JP3380524B2 - Impulse noise detector - Google Patents

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 may occur in which electric discharge occurs from an insulator. Radio waves are radiated by this discharge. Since the radiated radio wave is impulsive, it has a wide frequency bandwidth and also has a component that matches the reception frequency of television or radio. Since this component is an unnecessary component for radio and television radio waves,
It becomes a noise radio wave and becomes a cause of radio interference. In particular, at a location relatively distant from the broadcasting station (television tower), the level of the broadcast wave of the television or the like becomes small, so that it becomes easy to be affected by the radio wave radiated from the insulator.

Therefore, if there is a house with a radio disturbance,
It is necessary to identify the one emitting the impulsive noise radio wave from the insulators installed around the house and take measures such as replacement. Therefore, a device for detecting the insulator, which is the source of the impulsive noise radio wave, is required.

FIG. 1 shows an example of a conventional radio wave detection device for detecting an impulsive noise radio wave. As shown in the figure, the output of the antenna 1 that receives radio waves is connected to the amplifier 2, and the received signal received by the antenna 1 is amplified therein. Then, the amplified signal is given to the wave detector 3, and AM detection is performed there. Further, the output of the detector 3 is connected to the low-pass filter 4 to remove the 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, and the detection signal passed through the low-pass filter 4 is converted into data that can be displayed on the display 6. As a result, the 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, the above-mentioned conventional device cannot sufficiently detect the impulsive noise radio wave for the following reason. That is,
The detection output of the impulsive noise radio wave when there is no broadcast wave, communication wave, etc. (the output of the signal processing circuit 5 of the conventional device, which is displayed on the display 6) is as shown in FIG.

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

Further, assuming a space where impulse noise radio waves are generated in an environment where broadcast waves and communication waves exist, the impulse noise radio waves are superimposed on the broadcast waves, and moreover, the impulse noise radio waves Since the signal level is lower than that of broadcast waves, there is a problem that it is easy to overlook impulse noise radio waves.

The present invention has been made in view of the above background. An object of the present invention is to solve the above problems and to provide an impulse noise detecting device capable of reliably detecting impulse noise radio waves. To provide.

[0009]

In order to achieve the above-mentioned object, the impulse noise detecting apparatus according to the present invention comprises:
The detection means for detecting a signal based on the received signal received by the antenna, and an 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 (Claim 1).

The change in gain should be such that the gain increases as the input signal level increases. Further, although the output means corresponds to the “signal processing circuit 40 and the display 41” in the embodiment, it may be an indicator or other display means, or a printing means such as a printer instead of the display means, and other various outputs. Means can be applied.

Preferably, the non-linear amplifier has a non-linear region set to a level range input to the non-linear amplifier at least when receiving impulsive noise to be detected. In the non-linear region, the input level increases. Accordingly, the gain is also increased (claim 2).

The level of the impulsive noise radio wave discharged from the insulator or the like is almost constant at the discharge source. Therefore, if the distance between the source and the observation point changes,
The received signal level also differs greatly. On the other hand, the received signal level of the broadcast wave or the like does not change significantly when the observation point is moved to some extent. Further, in the case of other noises, when the observation point is moved, noise existing around the moving destination is detected, and therefore, the noise is still within a substantially constant range.

Therefore, when the observation point is moved, the received signal level changes due to the impulse noise-based signal and the other signals are constant. If there is noise and it does not fluctuate, 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 remarkably changes with the movement of the observation point when the impulsive noise is received. Therefore, it becomes easy to recognize the presence or absence of impulse noise.

More preferably, the non-linear amplifier is
A level range lower than the level range input to the non-linear amplifier when receiving impulsive noise is configured to be set to a low gain region (claim 3).

In this way, other noise with a low input level is compressed and displayed on the output, so that the presence or absence of impulsive noise becomes more noticeable. Moreover, since some output waveform (the 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 impulse noise.

Further, it is preferable that the antenna has good directivity (claim 4). In other words, if there is directivity, it is easy to understand in which direction the source of impulse noise is located.

Furthermore, the extraction means (in the embodiment, the frequency conversion section 20) is provided between the antenna and the nonlinear amplifier.
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 reception level higher than that of an impulsive noise radio wave such as a broadcast wave (claim 5).

Paying attention to the fact that the frequency characteristics of the impulsive noise radio wave are flat, the observation frequency is set to a frequency band in which there is no non-detection target such as communication waves and broadcast waves at the observation point, and the observation frequency band is set. I tried to detect and detect the radio waves in. As a result, the impulsive noise radio wave existing in the observation frequency band can be detected without being interfered by the broadcast wave, communication wave, or the like having a high radio wave intensity which is not the observation target. When the impulsive noise radio wave is detected in the observation frequency band, it can be said that the radio wave also exists in the frequency band such as the broadcast wave.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows a first embodiment of the present invention. As shown in the figure, the output of the antenna 10 for receiving radio waves is connected to the non-linear amplifier 12, and the received signal received by the antenna 10 is amplified therein. In this way, using the non-linear amplifier 12 as an amplifier
This is a feature of the present invention. Then, the amplified signal is supplied to the detector 13, and AM detection is performed there. That is, a signal of a predetermined frequency is detected.

Furthermore, the output of the detector 13 is connected to a low-pass filter 14 to remove the harmonics generated during detection so that only the fundamental wave component passes. Then, the signal passed through the low-pass filter 14 is given to the rectifier 15,
Align the signal polarities (positive / negative).

A signal processing circuit 16 is connected to the subsequent stage of the rectifier 15. The signal processing circuit 16 is adapted to perform a numerical operation for displaying the received signal on the display 17, as in the conventional case. 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 a strong directivity. As a result, it is possible to receive only the radio waves coming from within the specific angle range to which the antenna 10 faces.

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

As shown in the figure, in the present embodiment, the low gain region is in the low input level range (-90 dB or less), the saturation region is in the high input level range (-60 dB or more), and the intermediate range is. This is a non-linear region where the gain changes according to the input voltage. Then, the input level range in 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 in the nonlinear region becomes the input level of the impulsive noise to be detected, The input level range of the low gain region is adjusted to be the input level of other noise.

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

A level diagram showing the output level of each element when an input of -50 dB to -100 dB is applied to the non-linear amplifier 12 composed of elements having such input / output characteristics is shown in FIG. become. As is apparent from the figure, the final change in the output level when the input changes in steps of -10 dB changes most when the input changes from -80 to -70 dB. Also, the input is -50
At dB and -60 dB, both output levels are 0 dB and coincide with each other. When the input is -100 dB or less, the output level is almost the same as in the case of -100 dB.

By providing the non-linear amplifier 12 as described above, the following operational effects are obtained. That is, it is assumed that the received signal received by the antenna 10 is as shown in FIG. The illustrated example shows a state in which impulsive noise to be observed and various noises not to be observed are mixed.

By amplifying the signal having such an input waveform through the non-linear amplifier 12, the output of the non-linear amplifier 12 becomes as shown in FIG. As is clear from the figure, even if there is not much difference in the input level between the impulsive noise and other ordinary noise, the ordinary noise is compressed in the low gain region and its output level becomes small. On the other hand, in the case of impulsive noise to be detected,
Since it belongs to the non-linear region, the input level is extended,
The output level increases. Therefore, in the output waveform, the one based on the impulsive noise is greatly different from the one based on the impulsive noise, and the two can be easily distinguished.

Further, in the present embodiment, the output of the non-linear amplifier 12 is passed through the rectifier 15 via the low-pass filter 14, so that the signal waveform shown in FIG. 8 is inverted on the negative side and positive 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). This makes it possible to very clearly distinguish the generation of impulse noise.

Further, in the example shown in the figure, a waveform based on a signal such as a broadcast wave is not shown, but since the broadcast wave originally has a high input level and is located in the saturation region, it is output and displayed on the display 17. The waveform is not an impulse with a sharp tip as shown in FIG. 9, but an overflowed waveform, so that it can be distinguished from it.

In the present embodiment, other noises are located in the low gain region of the non-linear amplifier 12 and are compressed, but the present invention is not limited to this, and, for example, threshold processing is performed. In the case of a signal having a certain 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, in the case where threshold processing is performed, if there is no impulsive noise or broadcast wave, the output waveform displayed on the display 17 is constant at 0 level. The user is worried because it is unclear whether it is a malfunction or there is no impulsive noise. Therefore, as in the present embodiment, by setting the input level of the other noises in the low gain region, when the impulsive noise does not exist, the output waveform composed of the noise with the small output level is displayed. It is preferable because the user can surely recognize the absence of impulsive noise.

The reason why the constant gain region need not be set according to the input levels of other noises is that the input level of the impulsive noise is set to the non-linear region.
Specifically, it is as follows.

That is, in the case of other noises, it is white noise existing around the measurement point, and when moving the measurement point, 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 at any measurement point, it is within the constant input level range.

On the other hand, in the case of the impulsive noise generated by the discharge phenomenon such as the insulator noise, the generation level of the impulsive noise in the transmission source is constant. Therefore, the detected output level becomes higher as the distance between the observation target impulse noise generation position and the observation point becomes shorter. Moreover, the change in output level with the change in distance increases or decreases exponentially.

As a result, when measured by the impulse noise detector while moving, the output waveform displayed on the display 17 has a waveform portion based on the impulse noise that becomes larger as it gets closer to the transmission source. Moreover, since the input level of the impulsive noise is in the non-linear region and the gain increases as the input level increases, the degree of increase in the output level increases when approaching the transmission source. That is, as shown in FIG. 10 to FIG. 12, when it approaches the transmission source, it suddenly expands (waveform portion becomes high), and when it goes away, it suddenly contracts (waveform portion becomes low). Then, when it is further separated, it becomes difficult to distinguish it from other noises.

Therefore, when the user moves while looking at the display 17, the waveform portion corresponding to the impulsive noise has a peak that fluctuates with the movement (the other noise and the broadcast wave do not fluctuate vertically), so that the impulsive property is increased. Since it is easy to recognize the noise part and also the position where the peak is maximized, the position of the transmission source can be easily specified.

As described above, even when the input level of other noise is not set to the low gain region, the impulsive noise can be detected. Therefore, the low gain region is set in accordance with the input level of the other noise, as shown in FIG. When the output level of the other noise part is compressed as described above, the impulsive 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 entirely output, and when approaching the source of the impulsive noise, a waveform portion having a high peak suddenly appears. In the case of broadcast waves, a waveform portion that overflows the output range is output, and even if the waveform portion moves, the peak position does not change much. Therefore, it can be specified as the impulsive noise that the peak position changes with the movement.

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 insulators in which impulse noise is generated are based on the inspection point P. That is, as shown in FIG. 13, the inspector M standing at the inspection point P gradually rotates the directional region 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 in which the impulse noise radio wave is generated enters the directional region R, the outputs as shown in FIGS. 9 to 12 are displayed on the display 17, and the insulator G1 in which the impulse noise radio wave is not generated is displayed. Even if enters into the directional area, the detection output of constant amplitude is not displayed on the display. Therefore, the direction can be determined by checking the display.

Therefore, in order to detect the insulator generating the impulsive noise radio wave, if the direction is detected by the above-mentioned method, the insulator moves to the detected direction. At this time, the pointing direction of the antenna 10 is the moving direction.
Then, it is possible to judge that the insulator moving around while watching the amplitude of the detection signal displayed on the display 17 is generating the impulse noise radio wave in the surrounding insulator having the maximum amplitude.
Further, as shown in FIG. 10 to FIG. 12, when the insulator to be detected is approached, the peak sharply increases, so that it can be easily detected.

In the above embodiment, an antenna having a strong 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 that case, it is possible to check whether or not there is an insulator generating an impulsive noise radio wave 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 received by the antenna 10 is frequency-converted based on a signal of a predetermined frequency. I tried to process it.

That is, the frequency conversion section 20 includes a high frequency band pass filter 21 which passes a signal in a predetermined frequency range in the received output of the antenna 10 and a high frequency amplifier which amplifies the signal passed 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) of 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 range having a pass band in the range of 00 to 600 [MHz]. The frequency converter 23 is a mixer that frequency-mixes 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. It is designed to convert frequencies. That is, when 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 of the intermediate frequency converted by the frequency converter 23 is f. _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 The observation bandwidth is the bandwidth of the intermediate frequency bandpass filter. That is, if the frequency of the local oscillator 25 is changed while the radio waves of the same frequency are being received, the frequency of the intermediate frequency output from the frequency converter 23 also changes.

The output of the frequency converter 23 is given to the intermediate frequency band pass filter 24. Therefore, if the converted intermediate frequency is not in the pass band of the intermediate frequency band pass filter 24, it goes without saying. , Cannot pass through the intermediate frequency band pass filter 24. Therefore, even if the input signals have the same frequency, it may or may not be able to pass through the intermediate frequency bandpass 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 mixed with the output of the local oscillator 25 and converted into a predetermined intermediate frequency. The frequency of the converted intermediate frequency is the intermediate frequency band pass filter 24.
Only received signals that match the pass band of 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 of a desired frequency that satisfies the above expression.

This output signal is the nonlinear amplifier 1
Given to 2. Since the configuration and operational effects of the non-linear amplifier 12 and thereafter are similar to those of the above-described first embodiment, the corresponding members are designated by the same reference numerals, and detailed description thereof will be omitted.

Next, the operation of the above-mentioned device will be described. FIG. 15 shows a time waveform of the radio wave of the impulsive 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 regularly generated, impulse noise radio waves are randomly generated and their amplitudes are also scattered.

By the way, the frequency spectrum of the received signal is as shown in FIG. As is clear from this figure, the broadcast wave / communication wave is discretely generated at a predetermined frequency, but the impulsive noise radio wave is present over the entire frequency range. Although its signal level is also lower than that of broadcast waves, etc., when focusing on only impulse noise radio waves, noise radio waves of certain frequency components such as broadcast waves and frequency bands without broadcast waves, etc. It can be said that the generation state of the noisy radio wave is the same.

Therefore, originally, it is preferable to examine the frequency component 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, but the frequency component concerned is a broadcast wave or the like having a large signal level. Will be hidden by. Therefore, in this embodiment, it is equivalent to the frequency domain of the broadcast wave,
A region where there is no broadcast wave or the like having a strong signal level 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 impulsive noise radio wave and give it to the non-linear amplifier 12 and then the detector 13. Then, the time waveform of the detection signal in the detector 13, that is,
An example of the output waveform to the display 17 is shown in FIG. In this way, only impulse noise radio waves can be extracted and output can be displayed.

That is, the frequency converter 20 mixes the received signal and the output of the local oscillator 25 by the frequency converter 23 and passes them through the intermediate band pass filter, so that the frequency of the frequency-mixed intermediate frequency is changed. Only received signals having a predetermined frequency are extracted. The frequency of the received signal to be extracted is set to the observation frequency band where there is no broadcast wave. This makes it possible to reliably extract the impulsive noise radio wave, and since the noise radio wave has a flat frequency characteristic, when the noise radio wave is detected by this device, the noise radio wave also exists in the frequency band such as broadcast wave. Then it can be estimated.

Moreover, due to the effect of providing the non-linear amplifier 12, the peak of the impulsive noise fluctuates greatly according to the distance from the transmission source to the observation position, so that it is easy to identify.

Although illustration is omitted, when there is no impulsive noise radio wave in this observation frequency band, the signal waveform as shown in FIG. 17 does not appear and the output becomes almost zero level. This makes it possible to understand whether or not an impulsive noise radio wave is generated depending on whether or not a signal of a certain level or higher is detected (displayed on the display 17). Note that if the setting of the observation frequency band is incorrect and the frequency range is in the presence of broadcast waves, etc., the input voltage will become extremely large (in the range shown in FIG. 17, the voltage will be overwhelmed), so this condition is also easy. Can be identified.

As described above, by setting a frequency region in which no broadcast wave or the like exists and detecting a signal existing in that frequency region, an impulsive noise radio wave can be extracted and detected. When the sexual noise radio wave is detected, it can be estimated that the impulsive noise radio wave is generated even in the frequency range of the target broadcast wave or the like.

Furthermore, if the oscillation frequency of the local oscillator can be changed as in the present embodiment, the observation frequency band can be set in a frequency region in which there is no radio wave that is not a detection target such as a broadcast wave in any region. It is possible and versatility increases. Further, the observation frequency band can be finely adjusted, and the impulsive noise radio wave can be detected more reliably.

The apparatus shown in FIG. 14 can detect and detect a predetermined frequency signal by a kind of heterodyne method in which the frequency conversion is one step. However, the present invention is not limited to this, and for example, FIG. As shown in the figure, it may be configured by a kind of super-heterodyne type spectrum analyzer having frequency conversion in two stages. Further, in any of the formats shown in FIGS. 14 and 18, the non-linear amplifier may also function as the intermediate frequency amplifier in the heterodyne system, or may be provided separately.

Further, in the above embodiment, the oscillation frequency of the local oscillator 25 is variable by manual operation, but the present invention may be fixed. That is, since the frequencies of broadcast waves and the like are known in advance, it is possible to know which frequency range should be set as the observation frequency band. Therefore,
By setting the oscillation frequency of the local oscillator to a predetermined observation frequency band, impulse noise radio waves can be selected and extracted / detected, and the device configuration can be simplified and the cost can be reduced.

Furthermore, in the above-described embodiment, the operator checks the display 17 for the presence of impulse noise radio waves, but if only impulse noise radio waves are detected (input voltage: medium), the broadcast is performed. The levels of the input voltages when the waves are detected together (input voltage: high) and when there is no impulsive noise radio wave (input voltage: small) differ greatly. Therefore, the boundaries between the states are set to thresholds Th1 and Th2 (see FIG. 17), and when the signal level of the detection output is higher than Th1, it is determined that a broadcast wave or the like is being received, and Th1 to Th2. It can be determined that there is an impulsive noise radio wave in the case of between, and it can be determined that there is no impulsive noise radio wave in the case of less than Th2. This automatic determination can be realized by the signal processing circuit 16, for example.

Further, by making such automatic determination, when the oscillation frequency of the local oscillator 25 is changed, the change can be automatically made. That is, when the input voltage is higher than Th1, it can be realized by changing the frequency by the reference pitch.

Further, the map database and the position detecting means for detecting the current position can be interlocked with the above embodiment. That is, for example, a device using a non-directional antenna is installed in a vehicle such as an automobile. Then, the vehicle is moved within 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 automobile 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 incorporated in the device). , It is possible to identify the insulator emitting the impulse noise radio wave.

[0063]

As described above, in the impulse noise detecting apparatus according to the present invention, by providing the non-linear amplifier, it is possible to remarkably increase or decrease the received signal level based on the impulse noise accompanying the movement of the observation point. Therefore, it is possible to reliably detect the impulsive noise radio wave.

[Brief description of 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 impulsive noise radio wave.

FIG. 3 is a first impulsive noise detection device according to the present invention.
It is a figure which shows the embodiment of.

FIG. 4 is a diagram showing input / output characteristics of a non-linear amplifier.

FIG. 5 is a diagram illustrating a non-linear amplifier.

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

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

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

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 (No. 1) for explaining changes in the output waveform displayed on the display as the observation point moves.

FIG. 11 is a diagram (part 2) explaining a change in the output waveform displayed on the display due to the movement of the observation point.

FIG. 12 is a diagram (No. 3) for explaining the 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 an 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 and impulse noise radio wave.

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

17 is a diagram showing an example of a time waveform of a detection (detection) output of the detection device shown in FIG.

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

[Explanation of symbols]

10 antennas 12 Non-linear amplifier 13 Detector 14 Low pass filter 15 Rectifier 16 Signal processing circuit 17 Display 20 Frequency conversion unit (extraction means)

Claims (5)

(57) [Claims] 1. A detection means for detecting a signal based on a reception signal received by an antenna, and an output means for outputting a detection signal in the detection means, wherein an input signal level is provided between the antenna and the detection means. An impulsive noise detection device comprising a non-linear amplifier whose gain changes in response to the noise. 2. The non-linear amplifier has a non-linear region set to a level range input to the non-linear amplifier at least when receiving impulsive noise to be detected. In the non-linear region, the gain is increased as the input level is increased. The impulsive noise detection device according to claim 1, wherein the number also increases. 3. The non-linear amplifier, wherein a level range lower than a level range input to the non-linear amplifier when receiving impulsive noise is set to a low gain region. Impulsive noise detection device according to. 4. The impulsive noise detection device according to claim 1, wherein the antenna has a good directivity. 5. An extracting means is provided between the antenna and the non-linear amplifier, and the extracting means is for an observation frequency band in which there is no non-detection target signal having a reception level higher than that of an impulsive noise radio wave such as a broadcast wave. The impulse noise detection device according to any one of claims 1 to 4, wherein the device is configured to extract a signal.