JPH0326032A - Method for preventing erroneously switching of redundancy constitution in equipment - Google Patents

Abstract

PURPOSE:To prevent a system from being switched erroneously to a standby system by inserting a specific fixed pattern to the location of a stuff designation pulse when the input of a low-order group signal is interrupted at a transmission side and detecting the inserted pattern at a reception side. CONSTITUTION:When the input of a low-order group signal 41 is interrupted at the transmission side, a stuff designation pulse generating circuit 17 inserts a 01 alternate pattern 49 to the position of the stuff designation pulse 47, a multiplexing circuit 15 multiplexes a low-order group signal 44 and the stuff designation pulse 47 and outputs the result as a high-order group signal 45. A 01 alternate pattern detection circuit 29 at the reception side detects the 01 alternate pattern to send a 01 alternate pattern detection signal 58 to a switching trigger inhibiting circuit 31, an output interruption signal 57 is masked by the alternate pattern detection signal 58 and the output of the output interruption signal 57 from the switching trigger inhibiting circuit 31 is avoided. Thus, the switching of the system to the standby system erroneously in the case of the interruption of the input of the low-order group signal at the transmission side is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to stuffed multiplex transmission having a backup system, and in particular, when a low-order group signal is cut off on the transmitting side, the transmission to the backup system is erroneously performed. The present invention relates to an internal redundant structure for preventing switching or a method for preventing erroneous switching.

[Conventional technology]

Normally, stuff synchronous multiplex transmission is widely used as one type of multiplex transmission.

In this method, the frequency of the low-order digital signal is not directly matched to the frequency of the high-order group, but the bit signals of the low-order group are first stored in a memory.

Then, it is read out at the timing of a clock having a common frequency that is slightly faster than the signal frequency of the low-order group that is the target of multiplexing. By doing this, the pulse train signals of all the low-order groups can be placed on a common frequency and synchronized, but since the clock speed is slightly faster, the difference gradually increases and the pulse train signals from the low-order group It may happen that pulsing to memory becomes impossible. Therefore, a redundant stuff pulse corresponding to the difference between the two is inserted to prevent the difference from increasing.

On the other hand, on the receiving side, it is necessary to know the position of the stuff pulse within the pulse train in order to remove the extra stuff pulse.

For this reason, it is necessary to specify the position at which the stuff pulse is inserted in 1M, and to inform whether or not the stuff pulse is inserted at that position by a combination of other specific pulses.

Therefore, a stuff designation pulse is generated as a combination of the specific pulses, included in the multiplexed bit string of the higher order group, and sent to the partner station every frame period. Since this stuff designation pulse is a very important signal in stuff multiplex communication, the same signal is often sent to the other station in 3 or 5 consecutive bits.

As an example, assuming that the average stuffing rate of a 3-bit stuffing designation pulse is 173, a stuffing designation pulse as shown in FIG. 3 is transmitted. On the receiving side, it is common practice to detect stuff information by performing majority logic operations to improve resistance to errors caused by noise on the transmission path.

Conventionally, in such stuffed synchronous multiplex transmission, a redundant backup system has been installed to detect an output failure alarm when the low-order group signal output on the receiving side is disconnected due to some kind of failure. was used as the trigger for switching to the backup system.

[Problem to be solved by the invention]

In this way, in conventional staff synchronous multiplex transmission with an internal redundancy structure or backup system, if a low-order group input signal is cut off due to an operational error on the transmitting side, the corresponding channel in the multiplexed signal is A zero code indicating no signal is inserted. On the receiving side, the signal of its own channel is separated from the multiplexed signal, but since there is no signal, there is a drawback that an output cutoff alarm is detected and the system is switched to a standby system.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an internal redundancy structure or a method for preventing erroneous switching, which prevents switching to a standby system when the low-order group signal is cut off on the transmitting side.

[Means to solve the problem]

In the present invention, in stuffed multiplex transmission in which an input low-order group signal is converted into a high-order group output signal of a common speed and sent to the other station, this is detected when the input of this low-order group signal is interrupted. During this time, a predetermined fixed pattern is inserted into the stuff designated pulse position of the high-order group output signal, and the predetermined fixed pattern is detected in the low-order group signal generated by separating and converting the high-order group signal sent from the other station. When this occurs, the output of the backup system switching signal that is to be outputted by detecting an output cutoff alarm from this low-order group signal is stopped, and switching to the internal backup system is prohibited.

In other words, in the present invention, when the input of the low-order group signal is cut off on the transmitting side, a fixed pattern is inserted at the position of the stuff designated pulse and multiplexed with the high-order group signal, and this is detected on the receiving side to be sent to the backup system. Performs control to prohibit switching.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 shows a transmitting section of a stuff multiplex conversion apparatus to which an intra-device redundancy structure or a method for preventing erroneous switching is applied in one embodiment of the present invention.

In this transmitting section, the low-order group signal 41 inputted from the input terminal 11 is sent to the transmitting side buffer memory 12 and the clock extraction circuit 1.
3 and the input disconnection detection circuit 14.

The transmitting side buffer memory l2 includes a clock extraction circuit l3,
A write clock 42 and a successive clock 43 are inputted from the multiplexing circuit 15, respectively, and a low-order group signal 44 read out at the timing of the latter is inputted to the multiplexing circuit 15. The high-order group signal 45 multiplexed by this multiplexing circuit 15
is outputted from the output terminal 18.

The write clock 42 and the read clock 43 are also supplied to the phase comparator circuit 16, and when a predetermined phase difference is reached, a stuff request signal 46 is sent to the stuff designation pulse generation circuit 17.

The stuff designation pulse generation circuit 17 normally sends the stuff designation pulse 47 to the multiplexing circuit 15 in response to the stuff request signal 46, but when it receives the input disconnection detection signal 48 from the input disconnection detection circuit 14, it outputs the Oi alternating pattern signal 49. It is designed to be output.

The operation of the transmitter of the stuff multiplex converter having the above structure will be explained.

When the low-order group signal 41 is input to the input terminal 1l, it is supplied to the transmitting side buffer memory 12, the clock extraction circuit 13, and the input interruption detection circuit 14. The clock extraction circuit 13 extracts a clock from this low-order group signal 41 and supplies a write clock signal 42 to the sending buffer memory 12.

The low-order group signal 41 is written to the transmitting side buffer memory 12 at the timing of the write clock 42 and is temporarily stored. The write clock 4 is supplied from the multiplexing circuit 15.
The signal is read out by a successive clock 43 having a frequency slightly faster than 2, and sent to the multiplexing circuit 15.

The phase comparator circuit 16 compares the phases of the write clock 42 and the read clock 43 supplied to the sending buffer memory 12, and when the phase difference exceeds a predetermined threshold, generates a stuff request signal 46 as a stuff designation pulse. The signal is sent to the circuit 17. The stuff designation pulse generation circuit 17 generates a stuff or non-stanov stuff designation pulse 47 (FIG. 3) based on the stuff request signal 46 and outputs the stuff designation pulse 47 (FIG. 3) to the multiplexing circuit 1.
Send on 5th.

The multiplexing circuit 15 constructs a frame by multiplexing the low-order group signal 44 read out from the sending-side buffer memory 12 and the stuff designation pulse 47 from the stuff designation pulse generation circuit 17 together with the low-order group signals from other channels. Alternatively, it is outputted as a high-order group signal 45 from the output terminal l8.

At this time, when the input of the low-order group signal l1 is disconnected, it is detected by the input disconnection detection circuit 14, and an input disconnection signal 48 is sent to the stuff designation pulse generation circuit 17. This results in
The stuff designation pulse generating circuit 17 inserts a 01 alternating pattern 49 (FIG. 4) at the position of the stuff designation pulse. Furthermore, a zero code indicating no signal is inserted into the multiplexed high-order group signal 45 at this time.

FIG. 2 shows the receiving section of the same stuff multiplex conversion device.

In this receiving section, a high-order group signal 51 inputted from the input terminal 2l is separated into a low-order group signal 52 by a separation circuit 22, and is inputted to a receiving side buffer memory 23.

A write clock 53 and a read clock 54 are input from the destuff circuit 24 and the voltage controlled oscillation circuit 25, respectively, to the receiving side buffer memory 23, and reading and writing are performed at these timings. The low-order group signal 55 read from the receiving buffer memory 23 is output from the output terminal 26.

The destuffing circuit 24 generates a write clock 53 based on the destuffing control signal 56 from the separation circuit 22.

The write clock 53 and the read clock 54 are also supplied to the phase comparator circuit 27, and the voltage controlled oscillation circuit 25 is controlled so that the clock frequencies of both clocks are equal.

When the output disconnection detection circuit 28 detects an output disconnection state from the low-order group signal 55, the output disconnection detection circuit 28 switches the output disconnection signal 57 to the trigger prohibition circuit 3.
1 and output terminal 32.

01 alternating pattern detection circuit 29 is a destampf circuit 24
01 police box pattern detection signal 5 based on staff information from
8 is supplied to the switching trigger inhibition circuit 3l.

The operation of the receiving section of the stuff multiplexing converter having the structure described above will be explained.

The high-order group signal 51 inputted through the input terminal 21 is frame-synchronized by the separation circuit 22 and then separated into each channel and supplied to the low-order group signal 52, the I-ELI, and the reception buffer memory 23.

The destuffing circuit 24 extracts the destuffed write clock 53 based on the destuffing control signal 56 supplied from the separation circuit 22 and supplies it to the receiving buffer memory 23.

As a result, the low-order group signal 52 is transferred to the receiving side buffer memory 2.
3 and is temporarily stored. Then, it is read out by successive clocks 54 from the voltage controlled oscillation circuit 25,
It is output from the output terminal 26.

Here, the phase comparator circuit 27 compares the phases of the successive clock 53 outputted from the voltage controlled oscillation circuit 25 and the read clock 54 outputted from the destuffing circuit 24, and performs voltage controlled oscillation so that their frequencies match. It controls the circuit 25.

At this time, when the input of the low-order group signal is cut off in the opposing multiplexing converter, the high-order group signal with the 01 alternating pattern inserted at the position of the stuff designation pulse is input to the separation circuit 22, and the low-order group signal 52 After being separated, the signal is input to the destuffing circuit 24. The destuff circuit 24 then sends stuff information to the 01 alternation pattern detection circuit 29. As a result, the Ol alternating pattern detection circuit 2
9 detects the 01 alternating pattern and sends the 01 alternating pattern detection signal 58 to the switching trigger inhibition circuit 31.

On the other hand, the output disconnection detection circuit 28
A zero sign indicating no signal is detected from the output signal 55 from the output signal 55, and an output cutoff signal 57 is sent to the switching trigger inhibiting circuit 31.

However, since this output cutoff signal 57 is masked by the 01 alternation pattern detection signal 58 from the 01 alternation pattern detection circuit 29, the output cutoff signal 57 is no longer output from the switching trigger inhibition circuit 31.

In this way, it is possible to prevent erroneous switching to the standby system when the low-order group signal input is cut off on the transmitting side.

〔Effect of the invention〕

As explained above, according to the present invention, when the input of the low-order group signal is interrupted on the transmitting side, a specific fixed pattern is inserted at the position of the stuff designated pulse, and the receiving side detects this and outputs the signal. Since the shutdown alarm is masked, there is an effect that it is possible to prevent erroneous switching to the standby system.

[Brief explanation of drawings]

The drawings are for explaining one embodiment of the present invention. Among them, FIG. 1 is a block diagram showing the transmitting side of a stuff multiplexing device to which the present method is applied, and FIG. 2 is a block diagram showing the receiving side of the same device. The block diagram, FIGS. 3 and 4 are explanatory diagrams showing the stuff designation pulse train in normal times and in the case of input interruption, respectively. l1, 21... Input terminal, 12... Sending side buffer memory, 13...
... Clock extraction circuit, 14 ... Input disconnection detection circuit, 15 ... Multiplexing circuit, 16, 27 ... Phase comparison circuit, l7
...Staff designated pulse generation circuit, 18, 26
, 32... Output terminal, 22... Separation circuit, 23... Receiving side buffer memory, 24...
... Destuff circuit, 25 ... Voltage controlled oscillation circuit, 28 ... Output disconnection detection circuit, 29 ... 01 Alternating pattern detection circuit, 31 ...
...Switching trigger inhibition circuit. Island map 1 map 2 map

Claims (1)

[Claims] In stuffed multiplex transmission in which an input low-order group signal is stuffed multiplexed into a high-order group output signal of a common speed and sent to the other station, it is detected when the input of this low-order group signal is interrupted, and during that time the above-mentioned A predetermined fixed pattern is inserted into the stuff designated pulse position of the high-order group output signal, and when the predetermined fixed pattern is detected in the low-order group signal generated by separating and converting the high-order group signal sent from the other station, , an in-device device characterized in that the output of the backup system switching signal that is output by detecting an output cutoff alarm from the low-order group signal is stopped, and switching to the in-device backup system is prohibited. Method for preventing incorrect switching of redundant configuration.