KR100393672B1 - device for detecting oscillation in two-way communication system and method thereof - Google Patents

Abstract

The present invention relates to an apparatus and method for detecting an oscillation phenomenon in which a signal transmitted in one direction is fed back and re-input in a bidirectional communication system.

According to the present invention, when the power of the signal corresponding to the measurement band set according to the delay value of the bidirectional communication system is detected among the transmission signals, and the amount of power variation of the detected signal corresponds to the first level region or the second level region, The oscillation phenomenon is considered to have occurred. At this time, the delay value represents a propagation delay of a signal made through the communication system.

According to the present invention, since the oscillation state in a specific frequency band is recognized by using the correlation characteristics of the input / output signal and the oscillation signal in the bidirectional communication system, it is possible to accurately diagnose whether the oscillation occurs at an early stage and is proportional to the degree of system degradation. It is possible to diagnose the condition.

Description

Device and method for detecting oscillation in bidirectional communication system {device for detecting oscillation in two-way communication system and method}

The present invention relates to an oscillation detection device and a method thereof in a bidirectional communication system, and more particularly, to detect an oscillation generated by re-input of a part of a signal amplified and output in one direction during bidirectional communication between a base station and a terminal. And an apparatus and a method for suppressing the same.

In general, a representative mobile communication service system of two-way communication is composed of a base station transceiver system, a base station controller, a mobile switching center, and a mobile station.

The base station and the mobile station communicate in a constant frequency band, and each base station has a constant call radius. Therefore, by arranging a plurality of base stations appropriately so that the call radius of each base station overlaps each other, the area where the call is possible can be expanded.

However, even if the entire city is covered by the arrangement of such a plurality of base stations, a call shadow area is created which is not available in the island area, the underground space of a large building, and the inside of a high-rise building.

Due to the occurrence of the call shadow area, the mobile phone user may not receive smooth call service in the call shadow area, and in order to solve this problem, a repeater is installed in the shadow area.

The repeater performs a function of amplifying a weak signal supplied from the base station to the terminal and amplifying a signal transmitted from the terminal to the base station. The repeater consists of a forward path and a reverse path, and ends of each path are connected by a duplexer. The signal input to the repeater is input to each LNA unit through the duplexer and then supplied to the HPA terminal and the antenna of the final stage and output.

When the signal amplified and output from the repeater flows into the input port more than a certain level, oscillation of the system occurs. 1 illustrates a waveform diagram of an oscillation phenomenon occurring in various forms. As shown in FIG. 1, the oscillation phenomenon is a case where a single tone signal occurs in a frequency band, and a single tone signal is distributed in a random manner in a random form. For example, the signal waveform may appear in the form of drift of frequency, and in the case of generating an asymmetric signal in the form of a square wave.

When oscillation occurs, the input signal or noise signal unrelated to the input signal is amplified in a continuous loop to reach the output limit of the amplifier. At the output limit of the amplifier, the normal input signal also degrades the signal-to-noise ratio (S / N) due to the amplifier's distortion, making it difficult to demodulate the signal.

In particular, in the mobile communication system, the base station demodulates the signal output from the repeater to determine the state of the signal and controls the output of the signal transmitted to the terminal according to the determination result. Therefore, when the oscillation phenomenon occurs, accurate signal determination is not made. This adds to the deterioration of the system.

In addition, when oscillation is generated, a severe failure phenomenon in which a reception radio wave deterioration from a terminal communicating through a repeater to a base station affects other terminals in the CDMA system or the like causes the entire system to deteriorate. Therefore, in order to improve system performance, it is required to detect and suppress the oscillation phenomenon.

However, the oscillation of the form in which a single carrier signal is generated at a fixed frequency can be detected in hardware, but it is very difficult to detect the oscillation signal in the form of a random form varying with time.

In addition, even when a single carrier type oscillation signal is generated, detection is possible only when the maximum output is exceeded, and when the strength of the oscillation signal does not exceed the set output level, the detection is not easy.

Conventional methods for detecting oscillation include a method using a spectrum analyzer and a method using an RF switch.

The former method uses a spectrum analyzer to perform signal analysis on the frequency domain to display the result, and the user can determine whether the oscillation is based on the analysis result. However, this method is inexpensive because the spectrum analyzer is more expensive than the repeater, and the user has to monitor the results of the spectrum analyzer, so it is inefficient to deploy a large number of such monitoring personnel in the current situation where multiple repeaters are in operation. Continuous real-time monitoring of agents is not possible.

In addition, even if the spectrum analyzer automatically compares the analysis results with the stored oscillation signal pattern to detect oscillation phenomenon without user monitoring, the oscillation signal is so random that it is difficult to obtain other oscillation signal patterns in all cases. In addition, there is a disadvantage in that it takes a long time according to the comparison.

The latter method installs an RF switch at the end of the repeater, operates the RF switch at a polling time interval to block the path from which the output signal is fed back, and then monitors and outputs the power of the output signal of the repeater. It is determined whether the oscillation phenomenon occurs according to whether the power of the signal decreases.

However, this method is very difficult to detect the oscillation when the output signal power is small, and also call drop occurs because the signal transmitted to the terminal is blocked at a constant polling time interval. There is a possibility, and the detection accuracy is degraded in the call state. In addition, there is a high possibility of failure in the hardware according to the frequent increase in the number of switching, there is a disadvantage that can not be detected even if the oscillation state exists in the measurement cycle because the real-time measurement is not made.

In addition, in the repeater, since the output signal has the same frequency band as the input signal and the same signal type, it is impossible to distinguish the signal using the frequency difference between the input and output, and even before the oscillation phenomenon goes above a certain level even when the oscillation phenomenon occurs. Until now, the oscillation has a disadvantage in that it is difficult to determine the progress information.

Therefore, the technical problem to be achieved by the present invention is to improve the reliability of the bidirectional communication system by preventing system degradation by initially detecting and eliminating occurrence of oscillation at a low cost in the bidirectional communication system.

1 is a diagram illustrating various forms of oscillation phenomenon occurring in a bidirectional communication system.

2 is a diagram illustrating signal transmission characteristics of a repeater used in a bidirectional communication system.

3 is a diagram showing a transfer function model for signal analysis of a repeater system.

4A is a waveform diagram illustrating characteristics of the transfer function illustrated in FIG. 3, FIG. 4B is a waveform diagram illustrating characteristics of a delay change, and FIG. 4C is a waveform diagram illustrating characteristics of a signal transfer function according to a change of delay.

5 is a diagram illustrating an experiment result according to the oscillation waveform measurement.

6 is a diagram showing the structure of an oscillation detection apparatus according to an embodiment of the present invention.

7A to 7C illustrate an example in which the oscillation suppression unit is connected to the repeater system in the oscillation detection apparatus according to the embodiment of the present invention.

8 is a flowchart sequentially illustrating an oscillation detection and suppression process performed in an oscillation detection apparatus according to an embodiment of the present invention.

An oscillation detection apparatus according to an aspect of the present invention for achieving the above technical problem, as a device for detecting the oscillation phenomenon is fed back to the signal transmitted in one direction in the bidirectional communication system,

A signal conversion unit converting the transmission signal into a signal of a measurable band according to an applied local oscillation signal; A filter unit filtering the signal output from the signal converter; A power detector detecting power of the filtered transmission signal; A local oscillator for supplying a local oscillation signal to the signal converter in accordance with an oscillation measurement period set according to a delay value of the bidirectional communication system; And a controller for determining whether oscillation occurs according to the power of the signal detected in the measurement band set according to the oscillation measurement cycle, wherein the delay value represents a propagation delay of a signal made through the communication system.

The controller determines that the oscillation has occurred when the amount of power change of the signal detected in the measurement band corresponds to the first level region or the second level region having a value greater than the first level region. Meanwhile, when the signal corresponding to the second level region is greater than or equal to the set number in the second level region, the signal is determined to be a normal signal and the oscillation phenomenon occurs when the signal corresponding to the second level region is less than or equal to the set number. I think that.

The oscillation detection device of the present invention having the above characteristics is provided to the attenuator for reducing the output of the transmission signal under the control of the controller when the oscillation phenomenon occurs, or to the bidirectional communication system under the control of the controller. A power relay for shutting off power, a switch for blocking a path through which the transmission signal is fed back in the bidirectional communication system under the control of the controller, or a warning unit for warning the occurrence of oscillation under the control of the controller It may include.

In addition, the oscillation detection method according to another aspect of the present invention, as a method for detecting the oscillation phenomenon is fed back to the signal transmitted in one direction in the bidirectional communication system,

Detecting power of the transmission signal in a measurement band having a period set according to a delay value of the bidirectional communication system; Determining whether an amount of change in power of the signal detected in the measurement band corresponds to a first level region; Determining whether the amount of change in power of the detected signal corresponds to a second level area when the amount of power change of the detected signal is not the first level area; And determining that an oscillation phenomenon occurs when a power variation of the detected signal corresponds to a first level region or a second level region, wherein the delay value is a propagation delay of a signal made through the communication system. to be.

Here, in the oscillation determination step, when the amount of power variation of the signal detected in the measurement band corresponds to the second level region, when the signal corresponding to the second level region is equal to or greater than the set number, the oscillation phenomenon is determined as a normal signal, When the corresponding signal is less than or equal to the set number, it is determined that the oscillation phenomenon has occurred, wherein the second level region has a larger value than the first level region.

In addition, the oscillation detection method according to an aspect of the present invention, when the oscillation phenomenon occurs by reducing the output of the transmission signal to reduce the effect of the oscillation phenomenon; Cutting off the power provided to the bidirectional communication system when the oscillation occurs so that the influence of the oscillation is removed; Blocking a path through which the transmission signal is fed back when the oscillation occurs in the bidirectional communication system; The method may further include a step of warning when the oscillation phenomenon occurs.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, in the embodiment of the present invention, the principle of detecting the oscillation phenomenon will be described.

2 shows the signal transfer characteristics of a repeater used in a bidirectional communication system. As shown in FIG. 2, an arbitrary input signal Si (t) is a G (transfer function) which is a transfer function of the system, and an equipment delay which is a propagation delay occurring in a SAW filter or a dielectric filter or an amplifier in the system. It is output as an output signal So (t) via D).

In such a repeater system, an output signal So (t) is introduced into an input port via a space along an oscillation path, and a part of the output signal So (t) is space propagated between the repeater antennas. A delay is introduced into the input port with a loss of -G2 (propagation loss in space) via a spatial delay D2.

The transfer function model for signal analysis of the repeater system is shown in FIG. 3, the waveform diagram showing the characteristics of the transfer function in FIG. 4A, the waveform diagram showing the characteristics according to the delay change in FIG. 4B, and the delay change in FIG. 4C. Waveforms showing the characteristics of the signal transfer function are shown, respectively, and the oscillation waveform experiment results are shown in FIG. 5.

According to the transfer function shown in FIG. According to the characteristics of the transfer function, as shown in FIG. 4A, a sinusoidal signal is generated at a specific frequency (all frequency bands) regardless of an input signal according to the change of isolation, and the magnitude of the value of the isolation. It can be seen that the amplitude characteristics change according to. In other words, as the value of isolation decreases, the amplitude of the oscillation signal increases proportionally. Therefore, the degree of oscillation in the repeater can be known by using the ripple or peak value of the periodic signal in a specific frequency band.

4A, 4B, and 4C, the amplitude characteristics remain the same as the delay value changes, but the frequency period of the signal changes, as shown in FIG. 4C, as shown in FIG. 4C. It can be seen that the larger the delay value), the shorter the frequency period of the oscillation signal.

As a result of this signal analysis, as the oscillation progresses regardless of the input signal, a signal of a certain frequency is generated, and the amplitude of the signal increases in inverse proportion to the isolation value, and the frequency decreases in proportion to the delay value of the equipment. Can be.

Therefore, in the exemplary embodiment of the present invention, a signal change is performed by monitoring a signal at a specific point that can be calculated based on an isolation value and a delay value, rather than determining the degree of deterioration by analyzing the signal in the state where the oscillation progresses. To detect whether the system oscillation occurs early.

Based on this principle, the structure and operation of the oscillation detection apparatus in the bidirectional system according to the embodiment of the present invention will be described in detail.

In FIG. 6, an oscillation detection device (hereinafter, referred to as an oscillation detection device) in a bidirectional communication system according to an embodiment of the present invention transmits an RF (radio frequency) signal received through an antenna (not shown) to an IF (intermediate frequency). A signal converter 10 for converting the signal into an amplified output, a filter unit 20 for filtering the amplified IF signal, and a power detector 30 for detecting power of a signal existing in a measurement band set according to characteristics of a system The microprocessor 40 controls the signal transmission / reception operation and determines whether the oscillation is generated based on the power of the signal detected by the power detector 30, and sends the local oscillation signal to the signal converter 10 under the control of the microprocessor. It provides a local oscillator (50).

In addition, the oscillation detection device further includes an oscillation suppression unit 60 that optionally includes an RF switch 61, an attenuator 62, a power supply relay 63, or a warning unit 64 for suppressing oscillation at the time of oscillation detection. do.

Looking at each component of the oscillation detection device in more detail, the signal conversion unit 10, for example, according to the local oscillation signal provided from the local oscillator 50 to the input RF signal of the 45 MHz or 100 MHz band IF signal And converts the converted signal into amplified output.

The IF filter unit 20 filters and outputs only a signal corresponding to a set bandwidth among the input IF signals. The bandwidth of the IF filter unit 20 is determined according to the minimum frequency of the signal to be analyzed. In this embodiment, the minimum period of the oscillation signal to be analyzed is changed according to the delay value (equipment delay) of the repeater system, and since the commercially available repeaters mostly have a delay value of 2 to 5 μsec, the minimum frequency is approximately 200 kHz, and a 10-40 kHz filter is required for such 200 kHz signal analysis.

Therefore, in this embodiment, a 5 ㎑ ± 10 크리스탈 crystal filter and a 40 SA SAW (surface acoustic wave) filter are used for the IF filter unit 20, and a selection switch for selecting such a filter and patching of the input / output signal ( patching) may be further included.

The IF filter unit 20 uses a filter having excellent narrow band out-of-band suppression characteristics, thereby minimizing the influence of signals generated in a signal band other than the analysis target during the oscillation phenomenon, thereby improving the accuracy of the system. Since the narrowband filter has a small amount of power passing through it, a fine analysis of the signal power level in the subsequent power detector is possible.

In the present embodiment, since the local oscillating signal is swept to sense the strength of the signal passing through the filter unit 20, the bandwidth of the filter unit becomes the signal analysis resolution of the present system.

Meanwhile, the power detector 30 may include a first power detector 32 and a second power detector 33, and a signal distributor for distributing an input signal to the first power detector 32 or the second power detector 33 ( 31). As shown in FIG. 1, the oscillation signal appears in the form of drifting over a frequency band or as a signal in the form of a singleton having a peak value. Accordingly, the first power detector 32 according to the present exemplary embodiment detects a signal corresponding to a first level, that is, a noise level region, in the measurement band in order to detect an oscillation signal in the form of drifting from an input signal over a frequency band. In order to detect the oscillation signal in the form of a singleton from the input signal, the second power detector 33 detects a signal corresponding to a second level region larger than the first level from the input signal.

For example, as illustrated in FIG. 1, in order to detect an oscillation signal that is generated over a signal band in which a call signal exists and a non-signal band in which a call signal does not exist, the first power detector 32 has a no signal band. That is, when there is no call signal, a signal having a power corresponding to the first level region is detected, and the second power detector 33 detects a signal level or a signal band, that is, when there is a call signal. Detects a signal (call signal or singleton signal) having a corresponding power.

At this time, the second power detector 33 controls only the normal data in the oscillation signal lock state except for the excessive signal detection data generated between each step during the local oscillation signal step sweep under the control of the microprocessor 40. Extract. In the present embodiment, the second power detector 33 uses an AD8307 RF power detector manufactured by an analog device, but is not limited thereto.

The local oscillator 50 generates an oscillation signal for conversion of the RF signal to the IF signal. As described above, since the periodic value of the oscillation signal changes according to the delay value of the repeater itself, the step size and lock time of the oscillator are variably set according to the repeater system.

For example, if the delay of the repeater itself is 4 Hz, the frequency difference between peaks of the oscillation signal is 250 Hz. In order to sample a peak to peak signal from a 250 kHz frequency signal, a signal detection of at least 250 kHz × 2 is required, and a small amplitude change of the signal can be detected by increasing the number of detections. Therefore, in determining the fineness of the oscillation according to the setting of the system, the characteristic changes depending on values such as frequency difference between peaks, sampling, and the number of times of detection (quantization).

In the CDMA system, the peak of the 250 kHz signal existing in the 1 MHz signal band is six, and one peak peak value is sampled six times in 40 ㎑ steps. When the time between sampling is 3 msec, the required time is 18 msec. It takes Therefore, peak detection in one CDMA data frame 20 ms at which no RF output change occurs can be made. On the other hand, when the delay value of the repeater itself is 500 Hz, the period of the peak value is 2 MHz, and the step value for sampling is based on 1FA (signal band) and 2.5 MHz.

The peak peak value for sampling according to the equipment delay of the repeater system itself may be set by using an initial default setting using hardware or by using software.

In addition, two local oscillators with different step sizes and lock times of the oscillation signal may be selectively used to allow for faster response or finer detection of the system.

The microprocessor 40 determines whether the oscillation occurs based on the signal output from the power detector 30, and controls the local oscillator to adjust the step of the local oscillation signal for oscillation detection.

When the oscillation is detected, the microprocessor 40 operates the oscillation suppression unit 60, that is, the RF switch 61 or the attenuator 62 or cuts off the power supply of the power relay 63 to suppress the oscillation signal output. In addition, through the warning unit 64 to notify the user of the occurrence of oscillation is to be made accordingly.

7A to 7C illustrate an example in which an oscillation suppression unit (RF switch, attenuator, power relay) is connected to a repeater system in an oscillation detection apparatus according to an exemplary embodiment of the present invention.

As shown in FIG. 7A, the oscillation detection device according to the embodiment of the present invention is connected to an RF switch 61 forming a signal input path of a receiving antenna of a repeater system, so that the RF switch operates under the control of a microprocessor. You can do that. In this case, when oscillation occurs, the microprocessor controls the RF switch to block the input path of the received signal so that the signal fed back from the output terminal is not input.

In addition, as shown in FIG. 7B, the oscillation detection device according to the embodiment of the present invention may be connected to the attenuator 62 of the system of the repeater to adjust the magnitude of the signal output from the repeater system. For example, as shown in FIG. B, when the attenuator 62 is configured as a variable resistor and oscillation occurs, the microprocessor sets a large value of the variable resistor so that the magnitude of the signal amplified and output from the repeater system is reduced. It is possible to reduce the effects of the occurrence of the rash.

In addition, as shown in Fig. 7c, by connecting to an AC relay supplying AC power to the repeater system of the oscillation detection apparatus according to an embodiment of the present invention, when the oscillation phenomenon is detected by operating the AC relay to the repeater system AC power off can be made.

In the present embodiment, one of the above various methods for reducing the output of the oscillation signal to minimize the effect on the system can be set according to the system environment, and the microprocessor can set the RF switch or Activate the attenuator or power relay selectively.

On the other hand, the oscillation detection apparatus according to an embodiment of the present invention having such a structure may be embedded in the repeater system, in which case the microprocessor in the repeater system may perform the oscillation detection and control of the signal together. In addition, the oscillation detection device may be independently implemented as an external form.

Next, the operation of the oscillation detection apparatus according to the embodiment of the present invention will be described based on this structure.

FIG. 8 sequentially illustrates the oscillation detection and suppression process performed in the oscillation detection apparatus according to the embodiment of the present invention.

When oscillation occurs in a repeater system in the case of bidirectional communication, a sinusoidal signal is generated in a specific frequency band regardless of an input signal, and the amplitude of the generated signal is inversely proportional to the isolation value, and the peak frequency of the signal The and frequency depend on the equipment delay of the system and the value always remains constant.

Therefore, in the embodiment of the present invention, first, as shown in Fig. 8, check the equipment delay generated in the repeater system itself used in the bidirectional communication system, and sets the oscillation period in which the oscillation signal may occur according to the equipment delay, The oscillation period is determined by measuring the power of a signal detected at a specific point according to the oscillation period. For convenience of explanation, the measurement point for each period set to detect the oscillation phenomenon is referred to as a measurement band.

Then, the step of the local oscillator is set in accordance with the set oscillation measurement period and the frequency of the local oscillator is set (S100 to S110). Here, the step of the oscillation signal is set according to 1 / delay ÷ sampling frequency, where 1 / delay represents the peak peak frequency difference of the oscillation signal.

After the control values for detecting the oscillation are set as described above, the microprocessor 40 of the oscillation detection apparatus according to the exemplary embodiment of the present invention sweeps the oscillation signal of the local oscillator 50 in a predetermined step to set a signal in the measurement band. The power level is detected (S120).

That is, the local oscillator 50 is operated according to the enable signal output from the microprocessor, and then sweeps and outputs the oscillation signal in a setting step (for example, 20 Hz) according to the applied clock signal. The local oscillation signal output from 50 is provided to the signal converter 10. In this embodiment, the sweep span is based on 1.25 MHz, which is a frequency band occupied by one terminal in a CDMA system.

The signal converter 10 converts the RF signal received through the antenna into an IF signal according to the oscillation signal applied, and outputs the IF signal. The IF signal is amplified and then amplified and filtered through the filter unit 20, respectively. It is input to the power detector 30.

The first power detector 32 of the power detector 30 detects the power intensity of the signal in the region of the first level (between the first set value and the second set value) which is the noise level in the measurement band, and the second power. The detector 33 detects the power intensity of the signal having a second level region (more than the second set value) in the measurement band that cannot be detected by the first power detector 32.

Next, the microprocessor 40 determines whether the oscillation has occurred based on the level of the signal in the measurement band detected by the power detector 30. Specifically, when the amount of change in the signal level in the measurement band is equal to or less than the first set value (3 dB), that is, when the level of the RF signal output from the antenna of the repeater system is low and does not affect the communication system, the local oscillator ( Sweep operation of 50) is performed to perform signal power detection in the measurement band (S130 to S140). However, when the amount of change of the signal level in the measurement band detected by the first power detector 32 is located between the first set value 3 ms and the second set value 10 ms, it is determined that oscillation has occurred. (S150).

When there is no call from the terminal, as shown in FIG. 1, an oscillation phenomenon may occur in which a signal of a certain level is rippled. In the exemplary embodiment of the present invention, the oscillation phenomenon is measured when the signal ripple is detected at a specific level even though there is no call signal above the set level by measuring the signal change in the measurement band set according to the equipment delay of the repeater system. It is judged as an initial state in which this occurs.

On the other hand, after the microprocessor outputs and drives the enable signal to the second power detector 33, the amount of change of the signal level in the measurement band detected by the second power detector 33 is equal to or greater than the second set value (10 Hz). In this case, it is determined that there is a call signal to determine whether oscillation has occurred. In general, the call signal exists in most of the signal band (1.25MHz), but in the case of a single-tone signal by oscillation, it exists only in a specific frequency band. Therefore, the microprocessor determines that the signal is an oscillation signal when the signal having the peak value within the measurement band is less than or equal to a set number, for example, once, and if the signal having the peak value within the measurement band is repeatedly generated more than once. It is determined that the signal is a call signal (S160 to S180). At this time, when a reverse call signal (a signal transmitted from a terminal to a base station) is generated, the output fluctuates severely, so that the sweep time of the local oscillator is increased to take an average value or to reverse the call to increase the accuracy of the measurement. Hops to an FA band (CDMA channel band) where is not generated.

As such, when there is a signal corresponding to the first level region in the measurement band or a signal having a peak value in the second level region does not occur repeatedly, the microprocessor 40 determines that the oscillation has occurred. The RF switch 61, the attenuator 62, or the power relay 63 are selectively operated in accordance with the set method in order to solve the oscillation phenomenon set in step S190.

However, when the signal corresponding to the first level region or the signal corresponding to the second level region is not detected through the power detector 30, it is determined that the oscillation phenomenon does not occur, and the measurement band according to the oscillation measurement period. Then, the oscillation detection process described above is repeated. Also

The invention is susceptible to various modifications and implementations without departing from the scope of the following claims.

As described above, according to the present invention, since the oscillation state in a specific frequency band is recognized by using the correlation characteristic of the input / output signal and the oscillation signal in the bidirectional communication system, whether or not the oscillation occurs can be accurately diagnosed, and the degree of system degradation Proportional condition diagnosis is possible.

In addition, since the system detects oscillation in a specific frequency band in which oscillation may occur according to the delay characteristics of the system itself, it is possible to detect whether oscillation occurs in real time quickly, and complicated algorithms according to oscillation detection are not required. The system structure can be simplified.

In addition, since the detection can be performed even when the oscillation signal is weak, the detection accuracy can be further improved, and the initial oscillation detection can be performed to remove the influence of the oscillation at an early stage.

Claims (9)

An apparatus for detecting an oscillation phenomenon in which a signal transmitted in one direction is fed back and re-input in the bidirectional communication system, A signal conversion unit converting the transmission signal into a signal of a measurable band according to an applied local oscillation signal; A filter unit filtering the signal output from the signal converter; A power detector detecting power of the filtered transmission signal; A local oscillator for supplying a local oscillation signal to the signal converter in accordance with an oscillation measurement period set according to a delay value of the bidirectional communication system; Control unit for determining whether the oscillation occurs according to the power of the signal detected in the measurement band set according to the oscillation measurement period Wherein the delay value is a propagation delay of a signal made through the communication system. The method of claim 1. The controller determines that oscillation has occurred when the power variation of the signal detected in the measurement band corresponds to a first level region or a second level region having a value greater than the first level, and corresponds to the second level region. In this case, when the signal corresponding to the second level region is greater than or equal to the set number, the signal is determined to be a normal signal, and when the signal corresponding to the second level region is equal to or less than the set number, the oscillation signal is detected. Device. The method of claim 1. And an attenuator for reducing the output of the transmission signal under control of the controller when the oscillation phenomenon occurs. The method of claim 1. And a power relay for shutting off power provided to the bidirectional communication system under the control of the controller when the oscillation phenomenon occurs. The method of claim 1. And a switch for blocking a path through which the transmission signal is fed back in the bidirectional communication system under the control of the controller when the oscillation phenomenon occurs. The method of claim 1. The oscillation signal detection device further comprises a warning unit for warning the occurrence of the oscillation under the control of the controller when the oscillation phenomenon occurs. In the bidirectional communication system, a method for detecting an oscillation phenomenon in which a signal transmitted in one direction is fed back and input again, Detecting power of the transmission signal in a measurement band having a period set according to a delay value of the bidirectional communication system; Determining whether an amount of change in power of the signal detected in the measurement band corresponds to a first level region; Determining whether the amount of change in power of the detected signal corresponds to a second level area when the amount of power change of the detected signal is not the first level area; And Determining that an oscillation phenomenon occurs when the amount of change in power of the detected signal corresponds to a first level region or a second level region Including, And the delay value is a propagation delay of a signal made through the communication system. The method of claim 7, wherein In the oscillation determination step, when the amount of power variation of the signal detected in the measurement band corresponds to the second level region, and when the signal corresponding to the second level region is equal to or greater than the set number, the oscillation phenomenon is determined as a normal signal and is applied to the second level region. It is determined that the oscillation phenomenon occurs when the corresponding signal is less than or equal to the set number, and the second level region has a larger value than the first level region. The method of claim 7, wherein When the oscillation phenomenon occurs, reducing the output of the transmission signal to reduce the effect of the oscillation phenomenon; Cutting off the power provided to the bidirectional communication system when the oscillation occurs so that the influence of the oscillation is removed; Blocking a path through which the transmission signal is fed back when the oscillation occurs in the bidirectional communication system; Steps to warn when a rash occurs And optionally further comprising an oscillating signal.