voltage measuring device for measuring voltage,
A voltage measuring terminal for obtaining a voltage signal indicating the voltage at the observation point;
Attenuating means for attenuating the voltage signal by a predetermined attenuation amount;
Modulating means for modulating the attenuated voltage signal in the frequency range of the radio wave region and outputting a modulated signal;
A transmission cable for transmitting the modulated signal;
Demodulating means for outputting the voltage signal obtained by demodulating the modulated signal transmitted by the transmission cable to the voltage measuring device;
A voltage probe comprising: further,
First frequency converting means for converting the frequency of the modulated signal and outputting the frequency-converted modulated signal to the transmission cable;
Second frequency conversion means for converting the frequency-converted modulated signal transmitted by the transmission cable into a frequency before frequency conversion by the first frequency conversion means;
A high-pass filter that cuts off a noise band of the modulation signal after frequency conversion by the second frequency conversion means and outputs to the demodulation means;
The voltage probe according to claim 1, comprising: The modulation means, when using spread spectrum modulation, based on the frequency amplitude characteristics of known noise generated by a strong electromagnetic field, set a spreading factor to ensure a signal-to-noise ratio equal to or higher than a predetermined value,
The voltage probe according to claim 1 or 2, wherein further,
An antenna that receives intrusion noise,
Detecting means for converting the noise level into a voltage value and outputting the voltage value;
Voltage control means for determining a signal level of a modulation signal transmitted through the transmission cable based on the voltage value and outputting an attenuation level;
Variable attenuation means for attenuating and outputting the modulation signal output from the modulation means according to the attenuation level;
The voltage probe according to claim 1, 2, or 3. A voltage probe connected to a voltage measuring device for measuring voltage,
A plurality of voltage measurement terminals for obtaining one voltage signal indicating a voltage at a plurality of observation points, respectively;
Attenuation means equal in number to the voltage measurement terminals, each connected to one voltage measurement terminal and attenuating a voltage signal by a predetermined attenuation amount
Each of which is connected to one attenuating means and performs spread spectrum modulation of the attenuated voltage signal using a different code, and the same number of modulating means as the voltage measuring terminals;
Multiplexing means for multiplexing the modulation signals output from the respective modulation means into one modulation signal;
First frequency conversion means for converting the frequency of the multiplexed modulation signal and outputting the frequency-modulated modulation signal;
A transmission cable for transmitting the modulated signal after the frequency conversion;
Second frequency conversion means for converting the frequency-converted modulated signal transmitted by the transmission cable to a frequency before frequency conversion by the first frequency conversion means;
A high-pass filter that blocks and outputs a noise band of the modulation signal after frequency conversion by the second frequency conversion means;
Signal distribution means for distributing the modulated signal after passing through the high-pass filter in the same number as the voltage measurement terminals;
A demodulator having the same number as that of the voltage measuring terminals, each of which receives the modulated signal after distribution, and outputs a voltage signal obtained by demodulating with the code used in the corresponding modulating unit, to the voltage measuring device;
A voltage probe comprising: The first frequency converting means converts the frequency of the modulation signal from the AF region to the RF region through the IF region,
The second frequency converting means converts the frequency of the modulation signal from the RF region to the AF region through the IF region,
The voltage probe according to claim 2 or 5, wherein A voltage measurement system comprising a voltage measurement device for measuring a voltage, a voltage probe, and a transmission cable connecting between the voltage measurement device and the voltage probe,
The voltage probe is
A voltage measuring terminal for obtaining a voltage signal indicating the voltage at the observation point;
Attenuating means for attenuating the voltage signal by a predetermined attenuation amount;
Modulating means for modulating the attenuated voltage signal in the frequency range of the radio wave region and outputting a modulated signal;
With
The transmission cable transmits the modulation signal to the voltage measuring device,
The voltage measuring device includes:
Demodulation means for demodulating the modulation signal transmitted by the transmission cable to obtain the voltage signal;
A voltage measurement system comprising: further,
The voltage probe is
First frequency converting means for converting the frequency of the modulated signal and outputting the modulated signal after frequency conversion to the transmission cable;
With
The voltage measuring device includes:
Second frequency conversion means for converting the frequency-converted modulated signal transmitted by the transmission cable into a frequency before frequency conversion by the first frequency conversion means;
A high-pass filter that cuts off a noise band of the modulation signal after frequency conversion by the second frequency conversion means and outputs to the demodulation means;
The voltage measurement system according to claim 7, further comprising: The modulation means, when using spread spectrum modulation, based on the frequency amplitude characteristics of known noise generated by a strong electromagnetic field, set a spreading factor to ensure a signal-to-noise ratio equal to or higher than a predetermined value,
The voltage measurement system according to claim 7 or 8, wherein further,
The voltage probe is
An antenna that receives intrusion noise,
Detecting means for converting the noise level into a voltage value and outputting the voltage value;
Voltage control means for determining a signal level of a modulation signal transmitted through the transmission cable based on the voltage value and outputting an attenuation level;
Variable attenuation means for attenuating and outputting the modulation signal output from the modulation means according to the attenuation level;
The voltage measurement system according to claim 7, 8 or 9. A voltage measurement system comprising a voltage measurement device for measuring a voltage, a voltage probe, and a transmission cable connecting between the voltage measurement device and the voltage probe,
The voltage probe is
A plurality of voltage measurement terminals for obtaining one voltage signal indicating a voltage at a plurality of observation points, respectively;
Attenuation means equal in number to the voltage measurement terminals, each connected to one voltage measurement terminal and attenuating a voltage signal by a predetermined attenuation amount
Each of which is connected to one attenuating means and performs spread spectrum modulation of the attenuated voltage signal using a different code, and the same number of modulating means as the voltage measuring terminals;
Multiplexing means for multiplexing the modulation signals output from the respective modulation means into one modulation signal;
First frequency conversion means for converting the frequency of the multiplexed modulation signal and outputting the frequency-modulated modulation signal;
With
The transmission table transmits the modulated signal after the frequency conversion to the voltage measuring device,
The voltage measuring device includes:
Second frequency conversion means for converting the frequency-converted modulated signal transmitted by the transmission cable to a frequency before frequency conversion by the first frequency conversion means;
A high-pass filter that blocks and outputs a noise band of the modulation signal after frequency conversion by the second frequency conversion means;
Signal distribution means for distributing the modulated signal after passing through the high-pass filter in the same number as the voltage measurement terminals;
Each of the modulated signals after distribution is input and demodulated by the code used in the corresponding modulating means to obtain a voltage signal, the same number of demodulating means as the voltage measuring terminals,
A voltage measurement system comprising: The first frequency converting means converts the frequency of the modulation signal from the AF region to the RF region through the IF region,
The second frequency converting means converts the frequency of the modulation signal from the RF region to the AF region through the IF region,
The voltage measurement system according to claim 8 or 11, wherein

Images