JP2001168772A - Device and method for switching hot standby line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid switching of an unnecessary transmission line due to the erroneous detection of a silent fail signal, which is caused by the fault of a device, in a hot standby line switching circuit. SOLUTION: The hot standby line switching circuit has a function for detecting the device fault of the line transmitting a control signal giving the instruction of line switching and it invalidates the control signal based on a silent fail state, which is detected by a system where the device fault is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot standby line switching device and a hot standby line switching method for switching between an active and standby transmitting / receiving device in a hot standby system.

[0002]

2. Description of the Related Art In a hot standby line switching apparatus having both a working system and a standby system, line switching is performed using alarms output from various parts of the system. If an alarm is not output despite the occurrence, an abnormal signal is transmitted to the receiving system via the wireless transmission path, and a silent failure state is set.

Hitherto, various proposals have been made to avoid such a silent fail state.

For example, in a hot standby switching apparatus disclosed in Japanese Patent Application Laid-Open No. 63-283236, when a warning is issued to both a working system and a standby system of a receiving system, a line which is in a silent fail state is described. The transmission line switching control signal is transmitted to the transmission system using the reverse line, and the silent line failure state is avoided by switching the transmission side line.

In a hot standby switching apparatus disclosed in Japanese Patent Application Laid-Open No. 63-309033, a line switching signal is transmitted from a terminal station using a line opposite to a line in a silent fail state. With this line switching signal, the standby transmission / reception device is switched to the active transmission / reception device.

A hot standby switching device disclosed in Japanese Patent Laid-Open Publication No. 1-194522 discloses a switching device for switching between a working system and a standby system transmitting device, and a direction for coupling a part of a signal reflected by the switching device. A directional coupler, and detects a signal coupled by the directional coupler, and monitors the operation of the switching device based on the detected signal.

Japanese Patent No. 2616473 (Japanese Unexamined Patent Application Publication No.
In the hot standby switching apparatus disclosed in Japanese Patent Application Publication No. 6561), when it is detected that the source terminal station of the received signal has a cause of failure, a notification indicating the occurrence of the failure is sent from the relay destination station. Also does not switch its own transmitting device.

[0008] Japanese Patent No. 2735511 (JP-A-9-87)
No. 06) discloses a hot standby switching device that compares the time difference between two different line degradation alarms that are issued when the line is degraded, and if the time difference is equal to or greater than a certain value, transmits a line switching signal to the opposite station. Output is stopped.

Japanese Patent Publication No. Hei 7-28241 (Japanese Unexamined Patent Publication No.
No. 177729) is provided with switching connection means for connecting a backup path in the transmitting and receiving apparatus, performing loopback of the own station, and detecting abnormality of the backup path at the transmitting end and the receiving end, and using the working and protection paths at the receiving end. Monitoring the transmission line quality of the
When the transmission path quality of both the working path and the protection path is deteriorated, a working protection switching signal is output to the transmitting end, the working protection switching signal is transmitted from the receiving end to the transmitting end, and the local station loops back at the transmitting end. When there is no abnormality in the route, the switching between the working and the standby is performed.

FIG. 4 is a block diagram showing an example of a conventional hot standby line switching device. In FIG. 4, the direction from terminal station D to terminal station E is a downlink, and the direction from terminal station E to terminal D is an uplink.

The terminal station D includes a transmitting end 130 and an antenna 131
A transmission system and a reception system are provided between the transmission and reception systems, and the transmission system is further divided into an active system and a standby system.

The transmission system includes a hybrid 101c, modulation circuits 102i and 102j, and transmission circuits 103i and 103
j, a transmission side control circuit 104e, a transmission line switch 105e, and a circulator 106e.

On the other hand, the receiving system includes a receiving device 201.

The terminal E is connected to the antenna 13 in the same manner as the terminal D.
2 and a receiving end 133, a receiving system and a transmitting system are provided, and the receiving system is further divided into a working system and a standby system.

The receiving system includes a circulator 106f, a hybrid 107e, and receiving circuits 108i and 108j.
, Demodulation circuits 109i and 109j, and monitoring circuit 203
And a reception line switch 110c.

On the other hand, the transmission system has a transmission device 202.

[0017]

First, referring to FIG.
Although the downlink is not in the silent fail state, the circulator 10
A failure occurs between 6e and the receiving device 201, and as a result of the failure, a warning indicating a line failure is output from the receiving device 201, and the silent fail signal continues to be erroneously detected. The following describes the case where

At this time, since the receiving apparatus 201 has detected the silent fail signal, it sends out the silent fail switching control signal 13e to the transmitting side control circuit 104e. The transmission-side control circuit 104e switches the transmission line changeover switch 105e even though the downlink is not in the silent fail state, so that unnecessary line switching is performed in the downlink even though the downlink is normal. Will be

As described above, when a failure occurs in both systems due to a device failure or the like somewhere in the uplink, and if a silent fail signal is erroneously detected, unnecessary line switching is performed in a normal downlink. There was a problem that would be.

In FIG. 4, when the downlink is not in the silent fail state, the line degradation due to weather conditions occurs temporarily in the radio transmission line of the uplink. Will not be output, but a case where a silent fail signal is erroneously detected temporarily will be described.

At this time, since the receiving circuit 201 has detected the silent fail signal, it sends out the silent fail switching control signal 13e to the transmitting side control circuit 104e. Since the transmission-side control circuit 104e switches the transmission line switch 105e even though the downlink is not in the silent fail state, unnecessary line switching is performed in the downlink despite the nature of the downlink. Will be

As described above, in the uplink wireless transmission path, line deterioration occurs temporarily due to changes in weather conditions and the like.
As a result, when a silent fail signal is erroneously detected, unnecessary line switching is performed on a normal downlink.

Further, in FIG. 4, when the downlink is in a silent fail state and the silent fail signal is normally transmitted to the receiving apparatus 201 of the terminal D using the uplink, the receiving apparatus of the terminal D At 201,
A case where the silent fail signal detection unit of the currently operating system locally fails will be described.

In this case, although the silent fail signal is normally transmitted to the receiving device 201,
Since the silent fail signal detection unit is out of order, the receiving device 201 cannot output the silent fail switching control signal 13e to the transmitting side control circuit 104e, and there is a problem that the silent fail state continues. Was.

The present invention has been made in view of the above-mentioned problems in the conventional hot standby line switching apparatus, and has an effect on both the active system and the standby system of a line used for signal transmission. Unnecessary switching of the transmission line due to erroneous detection of a silent fail signal caused by a failure can be prevented, and due to erroneous detection of a silent fail signal due to temporary line deterioration caused by weather conditions or other causes. An object of the present invention is to provide a hot standby line switching device and a hot standby line switching method that can prevent unnecessary switching of transmission lines.

[0026]

In order to achieve this object, a first aspect of the present invention is a hot standby line switching apparatus having a working and a standby transmitting / receiving apparatus,
In the silent failure state, after transmitting a control signal to the transmission device using a line opposite to the line that has detected the silent failure state, it is possible to avoid a failure by switching the line switch of the transmission device. The hot standby line switching device has a function of detecting a device failure of a line transmitting the control signal, and a function of invalidating a control signal based on a silent fail state detected in a system in which the device failure is detected. A hot standby line switching device is provided.

A second aspect of the present invention is a hot standby line switching device having a working and a standby transmitting / receiving device, wherein the transmitting device uses a line opposite to the line in which the silent fail state is detected in the silent fail state. After transmitting the control signal to the hot standby line switching device capable of avoiding a failure by switching the line switch of the transmitting device, the control signal in the silent fail state transmitted from the receiving device, the control signal of the transmitting device A hot standby line that enables detection of the control signal by a standby system even when a local failure occurs in the currently operating system by detecting the current and standby systems. A switching device is provided.

A third aspect of the present invention is a hot standby line switching device having a working and a backup transmission / reception device, wherein the transmission device uses a line opposite to the line in which the silent failure state is detected in the silent failure state. A timer for detecting a control signal based on a silent fail state transmitted from a receiving device in a hot standby line switching device capable of avoiding a failure by switching a line switch of the transmitting device after transmitting a control signal to the transmitting device A hot standby line switching device for switching a line when the control signal is continuously detected for a predetermined period of time.

A fourth aspect of the present invention is a hot standby line switching device having a working and a backup transmission / reception device, wherein in a silent failure state, the transmission device uses a line opposite to the line that detected the silent failure state. After sending a control signal to the hot standby line switching device capable of avoiding a failure by switching the line switch of the transmission device, a working system detection circuit, a standby system detection circuit, a determination circuit, a timer And a first signal indicating that frame synchronization has not been established in the active transmission / reception device, and a second signal indicating that a silent failure state has been detected. Two signals and, when only the second signal is received, transmits a first detection signal to the determination circuit, the The standby detection circuit receives a third signal indicating that frame synchronization has not been established in the standby transmission / reception device, and a fourth signal indicating that a silent fail state has been detected, and outputs only the fourth signal. When receiving, a second detection signal is transmitted to the determination circuit, and the determination circuit, when receiving at least one of the first detection signal and the second detection signal, a silent detection signal to the timer And the timer switches the line when the silent detection signal is received continuously for a predetermined period of time.

A fifth aspect of the present invention provides a hot standby line switching system including any one of the above hot standby line switching devices and including a first and a second terminal station facing each other.

According to a sixth aspect of the present invention, there are provided a plurality of terminal stations each having a working and a backup transmitting / receiving apparatus, which are in opposition to each other, and at least one intermediate relay station having any one of the above hot standby line switching apparatuses. And a hot standby line switching system comprising:

According to a seventh aspect of the present invention, in the hot standby line switching device having the working and standby transmission / reception systems, in the silent fail state, the second line opposite to the first line that has detected the silent fail state is used. In a hot standby line switching method for performing line switching, the method includes a step of detecting a device failure of the second line and a step of invalidating a detection result of a silent failure state detected in a system in which the device failure is detected. A hot standby line switching method is provided.

In the hot standby line switching device having the working and backup transmission / reception systems, a second line opposite to the first line that detects the silent failure state is used in the silent failure state. In a hot standby line switching method for performing line switching, the method includes a step of detecting a control signal indicating a silent fail state transmitted from a receiving system in both a working system and a standby system of the transmitting system, and localizing the control signal to a currently operating system. The present invention provides a hot standby line switching method that enables a standby system to detect the control signal even when a temporary failure occurs.

According to a ninth aspect of the present invention, in the hot standby line switching device having the active and standby transmission / reception systems, the second line opposite to the first line detecting the silent failure state is used in the silent failure state. In a hot standby line switching method for performing line switching, a step of detecting a control signal based on a silent failure state transmitted from a receiving system, and a step of switching a line when the control signal is continuously detected for a predetermined time. And a hot standby line switching method comprising:

As described above, according to the hot standby line switching apparatus according to the present invention, a state in which an abnormal signal is transmitted to the opposite station without generating an alarm indicating a device failure in the transmitting apparatus (this state). Is defined as a "silent fail state"), the receiving apparatus detects the sign, and transmits a control signal to the transmitting apparatus using a line opposite to the line on which the sign of the silent fail state is detected, and then transmits the signal. A failure can be avoided by detecting a silent failure state and switching a line changeover switch by a transmission-side device having a circuit for determining the control signal.

In this case, by monitoring the line state of the line transmitting the control signal, when transmitting the control signal to the transmission side device, the line generated due to a device failure, a weather condition occurring on the wireless transmission line, or the like. Unnecessary line switching operation caused by a control signal erroneously detected due to deterioration or the like can be prevented.

Further, the transmitting apparatus always detects the control signal transmitted from the receiving apparatus in both the working and protection systems, so that a local fault occurs in the currently operating system. Also, the control signal can be detected by the standby system and the line switching control can be performed.

Hereinafter, the operation of the hot standby line switching apparatus according to the present invention will be described with reference to FIG.

In FIG. 1, a terminal station A and a terminal station B are hot-standby line switching devices having working and protection transmission / reception systems, and face each other. The direction from terminal station A to terminal station B is referred to as a downlink, and the direction from terminal station B to terminal station A is referred to as an uplink.

In the down line, the monitoring circuit 111b of the receiving system of the terminal B is connected to the demodulating circuits 10 of both the working system and the standby system.
Out-of-frame alarm 15 output by 9c and 109d
When c and 15d are detected continuously for a predetermined period of time, it is determined that there is a possibility of a silent failure state, and a signal 17b (hereinafter, referred to as "silent failure") for notifying the terminal station A of the silent failure state using the uplink. Fail detection signal "
Is transmitted to the working and protection modulation circuits 102c and 102d in the transmission system of the terminal station B.

The modulation circuits 102c and 102d convert the silent fail detection signal 17b into the baseband signals 22c and 2d.
The signal is multiplexed into 2d, modulated, and transmitted to transmission circuits 103c and 103d. The transmission circuits 103c and 103d output the RF signal 23
c and 23d are sent to the transmission line switch 105b. The transmission line switch 105b selects one of the active or standby RF signals 23c and 23d according to the switching control signal 14b output from the transmission side control circuit 104b, and transmits the selected RF signal 23c or 23d to the circulator 106b. And sends it out to the antenna 123.

In the receiving system of the terminal station A, the signal transmitted from the terminal station B is split into a working system and a protection system in the hybrid 107a, and after performing frequency conversion via the receiving circuits 108a and 108b, the working system The signals are input to the demodulation circuits 109a and 109b of the system and the standby system.

The demodulation circuits 109a and 109b demodulate the transmitted signal and synchronize the frames. When the frame synchronization is not established, the frame synchronization alarm 1 is output.
5a and 15b are output to the monitoring circuit 111a.

The demodulation circuits 109a and 109b further include:
Silent fail detection signal 17b multiplexed at terminal B
Is extracted, and silent fail extraction signals 16a and 16b are extracted.
Is output to the determination circuit 112a.

The judging circuit 112a includes demodulating circuits 109a, 1
09b output the silent fail extraction signal 16a,
At the same time, the out-of-frame alarms 15a and 15b output from the demodulation circuits 109a and 109b are monitored.
It is confirmed that the silent fail extraction signals 16a and 16b are received in a state where the signals a and 15b are not output. At this time, the determination circuit 112a outputs the frame out-of-sync alarm 15a for at least one of the active system and the standby system.
If the silent fail extraction signal 16a (or 16b) is continuously detected for a predetermined time in a system in which (or 15b) is not detected, it is determined that the opposite station has sent the silent fail detection signal 17b. Sends a silent fail switching control signal 13a to the transmission side control circuit 104a.

The transmission side control circuit 104a is a modulation circuit alarm signal 11a in a system opposite to the system operated by the transmission system.
(Or 11b) and when the silent fail switching control signal 13a is detected in a state where the transmitting circuit alarm signal 12a (or 12b) is not detected, the transmission line switching switch is set so as to select the system opposite to the currently operating system. The switching control signal 14a is sent to 105a.

The transmission line changeover switch 105a selects a system opposite to the currently operating system according to the changeover control signal 14a.

As described above, according to the present invention, the possibility of a silent failure state is detected, and a detection signal is transmitted via a line in a direction opposite to the detected line to perform line switching control. At this time, the line state of the line in the reverse direction is monitored, and line switching control is determined based on the silent fail extraction signals of both the active and standby systems. Further, line switching is performed only when a silent fail extraction signal is continuously detected for a predetermined time. This can prevent unnecessary line switching due to erroneous detection of a silent fail state due to line failure or line deterioration.

[0049]

FIG. 1 is a block diagram of a hot standby line switching apparatus according to a first embodiment of the present invention. In FIG. 1, a terminal station A and a terminal station B have a transmission / reception function of two systems, a working system and a protection system, and are capable of switching between the working system and the protection system according to a device failure or other causes. It is a switching device. The terminal station A and the terminal station B are arranged to face each other, and mutually transmit and receive signals.

First, in the transmission system of the terminal station A, the baseband signal input from the transmission terminal 121 is branched into the working system and the protection system in the hybrid 101a, and converted into the working system modulation circuit 102 as the baseband signals 21a and 21b.
a and the standby system modulation circuit 102b.

The modulation circuits 102a and 102b multiplex a frame synchronization signal, an error detection parity bit, and a silent fail detection signal 17a to be described later, and perform modulation on the baseband signals 21a and 21b.
The modulated signals 22a and 22b are transmitted to the transmitting circuits 103a and 103b of the working and standby systems.

At this time, the modulation circuits 102a and 102b monitor the abnormality of the modulation circuit including the equipment failure, and when abnormal, output the modulation circuit alarm signals 11a and 11b to the transmission side control circuit 104a.

The transmission circuits 103a and 103b convert the modulated signals 22a and 22b into signals to be transmitted to the wireless transmission path, and then transmit the signals as RF signals 23a and 23b to the transmission line switch 105a.

At this time, the transmission circuits 103a and 103b
It monitors transmission system abnormalities including equipment failures, and when abnormalities occur, outputs transmission circuit alarm signals 12a and 12b to the transmission side control circuit 104a. The transmission side control circuit 104a monitors the modulation circuit alarm signals 11a and 11b output from the modulation circuits 102a and 102b and the transmission circuit alarm signals 12a and 12b output from the transmission circuits 103a and 103b. A switch control signal 14a is output to the transmission line switch 105a so as to select a system on which no alarm is generated.

The transmitting side control circuit 104a further monitors a silent fail switching control signal 13a described later,
When the silent failure state is detected, it is confirmed that the modulation circuit warning signal 11a (or 11b) and the transmission circuit warning signal 12a (or 12b) of the system not selected by the transmission line switch 105a are not output. After that, the transmission line switch 105a is controlled so that the system selected by the transmission line switch 105a is the system on the opposite side.

The transmission line switch 105a selects the active or standby RF signal 23a or 23b in accordance with the switching control signal 14a, and selects the circulator 106.
output to a. A signal input to the antenna 122 via the circulator 106a is transmitted to the terminal station B via a wireless transmission path.

Next, in the receiving system of the terminal station A, the terminal station B
From the wireless transmission path input through the antenna 122 and input into the hybrid 107a through the circulator 106a. The hybrid 107a branches the signal on the wireless transmission path into the working system and the protection system, and
As 4a and 24b, they are sent to the active receiving circuit 108a and the standby receiving circuit 108b.

The receiving circuits 108a and 108b perform frequency conversion on the signals 24a and 24b on the radio transmission path, and convert the converted signals 2a and 24b.
5a and 25b are output to demodulation circuits 109a and 109b.

The demodulation circuits 109a and 109b output the transmission signal 2
5a and 25b are demodulated into baseband signals 26a and 26b, and frame synchronization is performed. When frame synchronization is not established, frame loss alarms 15a and 15b are output.
b to the monitoring circuit 111a.

The demodulation circuits 109a and 109b further include:
The parity bits for error detection multiplexed at the terminal station B are analyzed, and when a certain or more bit error exists in the transmission signals 25a and 25b or when frame synchronization is not established, the demodulation circuit alarm signals 18a and 18b Is output to the reception line switching control circuit 113a.

The demodulation circuits 109a and 109b further include:
Silent fail detection signal 17b multiplexed at terminal B
Is extracted, and silent fail extraction signals 16a and 16b are extracted.
Is output to the determination circuit 112a.

The baseband signals 26a and 26b demodulated by the demodulation circuits 109a and 109b are sent to the reception line switch 110a.

The reception line switching control circuit 113a monitors the demodulation circuit alarm signals 18a and 18b output from the demodulation circuits 109a and 109b, and selects a system on which no alarm is generated in a normal state. A reception line switching control signal 19a is output to the line switching switch 110a.

The receiving line switching switch 110a selects either the working or protection baseband signals 26a, 26b in accordance with the receiving line switching control signal 19a and outputs it to the receiving end 126.

The monitoring circuit 111a is provided with the working demodulation circuit 10
9a and the out-of-frame alarms 15a and 15b output from the standby system demodulation circuit 109b are monitored, and the out-of-frame alarms 15a and 15b from both the active system and the standby system are monitored.
Is detected continuously for a predetermined period of time, it is determined that there is a possibility of a silent fail state, and the silent fail detection signal 17a is transmitted to the active modulation circuit 1 of the transmitting system of the terminal station A.
02a and the standby system modulation circuit 102b. Thereafter, the silent failure detection signal 17a is transmitted to the terminal station B via a wireless transmission path in order to switch the transmission line switch 105b of the terminal station B.

The decision circuit 112a outputs the silent fail extraction signals 16a and 16b sent from the terminal station B and extracted by the demodulation circuits 109a and 109b, and the out-of-frame alarm 1 output by the demodulation circuits 109a and 109b.
5a and 15b are monitored. If the silent fail extraction signal 16a (or 16b) is detected in at least one of the working system and the standby system in a system in which the out-of-frame alarm 15a (or 15b) is not detected, It determines that the station B has sent the silent fail detection signal 17b, and outputs a silent fail switching control signal 13a to the transmission side control circuit 104a.

FIG. 2 shows a decision circuit 112 in the receiving system of the terminal A of the hot standby line switching apparatus according to the present embodiment.
It is a block diagram showing one Example of a.

As shown in FIG. 2, the determination circuit 112a
The active system detection circuit 114a, the standby system detection circuit 114b, the determination unit 115, and the timer circuit 116 are configured.

The active side detection circuit 114a monitors the out-of-frame alarm 15a and the silent fail extraction signal 16a output from the active system demodulation circuit 109a, and outputs the silent fail extraction signal 16a when the out-of-frame alarm 15a is not detected. Is detected, a detection signal 27a is output to the determination unit 115.

Similarly, the standby side detection circuit 114b monitors the out-of-synchronization alarm 15b and the silent fail extraction signal 16b output from the standby demodulation circuit 109b, and performs the silent failure in a state where the out-of-frame alarm 15b is not detected. When the extraction signal 16b is detected, a detection signal 27b is output to the determination unit 115.

The silent fail extraction signals 16a, 16
By monitoring the out-of-frame alarms 15a and 15b in conjunction with b, when the silent fail extraction signals 16a and 16b are erroneously detected due to a device failure or other causes, the silent fail extraction signals 16a and 16b are monitored.
6b is invalidated, and an incorrect silent fail extraction result is prevented from being output to the determination unit 115.

When one or both of the active system and the standby system detect the detection signals 27a and 27b, the determination unit 115 sends a silent detection signal 28 to the timer circuit 116.

As described above, by performing silent failure detection in both the active system and the standby system, a failure occurs on the operation side in a situation where line switching does not occur due to a local device failure or the like. Even when this occurs, the silent detection signal 28 can be output.

When the timer circuit 116 continues to receive the silent detection signal 28 for a predetermined time, it outputs a silent fail switching control signal 13a to the transmission side control circuit 104a.

As described above, by providing output protection for a certain period of time in the detection result of the silent fail signal, erroneous detection of a silent fail due to temporary line deterioration or the like can be prevented.

While the configuration and functions of the terminal station A have been described above, the terminal station B has the same configuration and functions.

Next, an example of a line switching operation in the hot standby line switching device according to the present embodiment will be described.

In FIG. 1, the direction from terminal station A to terminal station B is the down line, the direction from terminal station B to terminal station A is the up line, and the transmission and reception systems of terminal A and terminal B are It is assumed that all are operated using the active system.

Here, in the transmission system of the terminal station A, the modulation circuit alarm signals 11a and 11b and the transmission circuit alarm signal 12
a and 12b are not output, but a failure has occurred between the transmission circuit 103a and the transmission line switch 105a, so that the demodulation circuit 1
09c and 109d are out-of-frame alarms 15c and 15d.
Consider the case where d is output.

In the transmission system of the terminal station A, the transmission line switch 105a selects the working RF signal 23a, and the working modulation circuit 102a and the working transmission circuit 10a.
3a does not output the modulation circuit alarm signal 11a and the transmission circuit alarm signal 12a, respectively.
4a is a switching control signal 1 such that the active system is selected as it is.
4a is output to the transmission line switch 105a.

The transmission line switch 105a selects the working RF signal 23a in accordance with the switching control signal 14a, and the selected working RF signal 23a is input to the antenna 122 via the circulator 106a and transmitted via the radio transmission path. And transmitted to the terminal B.

In the receiving system of the terminal station B, the signal transmitted from the terminal station A via the radio transmission path is transmitted to the antenna 123.
And the hybrid 10 via the circulator 106b
7b, the hybrid 107b splits the received signal into working and protection signals, and the receiving circuit 108
The signals are input to demodulation circuits 109c and 109d via c and 108d.

However, at this time, since the transmission system is out of order, the demodulation circuits 109c of both the working system and the protection system are
Reference numeral 109d outputs the out-of-frame alarms 15c and 15d, and the monitoring circuit 111b detects the out-of-frame alarms 15c and 15d for both the active and standby systems.

The monitoring circuit 111b continuously outputs the frame out-of-synchronization alarm 15c in both the active and standby systems for a predetermined time or more.
15d, it is determined that there is a possibility of a silent failure state, and the silent failure detection signal 17b is detected.
Is output to the modulation circuits 102c and 102d of the transmission system.

The time from when the monitoring circuit 111b detects the out-of-frame alarms 15c and 15d to when it outputs the silent fail detection signal 17b is such that it can be determined that it is clearly different from temporary line deterioration due to a natural phenomenon or the like. , That is, from several tens of seconds to several minutes.

The monitoring circuit 111b outputs the silent failure detection signal 17b to the modulation circuits 102c and 102d. The modulation circuits 102c and 102d multiplex and modulate the frame synchronization signal, the error detection parity bit and the silent fail detection signal 17b with the baseband signals 22c and 22d in both the working and protection systems, respectively. The signal is output to the transmission line switch 105b via the switch 103d.

The transmission line changeover switch 105b selects the working RF signal 23c, and the working modulation circuit 102
c and the active transmission circuit 103c output the modulation circuit alarm signal 11
c, since the transmission circuit alarm signal 12a is not output, the transmission-side control circuit 104b
The switch control signal 14b is output to the transmission line switch 105b so as to select c.

The transmission line switch 105b selects the working RF signal 23c according to the switching control signal 14b, and the selected RF signal 23c is
The signal is input to the antenna 123 via the terminal b and transmitted to the terminal station A via the wireless transmission path.

In the receiving system of the terminal station A, the transmission signal sent from the terminal station B is branched into a signal for the working system and a signal for the standby system in the hybrid 107a.
The signals are sent out to the working demodulation circuit 109a and the standby demodulation circuit 109b via a and 108b. Working demodulation circuit 1
09a and the standby demodulation circuit 109b synchronize the frames, extract the silent fail detection signal 17b sent from the terminal station B, and output the same as the silent fail extraction signals 16a and 16b to the determination circuit 112a.

At this time, since frame synchronization has been established in both the working and protection systems, the demodulation circuits 109a,
9b does not output the out-of-frame alarms 15a and 15b.

The determination circuit 112a provides the frame loss alarms 15a and 15b in both the active system and the standby system.
Has not been detected, and the silent fail extraction signal 16
a and 16b are continuously detected for a predetermined period of time, so that the silent failure detection signal 17
It is determined that “b” has been transmitted, and the silent failure switching control signal 13a is output to the transmission side control circuit 104a.

The transmission-side control circuit 104a detects the silent-fail switching control signal 13a and, after confirming that the standby modulation circuit alarm signal 11b and the transmission circuit alarm signal 12b are not output, switches the operation line to the standby state. The switching control signal 14a is output to the transmission line switch 105a so as to switch to the system.

The transmission line switch 105a receives the switching control signal 14a, selects the standby RF signal 23b, and outputs it to the circulator 106a.

Here, the working system demodulation circuit 109a of the terminal station A
In the above, although the portion that outputs the silent fail extraction signal 16a locally fails and receives the silent fail detection signal 17b from the terminal station B,
It is assumed that the silent fail extraction signal 16a is not output.

The determination circuit 112a does not detect the out-of-frame alarms 15a and 15b of both the active system and the standby system, but detects the silent fail extraction signal 16b of the standby system. In this case, the determination circuit 112a continuously detects the silent fail extraction signal 16b for a predetermined period of time without detecting the standby frame out-of-sync alarm 15b. It is determined that the detection signal 17b has been transmitted, and the silent-fail switching control signal 13a is transmitted to the transmission-side control circuit 10.
4a.

The transmission-side control circuit 104a detects the silent-fail switching control signal 13a and, after confirming that the standby-system modulation circuit alarm signal 11b and the transmission circuit alarm signal 12b are not output, switches the operation line to the standby mode. The switching control signal 14a is output to the transmission line switch 105a so as to switch to the system.

Upon receiving the switching control signal 14a, the transmission line switch 105a selects the standby RF signal 23b and outputs it to the circulator 106a.

The above description is for the case where the downlink is in a silent fail state. In FIG. 1, the same operation is performed even when the uplink enters a silent fail state.

Next, the downlink is operating normally without any alarm being output, but a failure occurs between the circulator 106a and the hybrid 107a in the receiving system of the terminal A, and System demodulation circuits 109a, 10
9b outputs the out-of-frame alarms 15a and 15b, and erroneously outputs the silent fail extraction signals 16a and 16a.
It is assumed that 16b is output.

In the receiving system of the terminal station A, the demodulation circuits 109a and 109b of both systems output the frame loss alarm 15a,
15b and silent fail extraction signals 16a, 16b
Is output.

The determination circuit 112a outputs a frame loss of synchronization alarm 15a for at least one of the active system and the standby system.
When the silent fail extraction signal 16a (or 16b) is continuously detected for a predetermined time in a system in which (or 15b) has not been detected, the terminal station B which is the opposite station is detected.
Determines that the silent fail detection signal 17b has been transmitted from the controller, and outputs a silent fail switching control signal 13a to the transmission side control circuit 104a. In this case,
The determination circuit 112a detects the silent fail extraction signals 16a and 16b from both systems and also detects the frame out-of-synchronization alarms 15a and 15b, and therefore does not output the silent fail switching control signal 13a.

In the transmission system of the terminal station A, the transmission line switch 105a selects the RF signal 23a of the active system, does not detect the silent fail switching control signal 13a, and the active system modulation circuit 102a and the active system modulation signal 102a. Since the system transmission circuit 103a does not output the modulation circuit warning signal 11a and the transmission circuit warning signal 12a, respectively, the transmission side control circuit 104a outputs the switching control signal 14a so as to select the working system as it is.

The transmission line switch 105a keeps selecting the active RF signal 23a in accordance with the switching control signal 14a.

Although the downlink is operating normally without outputting any alarm, the degradation of the line due to weather conditions in the uplink radio transmission line is shorter than the time for which the timer circuit 116 performs output protection. Along with this, the demodulation circuits 109a and 109b of the terminal station A do not output the out-of-frame alarms 15a and 15b, and output the silent fail extraction signals 16a and 16b to the timer circuit 11a.
Consider a case where the output is performed for a time shorter than the time for performing the output protection in 6.

In the receiving system of the terminal station A, the demodulation circuit 10
9a and 109b output the silent fail extraction signals 16a and 16b for a time shorter than the time for which the timer circuit 116 performs output protection.

In FIG. 2, detection circuits 114a and 114
b indicates that the silent fail extraction signals 16a and 16b are not detected when the out-of-frame alarms 15a and 15b are not detected.
b, the detection signals 27a, 27b
Is output.

The determination section 115 detects the detection signals 27a, 27b
Is detected, the silent detection signal 28 is output to the timer circuit 116. When detecting the silent detection signal 28, the timer circuit 116 activates the timer to protect the output for a predetermined time, and does not output the silent fail switching control signal 13a during the output protection.

When the timer circuit 116 detects the silent detection signal 2
8, when the timer operation is started and the line degradation of the wireless transmission line is recovered while the output of the silent fail switching control signal 13a is protected, the demodulation circuits 109a, 10a
The silent fail extraction signals 16a and 16b are no longer output from 9b.

As a result, since the detection circuits 114a and 114b do not detect the silent fail extraction signals 16a and 16b, the output of the detection signals 27a and 27b is stopped.

The determination section 115 detects the detection signals 27a, 27b
Is not detected, and the output of the silent detection signal 28 is stopped.

The timer circuit 116 outputs the silent detection signal 2
8, the timer operation is stopped, and the silent fail switching control signal 13a is not output.

In the transmission system of the terminal station A, the transmission line changeover switch 105a selects the active system RF signal 23a, does not detect the silent fail switching control signal 13a, and uses the active system modulation circuit 102a. Since the active system transmission circuit 103a does not output the modulation circuit warning signal 11a and the transmission circuit warning signal 12a, respectively, the transmission side control circuit 104a sends the switching control signal 14a to the transmission line switch 105a so as to select the current system as it is. Output to

The transmission line switch 105a continues to select the active RF signal 23a in accordance with the output of the switching control signal 14a.

In the above description, the case where the downlink operates normally without outputting any alarm, but the silent fail extraction signal 16a (or 16b) is erroneously output in the uplink receiving system. It is an explanation. Although the uplink operates normally without outputting any alarm, the same operation is performed even when the silent fail extraction signal 16c (or 16d) is erroneously output in the downlink reception system. .

In the embodiment described above, the hot standby line switching device having the working and protection transmission / reception systems between the terminal stations A and B which are in opposition to each other has been described. The present invention can be applied to a line having a station. In this case, the number of regenerative relay stations is arbitrary. That is, the present invention can be applied to both a case where there is one regenerative relay station between terminal stations and a case where there are a plurality of regenerative relay stations.

Hereinafter, a hot standby line switching apparatus according to the second embodiment of the present invention will be described with reference to FIG.

In FIG. 3, the direction from terminal station A to terminal station B via intermediate relay station C is the downward direction, and the direction from terminal station B via intermediate relay station C to terminal station A is the upward direction. It will be described as.

At the downlink intermediate relay station C, the signal on the radio transmission path input from the antenna 127 is input to the hybrid 107c via the circulator 106c.

The hybrid 107c splits the signal on the wireless transmission line into signals for both the working system and the protection system, and sends the split signals 24e and 24f to the receiving circuits 108e and 108f. The receiving circuits 108e and 108f perform frequency conversion on the signals 24e and 24f on the wireless transmission path, and transmit signals 25e and 25f.
Output to the demodulation circuits 109e and 109f as f.

The demodulation circuits 109e and 109f output the transmission signal 2
5e and 25f are demodulated into baseband signals 26e and 26f, and frame synchronization is performed. If frame synchronization is not established, it is determined that a device has failed, and frame loss alarms 15e and 15f are determined by the determination circuit 112c and the monitoring circuit 1c.
11c.

The demodulation circuits 109e and 109f analyze the parity bits for error detection multiplexed at the terminal station A, and when the transmission signals 25e and 25f have a certain bit error or more or when the frame synchronization is not established. Outputs the demodulation circuit alarm signals 18e and 18f to the transmission side control circuit 117a.

The demodulation circuits 109e and 109f further include:
The multiplexed silent fail detection signal 17a at the terminal station A is extracted, and the silent fail extraction signal 16e,
16f is output to the determination circuit 112c. The demodulated baseband signals 26e and 26f are applied to a modulation circuit 102e,
Output to 102f.

The determination circuit 112c outputs the silent failure extraction signals 16e and 16f and the frame loss alarm 15
e, 15f, and monitors at least one of the active system and the standby system for an out-of-frame alarm 15e (or 1).
When the silent fail extraction signal 16e (or 16f) is continuously detected for a predetermined time in a system in which 5f) is not detected, it is determined that the silent failure detection signal 17a has been transmitted from the terminal A which is the opposite station. Judge,
The silent failure switching control signal 13c is output to the uplink transmission side control circuit 117b.

The monitoring circuit 111c includes a demodulation circuit 109e,
Out-of-frame alarm 15e output from 109f,
15f, and if the out-of-frame alarms 15e and 15f are detected in both the active system and the standby system for a predetermined period of time, it is determined that there is a possibility of a silent failure state. 17c is the modulation circuit 102g, 102h on the uplink side of the intermediate relay station C.
Output to

The modulation circuits 102e and 102f output a frame synchronization signal, an error detection parity bit, and a silent failure detection signal 17 output from the monitoring circuit 111d.
While multiplexing d, the baseband signals 26e and 26f output from the demodulation circuits 109e and 109f are modulated, and the signals 23e and 23f are transmitted to the transmission line switch 105c via the transmission circuits 103e and 103f.

The transmission-side control circuit 117a
Transmission circuit alarm signal 12 output from 3e, 103f
e, 12f, modulation circuit alarm signals 11e, 11f output from modulation circuits 102e, 102f, demodulation circuit 109
e, demodulation circuit warning signal 18e output from 109f,
18f, and in a normal state, outputs a switching control signal 14c to the transmission line switch 105c so as to select a system on which no alarm is generated.

The transmission-side control circuit 117a further monitors the silent-fail switching control signal 13d output from the determination circuit 112d. System transmission circuit alarm signal 12e (or 12f), modulation circuit alarm signal 11e (or 11f).
f) and demodulation circuit alarm signal 18e (or 18f)
After confirming that is not output, the system on the opposite side is selected by the transmission line switch 105c.
The switching control signal 14c is sent to the transmission line switch 105c.

The transmission line switch 105c selects the active or standby RF signal 23e, 23f according to the switching control signal 14c, and outputs the selected RF signal 23e or 23f to the circulator 106d.

The RF signal 23e or 23f input to the antenna 128 via the circulator 106d is transmitted to the terminal B via a wireless transmission path.

The above is a description of the downlink,
The same operation as the downlink is performed for the uplink.

Further, even when a plurality of intermediate relay stations are connected, each intermediate relay station performs the same operation as the intermediate relay station C in the above description.

[0132]

As described above, the hot standby line switching device and the hot standby line switching method according to the present invention have the following effects.

The first effect is that unnecessary switching of the transmission line due to erroneous detection of a silent fail signal caused by a device failure that affects both the working system and the protection system used for transmitting the control signal. Can be prevented.

The reason is that when a silent fail signal transmitted from the opposite station is extracted, the alarm of the line transmitting the silent fail signal is monitored.
This is because the configuration is such that a line switching control signal is not output even if a device failure or the like occurs in a transmission line and a silent fail signal is erroneously extracted.

The second effect is that, in the system on the operation side of the line used to transmit the control signal, the false detection of the silent fail signal caused by the local device failure that does not output the device failure alarm causes Unnecessary switching can be prevented.

The reason is that when the silent fail signal is received and extracted, both the operation side and the standby side extract the silent fail signal, and output the extracted silent fail signal to the determination circuit, so that the operation side can receive the silent fail signal. Even if a local device failure that does not output a device failure alarm occurs in the system, that is, regardless of the state of the system on the operation side, there is a judgment circuit that can detect a silent fail signal. It is because.

A third effect is that unnecessary switching of the transmission line due to erroneous detection of a silent fail signal caused by temporary line deterioration due to weather conditions or the like in a wireless transmission line of a line used for transmission of a control signal. That can be prevented.

The reason is that the judgment circuit for detecting the transmitted silent fail signal has a timer,
This is because this determination circuit is configured to apply protection for a certain period of time when detecting a silent fail signal, and to output a control signal only when a silent fail signal is detected continuously for a certain period or more. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a hot standby line switching device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a determination circuit in the hot standby line switching device shown in FIG. 1;

FIG. 3 is a block diagram of a hot standby line switching device according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional hot standby line switching device.

[Explanation of symbols]

101a, 101b, 107a, 107b Hybrid 102a, 102b, 102c, 102d Modulation circuit 103a, 103b, 103c, 103d Transmission circuit 104a, 104b Transmission side control circuit 105a, 105b Transmission line switch 106a, 106b Circulator 108a, 108b, 108c, 108d Receiving circuit 109a, 109b, 109c, 109d Demodulating circuit 110a, 110b Receiving line selector switch 111a, 111b Monitoring circuit 112a, 112b Judgment circuit 113a, 113b Receiving side control circuit 114a, 114b Detection circuit 115 Judgment unit 116 Timer circuit 121 Transmission end 122, 123, 127, 128 Antenna 126 Receiving end

Claims (9)

[Claims] 1. A hot standby line switching device provided with a working and a backup transmission / reception device, wherein a control signal is transmitted to a transmission device using a line opposite to a line in which a silent failure state is detected in a silent failure state. After sending
A hot standby line switching device capable of avoiding a failure by switching a line switch of the transmitting device, the device having a function of detecting a device failure of a line transmitting the control signal, wherein the device failure is detected. A hot standby line switching device having a function of invalidating a control signal based on a silent fail state detected in a system. 2. A hot standby line switching device having a working and a backup transmitting / receiving device, wherein a control signal is transmitted to a transmitting device by using a line opposite to a line in which a silent fail state is detected in a silent fail state. After sending
In a hot standby line switching device capable of avoiding a failure by switching a line switch of the transmission device, a control signal based on a silent fail state transmitted from a reception device is transmitted to both a working system and a protection system of the transmission device. A hot-standby line switching device that detects a control signal by a standby system even if a local failure occurs in a currently operating system by detecting the hot-standby line switching device. 3. A hot standby line switching device provided with a working and a backup transmitting / receiving device, wherein a control signal is transmitted to a transmitting device using a line opposite to a line in which a silent fail state is detected in a silent fail state. After sending
A hot standby line switching device capable of avoiding a failure by switching a line switching switch of the transmission device, comprising a timer circuit for detecting a control signal based on a silent fail state transmitted from the reception device, A hot standby line switching device for switching a line when the control signal is continuously detected for a predetermined time. 4. A hot standby line switching device having a working and a backup transmitting / receiving device, wherein a control signal is transmitted to a transmitting device by using a line opposite to a line in which a silent fail state is detected in a silent fail state. After sending
In a hot standby line switching apparatus capable of avoiding a failure by switching a line switching switch of the transmission device, a silent failure determination circuit including an active system detection circuit, a standby system detection circuit, a determination circuit, and a timer The working detection circuit receives a first signal indicating that frame synchronization is not established in the working transmission / reception device, and a second signal indicating that a silent fail state has been detected, When receiving only the second signal, transmits a first detection signal to the determination circuit, the protection system detection circuit, a third signal indicating that frame synchronization is not established in the protection system transmitting and receiving device, Receiving a fourth signal indicating that a silent failure state has been detected, and when receiving only the fourth signal, the determination circuit sends a fourth signal to the determination circuit. Transmitting a detection signal, the determination circuit, when receiving at least one of the first detection signal and the second detection signal, transmits a silent detection signal to the timer, the timer is a predetermined time A hot standby line switching device for switching lines when the silent detection signal is continuously received. 5. A hot standby line switching system comprising the hot standby line switching device according to any one of claims 1 to 4, comprising a first and a second terminal station facing each other. 6. A plurality of terminal stations each comprising a working and a backup transmitting / receiving apparatus and having a mutually facing relationship, and at least a hot standby line switching apparatus according to any one of claims 1 to 4. A hot standby line switching system consisting of one intermediate relay station and 7. A hot standby line switching device provided with a working and a backup transmission / reception system, wherein in a silent fail state, line switching is performed using a second line opposite to the first line that has detected the silent fail state. A hot standby line switching method, comprising: a step of detecting a device failure of the second line; and a step of invalidating a detection result of a silent fail state detected in a system in which the device failure is detected. Switching method. 8. A hot standby line switching device provided with a working and a backup transmission / reception system, wherein in a silent fail state, line switching is performed using a second line opposite to the first line that has detected the silent fail state. The hot standby line switching method includes a step of detecting a control signal indicating a silent failure state transmitted from the receiving system in both the working system and the standby system of the transmitting system, wherein a local failure occurs in the system currently operating. A hot standby line switching method that enables the control signal to be detected by a standby system even when a problem occurs. 9. A hot standby line switching apparatus provided with a working and a backup transmission / reception system, wherein in a silent fail state, line switching is performed using a second line opposite to the first line that has detected the silent fail state. In the hot standby line switching method to be performed, a step of detecting a control signal based on a silent failure state transmitted from a receiving system, and a step of switching a line when the control signal is continuously detected for a certain period of time. Hot standby line switching method provided.