JPH0556022A - Transmission line switching circuit - Google Patents

Abstract

PURPOSE:To eliminate the mis-alarming of a transmission line monitoring alarm detected after the switching of the transmission line. CONSTITUTION:Transmission line monitoring signal insersion circuits 1, 2 insert respectively a transmission line monitoring signal outputted from counters 3, 4 to data signals 101, 102 from transmission lines 1, 2. A selector 8 selects either of the transmission lines 1, 2. A transmission line monitoring signal detection circuit 9 detects the transmission line monitoring signal inserted in the data signal based on the output signal of a counter 10 to output a transmission line monitoring alarm signal 119. A selector 5 selects any of frame pulse signals from the transmission lines 1, 2. A latch circuit 6 latches a switching input signal 109 based on the output of the selector 5 and outputs the latched signal to the selector 8 or the like as a switching output signal 108. The selectors 8, 5 select the different transmission lines. The switching signal 109 synchronously with the frame pulse of the transmission line being the switching destination is used to switch the selector 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line switching circuit,
In particular, it relates to a transmission line switching circuit that switches two transmission lines having different phases.

[0002]

2. Description of the Related Art Conventionally, a transmission line switching circuit of this type is shown in FIG.
It has the configuration shown in. Transmission line supervisory signal insertion circuit 1
Inserts the transmission path monitoring signal output from the counter 3 into the data signal 101 from the transmission path 1 by the clock signal 102 and outputs the data signal 107 with the transmission path monitoring signal to the selector 11. The counter 3 inputs the clock signal 102 and the frame pulse signal 103 from the transmission line 1,
The above-mentioned transmission line monitoring signal to be inserted into a predetermined pulse position of the data signal 101 is output. The transmission line monitoring signal insertion circuit 2 and the canter 4 are provided on the transmission line 2 side and have the same functions as described above. The selector 11 is provided for each signal on the transmission line 1 side and the transmission line 2
One of the signals on the side is selected by a switching signal 109 from an external transmission path monitoring device. That is, normally the transmission line 1
When the switching line 109 is selected and the switching signal 109 is inverted due to a failure on the transmission line 1 side, the switching line 109 is immediately switched to the transmission line 2 side.

The transmission line supervisory signal detection circuit 9 uses the transmission line supervisory signal for detection output from the counter circuit 10 to generate the data signal 130 with the transmission line supervisory signal from the selector 11.
Transmission line monitoring signal is detected and is transmitted to the outside. Transmission line monitoring alarm signal 1
33 and the data signal 134 are output. That is, the transmission path monitoring signal is used to monitor the transmission path before and after it including the selector 11, and if the transmission path monitoring signal is abnormal, the transmission path monitoring alarm signal 133 is issued.

[0004]

As described above, in the conventional example, since the transmission path is switched as soon as the switching signal 109 is inverted, the data of the first frame of the selected data signal after the switching is transferred between the transmission paths. If the phases are different, the data before and after the switching is connected, so that the transmission path monitoring signal inserted in the preceding stage of the selector 11 may not be detected depending on the switching timing. Therefore, there is a problem that the transmission line monitoring alarm signal 133 gives a false alarm.

[0005]

A transmission line switching circuit according to the present invention receives a first frame pulse signal and a first clock signal from a first transmission line and outputs a first transmission line monitoring signal. A first counter and a first counter from the first transmission line.
The data signal of the first clock signal
A first transmission path supervisory signal insertion circuit for inserting the transmission path supervisory signal and outputting a data signal with a first transmission path supervisory signal;
A second counter for inputting the second frame pulse signal and the second clock signal from the second transmission line and outputting a second transmission line monitoring signal; and a second counter for the second transmission line. A second transmission path supervisory signal inserting circuit for inserting the second transmission path supervisory signal into a data signal by the second clock signal and outputting a data signal with a second transmission path supervisory signal; and the first transmission. A data signal with a channel monitoring signal, the first clock signal and the first frame pulse signal, and a second data signal with a channel monitoring signal, the second clock signal and the second frame pulse signal. A first selector for inputting, selecting one of the outputs and outputting the first selector;
Third counter for inputting the third clock signal and the third frame pulse signal output from the selector, and outputting the third transmission line monitoring signal, and the third transmission line output by the first selector. A transmission line that detects a transmission line monitoring signal inserted in a data signal with a monitoring signal by the third clock signal and the third transmission line monitoring signal, and outputs a transmission line monitoring alarm signal and a data signal to the outside. A monitoring signal detection circuit; and a second selector which receives the first frame pulse signal and the second frame pulse signal and selects a transmission path side opposite to the transmission path side selected by the first selector, A switching input signal input from the outside is latched by the output signal of the second selector, output to the first selector as a switching output signal, and at the same time detected as the transmission line monitoring signal as a reset signal. It includes a latch circuit for output to the road, and an inverter circuit for inverting the switching output signal output to the second selector.

[0006]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. The transmission line monitoring signal insertion circuit 1 inserts the transmission line monitoring signal output from the counter 3 into the data signal 101 from the transmission line 1 by the clock signal 102 and outputs the data signal 107 with the transmission line monitoring signal to the selector 8. .. The counter 3 inputs the clock signal 102 and the frame pulse signal 103 from the transmission line 1 and outputs the above-mentioned transmission line monitoring signal to be inserted into a predetermined pulse position of the data signal 101. The transmission line monitoring signal insertion circuit 2 and the counter 4 are the transmission line 2
It has the same function as above. The selector 8 selects one of the signals on the transmission line 1 side and the signals on the transmission line 2 side by the switching output signal 118 output from the latch circuit 6. That is, normally, the transmission path 1 side is selected, and when the switching output signal 118 is inverted due to the failure on the transmission path 1 side, the transmission path 1 side is switched.

The transmission line supervisory signal detection circuit 9 detects the transmission line supervisory signal contained in the data signal 115 with the transmission line supervisory signal from the selector 8 by the transmission line supervisory signal for detection output from the counter circuit 10 and externally detects it. A transmission line monitoring alarm signal 119 and a data signal 120 are output to the. That is, the transmission line monitoring signal is used to monitor the transmission lines before and after the transmission line including the selector 8 and the transmission line monitoring alarm signal 119 is issued if the transmission line monitoring signal is abnormal. Further, the selector 5 inputs the frame pulse signal 103 of the transmission line 1 and the frame pulse signal 106 of the transmission line 2 and selects either one from the switching output signal 118 inverted by the inverter circuit 7. That is, the transmission path side opposite to the one selected by the selector 8 is selected. The latch circuit 6 receives the switching input signal 109 from the external transmission line monitoring device and the output signal of the selector 5, latches the switching input signal 109 with the output signal of the selector 5, and selects the switching output signal 118 as the above-mentioned switching output signal 118. 8 to the transmission path monitoring signal detection circuit 9 as a reset signal.

Next, the operation will be described with reference to FIG. FIG. 2 is a time chart for explaining the switching operation of this embodiment. First, it is assumed that the selector 8 selects the transmission line 1 as an initial state. At this time, the selector 5 selects the frame pulse signal 106 of the transmission line 2. Figures (a)-(d)
Shows the states of the frame pulse signal and the data signal with the transmission path monitoring signal on the transmission paths 1 and 2 having different phases, respectively. A transmission line monitoring signal is inserted in each frame of the data signal with the transmission line monitoring signal. When the switching input signal 109 shown in FIG. 6E is inverted due to a failure of the transmission line 1, the switching output signal 108 shown in FIG. Since it is latched by the frame pulse 106 of the path 2 and is output as the switching output signal 108, it is inverted at the delay timing shown in the figure.

By the inversion of the switching output signal 108, the selector 8 selects and switches the transmission line 2 side. Figures (g) and (h)
Shows the frame pulse signal 117 output from the selector 8 and the data signal 115 with the transmission line monitoring signal.
The figure (h) shows the transmission line monitoring alarm signal 119 output from the transmission line monitoring signal detection circuit 9, but this detection output signal is output at the next frame pulse and reset at the same time. However, when the selector 8 is switched, the switching output signal 108 is input as a reset signal and resets the detection output signal of the previous frame, so that it is not output as shown by the dotted line in the figure.

[0010]

As described above, according to the present invention, the switching of the transmission path is switched in synchronization with the frame pulse, so that the transmission path monitoring signal included in the frame before and after the switching can be surely detected. This has the effect of preventing the occurrence of false alarms.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of this embodiment.

FIG. 2 is a time chart explaining the switching operation of the present embodiment.

FIG. 3 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

 1, 2 Transmission line monitoring signal insertion circuit 3, 4, 10 Counter 5, 8 Selector 6 Latch circuit 7 Inverter circuit 9 Transmission line monitoring signal detection circuit 101, 104, 120 Data signal 102, 105, 116 Clock signal 103, 106, 117 frame pulse signal 109 switching input signal 119 transmission line monitoring alarm signal

Claims (1)

[Claims] 1. A first counter for inputting a first frame pulse signal and a first clock signal from a first transmission line and outputting a first transmission line monitoring signal; and the first transmission line. A first transmission line supervisory signal inserting circuit for inserting the first transmission line supervisory signal into the first data signal from the device by the first clock signal and outputting a data signal with a first transmission line supervisory signal, A second counter for inputting the second frame pulse signal and the second clock signal from the second transmission line and outputting a second transmission line monitoring signal; and a second counter for the second transmission line. A second transmission path supervisory signal inserting circuit for inserting the second transmission path supervisory signal into a data signal by the second clock signal and outputting a data signal with a second transmission path supervisory signal; and the first transmission. Data signal with path monitoring signal, the first clock signal And a first frame pulse signal, a data signal with the second transmission path supervisory signal, the second clock signal and the second frame pulse signal, which are input and selected and output. A selector, a third counter that receives the third clock signal and the third frame pulse signal output from the first selector, and outputs a third transmission line monitoring signal, and an output from the first selector The transmission line monitoring signal inserted in the data signal with the third transmission line monitoring signal is detected by the third clock signal and the third transmission line monitoring signal, and is transmitted to the outside. And a transmission path side opposite to the transmission path side selected by the first selector, which receives the first frame pulse signal and the second frame pulse signal. The second to select
And a switching input signal input from the outside by the output signal of the second selector, output to the first selector as a switching output signal, and at the same time output to the transmission line monitoring signal detection circuit as a reset signal. A transmission line switching circuit comprising: a latch circuit; and an inverter circuit that inverts the switching output signal and outputs the inverted output signal to the second selector.