JPH0129106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switching device for duplex digital transmission lines.

Multiple analog signals are encoded and multiplexed into one digital signal, the multiplexed signal is sent and received via a digital multiplex transmission path, and on the receiving side, multiple analog signals from the received signal are separated, decoded and converted, and each is handled accordingly. In order to improve the reliability of lines such as those connected to analog lines, a method is adopted in which the multiplexed parts of the digital multiplex transmission line and the transmitting/receiving terminal stations are duplicated.

In this type of conventional system, the sender simply
Duplicate circuits are provided for encoding and multiplexing a plurality of analog signals, and the circuits are sent out to two digital multiplex transmission paths, respectively. Then, on the receiving side, as shown in FIG. 1, the signals from each digital multiplex transmission path are separated, decoded and converted into a plurality of analog signals by separation/decoding/conversion sections 1 and 2, respectively. A plurality of analog signals A ₁ output from the separation/decoding/conversion section 1
~A _o are connected to analog lines L ₁ -L _o via normal contacts a ₁ -a _o of relay A, respectively. Similarly, the separation/decoding/conversion unit 2 also converts a plurality of analog signals A′ ₁ to
A′ _o is output, but since the switching contact side of relay A is open, it is not connected to analog lines L ₁ to _{L o} . If a fault occurs in the digital multiplex transmission line connected to terminal 3, the fault is detected by fault detection circuit 5, and upon receiving the output of fault detection circuit 5, control section 7 operates relay A. Switch that contact. Therefore, this time, the plurality of analog signals A' ₁ to A' _o outputted from the separation/decoding/conversion section 2 are connected to the respective analog lines L ₁ to L _o , and the analog lines do not become an obstacle. When a fault occurs in the multiplex line connected to the terminal 4 side, it is similarly detected by the fault detection circuit 6, and the control unit 7 restores the relay A to resume reception from the multiplex transmission line on the terminal 3 side. can do.

In the conventional device described above, relay A is connected to an analog line.
Since switching contacts are required for the number of lines L ₁ to L _o , one relay is insufficient when the number of lines increases. That is, the number of relays A must be increased. Therefore, there is a drawback that space is required to mount a large number of relays A, and power consumption also increases. Further, the contact resistance of the relay contacts is unstable with respect to minute signals, and there is a risk of contact failure. Although it is possible to use an electronic circuit without using relay A, this would require as many switching circuits as there are lines, and there is still a limit to the number that can be controlled by one control circuit.

The purpose of the present invention is to solve the above-mentioned conventional drawbacks and
Eliminates numerous switching contacts in the analog part,
The object of the present invention is to provide a compact, low-power digital transmission line switching device.

The switching device of the present invention is connected to a duplex digital multiplex transmission line, and includes a working and standby separation/decoding/converting unit that separates and decodes a received digital multiplex signal into a plurality of analog signals, and a switching device connected to a duplex digital multiplex transmission line. Equipped with a fault detection circuit to detect
Normally, the plurality of analog signals output from the working separation/decoding/conversion section are connected to the corresponding plural analog lines, and in the event of a failure in the working multiplex transmission path, the plurality of analog signals output from the standby separation/decoding/conversion section are connected to the respective analog lines. In a digital transmission line switching device each connected to a plurality of analog lines, a plurality of hybrid circuits input the analog signals output from the working and standby separation/decoding/conversion units and connected to the corresponding analog lines; a pseudo signal generation circuit that generates a minimum level digital signal; a logic circuit that selectively outputs the output signal of the pseudo signal generation circuit or the received digital multiplexed signal; and selection of the logic circuit based on the output of the fault detection circuit. and a control section for controlling the digital multiplex transmission line, which normally inputs the received signal from the currently used digital multiplex transmission line to the currently used separation/decoding/conversion section and inputs the output signal of the pseudo signal generation circuit to the standby separation/decoding/conversion section. input, and if the current digital multiplex transmission line is at fault,
The present invention is characterized in that the output signal of the pseudo signal generation circuit is input to the active separation/decoding/conversion section, and the received signal from the backup digital multiplex transmission path is input to the backup separation/decoding/conversion section.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a block diagram showing one embodiment of the present invention. That is, the analog signals A ₁ -A _o and A' ₁ -A' _o outputted from the separation/decoding/conversion sections 1 and 2 are respectively combined by the hybrid circuit H and connected to the analog lines L ₁ -L _o . As the hybrid circuit H, a hybrid coil, a resistance hybrid circuit, etc. are used. Alternatively, it may be an analog adder that simply adds both inputs and outputs the result. A pseudo signal generation circuit 8 that generates a digital signal of the minimum level when there is no call, and logic circuits 9 and 10 are provided. are selectively selected and input to the separation/decoding/conversion section 1. In normal times when the fault detection circuit 5 does not detect a fault, the logic circuit 9 selects the digital multiplexed signal input from the terminal 3 and inputs it to the separation/decoding/conversion section 1 in response to a control signal from the control section 7 . On the other hand, the logic circuit 10 selects the digital multiplexed signal from the terminal 4 or the output of the pseudo signal generation circuit 8 and inputs it to the separation/decoding/conversion section 2. However, in normal times, the control signal of the control section 7 The output signal of the pseudo signal generating circuit 8 is selected according to the following. Therefore, the analog signals A ₁ to A _o separated and decoded by the separation/decoding/conversion section 2 are all at the minimum level (no voltage) during no call. As a result, the analog lines L ₁ to _{L o} receive analog signals A ₁ to A _o , respectively.
is supplied. When the fault detection circuit 5 detects a fault, the control unit 7 controls the logic circuits 9 and 10, the logic circuit 9 selects the output of the pseudo signal generation circuit 8, and the logic circuit 10 selects the output of the digital signal input from the terminal 4. Since multiplexed signals are selected, the analog signals A ₁ to A _o become voltageless, and the analog signals A′ ₁ to
A′ _o is supplied to analog lines L ₁ to _{L o} . That is, the digital multiplex transmission path is switched. In this case, there is no need to switch the signal path using a plurality of switching contacts in the analog part. Therefore, there is no need for relays to switch a large number of contacts as in the past, and everything can be configured with electronic circuits.
This has the effect of improving the reliability of the device and achieving miniaturization and low power consumption. Another advantage is that failures of individual analog lines due to poor contact of relay contacts can be eliminated. The logic circuits 9 and 10 may be simple switching circuits, and the pseudo signal generating circuit can be easily constructed by, for example, a pulse oscillator that generates continuous pulses in synchronization with the digital multiplexed signal. However, it must be a digital signal that conforms to code conversion conventions and conforms to the minimum level of analog signals during no-call periods.

As described above, in the present invention, the digital multiplexed signal is input to the separation/decoding/conversion section on the active side, and the minimum level digital signal during no call output from the pseudo signal generation circuit is input to the separation/decoding/conversion section on the protection side. Then, the analog signals output from both separation/decoding/conversion sections are combined by a hybrid circuit and supplied to each analog line, and in the event of a failure in the multiplex section,
Since the configuration is configured such that the output signal of the pseudo signal generation circuit is inputted to the separating/decoding/converting unit that caused the failure, and the input signal from the digital multiplex transmission line is input to the other separating/decoding/converting unit, the input signal from the digital multiplex transmission line is At the time of switching, there is no need to switch between multiple analog line sections as in the conventional case. Therefore, there is no need for an increase in space and power consumption due to an increase in switching relays when a large number of analog signals are multiplexed. In addition, it can be configured entirely using electronic circuits, which has the effect of improving the reliability of the device, making it more compact, and reducing power consumption.In addition, there is no risk of analog line failures due to poor contact of relay contacts, etc. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional digital transmission line switching device, and FIG. 2 is a block diagram showing an embodiment of the present invention. In the figure, 1, 2...separation decoding conversion unit, 3, 4
...Terminal, 5, 6...Fault detection circuit, 7...Control unit, 8
...Pseudo signal generation circuit, 9,10...Logic circuit, A...
Relay, H...hybrid circuit, _L1 ~ _Lo ...analog line, _A1 ~ _Ao , _A'1 ~ _A'o ...analog signal,
a ₁ ~ _{a o} …Relay contact.

Claims (1)

[Claims] 1 Active and backup separation/decoding/conversion units that are connected to the duplex digital multiplex transmission line and separate and decode the received digital multiplex signal into multiple analog signals, and a failure detection circuit that detects failures in the digital multiplex transmission line. A plurality of analog signals output from the currently used separation/decoding/conversion section are normally connected to a plurality of corresponding analog lines, and in the event of a failure in the current multiplex transmission line, the plurality of analog signals output from the standby separation/decoding/conversion section are connected to the respective analog lines. in the digital transmission line switching device that connects the analog signals of the respective analog signals to the plurality of analog lines, a plurality of hybrid circuits that input the analog signals output from the working and standby separation decoding/converting units and connect the analog signals to the corresponding analog lines. and a pseudo signal generation circuit that generates a minimum level digital signal during no call, a logic circuit that selectively outputs the output signal of the pseudo signal generation circuit or the received digital multiplexed signal, and an output of the fault detection circuit. and a control section that controls selection of the logic circuit, and normally inputs the received signal from the currently used digital multiplex transmission line to the currently used separation/decoding/conversion section, and causes the standby separation/decoding/conversion section to generate the pseudo signal. The output signal of the circuit is inputted, and when the current digital multiplex transmission line is in trouble, the output signal of the pseudo signal generation circuit is inputted to the current separation/decoding/conversion unit, and the backup digital multiplex transmission line is input to the backup separation/decoding/conversion unit. A digital transmission line switching device characterized by inputting a received signal from.