JP3080013B2 - Line switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching apparatus, and more particularly to CCITT, G. 13 according to Recommendation 703
9.264 Mbit / sec CMI signal or 155.
The present invention relates to a line switching device as a (1 + n) switcher used for a transmission device transmitting a 52 Mbit / sec CMI signal.

[0002]

2. Description of the Related Art FIG. 3 shows a schematic configuration of a conventional (1 + n) switcher of this type. In the figure, n working interface circuits 21 to 2n include n pairs of working lines (input / output signal lines) e1 and f1, e2 and f2,..., En and fn.
, Respectively.

A set of standby systems is provided for these n active systems, and the standby system includes a pair of standby lines e0 and f0 and an auxiliary interface circuit 20.

If a failure occurs in one of these n active systems, it becomes necessary to switch the failed system to a standby system and operate it. Therefore, a switching element 1 which is a (1 + n) switcher is provided. The switching element 1 includes first to n-th n pairs of input / output signal lines a1 and b1, a2.
, B2,..., An and bn, and first to n-th n pairs of working input / output lines c1, d1, c2, d2,.
.., Cn and dn. These are the first to n-th n
The pair of working input / output lines are connected to corresponding working interface circuits 21 to 2n, respectively.

The switching element section 1 further has a pair of spare input / output lines c0 and d0. The pair of spare input / output lines c0 and d0 are connected to the spare interface circuit 20.

In such a configuration, normally, as shown by a dotted line in the figure, the switching element unit 1 connects the first to n-th n pairs of input / output signal lines to the first to n-th n pairs of current input / output lines. It operates to connect to each line.

Here, for example, the second working system (the working system lines e2 and f2 or the working interface circuit 22)
), The switching element unit 1 switches the second input / output signal lines a2 and b2 from the second working input / output lines c2 and d2 based on an external control command. It operates so as to be disconnected and connected to the spare input / output lines c0 and d0.

Since the switching element 1 of the (1 + n) switcher shown in FIG. 3 is generally assembled as a single module, one of the switching elements (switch, relay, etc.) fails. Occurs, it is necessary to replace the switching element part 1 with a new switching element part. Even though the remaining n switching elements (switches, relays, etc.) are normal, they are discarded and economically advantageous. Absent.

Therefore, Japanese Patent Application Laid-Open Nos. Sho 62-135201, 62-216430 and 1-14
No. 9530 discloses an example in which n switching elements are independently arranged for n active systems to facilitate maintenance operation.

[0010]

In the (1 + n) switcher described above, no consideration is given to the matching of input / output signals between each working line and the corresponding switching element. There is a problem that input / output signal loss, impedance fluctuation, and the like occur when the relay is inserted into each of the input / output signal lines, thereby lowering the transmission efficiency of the input / output signals.

An object of the present invention is to provide a line switching apparatus which facilitates maintenance operation and can suppress a decrease in transmission efficiency of input / output signals.

[0012]

According to the line switching apparatus of the present invention, a failure occurs in n sets (n is a natural number of 2 or more) of working lines and any one of the n working lines. And the n sets of working lines are provided with n switching means from the corresponding first switching means to the n-th switching means, and the first switching means is connected to the protection line. The connection and the n-th switching from the first switching means are connected in cascade. Each of the n switching means includes a pair of active input / output lines including an input signal line, a signal output line, and a current output line and a current input line connected to the corresponding n sets of current lines. And a switch for selectively switching between connection to the adjacent switching means closer to the protection line and connection to the corresponding working line. Further, an input signal including an attenuator arranged between the signal input line and the active system output line to attenuate reflection on the input signal line, and a mismatch attenuation matching device for matching a mismatch attenuation of a signal of the input signal line. A matching circuit, an attenuator arranged between the signal output line and the working system input line to attenuate reflection on the output signal line, and a mismatch attenuation amount matching unit for matching a mismatch attenuation of a signal of the output signal line. including
An output signal matching circuit is provided.

More specifically, the line switching apparatus according to the present invention comprises: n sets (n is a natural number of 2 or more) of working lines;
It includes a protection line that is switched when any one of the n working lines fails, and the n sets of working lines are connected from the corresponding first switching circuit to the n-th switching circuit. It has n switching circuits. Each of the n switching circuits includes a pair of active input / output lines including an input signal line, a signal output line, and a current output line and a current input line connected to the corresponding n sets of current lines. And

Further, the first switching circuit includes an output-side protection system input line, an input-side protection system output line, an output-side protection system output line, and an input-side protection system input line that are respectively connected to the protection line. It has first to fourth switches. Here, the first switch switches the connection to the input signal line between the working output line and the input side intermediate line, and the second switch switches the connection to the input side standby system output line between the input side intermediate line and the input side intermediate line. The third switch switches the connection to the output signal line between the working input line and the output intermediate line, and the fourth switch outputs the connection to the output standby input line. It has a function of switching between the side intermediate line and the output side standby system output line.

[0015] Further, from the second switching circuit to the (n-1) th
The switching circuit includes an input-side standby system output line connected to the input-side standby system input line of the switching circuit closer to the standby line and an output-side standby system output line of the switching circuit farther from the adjacent standby line. And a fifth to eighth switches for switching between the respective lines in the same manner as described above.

Further, in the line switching apparatus according to the present invention, the switching circuit may further include an input signal matching circuit disposed between the signal input line and the working system output, and a switching circuit between the signal output line and the working system input. An output signal matching circuit, and the input signal matching circuit and the output signal matching circuit,
It is characterized in that it includes an attenuator for attenuating the reflection in the output signal line and a mismatch attenuation matching device for matching the mismatch attenuation of the signal of the output signal line.

Here, the input signal matching circuit is further characterized in that it includes a DC circuit breaker for blocking a DC component of the input signal.

Further, the line switching apparatus of the present invention is provided for n sets of active systems having n active interface circuits provided for n sets of active lines, respectively, and for a protection line. And a set of standby systems having one standby interface circuit. A switching control circuit is provided for switching each switch of the switching circuit depending on whether the working system is normal.

When all of the n working systems are normal, the switching control circuit includes:
First, connect the input signal line to the working output line.
And the fifth switch are controlled, and the third switch and the seventh switch are controlled to use the output signal line as the active system input line, respectively. On the other hand, when a failure occurs in any one of the n working systems, the first switch or the third switch of the failed switching circuit is switched to the intermediate line, and the second switch is switched to the intermediate line. Alternatively, the fourth switch is switched to the intermediate line, and the second switch and the sixth switch in the switching means of the working system connected closer to the protection system than the working system in which the failure has occurred are connected to the input side protection system input. It has a function of connecting the fourth switch and the eighth switch to the output-side standby system output line while connecting to the line.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing a specific example of the switching element in the embodiment of the present invention. This circuit is provided one for each of the n sets of working systems.

An input signal from the input signal line a is input to the input matching circuit 100. This input matching circuit 100
Is an attenuator composed of resistors R1 to R3 and a capacitor C
1, a grounding processing circuit including a switch SW1 and a resistor R4, a mismatch attenuation matching circuit including a transformer T1 and a capacitor C2, a DC cutoff circuit including a transformer T2, and a terminating element including a resistor R5. .

The attenuator reduces the reflection of the input signal, and the grounding processing circuit enables the external conductor (grounding conductor) of the input signal line a to be grounded or opened by the switch SW1. The switch SW1 is turned on and off according to the state.

The mismatch attenuation matching circuit is for matching the mismatch attenuation of the input signal, the DC cutoff circuit is for cutting the DC component of the input signal, and the terminating resistor is for terminating the input signal. Do.

The input signal after termination is transmitted to relays RL1 and RL2.
And is normally led out to a working system output line c via a relay RL1 as shown in the figure.
Further, a standby input line g and a standby output line h on the input side are provided, and a relay RL2 is normally provided as shown in the figure.
Therefore, both input / output lines g and h are in a bypass (short circuit) state.

The output matching circuit 101 on the output signal line b side
In, the attenuator is constituted by resistors R6 to R8,
The mismatching attenuator matching circuit includes a transformer T3 and a capacitor C3.
, And the DC cutoff circuit is configured by the transformer T4. The outer conductor of the output signal line b is grounded by a resistor R9.

The working input line d is normally led to an output signal line b via an output matching circuit 101 via a relay RL3 of a switch circuit. An output-side standby system input line i and a standby system output line j are provided, and both input / output lines i and j are normally bypassed (short-circuited) by a relay RL4 as shown in the figure. Note that intermediate lines are provided between RL1 and RL2 and between RL3 and RL4 to connect them.

The relay coils of the respective relays RL1 to RL4 of the switch circuit are excited based on a switching control input k from the outside, and are switched to a state opposite to that shown in the figure. As a result, the input signal of the input signal line a is led to the input-side standby system output line h via the relays RL1 and RL2, and the input signal from the output-side standby line i is set to the relay R
It will be led to the output signal line b via L3 and RL4.

FIG. 2 shows (1+) using the switching element of FIG.
n) It is a block diagram of an embodiment of the present invention which constitutes a switcher system, and the same parts as those in FIG. 3 are denoted by the same reference numerals.

The n pairs of working lines e1 and f1, e2 and f2
..., N corresponding to each of n sets of active systems including en and fn and n active interface circuits 21 to 2n
The switching elements 11 to 1n are provided, and each of these switching elements has the configuration shown in FIG.

A set of standby systems is provided, and a pair of standby lines e0 and f0 and one standby interface circuit 20 are provided.
It consists of

Normally, a pair of input / output signal lines a1 and b1 of the switching element 11 are connected to a pair of working input / output lines c and d.
To the input / output lines c1 and d1 of the working interface circuit 21. Other switching elements 12-1
The same applies to n.

The pair of input / output lines c0 and d0 of the spare interface circuit 20 are connected to the input-side spare system output line h and the output-side spare system input line i of the first switching element 11, respectively. The eleventh input-side standby system input line g and the output-side standby system output line j are connected to the input-side standby system output line h and the output-side standby system input line i of the second switching element, respectively. Are connected in cascade up to the switching element 1n. Then, the n-th switching element 1n
Is connected to the output side standby system output line j.

Normally, since the relays RL1 to RL4 of the switch circuits of the switching elements 11 to 1n are in the state shown in FIG. 1, the first to n-th input / output signal lines a1 and b1 to
an and bn are the corresponding working input / output lines c1 and d1, respectively.
To cn, dn and to the corresponding working interface circuits 21 to 2n, respectively.

The output line d0 of the spare interface circuit 20 is connected to the first switching element 11 to the n-th switching element 1
n is connected to the input line c0 of the backup interface circuit 20 via a bypass path cascade-connected to n.

In this state, for example, if a failure occurs in the second working system, the second switching element 12 enables the switching control input k, thereby setting the second input / output signal lines a2 and b2. By switching to the input side standby system output line h and the output side standby system input line i, the standby interface circuit 20 is connected via a cascade-connected path.
It is connected to.

[0037]

As described above, according to the present invention, a switching element is provided independently for each of a plurality of active systems.
A switch element such as a relay can be flexibly dealt with in response to a failure of each switching element or the addition of an active system, and a signal matching circuit and an attenuation circuit for input / output signals are added to each switching element. There is an effect that the switching element itself can suppress reflection and transmission loss caused by inserting the signal into the input / output signal line. Therefore, it is not necessary to add an input / output signal matching circuit or the like to the interface circuit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a switching element according to an embodiment of the present invention.

FIG. 2 is a system block diagram of an embodiment of the present invention.

FIG. 3 is a system block diagram of a conventional (1 + n) switcher.

[Explanation of symbols]

 11-1n switching element 20 spare interface circuit 21-2n working interface circuit 100 input signal matching circuit 101 output signal matching circuit

Claims (5)

(57) [Claims] 1. A system comprising: n sets (where n is a natural number of 2 or more) of working lines; and a protection line that is switched when any one of the n sets of working lines fails. The n sets of working lines include n switching units from a corresponding first switching unit to an n-th switching unit, wherein the first switching unit is connected to the protection line and performs a first switching operation. The n-th switching means are connected in cascade, and each of the n switching means includes an input signal line, a signal output line, and a working output line and a working system connected to a corresponding n sets of working lines. A pair of working input / output lines including an input line, a switch for selectively switching between a connection to the adjacent switching means closer to the protection line and a connection to the corresponding working line, An attenuator disposed between an input line and the working output line to attenuate reflection on the input signal line; and a mismatch attenuation matching device for matching a mismatch attenuation of a signal of the input signal line. An input signal matching circuit, an attenuator disposed between the signal output line and the working input line, for attenuating reflection on the output signal line, and a mismatch for matching a mismatch attenuation of a signal on the output signal line. An output signal matching circuit including a matching attenuation amount matching device, and a line switching device. 2. A system comprising: n sets (where n is a natural number of 2 or more) of working lines; and a protection line which is switched when any one of the n sets of working lines fails. The n sets of working lines each include n switching units from a corresponding first switching unit to an n-th switching unit, wherein each of the n switching units includes an input signal line, a signal output line, A pair of working system input / output lines including a working system output line and a working system input line connected to the corresponding n sets of working lines, respectively, and the first switching means further comprises: The output side standby system input line and the input side standby system output line to be connected, the output side standby system output line, the input side standby system input line, and the connection to the input signal line are connected to the active system output line and the input side. A first switch for switching between an input line and an intermediate line; a second switch for switching a connection to the input-side standby system output line between the input-side intermediate line and the input-side standby system input line; A third switch for switching a connection to a line between the working input line and the output intermediate line, and a connection to the output-side standby input line between the output intermediate line and the output-side standby output line And a fourth switch for switching from the second switching means to the (n-1) th switching means, wherein each of the switching means is connected to an input side standby system input line of the switching means which is adjacent to and closer to the protection line. An input-side standby system output line to be connected, and an output-side standby system connected to an output side standby-system output line of the switching means that is adjacent to and farther from the standby line. A power line, a fifth switch for switching connection to the input signal line between the working output line and the input intermediate line, and a connection to the input standby output line to the input intermediate line and the input. A sixth switch for switching between the input side and the standby side input line; a seventh switch for switching the connection to the output signal line between the active side input line and the output intermediate line; and the output side standby input line. And an eighth switch for switching the connection to the output side intermediate line and the output side standby system output line. 3. The switching means further includes: an input signal matching circuit disposed between the signal input line and the working system output; and an output disposed between the signal output line and the working system input. A signal matching circuit, wherein the input signal matching circuit includes: an attenuator for attenuating reflection on the input signal line; and a mismatch attenuation matching device for matching a mismatch attenuation of a signal of the input signal line. The output signal matching circuit includes: an attenuator for attenuating reflection on the output signal line; and a mismatch attenuation matching device for matching a mismatch attenuation of a signal on the output signal line. Item 2. The line switching device according to Item 1. 4. The line switching device according to claim 2, wherein said input signal matching circuit further includes a DC circuit breaker for blocking a DC component of said input signal. 5. The line switching apparatus, wherein n sets of active systems having n active interface circuits provided corresponding to the n sets of active lines, respectively, and provided in correspondence with the protection line. And a set of standby systems having one standby interface circuit. When all of the n sets of active systems are normal, the input signal lines are connected to the active system in all the switching means. Controlling the first switch and the fifth switch so as to be connected to a system output line, controlling the third switch and the seventh switch to connect the output signal line to the working system input line, respectively, When a failure occurs in any one of the active systems of the set, the first switch or the third switch of the switching means in which the failure has occurred is switched to the intermediate line. Switching the second switch or the fourth switch to the intermediate line, and switching the second switch or the fourth switch in the switching means of the working system which is connected closer to the standby system than the working system in which the failure has occurred. And the sixth switch are connected to the input side standby system input line,
4. The line switching device according to claim 1, further comprising: a switching control circuit that connects the fourth switch and the eighth switch to an output-side standby system output line.