JP2611246B2 - Instantaneous interruption synchronous switching device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a line switching device for switching a working line to a protection line when a failure occurs in a working line in digital wireless communication, and in particular, to a line switching device without interruption. The present invention relates to an instantaneous interruption synchronous switching device capable of performing synchronous switching.

2. Description of the Related Art Conventionally, a line switching device that switches a working line to a protection line switches a data signal and a lock signal simultaneously by a switching control signal when switching lines.

FIG. 3 is a circuit diagram showing an embodiment of the conventional device.
Is a data signal switch, 2 is a clock signal switch, 3 is a voltage controlled oscillator, 4 is a phase comparator, 5 is a waveform shaping circuit, and a clock signal switched by the switch 2 by a switch control signal. Is input to the voltage controlled oscillator 3 via the phase comparator 4. At the same time, the switching control signal also switches the data signal switch 1 to input the data signal to the waveform shaping circuit 5.

[Problems to be Solved] As described above, the conventional line switching device switches a data signal and a clock signal simultaneously by a switching control signal at the time of line switching.

For this reason, although the voltage controlled oscillator 3 reproduces (generates) a clock signal synchronized with the input clock signal, its output is inevitably delayed and cannot be synchronized with the input clock at the time of switching. As a result, an error occurs in the time until the output clock signal of the voltage controlled oscillator 3 synchronizes with the switched clock signal, and there is a disadvantage that the instantaneous interruption synchronous switching is not performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and prevents instantaneous synchronization by preventing an error from occurring until a switched clock signal and an output clock signal of a voltage controlled oscillator 3 are synchronized. It is an object of the present invention to provide an instantaneous interruption synchronous switching device capable of switching.

[Means for Solving the Problem] A switch for switching between a working and a standby data signal by a switching control signal, a switch for switching between a working and a standby clock signal by a switching control signal, and a clock signal selected by a switching control signal A reception synchronization switching device having a phase comparator for performing phase comparison detection with a voltage controlled oscillator output signal and a waveform shaping circuit for shaping a data signal with an output signal voltage-controlled by the phase comparison signal; Is provided to the switch for switching between the working and backup data signals with a delay from the switch for switching between the working and backup clock signals.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of the instantaneous interruption-free synchronous switching device according to the present embodiment, and FIG. 2 is a diagram showing an operation of a clock switching method for switching between a working and a standby clock signal.

In FIG. 1, 1 is a data signal switch, 2 is a clock signal switch, 3 is a voltage controlled oscillator, 4 is a phase comparator, and 5 is a waveform shaping circuit, which is the same as that of the conventional device. . Reference numeral 6 denotes a delay circuit for delaying a switching control signal sent to the switch 1.

In this device, the working side data signal 11 and the protection side data signal 12 are connected to the switch 1, and the working side clock signal 21 and the protection side clock signal 22 are connected to the switch 2. The switching control signal 30 is connected to these switches 1 and 2, but the above-described delay circuit 6 is provided between the switching control signals 30 and 1. The output of the data signal switch 1 is input to the waveform shaping circuit 5, and the output of the clock signal switch 2 is input to the phase comparator 4 of the phase locked loop circuit.

The waveform shaping circuit 5 is connected to the output of the voltage controlled oscillator 3 and outputs a data signal. FIG. 2 shows the clock switching operation of the instantaneous interruption synchronous switching device having such a circuit configuration.

When switching the working-side data signal to the protection-side data signal, first, the switching control signal 30 controls the working-side clock signal.
Switch from 21 to the standby clock signal 22. The switched clock signal 22 is synchronized by the clock synchronization circuit as shown in the output waveform of the voltage controlled oscillator (VCO) in FIG. The time τ shown in FIG. 2 is an error occurrence time.

The delay circuit 6 in FIG. 1 delays the switching control signal 30 longer than the error occurrence time τ. By switching the data signal with the switching control signal 30 (delay circuit output) delayed by the error occurrence time τ, the waveform shaping circuit 5 can obtain the output of the voltage controlled oscillator 3 in a synchronized state, and without any error. Data signals can be switched, and instantaneous interruption synchronous switching can be performed.

[Effects of the Invention] As described above, the present invention switches the clock signal by the switching control signal, and then switches the data signal after delaying the switching control signal by the delay circuit. An error does not occur until the output clocks of the oscillators are synchronized, thereby providing an effect of enabling instantaneous interruption synchronous switching.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a hitless synchronous switching circuit according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a switching operation. FIG. 3 is a circuit diagram of a conventional circuit. 1, 2: switch, 3: voltage controlled oscillator 4: phase comparator, 5: waveform shaping circuit 6: delay circuit, 30: switch control signal

Claims (1)

(57) [Claims] 1. A switching device for switching between a working and protection data signal by a switching control signal, a switching device for switching between a working and protection clock signal by a switching control signal, a clock signal selected by the switching control signal, and a voltage controlled oscillator In a reception synchronization switching device having a phase comparator that performs phase comparison detection with an output signal, and a waveform shaping circuit that shapes a data signal with an output signal that is voltage-controlled by the phase comparison signal, the switching control signal includes: A non-instantaneous lossy synchronous switching device, characterized in that a delay circuit is provided which is delayed and sent to a switch for switching between the working and backup data signals rather than a switch for switching between working and backup clock signals.