JPH06132921A - Switching circuit for multiple signal transmitting device of redundant constitution - Google Patents

Abstract

PURPOSE:To eliminate the hits of other nondefective channel signals by evading the immediate switching of a stand-by unit and then switching this unit in the timing of a blank part of a channel despite the fault of a switching device. CONSTITUTION:A switch control circuit 20 set between an input buffer circuit 6 and an output buffer circuit 9 is controlled by the signal supplied from a DMUX 5. That is, the DMUX 5 has a function to detect the fault of a package and then outputs an alarm signal (q) when a fault is confirmed in either channel output. A control package outputs a selection signal to a separate package for the switching to a stand-by unit. When an enable signal is supplied from the buffer 6, a signal synchronous with a blank part of 8mus of a channel signal is supplied to the circuit 10 from the DMUX 5. Then the faulty package is switched to the stand-by unit by the enable signal supplied to an output buffer 8 in the timing of the blank part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching circuit for switching between a working unit and a spare unit in a transmission apparatus having a working / standby redundant configuration, and more specifically, this transmission apparatus transmits time-division multiplexed channel signals. The present invention relates to a unit switching means for removing an influence on another system when a unit is switched in a device for separating into channels.

[0002]

2. Description of the Related Art Conventionally, in an important communication system, at least two identical units are provided in the main part so that the communication is not interrupted even if the device fails. As such, the other is used as a backup device and is configured with redundancy so that it immediately switches to the backup device when a failure occurs in the current device, but it is important not to cause a slight interruption during switching. It is a problem.

FIG. 2 is a block diagram showing an example of a conventional working / standby switching circuit in a channel signal separation device used in a switch for time division multiplexing communication. The channel separation device shown in this example is a TDM (time division) device. It is a circuit that separates each channel signal from the main signal MS in which 16 channels are multiplexed by the multiplex) by the separation package and supplies it to each channel board.

Since this circuit is an important part, in addition to the normal working unit 1, the unit 2 having the same function as described above is used.
Is provided as a spare unit, and a control package 3 and an alarm package 4 are provided to switch between these two units.
Have and.

In this circuit, the multiplexed main signal MS
Are input in parallel to the two separation packages 1 and 2, and 16 channel output terminals a to p and a'to p'are connected by wire or OR for each channel, and channels not shown are shown. The alarm signals q and q'output from the separate packages 1 and 2 are supplied to the alarm package 4, and the switching request signal from the alarm package 4 is also provided. The selection signals s and s'are output from the control package to which r is input, and are supplied to the two separation packages 1 and 2.

Describing the operation in this configuration, normally, the selection signal s for the active package 1 is selected from the control package 3 so that the output is generated only from the active package 1.
At the same time, and at the same time, the selection signal s ′ for the spare package 2 which is in the non-operating state is set to the high potential.

Each of the packages 1 and 2 has a failure detecting function, and when a failure is detected in its own package, alarm signals q and q '.
When the alarm package 4 receives the alarm, a switching signal r is generated and operated to switch the package.

FIG. 3 is a block diagram showing an example of the internal structure of the conventional separation packages 1 and 2. FIG. 3 shows an example of the internal structure of the package 1.

In this figure, the DMUX 5 is a circuit for separating the 16-channel signal from the main signal MS and generally uses commercially available IC components. At the same time, the DMUX 5 has a failure diagnosing function. Is output.

The input buffer 6 is an inverter as shown in FIG.
The pull-up resistor 8 is connected between the input terminal of the target 7 and the power supply, and the low potential of the selection signal s for determining the operating state is converted into a high potential to be used as an enable signal. It is supplied to the output buffer circuit 9. On the other hand, the output buffer circuit 9 comprises 16 3-state gates, and
It functions as a gate corresponding to each of the channel signals separated by X5. That is, when the selection signal s is supplied at a low potential, it is inverted by the input buffer 6 to become a high potential, and each of the three state gates of the output buffer circuit is obtained.
Since each gate signal is supplied to the enable terminal of each channel, all the channel signals a to p are input to each channel panel (not shown).

However, the conventional standby device switching circuit having the above-mentioned structure has a drawback that other channel signals which are not signaled and abnormal at the same time are also momentarily cut off depending on the timing at which the unit switching signal is generated. .

This will be described in detail with reference to the drawings.

FIG. 4 is a signal timing chart in the case of separating the multiplexed signal of 6 channels × 16 lines, a total of 96 channels by the apparatus shown in FIGS. Channels are arranged in time division. In this array, one channel has 19.5 μs, and a signal blank portion of 8 μs is added at the end so that a total of 125 μs is one cycle and the channel signals are repeatedly separated in order.

When a failure occurs in the circuit of the system of the main signal output a in such a state, channels 1 to 6
All signals are disconnected. In the circuits shown in FIGS. 2 and 3, the unit switching signal is generated by detecting the failure of the unit in use, but the timing is not synchronized with the output signal. Therefore, if switching is performed at the timing of outputting the channel 8 of the main signal output a, for example, the signals of the remaining 15 channels 12, 18, ... 24 of the main signal outputs b to d are also interrupted. It will be. That is, there is a drawback in that the operation of many other channels is hindered in order to rescue the failed channel.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems in the above-mentioned conventional working standby switching circuit, and has a redundant structure which does not hinder the operation of other channels when the unit is switched. It is an object of the present invention to provide a switching circuit for a transmission device having a.

[0016]

SUMMARY OF THE INVENTION To achieve this object, the present invention is a transmission apparatus for separating a plurality of time division multiplexed channel signals into respective channel signals, which is provided with a plurality of units having the same function and is used. In a switching circuit of a transmission apparatus having a redundant configuration for switching to another unit when a failure occurs in a unit inside, when a switching signal occurs to each unit, the unit in the signal blank portion in the multiplexed signal to be separated It is characterized by having means for executing a selection operation.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A switching circuit of a transmission device having a redundant configuration of the present invention will be described in detail below with reference to the illustrated embodiments.

FIG. 1 is a block diagram showing an embodiment of a package adopting the working / spare package switching circuit of the present invention. The same numerals and symbols as those in FIGS. 2 and 3 are the same functional blocks. Is shown.

The difference of this embodiment from the above-mentioned conventional package (FIG. 3) is that a switching control circuit 10 is interposed between the input buffer circuit 6 and the output buffer circuit 9, and this switching control circuit 10 is provided. It is configured so as to be controlled by the signal supplied from the DMUX 5.

That is, referring to FIG. 2, the main signal MS is a signal in which 96 channels are multiplexed by TDM (time division multiplexing), and each channel signal is separated by the separation package 1. This is a circuit which is separated and supplied to each channel panel not shown. The DMUX 5 of this circuit has a function of detecting a failure of the package, and when any one of the channel outputs has a failure as described above, an alarm signal q (q ^' in the separate package 2) is issued. Output.

[0021] The control alarm signal is supplied package - select to switch to the spare unit in di 3 signals S, S ^'
Is output to the separation packages 1 and 2.

When this signal is supplied, an enable signal is output from the input buffer 6 of the separation package shown in FIG. 1 and input to the switching control circuit 10.

The switching control circuit 10 is supplied from the DMUX with a signal synchronized with the blank portion of 8 μs of the channel signal shown in FIG. 4, and the signal is turned on at the timing of the blank.
A bull signal is output to the output buffer 8, and this signal switches the separation unit from the working unit to the standby unit.

The switching control circuit 10 is a circuit that functions as described above, and specifically, for example, only one RS flip-flop circuit is required. If the switching timing signal supplied from the DMUX 5 is produced by the switching control circuit 10, the DMUX 5 supplies one of the main signal outputs shown in FIG.
It is also possible to detect the blank portion as the switching timing inside 0.

As described above, even if a unit failure is detected and a selection signal for switching the unit is output from the control package 3, the unit is not switched immediately and the timing of the blank portion of the channel signal is waited for. ,
This is what you do. Therefore, for a channel with an abnormality, a normal channel signal cannot be obtained until the next signal blank timing occurs, but with respect to other channels without an abnormality, there is no instantaneous interruption and the conventional problem is solved. It becomes possible to solve it.

Since the other operations are the same as those of the conventional circuit shown in FIGS. 2 and 3, the description thereof will be omitted. The present invention is not limited to the circuit configuration described above, and any circuit having a similar function may be used.

Also, in the above description, the case where two units are switched has been shown, but it is clear that, even when there are three or more units, it is possible to switch to the blank part of the channel signal, and the signal format to be handled is also the same. If the signal to be periodically processed has a blank portion, the present invention can be similarly applied.

[0028]

According to the present invention having the above-described structure, even if the switching device fails and the selection signal is output to switch to the spare unit, the switching is not immediately performed,
Since the switching is executed after waiting for the timing of the blank portion of the channel signal, the other channel signals having no abnormality are not interrupted at all.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a unit used in the present invention.

FIG. 2 is a block diagram showing an example of a working / standby unit switching circuit to which the present invention is applied.

FIG. 3 is a block diagram showing an internal configuration example of a conventional working / spare unit.

FIG. 4 is a diagram showing an example of a signal format of a transmission device to which the present invention is applied.

[Explanation of symbols]

1 working unit (separate package), 2 spare unit (separate package), 3 control unit, 4 alarm package, 5 DMUX, 6 input buffer, 7
Inverter gate, 8 pull-up resistors, 9 output buffer circuit, 10 switching control circuit.

Claims (1)

[Claims] 1. A transmission device for separating a plurality of time-division multiplexed channel signals into respective channel signals, comprising a plurality of units having the same function, and when a unit in use fails. In the switching circuit of the transmission device having the redundant configuration for switching to the unit of the above, when the switching signal is generated to each of the units, there is provided a unit selecting operation in the blank portion of the channel signal in the multiplexed signal to be separated. A switching circuit of a transmission device having a redundant configuration characterized by the above.