JPH0468831A - Stuff synchronizing system - Google Patents

Abstract

PURPOSE:To stabilize a voltage controlled oscillator(VCO) on the reception side by a simple circuit by providing a limiter in the front step of the VCO in the stuff synchronizing system. CONSTITUTION:Velocity converters 1 and 2 to convert plural asynchronous low-order group signals to synchronizing signals, and a synthesizer 4 to synthesize the plural signals synchronized by the velocity converters 1 and 2 to one train of signals are provided. Then, a radio transmitter 5 to transmit the synthesized signals, and a radio receiver 6 are provided. Further, a separator 7 to separate one train of signals into the original plural signals, and velocity converters 8 and 9 to convert the separated synchronized signals to the original asynchronous low-order group signals are provided. Then, VCO 12 and 13 to convert a stuff control signal to a frequency, limiters 10 and 11 to regulate the variable frequency ranges of the VCO 12 and 13, and multipliers 17 and 18 to constitute a PLL loop are provided. By providing the limiters in the front step of the VCO for velocity conversion in a reception part, the variable frequency range of the VCO is narrowed down. Thus, even in the case of interrupting the inputs of asynchronous low-order group signals, the oscillation frequency of the VCO can not be away from normal input time so much.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to synchronization protection means in a stuff synchronization method.

〔overview〕

The present invention provides a synchronization protection means for a stuff synchronization method, in which a means for suppressing fluctuations in oscillation frequency is provided in a phase-locked loop circuit on the receiving side, thereby maintaining a constant stuffing rate. This is so that it can be omitted.

[Conventional technology]

Conventional stuff synchronization involves inserting stuff pulses into each asynchronous code string to increase the frequency and synchronize, and the receiving side detects the stuff control signal and stuff pulse to obtain frequency information of the original asynchronous code string. was used to control speed conversion. In addition, in order to prevent the vCO's oscillation frequency from fluctuating significantly when the input on the transmitting side is disconnected, a large-scale stuffing control circuit is installed to detect input disconnection and control the stuffing rate to a constant level. was.

[Problem to be solved by the invention]

In such a conventional stuff synchronization method, asynchronous low-order group signals are multiplexed and synchronized after speed conversion by stuff synchronization, and on the receiving side, the multiplexed signals are separated and speed converted.
The signal is converted into the original asynchronous low-order group signal, and at this time, the vCO of the speed converter is synchronized with the frequency of the asynchronous low-order group signal on the transmitting side obtained by the stuff pulse. therefore,
If the power of the asynchronous low-order group signal train on the transmitting side is cut off, the frequency of the asynchronous low-order group signal on the transmitting side obtained by the stuff pulse will be lost, and there is a risk that it will exceed the synchronization range of Vco. This method requires a large-scale staff control circuit to stabilize the VCO on the receiving side by sending constant pulses when the asynchronous low-order group signal power is cut off on the transmitting side, which has the disadvantage of increasing costs. Ta.

SUMMARY OF THE INVENTION In order to eliminate such drawbacks, it is an object of the present invention to provide a stuff synchronization method that can stabilize the VCO on the receiving side with a simple circuit.

[Means to solve the problem]

The present invention provides a transmitting device having a first speed converting means for inserting stuff pulses into a plurality of asynchronous low-order group signals to perform speed conversion and generate a synchronizing signal, and a combining means for combining the synchronizing signals into a series of signals; Separation means for separating the above-mentioned series of signals coming from the transmitting device into a plurality of synchronization signals; a second rate conversion means for removing stuff pulses from the separated synchronization signals to restore the original asynchronous low-order group signal; In the stuff synchronization method comprising a receiving device having a phase-locked loop circuit that defines the frequency of the second speed conversion means based on stuff pulses, the phase-locked loop circuit transmits an asynchronous lower-order group signal to the receiving device. The present invention is characterized in that it includes a fluctuation suppressing means for suppressing fluctuations in the oscillation frequency of the voltage controlled oscillator of its own circuit when the arrival is interrupted. Here, it is desirable that the upward fluctuation suppressing means is a limiter inserted before the voltage controlled oscillator.

[Effect]

When the arrival of the asynchronous low-order group signal to the receiving device is interrupted, the oscillation frequency of the voltage controlled oscillator of the phase-locked loop circuit fluctuates significantly, making it impossible for the phase-locked loop circuit to follow smoothly when the arrival of the asynchronous low-order group signal resumes. A limiter is provided before the voltage controlled oscillator to suppress fluctuations in the oscillation frequency.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of this embodiment.

As shown in FIG. 1, this embodiment includes a speed converter 1.2 that converts a plurality of asynchronous low-order group signals into synchronous signals, and a plurality of signals synchronized by the speed converter 1.2. a combiner 4 for combining signals into a plurality of signals, a wireless transmitter 5 for transmitting the combined signal, a wireless receiver 6 for receiving the transmitted signals, and a combiner 4 for combining signals into a plurality of original signals. a speed converter 8.9 that converts the separated synchronization signal into the original asynchronous low-order group signal, V C012, 13 that converts the stuff control signal into a frequency, and V6O1.
Limiter 10.1 defining a variable frequency range of 3,13
1 and multipliers 17 and 18 forming a PLL loop.

As shown in FIG. 1, this embodiment includes a speed converter 1.2 that inserts stuff pulses into a plurality of asynchronous low-order group signals to perform speed conversion and generate a synchronization signal, and a speed converter 1.2 that converts the synchronization signal into a series of signals. a transmitting section having a combiner 4 that combines the signals into a plurality of synchronized signals; a separator 7 that separates the above-mentioned series of signals coming from the transmitting section into a plurality of synchronous signals; A speed converter 8.9 that restores the next group signal and a phase locked loop circuit 14 that defines the frequency of this speed converter 8.9 based on stuff pulses.
．． Further, as a feature of the present invention, the phase locked loop circuit 14.15 has VC012, 13
It has a limiter 10.11 inserted in the front stage.

Next, the operation of this embodiment will be explained.

Even if the asynchronous low-order group signal is disconnected in the transmitter and the stuff signal is not sent normally, the VCO 12 for speed conversion in the receiver
, 13 are controlled by limiters 10 and 11 so that they do not deviate too much from their normal frequencies.

Conventionally, the stuff control signal of the transmitter was manipulated to prevent the receiver's VCO from deviating too much from its normal state, which made the circuit complicated; however, in the present invention, a limiter is added to the receiver. It can be controlled only by

〔Effect of the invention〕

As explained above, the present invention provides a V for speed conversion of a receiving section.
By providing a limiter in the front stage of the CO, the variable frequency range of the VCO is narrowed, so even if the asynchronous low-order group signal input is cut off at the transmitter, the oscillation frequency of the VCO will not deviate much from the normal input, and therefore the normal input will not occur. This has the advantage that the VCO can immediately follow the situation.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a block configuration diagram showing the configuration of a conventional example. 1.2.8.9 Speed converter, 3 Stuff control circuit, 4 Combiner, 5 Wireless transmitter, 6
...Radio receiving device, 7...Separator, 10.11...
Limiter, 12.13...VCO114,15...
Phase-locked loop circuit, 16... Reference oscillator, 17.1
111... Multiplier.

Claims (1)

[Claims] 1. A first speed converting means for inserting stuff pulses into a plurality of asynchronous low-order group signals to perform speed conversion and generate a synchronizing signal, and a synthesizing means for combining the synchronizing signals into a series of signals. a transmitting device, a separating means for separating the above-mentioned series of signals coming from the transmitting device into a plurality of synchronous signals, and a second device for removing stuff pulses from the separated synchronous signals to restore the original asynchronous low-order group signal. In a stuff synchronization method comprising a speed conversion means and a receiving device having a phase locked loop circuit that defines the frequency of the second speed conversion means based on stuff pulses, the phase locked loop circuit is configured to provide an asynchronous low voltage to the receiving device. A stuff synchronization method characterized by comprising a fluctuation suppressing means for suppressing fluctuations in the oscillation frequency of a voltage controlled oscillator in its own circuit when the arrival of the next group signal is interrupted. 2. The stuff synchronization system according to claim 1, wherein the fluctuation suppressing means is a limiter inserted before the voltage controlled oscillator.