JPH0964830A - Silent failure detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a silent failure in a comparatively simple way and even by means of remote control with respect to the silent failure detection method detecting a hidden failure. SOLUTION: The method detects a silent failure of a transmitter and a receiver of a communication system, and an attenuation control section 7 controls an attenuation of a variable attenuator 2 being a component of an automatic output control circuit so as to be minimized via a changeover section 6 as to a signal given to an amplifier 1 receiving back-off processing in the case of detecting a silent failure of the transmitter. Then an output signal from the amplifier 1 branches partly via a directional coupler 3 and the distributed signal is detected by a diode 4, the detected signal is given to a detection processing section 8, which detects the level of the output signal and compares it with an output signal level when the attenuation of the variable attenuator 2 is minimized in a normal state, and when the result of comparison indicates an exceeded allowable value, it is discriminated that a silent failure denoting progress of the deteriorated amplifier 1 is in existence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of detecting a silent feria for detecting hidden obstacles in a communication system. Generally, various communication systems have a configuration in which a plurality of relay stations are arranged between a transmitting terminal station and a receiving terminal station. In each of the stations thus distributed, a means for monitoring the state of the equipment of each part is provided, and when a failure is detected, an alarm signal is output. Switching is performed and repair work is performed at the point of failure. However, it has not been performed to identify the state before the failure.

[0002]

2. Description of the Related Art Temperature, voltage, current, frequency, signal level or error rate of transmission data of devices in various communication systems is detected, and an alarm signal is output when a predetermined threshold value is exceeded. Is provided. This alarm signal is used to switch between active and standby and notify the maintenance person of the occurrence of a failure. In this case, if the maintenance person is stationed at the transmitting end station or the receiving end station, send it to the transmitting end station or the receiving end station, or, if a centralized monitoring station is installed, send an alarm signal to the centralized monitoring station. Is sent. The maintenance person searches for the faulty part by this alarm signal and performs the recovery work.

[0003]

The monitoring means of the prior art is as follows.
It monitors the temperature of each part, the input / output status, etc., and sends an alarm signal when a threshold value is exceeded to indicate that a failure has occurred. Communication can be continued by switching to the standby system. However, deterioration of each part due to aging progresses in both the active system and the standby system in the same way. Therefore, when a failure occurs in the active system, there is a possibility that the standby system also fails. If a failure occurs, the system will be down.

Therefore, there is a hidden failure (silent failure) before such a failure occurs.
Would be desirable to detect. However, in order to detect such a silent aria, an expensive measuring instrument and a great deal of labor are required, and the measurement is carried out at the place where the transceiver is installed. It was difficult. It is an object of the present invention to detect silent ferrier relatively easily and also enable remote control.

[0005]

The silent / feria detection method of the present invention comprises: (1) switching of the output signal level of a transmitting / receiving device of a communication system in a normal state, and switching of a received input signal level or unmodulated input. It includes a process of measuring and comparing output information such as the output signal level according to, and determining that there is a silent aria when the comparison result exceeds the allowable value.

(2) The output signal level in the state where the output signal level of the transmitter is maximized is measured in advance by switching the attenuation amount of the variable attenuator of the transmitter including the automatic output control circuit of the communication system to the minimum. In addition, at the time of silent / feria detection, the attenuation of the variable attenuator is switched to the minimum, the output signal level of the transmitter is measured, and it is compared with the measurement value of the output signal level measured in advance. When it exceeds, it is judged that there is a silent feria.

In a transmitter including an automatic output control circuit, a configuration is generally used in which a non-linear characteristic is avoided by applying a backoff. Therefore, the attenuation amount of the variable attenuator is set to the minimum and the maximum output signal level in the normal state is set. Is measured in advance, the attenuation amount of the variable attenuator is switched to the minimum at the time of silent / feria detection, and the output signal level of the transmission device at that time is measured and compared with the previously measured value. If the comparison result of the measured values is within the allowable value, the progress of deterioration is negligible and it is not a silent ferrier, but if it exceeds the allowable value,
Although it is not a failure, it can be determined that it is a silent fairy, which is a precursor to failure due to the progress of deterioration, and preventive measures can be taken.

(3) Further, a bandpass filter having an intermediate frequency signal of the receiving device when the oscillation frequency of the local oscillator of the transmitting device of the communication system is normal is provided so that the transmitting device can detect the silent / feria. Transmits an unmodulated signal, detects the output signal level of the bandpass filter that applies the intermediate frequency signal of the receiving device, and when this level decreases beyond the allowable value, the oscillation frequency of the local oscillator of the transmitting device or the receiving device. It is determined that there is a silent feria including fluctuations.

When the oscillation frequencies of the local oscillators of the transmitting device and the receiving device are normal at the time of detecting the silent aria, the frequency of the intermediate frequency signal of the receiving device is set in advance, and the output signal of the bandpass filter is obtained. The level is maximum. However, if the oscillation frequency of the local oscillator of either or both of the transmission device and the reception device is large, the frequency of the intermediate frequency signal of the reception device will deviate significantly from the set value, and the output of the narrow-band bandpass filter. The signal level decreases corresponding to the fluctuation range. Therefore, when the output signal level of this bandpass filter decreases below the allowable value, it is determined that there is a silent aria.

(4) In addition, after converting the intermediate frequency signal of the receiving device to a low frequency by a frequency converter, the level of the output signal of this bandpass filter is added to a bandpass filter having a normal frequency as a passband. When this level is detected or decreased below this level, the silent frequency including fluctuations in the oscillation frequency of the local oscillator of the transmitter or receiver is detected.
It is determined that there is a ferrier.

By converting the intermediate frequency signal of the receiving device into a low frequency by the frequency converter, a narrow-band bandpass filter can be easily realized, and silent faeria can be easily detected.

(5) The bit error rate when the attenuation amount of the variable attenuator for controlling the received input signal level of the receiver of the communication system is set so that the received input signal level becomes the threshold level is measured in advance. Every time, at the time of silent / feria detection, set the attenuation amount of the variable attenuator so that the received input signal level becomes the threshold level, measure the bit error rate, and when this bit error rate deteriorates beyond the allowable value, It is determined that there is a silent fairy.

The variable attenuator measures the bit error rate by using the received input signal level as a threshold level, and when the bit error rate is deteriorated by exceeding a permissible value of, for example, 10 ^-3 , it is not a failure but a deterioration point. It is determined that there is a silent fairy.

(6) Intermediate frequency signal level when the attenuation amount of the variable attenuator for controlling the reception input signal level of the receiver having the AGC function of the communication system is set so that the reception input signal level becomes the threshold level. Is measured in advance, and at the time of silent / feria detection, the attenuation amount of the variable attenuator is set so that the received input signal level becomes the threshold level, the intermediate frequency signal level is measured, and this measured value and the previously measured intermediate frequency signal are measured. It compares with the measured value of the level, and when the comparison result exceeds the allowable value, it is determined that there is a silent aria.

The receiver having the AGC function is controlled so that the intermediate frequency signal level becomes almost constant even if the received input signal level is changed, and the change range of the received input signal level is fading or the like. It is set corresponding to the minimum value and the maximum value of the expected received input signal level. However, the AGC range is narrowed due to deterioration of each part. Therefore, the intermediate frequency signal level when the received input signal level is set to the threshold level is measured by the variable attenuator, and the attenuation amount of the variable attenuator is set to the intermediate value when the received input signal level is set to the threshold level. The frequency signal level is measured and compared, and when the comparison result exceeds the allowable value, it means that the AGC range is narrowed, so it is determined that there is a silent failure.

[0016]

1 is an explanatory view of a first embodiment of the present invention, in which 1 is an amplifier, 2 is a variable attenuator using a pin diode or the like, 3 is a directional coupler, and 4 is for detection. A diode, 5 is a DC amplifier, 6 is a switching unit, 7 is an attenuation control unit, 8 is a detection processing unit, and 9 is a transmission unit. This embodiment shows a case where the present invention is applied to a transmitter, and the backoff (back
-off) shows a case of detecting a silent aria of the amplifier 1.

In the digital wireless communication system,
A back-off is applied to avoid operating the amplifier 1 near the saturation point. That is, by reducing the received input signal level by the variable attenuator 2 etc. and using the output of the amplifier 1 to some extent,
It is intended to obtain linear characteristics. As the backoff is increased, the effect of nonlinearity is reduced, but the transmission output signal level is lowered. Therefore, optimization is performed according to the output characteristics of the amplifier 1. For example, as an amplifier 1 for a 16QAM signal in the 2 GHz band, GaAsF
There is known a transmission device having a backoff of 8 dB when using an ET (field effect transistor).

Normally, the switching unit 6 is switched so that the output signal of the DC amplifier 5 is applied to the variable attenuator 2, the input signal is applied to the amplifier 1 via the variable attenuator 2, and the amplified output signal is The signal is added to the transmission unit 9 via the directional coupler 3 and is transmitted as a wired or wireless transmission signal. The amplified output signal partially branched by the directional coupler 3 is detected by the diode 4, amplified by the DC amplifier 5, and added to the variable attenuator 2 via the switching unit 6, for example, the impedance of the pin diode is changed. DC amplifier 5
The amount of attenuation is controlled by controlling the direct current from the. Therefore, an automatic output control circuit (ALC) is configured to stabilize the output signal level by increasing the amount of attenuation when the output signal level increases.

Further, the detection processing unit 8 monitors the output signal level of the amplifier 1 by the detection output signal of the diode 4, and the output signal level falls below the threshold value due to the failure of the automatic output control circuit (ALC) or the failure of the amplifier 1. An alarm signal is output when the voltage drops. This alarm signal can be sent to a maintenance person, or can be sent by superimposing it on the main signal in the sending section 9 and sent to a receiving terminal station where the maintenance person is resident.

When detecting a silent fairy,
The detection control signal is applied to the switching unit 6, the attenuation amount control unit 7, and the detection processing unit 8, and the switching unit 6 switches and connects the DC amplifier 5 to the attenuation amount control unit 7. Further, the attenuation amount control section 7 controls the attenuation amount of the variable attenuator 2 to be minimum and the input signal level of the amplifier 1 to be maximum, or the attenuation amount of the variable attenuator 2 is gradually decreased from maximum to minimum. The configuration is

The switching unit 6 can be composed of a semiconductor switching element such as a switch, a relay or a transistor. Further, the detection processing unit 8 stores the output signal level when the input signal level is maximized in the normal state such as the initial state of the amplifier 1 together with the failure detection unit and the storage unit. It includes a comparison means for comparing the output signal level thus generated with the output signal level at the time of silent / feria detection.

FIG. 2 is an explanatory diagram of output signal level characteristics.
The horizontal axis represents the input signal level of the amplifier 1, and the vertical axis represents the output signal level of the amplifier 1. With respect to the amplifier 1 in a normal state, the amount of attenuation of the variable attenuator 2 is minimized, the input signal level is set to IN, and the output signal level is measured in advance. If the output signal level in that case is P ₁ , The detection control signal causes the switching unit 6 to switch from the DC amplifier 5 to the attenuation amount control unit 7, and the attenuation amount control unit 7 minimizes the attenuation amount of the variable attenuator 2 to set the input signal level of the amplifier 1 to IN.
At this time, the detection processing unit 8 measures the output signal level of the amplifier 1.

If the output signal level in that case is P ₁ or in the vicinity thereof, it can be determined that the amplifier 1 does not have a silent aria, but the output signal level is, for example, P 1.
_{If it is 2} , and the deterioration of ΔP exceeds the predetermined value of the allowable deterioration, it is determined that there is a silent aria. That is, it can be determined that the deterioration is in progress although the failure of the amplifier 1 is not occurring. Further, when the attenuation amount of the variable attenuator 2 is gradually changed from the maximum value to the minimum value by the attenuation amount control section 7, the output signal level characteristic as shown in FIG. Becomes At the time of this silent / feria detection, the automatic output control circuit (ALC) of the amplifier 1 is disconnected, so after switching from the active side to the standby side, the silent
A fairy detection process will be performed.

FIG. 3 is an explanatory view of remote monitoring, in which the terminal station 1
A case where a plurality of relay stations 13 ₁ , 13 ₂ , ... Are arranged between ₁ and 12 and state information is collected under the control of the terminal station 12 is shown. For example, the terminal station 12 to the terminal station 11 are designated. When the request signal RQ ₀ is sent, the terminal station 11 sends the above-mentioned silent / feria detection result as a response signal AS ₀ to the terminal station 12. Now sends a request signal RQ ₁ is specified relay station 13 ₁ to the terminal station 12, relay station 13 _1,
Response signal AS based on the silent / feria detection result
_It is sent to the terminal station 12 as ₁ . Similarly, the terminal station 1
2 can collect information on the presence / absence of silent aria of the terminal station 11 and each relay station.

In this case, in FIG. 1, a request signal from the terminal station 12 is received and identified by a receiver (not shown), and in the case of a silent / feria detection request, the detection control signal is sent to the switching unit 6 and the attenuation amount. By adding to the control unit 7 and the detection processing unit 8, it is possible to detect the presence / absence of a silent aria of the amplifier 1 in the detection processing unit 8 and superimpose it on the main signal from the transmission unit 9 for transmission.

FIG. 4 is an explanatory view of the second embodiment of the present invention, in which 21 is a receiver, 22 is a high frequency amplifier (RFA),
Reference numeral 23 is a frequency converter (MIX), 24 is an intermediate frequency amplifier (IFA), 25 is a local oscillator (LOSC), 26 is a transmitting terminal station, 27 is a bandpass filter (BPF), 28 is a voltage detecting section, and 29 is a judgment. It is a department.

The transmitting terminal station 26 sends out a modulated signal according to a modulation system such as PSK or QAM, and the receiving device 21 amplifies it with a high frequency amplifier 22 and a local oscillator 25 in a frequency converter 23. The intermediate frequency signal (IF output signal) amplified by the intermediate frequency amplifier 24 is received and processed by a demodulator and a baseband processing circuit (not shown).

In such a communication system, if the oscillation frequency of the local oscillator of the transmitting terminal station 26 fluctuates, the error rate increases. Normally, even with such an increase in the error rate, there is no deterioration to the extent that an alarm signal is sent, so it was not possible to detect abnormal fluctuations in the oscillation frequency of the local oscillator of the transmitting terminal station 26. Therefore, in response to an instruction of silent / feria detection, the modulation at the transmitting terminal station 26 is stopped and a non-modulated signal (CW) is transmitted.

In the receiver 21, the unmodulated signal (C
W) is received and an unmodulated intermediate frequency signal is output. The frequency of the intermediate frequency signal (IF output signal) fluctuates corresponding to the fluctuations of the oscillation frequency of the local oscillator of the transmitting terminal station 26 and the oscillation frequency of the local oscillator 25 of the receiving device 21. Therefore, a bandpass filter 27 having a normal frequency as a center frequency is prepared, and the intermediate frequency signal passing through the bandpass filter 27 is detected by the voltage detection unit 28, and the determination unit 2
In 9, it is judged whether or not there is a silent feria.

For example, at a frequency of 6 GHz and an allowable deviation of 5 ×
If 10 ⁻⁵ is set, the band of the bandpass filter 27 is set to 30.
By setting the frequency to 0 kHz, it can be determined by the detection output signal of the voltage detection unit 28 whether or not it is within the allowable deviation. In the case of remote monitoring, the determination result of the presence / absence of silent / feria by the determination unit 29 can be superimposed on the main signal and transmitted.

FIG. 5 is an explanatory view of the third embodiment of the present invention, in which the same reference numerals as those in FIG. 4 indicate the same parts, 31 is a frequency converter (MIX), 32 is a local oscillator (LOSC), and 33.
Is a bandpass filter (BPF). In this embodiment, at the time of silent / feria detection, a non-modulated signal (CW) is transmitted from the transmitting terminal 26 as in the above-mentioned embodiment,
The receiving device 21 mixes the unmodulated intermediate frequency signal (IF output signal) from the intermediate frequency amplifier 24 with the output signal of the local oscillator 32 by the frequency converter 31 to convert it to a lower frequency, and to set a predetermined bandwidth. The signal that has passed through the band pass filter 33 is detected by the voltage detection unit 28, and the determination unit 29
The presence or absence of Silent Feria is determined by.

A narrow band bandpass filter is not easily manufactured as a desired bandwidth as the frequency is higher. However, in this embodiment, the frequency converter 31 shifts the intermediate frequency signal to a lower frequency. Since the conversion is performed, it becomes easy to configure the bandpass filter 33 with a desired bandwidth.

FIG. 6 is an explanatory view of the fourth embodiment of the present invention, in which 41 is a high frequency receiving section, 42 is a variable attenuator, 43 is a demodulation processing section, 44 is a reception processing section, 45 is a switching section, 46. , 4
Reference numeral 7 is a first and second setting unit, and 48 is a determination unit. This example measures the bit error rate and
The case where the detection of faeria is performed is shown.

The receiving device in service receives the signal by the high frequency receiving unit 41, converts the signal into, for example, an intermediate frequency, adds the intermediate frequency signal to the demodulation processing unit 43 while minimizing the attenuation amount of the variable attenuator 42. Then, the signal is demodulated, and the reception processing unit 44 performs the reception processing of the digital signal. In that case, the bit error rate BER is constantly measured. It is also possible to provide a configuration for digitally displaying the bit error rate BER of the measurement result.

The first setting unit 46 minimizes the setting of the attenuation amount, and the second setting unit 47 sets the attenuation amount such that (normal input signal level-threshold level) = attenuation amount. To do. The attenuation amount by the setting unit 47 is set in advance to be (normal input signal level)-(threshold level), and the bit error rate BER at this time is measured and recorded or stored. When the silent / feria is not detected, the switching unit 45 connects the first setting unit 46 to the variable attenuator 42 to minimize the attenuation amount of the variable attenuator 42.

At the time of silent / feria detection, the switching control unit 45 and the determination unit 48 are controlled by the detection control signal,
The switching unit 45 connects the second setting unit 47 to the variable attenuator 42. The variable attenuator 42 is controlled by the second setting unit 47.
Since the attenuation amount of is set to the value as described above, the input signal level becomes the threshold level, the bit error rate BER at this time is measured, and the determination unit 48 is measured by the reception processing unit 44. If the bit error rate BER is within the allowable range, it is determined that there is no silent aria. If the deterioration is beyond the allowable value, it is determined that there is a silent aria. The variable attenuator 42
Shows the case where it is provided after the high-frequency receiver 41, but it can be provided before the high-frequency receiver 41 or inside the high-frequency circuit. Further, as in the above-mentioned respective embodiments, it is possible to detect the silent fairy by remote control.

FIG. 7 is an explanatory diagram of the bit error rate. For example, the characteristic of the bit error rate BER with respect to the input signal level in the case of a normal receiving device is shown by the curve a, and the curve b is shown by the receiving device with deteriorated characteristics. Assuming that the bit error rate BER characteristic is obtained, when the bit error rate BER of the normal receiving apparatus is 10 ^-6 , the bit error rate BER of the receiving apparatus having the characteristic deterioration is 10 ^-3 . In this case, in the system configuration in which the alarm signal is not transmitted unless the bit error rate BER exceeds 10 ⁻³ , the alarm signal is not transmitted by the receiving device having the characteristic deterioration.

However, as described above, when the attenuation amount of the variable attenuator 42 is set by the second setting unit 47 to the input signal level at which the bit error rate BER of the normal receiving device becomes 10 ^-3 , characteristic deterioration is caused. In the case of the receiving device, the bit error rate BER is deteriorated to exceed 10 ⁻³ , so that it is determined that there is a silent failure.

FIG. 8 is an explanatory view of the fifth embodiment of the present invention, in which 51 is a variable attenuator and 52 is a high frequency amplifier (RF).
A), 53 is a frequency converter (MIX), 54 is an intermediate frequency amplifier (IFA), 55 is a switching unit, 56 and 57 are the first and the first.
The second setting unit 58 is a detection processing unit. Either or both of the high frequency amplifier 52 and the intermediate frequency amplifier 54 are
It has an AGC function and operates so as to make the amplified output signal level constant with respect to variations in the received input signal level. In the wireless communication system, the AGC operation range is usually set to be wider than that in the wired communication system in order to cope with fading.

The first setting unit 56 minimizes the amount of attenuation of the variable attenuator 51, and the second setting unit 57.
Indicates that the amount of attenuation of the variable attenuator 51 is (normal input signal level-threshold level). The detection processing unit 5
Reference numeral 8 has a configuration for detecting the amplified output signal level of the intermediate frequency amplifier 54 and determining the presence / absence of silent aria.

Normally, the switching unit 55 causes the first setting unit 5 to operate.
6 is connected to the variable attenuator 51, and the attenuation amount of the variable attenuator 51 is controlled to the minimum. Then, the high frequency amplifier 52
The intermediate frequency signal level is maintained at a predetermined value by the AGC function of the intermediate frequency amplifier 54 and the intermediate frequency amplifier 54. In addition, AGC
If the received input signal level fluctuates beyond the function range,
Since the amplified output signal level cannot be maintained at the predetermined value, the detection processing unit 58 sends an alarm signal.

When a silent / feria detection signal based on a maintenance person's input or a detection request signal from a remote station is added, the switching section 55 causes the second setting section 57 to change to the variable attenuator 51.
Connect to. As a result, the attenuation amount of the variable attenuator 51 is controlled to (input signal level in normal time-threshold level) as described above. The amplified output signal level at that time is detected by the detection processing unit 58, compared with the amplified output signal level at the time of normality, the presence or absence of silent aria is determined, and the determination result is notified to a maintenance person or a remote station.

FIG. 9 is an explanatory diagram of AGC characteristics, in which the vertical axis represents the output signal level and the horizontal axis represents the input signal level. The horizontal axis shows the lower input signal level on the right side and the higher input signal level toward the left side. The following shows the case. When the AGC range in a normal receiving device is A1, the input signal level is I
The output signal level is maintained constant even if the threshold level is reduced to IN ₂ from N ₁ , for example. However, when the range of AGC becomes narrow as shown by A2, the input signal level becomes IN
_{When the} threshold level IN ₂ is lowered from ₁ , the output signal level is also lowered. That is, the deterioration of the AGC function can be detected by forcibly lowering the input signal level by the variable attenuator 51 and detecting the output signal level by the detection processing unit 58. In other words, silent ferrier can be detected.

The present invention is not limited to the above-mentioned embodiments, but various additions and modifications can be made. For example, the above-mentioned embodiments are combined to detect the silent / feria of each part. You can also In addition, it is difficult to detect silent feria during in-service,
Since it is possible to determine the presence / absence of silent aria in a relatively short time with a simple operation, the transmitter / receiver that has become the standby system is detected by switching between the active and standby systems, and the silent aria is detected, improving the reliability of the communication system. can do.

[0045]

As described above, according to the present invention, the output state of the transmission output signal level, the reception intermediate frequency signal level, the set frequency component level, the bit error rate, etc., of the transmission device or the reception device of the communication system in the normal state Is measured, and when the silent faeria of the amplifier 1 with the back-off applied is detected, the attenuation amount of the variable attenuator 2 is minimized and the maximum output signal level of the amplifier 1 is compared with the normal time, and the silent faeria of the local oscillator is compared. At the time of detection, the output signal level of the band pass filter of the intermediate frequency signal when the unmodulated signal is transmitted and this unmodulated signal is received is measured and compared with the normal time, and the bit error rate of the receiving device is used. When silent / feria is detected, the received input signal level is attenuated to a threshold level and the bit error rate is measured and compared with the normal state, and the AGC function is used. During a silent Feria detection of the receiving apparatus including attenuates the received input signal level to the threshold level, as compared to normal by measuring the intermediate frequency signal level at that time, silent when the comparison result exceeds the allowable value
Since it is determined that there is a feria, it is possible to detect a silent feria before a failure occurs with a relatively simple configuration. Therefore, there is an advantage that system down can be prevented. Further, since silent / feria detection can be performed by remote control, there is an advantage that the system can be easily monitored at the terminal stations and the like even for distributed transmission devices and reception devices.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of output signal level characteristics.

FIG. 3 is an explanatory diagram of remote monitoring.

FIG. 4 is an explanatory diagram of a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a third embodiment of the present invention.

FIG. 6 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a bit error rate.

FIG. 8 is an explanatory diagram of a fifth embodiment of the present invention.

FIG. 9 is an explanatory diagram of AGC characteristics.

[Description of Reference Signs] 1 amplifier 2 variable attenuator 3 directional coupler 4 diode 5 DC amplifier 6 switching unit 7 attenuation amount control unit 8 detection processing unit

Claims (6)

[Claims] 1. A method for detecting a silent / feria of a transmitter / receiver of a communication system, wherein an output state such as an output level at a normal time and an output state such as an output level by switching a reception input signal level or an unmodulated input. And a method of determining that there is a silent aria when the comparison result exceeds a permissible value, and a method of detecting a silent fairy is included. 2. The output level in a state where the output level of the transmitter is maximized is previously measured by switching the attenuation amount of the variable attenuator of the transmitter including the automatic output control circuit of the communication system to the minimum. Every time the silent / feria is detected, the attenuation of the variable attenuator is switched to the minimum, the output level of the transmitter is measured, and the output signal level measured in advance is compared, and the comparison result is an allowable value. The silent ferria detection method according to claim 1, characterized in that it is determined that there is silent aria when the number of times exceeds. 3. A bandpass filter having an intermediate frequency signal of a receiving device when the oscillation frequency of a local oscillator of the transmitting device of the communication system is normal is provided, and when a silent / feria is detected, the transmitting device transmits the bandpass filter. An unmodulated signal is transmitted, the level of the output signal of the bandpass filter to which the intermediate frequency signal of the receiving device is added is detected, and when the level decreases below a permissible value, the transmitting device or the local portion of the receiving device is detected. 2. The method for detecting silent ferrier according to claim 1, wherein it is determined that there is silent ferrier including fluctuation of the oscillation frequency of the oscillator. 4. The level of the output signal of the bandpass filter is detected after the intermediate frequency signal of the receiving device is converted into a low frequency by a frequency converter and then added to a bandpass filter having a frequency in a normal state as a pass band. However, when the level is reduced below an allowable value, it is determined that there is a silent failure including a variation in the oscillation frequency of the local oscillator of the transmitter or the receiver.
The silent ferrier detection method described. 5. A bit error rate is measured in advance when the attenuation amount of a variable attenuator for controlling the reception input signal level of the reception device of the communication system is set so that the reception input signal level becomes a threshold level. When the silent / feria is detected, the bit error rate is measured by setting the attenuation amount of the variable attenuator so that the received input signal level becomes the threshold level, and the bit error rate deteriorates beyond the allowable value. The silent ferria detection method according to claim 1, characterized in that it is determined that there is silent aria. 6. An intermediate frequency signal level when an attenuation amount of a variable attenuator for controlling a reception input signal level of a reception device having an AGC function of the communication system is set so that the reception input signal level becomes a threshold level. Is measured in advance, at the time of silent / feria detection, the attenuation amount of the variable attenuator is set so that the received input signal level becomes a threshold level, the intermediate frequency signal level is measured, and the measured value and the previously measured value are measured. The method for detecting silent ferrier according to claim 1, wherein a silent ferrier is determined to be present when the comparison result exceeds a permissible value by comparing the measured value of the intermediate frequency signal level.