JP2001349915A - Impulsive noise detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impulsive noise detector capable of easily detecting an impulsive noise radio wave. SOLUTION: After the signal received by an antenna 10 is amplified by a non-linear amplifier 12, the detected signal obtained by detecting the amplified signal with a detector 13 is outputted to a display 17. A non-linear area of the non-linear amplifier is set in the level range inputted when the impulsive noise is received, the gain is also increased in the non-linear area as the input level is increased, and the input level range lower than the non-linear area is set to be a low gain area. The impulsive noise is expanded, the other noise is compressed and displayed, and the output level based on the impulsive noise changing in the reception level is largely fluctuated as a point of observation moves. Therefore, the signal which is largely fluctuated in the peak accompanying the movement is easily judged to be an impulsive noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impulse noise detecting device.

[0002]

2. Description of the Related Art For example, when wind blows during drying in winter, a phenomenon that electric discharge occurs from an insulator may be observed. Radio waves are emitted by this discharge. Since the emitted radio waves are impulse-like, the frequency bandwidth is wide and there are components that match the reception frequency of television or radio. Since this component is unnecessary for radio waves and TV radio waves,
It becomes a noise radio wave and contributes to radio interference. In particular, at locations relatively distant from a broadcasting station (television tower), the level of a broadcast wave from a television or the like also becomes small, so that it is easily affected by radio waves radiated from the insulator.

[0003] Therefore, if there is a house that has been affected by radio interference,
It is necessary to identify the insulator that emits impulsive noise radio waves from the insulators installed around the house and take measures such as replacement. Therefore, a device for detecting an insulator that is a source of the impulsive noise radio wave is required.

FIG. 1 shows an example of a conventional radio wave detecting device for detecting an impulse noise radio wave. As shown in the figure, the output of an antenna 1 for receiving a radio wave is connected to an amplifier 2, where a received signal received by the antenna 1 is amplified. Then, the amplified signal is supplied to the detector 3, where AM detection is performed. Further, the output of the detector 3 is connected to a low-pass filter 4 to remove harmonics generated at the time of detection so that only the fundamental wave component passes.
A signal processing circuit 5 is connected to the subsequent stage of the low-pass filter 4 so as to convert a detection signal passed through the low-pass filter 4 into data that can be displayed on a display 6. Thus, a time-varying radio signal is displayed as a voltage or current signal on the display 6 so that the user can confirm it.

[0005]

However, in the above-mentioned conventional apparatus, the impulse noise radio wave cannot be sufficiently detected for the following reasons. That is,
FIG. 2 shows the detection output of an impulse noise radio wave when there is no broadcast wave, communication wave, or the like (the output of the signal processing circuit 5 of the conventional device and displayed on the display 6).

FIG. 1 shows an impulse noise radio wave,
Other noises are mixed. Then, the impulse noise radio waves are mixed into other noises, and it is difficult to specify at a glance whether or not the impulse noise exists.

Further, assuming a space in which an impulse noise radio wave is generated in an environment where a broadcast wave and a communication wave exist, the impulse noise radio wave is superimposed on the broadcast wave. Since the signal level is lower than that of the broadcast wave, there is a problem that the impulse noise radio wave is easily overlooked.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to solve the above-mentioned problems and to provide an impulse noise detecting device capable of reliably detecting an impulse noise radio wave. To provide.

[0009]

In order to achieve the above object, an impulse noise detecting apparatus according to the present invention comprises:
Detection means for detecting a signal based on the received signal received by the antenna, and output means for outputting a detection signal in the detection means, between the antenna and the detection means,
A non-linear amplifier whose gain changes according to the input signal level is provided.

The change in gain is preferably such that the gain increases as the input signal level increases. In the embodiment, the output unit corresponds to the “signal processing circuit 40 and the display 41”, but may be an indicator or other display unit, or a printing unit such as a printer instead of the display unit. Means can be applied.

Preferably, the non-linear amplifier has a non-linear region set in a level range inputted to the non-linear amplifier at least when receiving an impulse noise to be detected, and in the non-linear region, the input level increases. (Claim 2).

The level of an impulse noise radio wave discharged from an insulator or the like at a discharged source is substantially constant. Therefore, if the distance between the source and the observation point changes,
Received signal levels also differ greatly. On the other hand, the level of a received signal such as a broadcast wave does not change significantly even when the observation point is slightly moved. In the case of other noises, when the observation point is changed, noise existing around the movement destination is detected, so that the noise is also within a substantially constant range.

Therefore, when the observation point is moved, the received signal level changes based on the impulse noise and the other signals are constant. If there is noise and there is no fluctuation, it can be determined that there is no impulsive noise. At this time, since the non-linear amplifier is used in the present invention, the gain changes with the fluctuation of the level, so that the output of the non-linear amplifier significantly changes with the movement of the observation point when receiving impulse noise. Therefore, it becomes easy to recognize the presence or absence of impulsive noise.

[0014] More preferably, the nonlinear amplifier includes:
The level range lower than the level range input to the non-linear amplifier when the impulse noise is received is set in a low gain region (claim 3).

[0015] In this manner, other noise having a small input level is compressed and output and displayed, so that the presence or absence of impulsive noise becomes more remarkable. In addition, since some output waveform (output level is not 0) appears even if it is compressed, it can be easily confirmed that the device is operating normally even if there is no impulsive noise.

The antenna may have good directivity (claim 4). In other words, if there is directivity, it is easy to understand in which direction the source of the impulse noise exists.

In addition, between the antenna and the non-linear amplifier, extraction means (in the embodiment, the frequency conversion unit 20)
The extraction means may be configured to extract a signal in an observation frequency band in which there is no non-detection target signal having a higher reception level than an impulsive noise radio wave such as a broadcast wave (claim 5).

Focusing on the fact that the frequency characteristics of the impulse noise radio wave are flat, the observation frequency is set to a frequency band where there is no non-detection target such as a communication wave or a broadcast wave at the observation point. The radio wave in is extracted and detected. Thereby, the impulse noise radio wave existing in the observation frequency band can be detected without being interfered by a broadcast wave, a communication wave, or the like having a high radio wave intensity which is not an observation target. When an impulse noise radio wave is detected in the observation frequency band, it can be said that the radio wave exists in a frequency band such as a broadcast wave.

[0019]

FIG. 3 shows a first embodiment of the present invention. As shown in the figure, the output of an antenna 10 for receiving a radio wave is connected to a non-linear amplifier 12, where the received signal received by the antenna 10 is amplified. The use of the non-linear amplifier 12 as the amplifier as described above
This is a feature of the present invention. Then, the amplified signal is supplied to a detector 13 where AM detection is performed. That is, a signal of a predetermined frequency is detected.

Further, the output of the detector 13 is connected to a low-pass filter 14 so that harmonics generated at the time of detection are removed, and only the fundamental wave component is passed. Then, the signal passed through the low-pass filter 14 is given to the rectifier 15,
Make the signal polarity (positive / negative) uniform.

A signal processing circuit 16 is connected to a stage subsequent to the rectifier 15. The signal processing circuit 16 performs a numerical operation for displaying the received signal on the display 17 as in the related art. As a result, the time-varying radio signal is displayed on the display 17 as a voltage or current signal so that the user can confirm it.

The antenna 10 used in this embodiment is an antenna having strong directivity. As a result, it is possible to receive only radio waves coming from within a specific angle range facing the antenna 10.

Next, a non-linear amplifier 1 which is a main part of the present invention will be described.
2 will be described. A nonlinear amplifier is an element having a logarithmic characteristic (for example, the collector current of a bipolar transistor −
(The voltage characteristic between the base and the emitter is used.), And the gain is made variable. That is, the rate of increase of the output with respect to the increase of the input is different. FIG. 4 shows an example of the input / output characteristics.

As shown in the figure, in the present embodiment, a low gain region is obtained in a low input level range (−90 dB or less), a saturation region is obtained in a high input level range (−60 dB or more), and a saturation region is obtained in an intermediate range. This is a nonlinear region where the gain changes according to the input voltage. Then, the input level range of the saturation region is set to the input level to the nonlinear amplifier 12 when the broadcast wave / communication wave is received, and the input level range of the nonlinear region becomes the input level of the impulsive noise to be detected. The input level range in the low gain region is adjusted to be the input level of other noise.

The adjustment of the input level range of each area is as follows.
As shown in FIG. 5, for example, the nonlinear amplifier 12 is connected in series with a first amplifier 12a, a nonlinear circuit element 12b, and a second amplifier 12c, and the characteristics of the elements 12a to 12c are appropriately set, so that the range of the nonlinear region is reduced. Can be adjusted. As is apparent from the figure, the first and second amplifiers 12
Each of a and 12c is constituted by a linear amplifier having a different saturation level.

A level diagram showing the output level of each element when an input of -50 dB to -100 dB is applied to the nonlinear amplifier 12 composed of elements having such input / output characteristics is shown in FIG. become. As is clear from the figure, the final change in output level when the input changes in steps of -10 dB changes most when the input changes from -80 to -70 dB. If the input is -50
At dB and -60 dB, the output levels match at 0 dB. When the input is -100 dB or less, the output level is almost the same as that at -100 dB.

As described above, the provision of the non-linear amplifier 12 has the following effects. That is, it is assumed that the reception signal received by the antenna 10 is as shown in FIG. This illustrated example shows a state in which impulsive noise to be observed and various noises that are not to be observed are mixed.

By amplifying the signal having such an input waveform through the nonlinear amplifier 12, the output of the nonlinear amplifier 12 becomes as shown in FIG. As is clear from the figure, even if the input level does not make a significant difference between the impulse noise and other normal noise, the normal noise is compressed in the low gain region, and the output level is reduced. On the other hand, in the case of impulsive noise to be detected,
Because it belongs to the nonlinear region, the input level is extended,
Output level increases. Therefore, in the output waveform, those based on the impulse noise are significantly different from those based on the other noise, and it is easy to discriminate between them.

Further, in this embodiment, the output of the nonlinear amplifier 12 is passed through the rectifier 15 through the low-pass filter 14, so that the signal waveform shown in FIG. 8 is inverted on the negative side as shown in FIG. Only the waveform. The waveform shown in FIG. 9 is output and displayed on the display 17 as an output waveform (measurement waveform). Thus, the appearance of the impulse noise can be distinguished very clearly.

In the illustrated example, a waveform based on a signal such as a broadcast wave is not shown. However, the broadcast wave and the like are originally provided with a large input level and are located in a saturation region, and are output and displayed on the display 17. The waveform is not an impulse having a sharp tip as shown in FIG. 9 but an overflow waveform, which can be distinguished therefrom.

In this embodiment, other noises are located in the low gain region of the nonlinear amplifier 12 and are compressed. However, the present invention is not limited to this. In the case of a signal having a fixed input level or less, the output level may be set to 0, or conversely, normal linear amplification may be performed for the reason described later. Further, it may be a non-linear region.

However, when threshold processing is performed, if no impulse noise or broadcast wave is present, the output waveform displayed on the display 17 is constant at 0 level. It is unclear whether there is a failure or no impulsive noise, and the user is anxious. Therefore, by setting the input level of other noises in the low gain region as in the present embodiment, when no impulse noise is present, an output waveform composed of noise having a small output level is displayed. This is preferable because the user can reliably recognize the absence of impulsive noise.

The reason why the constant gain region does not need to be set in accordance with the input level of other noises is that the input level of the impulse noise is set to a non-linear region.
Specifically, it is as follows.

That is, in the case of other noise, it is white noise or the like existing around the measurement point, and when the measurement point is moved, it is noise existing around each moved measurement point. Therefore, when the measurement point is moved, noise at the movement destination is detected, so that the measurement level is within a certain input level range at any measurement point.

On the other hand, in the case of impulse noise generated due to a discharge phenomenon such as insulator noise, the generation level of the impulse noise at the transmission source is constant. Therefore, the closer the distance between the point of occurrence of the impulse noise to be observed and the observation point, the greater the detected output level. In addition, the change of the output level with the change of the distance increases and decreases exponentially.

As a result, when measured by the impulse noise detection device while moving, the output waveform displayed on the display 17 is such that the waveform portion based on the impulse noise becomes larger as it approaches the source. In addition, the input level of the impulse noise is in a non-linear region, and the gain increases as the input level increases. Therefore, the degree of the increase in the output level when approaching the transmission source increases. That is, as shown in FIG. 10 to FIG. 12, when the light source approaches the transmission source, the light source suddenly expands (the waveform part becomes higher), and when it is farther away, the light source rapidly contracts (the waveform part becomes lower). Further, when the distance further increases, it becomes difficult to distinguish the noise from other noises.

Therefore, when the display 17 is moved while looking at the display 17, the peak of the waveform portion corresponding to the impulse noise rises and falls with the movement (other noises and broadcast waves do not fluctuate up and down). Since the noise portion can be easily recognized and the position where the peak is maximum can be easily specified, the position of the transmission source can be easily specified.

As described above, even when the input level of the other noise is not set in the low gain region, the impulse noise can be detected. Therefore, the low gain region is set in accordance with the input level of the other noise and is shown in FIG. When the output levels of the other noise portions are compressed as described above, the impulse noise can be recognized more remarkably. That is, when there is no impulsive noise, the waveform portion having a low level shown in FIG. 9 is output as a whole, and when approaching the source of the impulse noise, a waveform portion having a high peak suddenly appears. In the case of a broadcast wave or the like, a waveform portion that overflows the output range is output, and its peak position does not change much even if the waveform portion moves. Therefore, the peak position that changes with movement can be identified as impulsive noise.

Further, in the present embodiment, since the directional antenna is used as the antenna 10, it is possible to easily know in which direction the insulator existing in the direction of the impulse noise radio wave with respect to the inspection point P. That is, as shown in FIG. 13, the inspector M standing at the inspection point P gradually rotates the directional area of the antenna 11 within a range of 360 degrees while watching the detection output output to the display 17.
Then, when the insulator G generating the impulse noise radio wave enters the directivity region R, an output as shown in FIGS. 9 to 12 is displayed on the display 17, and the insulator G1 not generating the impulse noise radio wave is displayed. Does not display a detection output with a constant amplitude on the display even if the input signal enters the directivity area. Therefore, the direction can be determined by checking the display.

Therefore, in order to detect the insulator generating the impulse noise radio wave, if the direction is detected by the above method, the insulator is moved in the detected direction. At this time, the directional direction of the antenna 10 is the moving direction.
Then, the user moves while watching the amplitude of the detection signal displayed on the display 17, and it can be determined that the surrounding insulator having the maximum amplitude is generating an impulse noise radio wave.
Further, as shown in FIGS. 10 to 12, the peak sharply increases when approaching the insulator to be detected, so that the insulator can be easily detected.

In the above embodiment, an antenna having a high directivity is used as the antenna 11, but the present invention is not limited to this, and an antenna having no directivity may be used. In this case, it is possible to check whether or not an insulator generating an impulse noise radio wave exists around the inspection point.

FIG. 14 shows a second embodiment of the present invention. As shown in the figure, in the present embodiment, a frequency conversion unit 20 is provided between the antenna 10 and the nonlinear amplifier 12, and a signal of a predetermined frequency obtained by frequency-converting a signal received by the antenna 10 is provided. To process.

That is, the frequency conversion section 20 includes a high-frequency band-pass filter 21 for passing a signal in a predetermined frequency range out of the reception output of the antenna 10, and a high-frequency amplifier for amplifying the signal passing through the filter to a predetermined level. 22; a frequency converter (mixer) 23 for converting the frequency of the signal amplified by the high-frequency amplifier 22; and a predetermined frequency (intermediate frequency) among the signals frequency-converted by the frequency converter 23. An intermediate frequency band-pass filter 24 and a local oscillator (synthesizer) 25 for providing a local oscillation signal to the frequency converter 23 are provided.

The high-frequency band-pass filter 12 is, for example, 3
It is a relatively wide band whose pass band is in the range of 00 to 600 [MHz]. The frequency converter 23 is a mixer for frequency-mixing the two input signals, that is, the signal received and amplified by the antenna 10 and the local oscillation signal from the local oscillator 25. The frequency is converted. That is, assuming that the frequency of the radio wave received by the antenna 10 is f _RF and the frequency of the local oscillation signal (synthesizer signal) supplied to the frequency converter 23 is f _LO , the frequency f f of the intermediate frequency converted by the frequency converter 23 _IF is f _RF = f _LO + f _IF .

As a result, the frequency converter 20 lowers the received high frequency to another low frequency (intermediate frequency). And, because of the use of intermediate frequency band-pass filter 24 so that the f _IF constant frequency, the above equation, by selecting the observation frequency f _RF by suitably selecting the frequency f _{L O} of the local oscillator 25 And the observation bandwidth becomes the bandwidth of the intermediate frequency band-pass filter. That is, when the frequency of the local oscillator 25 is changed while radio waves of the same frequency are being received, the frequency of the intermediate frequency output from the frequency converter 23 also changes.

Since the output of the frequency converter 23 is supplied to the intermediate frequency band-pass filter 24, it is natural that if the frequency of the converted intermediate frequency is not in the pass band of the intermediate frequency band-pass filter 24, , Cannot pass through the intermediate frequency band-pass filter 24. Therefore, even if the input signals have the same frequency, they can be passed or not passed through the intermediate frequency band-pass filter 24 by changing the oscillation frequency of the local oscillator 25.

In other words, when radio waves having a plurality of different frequencies are received by the antenna 10, the frequencies of the plurality of received signals are frequency-mixed with the output of the local oscillator 25 and converted to a predetermined intermediate frequency. Then, the frequency of the converted intermediate frequency is applied to the intermediate frequency band-pass filter 24.
Are selected and passed. Therefore, by varying the oscillation frequency of the local oscillator 25, it is possible to select and output a reception signal having a desired frequency that satisfies the above equation.

This output signal is output to the nonlinear amplifier 1
2 given. Since the configuration and operation and effects after the nonlinear amplifier 12 are the same as those of the first embodiment, the corresponding members are denoted by the same reference numerals, and detailed description thereof will be omitted.

Next, the operation of the above-described device will be described. FIG. 15 shows a time waveform of the radio wave of the impulse noise radio wave Y when the broadcast wave and the communication wave X are mixed. As shown in the figure, while broadcast waves and the like are generated regularly, impulsive noise radio waves are generated randomly and their amplitudes are also different.

FIG. 16 shows the frequency spectrum of the received signal. As is apparent from this figure, the broadcast wave and the communication wave are discretely generated at a predetermined frequency, but the impulse noise radio waves are present over the entire frequency range. Although the signal level is lower than that of a broadcast wave or the like, when focusing only on the impulse noise radio waves, although there is a variation in magnitude, there is a noise radio wave of a certain frequency component such as a broadcast wave and a frequency band without a broadcast wave or the like. It can be said that the generation state of the noise radio wave is the same.

Therefore, it is normally preferable to examine the frequency components of the target broadcast wave or the like in order to measure the influence of the noise radio wave on the broadcast wave or the like. Hidden by Therefore, in this embodiment, it is equivalent to the frequency domain of the broadcast wave or the like,
An area where there is no strong broadcast wave or the like is set as an observation frequency band, and the oscillation frequency of the local oscillator 25 is set so that only signals existing in the observation frequency band can be detected.

As a result, the frequency conversion section 20 can select and extract only the impulse noise radio waves and supply them to the non-linear amplifier 12 and the detector 13. Then, the time waveform of the detection signal in the detector 13, that is,
FIG. 17 shows an example of an output waveform to the display 17. In this way, only the impulse noise radio waves can be extracted and output and displayed.

That is, the frequency converter 20 mixes the frequency of the received signal with the output of the local oscillator 25 by the frequency converter 23 and passes the intermediate signal through an intermediate band-pass filter, so that the frequency of the frequency-mixed intermediate frequency is reduced. Only a received signal having a predetermined frequency is extracted. The frequency of the received signal to be extracted was set to an observation frequency band in which no broadcast wave or the like exists. As a result, the impulse noise radio wave can be reliably extracted, and the noise radio wave has a flat frequency characteristic. Therefore, when the noise radio wave is detected by this device, the noise radio wave exists even in a frequency band such as a broadcast wave. Then it can be estimated.

Further, due to the effect of the provision of the nonlinear amplifier 12, the peak of the impulse noise greatly varies depending on the distance from the transmission source to the observation position.

Although not shown, when there is no impulse noise radio wave in this observation frequency band, the signal waveform as shown in FIG. 17 is not produced, and the output is almost zero level. Thereby, it can be understood whether or not an impulse noise radio wave is generated based on whether or not a signal of a certain level or more is detected (displayed on the display 17). In the case where the setting of the observation frequency band is incorrect and the frequency region becomes a frequency region where a broadcast wave or the like exists, the input voltage becomes extremely large (the input voltage is completely swung in the range shown in FIG. 17), so that such a state is also easy. Can be identified.

As described above, by setting a frequency region where a broadcast wave or the like does not exist and detecting a signal existing in the frequency region, an impulse noise radio wave can be extracted and detected, and an impulse noise wave can be detected in the frequency region. When an impulsive noise radio wave is detected, it can be estimated that an impulse noise radio wave is also generated in a frequency region such as a target broadcast wave.

Further, if the oscillation frequency of the local oscillator can be changed as in the present embodiment, it is possible to set the observation frequency band in a frequency region where there is no radio wave that is not a detection target such as a broadcast wave in any region. Can be used, increasing versatility. Further, fine adjustment of the observation frequency band can be performed, and the impulsive noise radio wave can be detected more reliably.

Although the apparatus shown in FIG. 14 can extract and detect a predetermined frequency signal by a kind of heterodyne method in which the frequency conversion is one step, the present invention is not limited to this. For example, FIG. As shown, it may be constituted by a kind of superheterodyne type spectrum analyzer in which the frequency conversion is performed in two stages. In any of the formats shown in FIGS. 14 and 18, the non-linear amplifier may also have the function of the intermediate frequency amplifier in the heterodyne system, or may be provided separately.

In the above embodiment, the oscillation frequency of the local oscillator 25 is made variable by manual operation. However, the present invention may be fixed. That is, since the frequency of the broadcast wave or the like is known in advance, it is also known which frequency range should be set as the observation frequency band. Therefore,
By setting the oscillation frequency of the local oscillator to the predetermined observation frequency band, an impulse noise radio wave can be selectively extracted and detected, and the apparatus configuration can be simplified and the cost can be reduced.

Furthermore, in the above-described embodiment, the presence or absence of the impulse noise radio wave is checked while the operator looks at the display 17, but when only the impulse noise radio wave is detected (input voltage: medium), the broadcast The level of each input voltage differs greatly when a wave or the like is also detected (input voltage: large) and when there is no impulsive noise radio wave (input voltage: small). Therefore, the boundaries between the states are set to thresholds Th1 and Th2 (see FIG. 17). If the signal level of the detection output is greater than Th1, it is determined that a broadcast wave or the like is being received, and Th1 is changed to Th2. It can be determined that there is an impulse noise radio wave in the case of, and that there is no impulse noise radio wave in the case of less than Th2. This automatic judgment can be realized by the signal processing circuit 16, for example.

Further, by making the automatic determination in this way, for example, when the oscillation frequency of the local oscillator 25 is changed, the change can be made automatically. In other words, when the input voltage is larger than Th1, this can be realized by performing a process of changing the frequency by the reference pitch.

Further, the map database and the position detecting means for detecting the current position can be linked with the above embodiment. That is, for example, a device using an antenna having no directivity is installed in a vehicle such as an automobile. Then, the user moves in the inspection area using the automobile or the like. At this time, the position detecting means measures the moving position of the automobile and associates it with the map database, so that it is possible to know at what time and where. Then, by associating with the time information, it is possible to know where the car was at the time when the signal received by the antenna 11 was determined to be an impulsive noise radio wave (detected by a clock or the like built in the device). From this, the insulator emitting the impulse noise radio wave can be specified.

[0063]

As described above, in the impulse noise detection device according to the present invention, the increase or decrease of the received signal level based on the impulse noise due to the movement of the observation point is remarkably exhibited by providing the nonlinear amplifier. Therefore, impulsive noise radio waves can be reliably detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional example.

FIG. 2 is a time waveform diagram of a detection output showing an example of an impulse noise radio wave.

FIG. 3 shows a first example of the impulse noise detection device according to the present invention.
It is a figure showing an embodiment.

FIG. 4 is a diagram illustrating input / output characteristics of a nonlinear amplifier.

FIG. 5 is a diagram illustrating a nonlinear amplifier.

FIG. 6 is a diagram showing a level diagram for specifying input / output characteristics of a nonlinear amplifier.

FIG. 7 is a diagram illustrating an example of an input waveform.

FIG. 8 is a diagram showing an output waveform of the nonlinear amplifier when the input waveform shown in FIG. 7 is received.

FIG. 9 is a diagram showing an output waveform of the rectifier when the input waveform shown in FIG. 7 is received.

FIG. 10 is a diagram (part 1) illustrating a change in an output waveform displayed on a display as the observation point moves.

FIG. 11 is a diagram (part 2) for explaining a change in an output waveform displayed on the display as the observation point moves.

FIG. 12 is a diagram (part 3) illustrating a change in the output waveform displayed on the display as the observation point moves.

FIG. 13 is a diagram illustrating an operation.

FIG. 14 is a diagram showing a second embodiment of the impulse noise detection device according to the present invention.

FIG. 15 is a diagram showing a time waveform of a reception signal (before detection) of each radio wave such as each broadcast wave or an impulse noise radio wave.

FIG. 16 is a diagram showing a frequency spectrum of each radio wave shown in FIG.

FIG. 17 is a diagram illustrating an example of a time waveform of a detection (detection) output of the detection device illustrated in FIG. 14;

FIG. 18 is a diagram showing another example of the impulse noise detection device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Antenna 12 Nonlinear amplifier 13 Detector 14 Low-pass filter 15 Rectifier 16 Signal processing circuit 17 Display 20 Frequency conversion part (extraction means)

Claims (5)

[Claims] 1. A detecting means for detecting a signal based on a received signal received by an antenna, and an output means for outputting a detected signal in the detecting means, wherein an input signal level is set between the antenna and the detecting means. An impulse noise detection device comprising a non-linear amplifier whose gain changes in response to the change. 2. The non-linear amplifier, wherein a non-linear region is set in a level range input to the non-linear amplifier at least when an impulsive noise to be detected is received, and in the non-linear region, a gain increases with an increase in input level. The impulse noise detection device according to claim 1, wherein the number is also increased. 3. The non-linear amplifier according to claim 2, wherein a level range lower than a level range input to the non-linear amplifier when receiving impulse noise is set in a low gain region. 2. The impulse noise detection device according to item 1. 4. The impulse noise detection device according to claim 1, wherein the antenna has good directivity. 5. An extraction means is provided between the antenna and the nonlinear amplifier, and the extraction means is provided for an observation frequency band in which no non-detection target signal having a higher reception level than an impulse noise radio wave such as a broadcast wave does not exist. The impulse noise detection device according to any one of claims 1 to 4, wherein the device is configured to extract a signal.