JPH0334638A - Circuit switching method - Google Patents

Abstract

PURPOSE:To execute the switching without momentary interrupt by bringing a main signal train of an existing circuit side and a main signal train of a stand-by circuit side to scramble before switching, and also, bringing them to descramble after the receiving synchronization. CONSTITUTION:At the time of switching an existing circuit 100 to a stand-by circuit 200, in the case initial values are the same on the existing circuit 100 side and the stand-by circuit 200 side, or the same phase is detected in both the circuits by '1'/'0' converting point detecting circuits 16, 16a, a scramble is applied to signal trains of both the circuits at the time point before synchronous switching by scramble circuits 13, 13a. Since a main signal train can varied by this scramble operation, even a light load signal train which is scarcely varied such as all '1' and all '0' of the body are continued for many hours the phase synchronization surely is secured by a synchronization switching circuit 8. Thereafter, to a signal train outputted from the synchronization switching circuit 8, a descramble is applied by a descramble circuit 14, and it is returned to a signal state before the scramble. In such a way, the switching without hit is realized.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a line switching method for seamlessly receiving and synchronously switching a signal string to which no signal in a wireless section is added between a working line and a protection line. [Prior Art] In digital wireless communications, a line switching device is used to switch the current line to a backup line when a failure occurs in the current line or when equipment is being inspected or maintained. . FIG. 2 is a circuit block diagram of a conventional line switching device, in which the working line 100 and the protection line 200 are provided with the same circuit. That is, the transmission system branch circuit 1 is provided with transmission code conversion circuits 2, 2a, transmission signal processing circuits 3, 3a, and the reception system is provided with frame synchronization circuits 4, 4a, reception signal processing circuit 5.5a, and reception code conversion circuits. A circuit 6.6a is provided. In addition, the backup line 200 has a working port &! 100
There is a distribution circuit 7 that distributes the signal sent to the protection line 200 to the working port @ioo when relieving the protection line 100, and a synchronous switching circuit 8 that inputs the signal from the distribution circuit 7 to the working line 100. It is provided. When switching lines, the synchronization switching circuit 8 switches the reception synchronization of the information signal sequence on the transmission path. In addition, in order to monitor the occurrence of a failure in the protection line 200, a pilot generation circuit 9. A pilot and pilot detection circuit 10 is provided on the receiving side, and the signal outputted from the transmitting side switch 11 that switches between the signal output to the working line 100 and the output signal of the pilot generating circuit 9, and the reception code conversion circuit 6.6a. A receiving side switch 12 is provided for switching between a protection line side signal and a working line signal. With this configuration, when the working line 100 is selected, in the protection line [200, the pilot signal output from the pilot generation circuit 9 is transmitted to the transmission side switching unit 11, the transmission code conversion circuit 2a, the transmission processing circuit 3a, and the frame synchronization circuit. 4a
, the received signal processing circuit 5a, the distribution circuit 7, and the receiving side switching device 12, and finally input to the pilot detection circuit 10. Therefore, by detecting this pilot signal, failures in the protection line can be detected and line quality can be monitored. [Problems to be Solved] In the case of a light load signal train with little change such as all 1's or all O's continuing for a long time, the conventional line switching device described above cannot switch between the main signal train on the working line side and the main signal on the protection line side. There was a risk that the phase difference between the two columns could not be accurately detected. Therefore, even though there is a phase difference, it is mistakenly determined that there is no phase difference between the main signal train on the working line side and the main signal train on the protection line side.
Momentary interruptions sometimes occurred during switching. Furthermore, since the fixed pattern signal train is frequency-divided within the reception synchronization switching circuit, there are no changing points, which may similarly cause instantaneous interruptions during switching. The present invention was made to solve this problem, and it is possible to reliably synchronize even in the case of a light load signal train with little change such as all 1s or all 0s for a long time, or a fixed pattern signal train. The purpose of the present invention is to provide a line switching method that can realize uninterrupted switching.

[Means for solving problems]

In order to achieve the above object, the present invention provides a line switching method for seamlessly receiving and synchronously switching a signal string to which no signal in a wireless section is added between a working line and a protection line, comprising:
A method is to use a scrambling circuit to scramble the main signal train on the working line side and the main signal train on the protection line side output from the reception signal processing circuit using a scrambling circuit before switching, and to descramble them using a descrambling circuit after receiving synchronization. be. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a line switching device for implementing the method of the present invention. In addition. The same parts as in FIG. 2 shown above are given the same reference numerals, and detailed explanations of those parts will be omitted. The line switching device shown in FIG. 1 is characterized by the receiving system signal path on the working line 100 side and the protection line 2
A scrambling circuit 13.13a for changing the frequency band of the input signal is provided in the signal path where the 00 reception system is distributed, that is, the signal path before entering the synchronous switching circuit 8, and a scrambling circuit 13.13a is provided in the signal path on the output side of the synchronous switching circuit 8. A desk scrambling circuit 14 is provided in the scrambling circuit 13.13a, and the signal frequency changed by the scrambling circuit 13.13a is returned to the original frequency. Here, a timing signal (for example, a power ON signal) 15 is output from the scramble circuit 13 on the working line 100 side to the scramble circuit 13a on the protection line 200 side.
The initial values of 13a are adjusted at the same time. Further, each scramble circuit 13, 13a includes 1. An O-conversion check output circuit 16, 1.6a is also provided, and when the circuit 16.16a detects the same phase on the working line 100 side and the protection line 200 side, each scramble circuit 13, 13a performs scrambling. By using the above-mentioned line switching device, the line switching method of the present invention can be carried out as follows. That is, when switching the working line 100 to the protection line 200, the initial values are the same on the working line 100 side and the protection line 200 side, or the 1°O conversion check circuit 16.
When the same phase is detected in both lines by 16a, the scrambling circuit 13.13a scrambles the signal trains of both lines before synchronization switching. This scrambling operation allows changes to be made to the main signal train, so even with light load signal trains with little change, such as all 1's or all O's continuing for a long time, the synchronization switching circuit 8 ensures phase synchronization. You can take it. Thereafter, the signal string output from the synchronization switching circuit 8 is descrambled by the descrambling circuit 14 to restore the signal state before scrambling. [Effects of the Invention] As explained above, according to the present invention, even in the case of a light load signal train in which all 1s or all O's continue for a long time or a signal train of a fixed pattern, synchronization can be reliably achieved, and no synchronization can be achieved. This has the effect of realizing momentary interruption switching.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining the present invention in detail, and FIG. 2 is a block diagram for explaining the prior art. 1: Branch circuit 5.5a: Received signal processing circuit 7: Distribution circuit 8: Synchronous switching circuit 13.13a Niscrumple circuit 14: Descrambling circuit 16.16a: 1,0 conversion check circuit

Claims (1)

[Claims] A line switching method in which a signal string to which no signal in the wireless section is attached is switched between a working line and a protection line without any interruption in receiving synchronization, and the main signal string on the working line side output from a reception signal processing circuit. and a main signal train on the protection line side are scrambled by a scrambling circuit before switching, and descrambled by a descrambling circuit after reception synchronization.