JPH0522268A - Synchronizing immediate pull-in system - Google Patents

Abstract

PURPOSE:To shorten the synchronization pull-in time when a synchronizing signal of its own station is synchronized with a synchronizing signal of a host station at application of power of its own station. CONSTITUTION:A control direction detection circuit 8 obtains a timewise direction F for phase control depending on the quantity between a time difference C of its own station and a time difference D of a host station as to its own station synchronizing signal and a host station synchronizing signal in response to a detection output F of a power application detection circuit 7, an absolute value difference detection control circuit 9 obtains a mean value between the time differences C and D, it is compared with a prescribed value H at a comparator circuit 10, and when the mean value is larger than the prescribed value, a pulse generation control circuit 12 generates a reset pulse K in response to the timewise direction F and the comparison result J to control the reset state of a frequency divider circuit 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for synchronizing a synchronizing signal generated in the local station with a synchronizing signal of the upper station when performing data communication with an opposite upper station.

[0002]

2. Description of the Related Art As shown in the block diagram of FIG. 3, an output of an oscillator (hereinafter, OSC) 1 is controlled by an automatic phase control circuit (hereinafter,
APC) 2 adjusts the phase, and then frequency-dividing circuit (hereinafter, DIV) 3 frequency-divides it to a desired frequency and sends it as local station synchronization signal (hereinafter, LSY) A, which is used for data transmission. It is used as a timing signal or the like.

Further, the upper station receiving unit (hereinafter referred to as REC) 4 receives the synchronization signal B from the upper station.
A time difference C from A is obtained by a time measurement circuit (hereinafter, TDM) 5, the time difference C is given to a comparison circuit (hereinafter, CMP) 6, and a higher station synchronization signal (hereinafter, MSY) in a higher station received by the REC 4 is obtained. The time difference D from the synchronization signal from the own station is also given to the CMP6, and the time difference C and D are compared by the CMP6, and the APC2 is controlled according to this result to synchronize the LSY • A with the MSY. Has become.

In the above phase control, the frequency of phase control is changed stepwise in order to shorten the synchronization pull-in time. When the comparison result by the CMP 6 is larger than a certain value, the rate is once per frame. When the comparison result becomes smaller than a fixed value, the ratio is set once for every 24 frames, and this control is continued until the comparison result becomes zero.

[0005]

However, when the power of the local station is turned on, LSY is in a completely asynchronous state with respect to MSY, and the synchronization pull-in time until LSY is synchronized with MSY is MSY and LSY. And the control width and control frequency of the local side phase control, the time required for completion of synchronization becomes long, and during this period, data communication cannot be performed normally. Therefore, an object of the present invention is to provide a synchronous immediate pull-in system that can quickly bring the synchronization to a completed state when the power of the local station is turned on.

[0006]

In order to achieve the above-mentioned object, the present invention uses the above-mentioned method, in which MSY and LSY in the upper station with respect to the time difference between MSY and LSY of the own station in accordance with the power-on of the own station. The time direction of the automatic phase control is calculated according to the magnitude relationship of the time difference between the two, and when the average value of the time differences between the own station and the upper station is larger than the predetermined value, the automatic phase control is performed according to the calculated time direction. I am supposed to.

[0007]

Therefore, the time direction of the automatic phase control is determined when the power is turned on, and the phase control is performed in accordance with this, so that the time required to complete the synchronization is shortened.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram, and FIG. 2 is a timing chart showing the operation status. In FIG. 1, in addition to the OSC1 to CMP6 shown in FIG. 3, a power-on detection circuit (hereinafter, PON) 7 or later is provided, PO
When N7 produces the detection output E in response to the power-on of its own station,
In accordance with this, the control direction detection circuit (hereinafter, CDD) 8 has a time difference C between MSY · B and LSY · A at its own station,
The magnitude difference of the time difference D between the MSY and the LSY in the upper station received from the upper station is obtained, the phase control is delayed when C> D, and the phase control is advanced when C <D. , The direction information F is sent out.

The time differences C and D are also given to an absolute value difference detection / control circuit (hereinafter referred to as ABD) 9, and the ABD
9, the average value G of the time differences C and D is obtained by calculating | C−D | / 2. This average value G is a predetermined value H from the reference value setting circuit (FST) 11 by the CMP 10.
Compared to.

The predetermined value set by the FST 11 is set to a value slightly smaller than that which is regarded as out of synchronization.
The comparison result of the average value G and the predetermined value H by 10 is | CD
When | / 2> H, the CMP 10 gives the comparison result J to the pulse generation control circuit (hereinafter, PGC) 12 and causes the PGC 12 to output the pulse K proportional to the comparison result J and according to the direction information F. Reset DIV3, A
Adjust the automatic phase control situation by PC2 and DIV3.

FIG. 2A is a diagram showing the relationship between MSY.S of the upper station MS and LSY.A of the own station SS when | CD | / 2> H, and the transmission between them. MSY by time
-S is received as MSY-B while LSY-A
Is received by the upper station MS as LSY · b, the time difference C of the own station SS is smaller than the time difference D of the upper station MS, and the condition | C−D | / 2> H is satisfied. Therefore, by advancing the timing of occurrence of LSY · A and adjusting the phase control in the direction of the arrow, C = D and synchronization is completed.

In contrast to the above, FIG. 2B shows | C-D | /
When 2 <H, the same relationship is shown, and under this condition, the synchronization pull-in is performed sufficiently quickly even by the phase control by only the APC2.
0 gives stop information to the PGC 12 to stop the transmission of the pulse K.

Therefore, the time difference due to the transmission time between the upper station MS and the own station SS is immediately erased, and the synchronization pull-in is performed immediately when the power is turned on. It takes about 1000 seconds, and the time required to complete the synchronization is greatly shortened.

[0014]

As is apparent from the above description, according to the present invention, the time difference between the synchronization signal of the upper station and the synchronization signal of the own station in response to the power-on of the own station is large and small in any relation between the upper station and the own station. If the average value of the time difference between the two stations is larger than a predetermined value, the automatic phase control is performed according to the obtained time direction. Since the synchronization pull-in time is significantly shortened and normal data communication can be started immediately, a remarkable effect can be obtained in the synchronization pull-in of data communication using the synchronization signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation status of FIG.

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

[Explanation of symbols]

 1 Oscillator 2 Automatic phase control circuit 3 Dividing circuit 4 Upper station receiving section 5 Time measurement circuit 6, 10 Comparison circuit 7 Power-on detection circuit 8 Control direction detection circuit 9 Absolute value difference detection / control circuit 11 Reference value setting circuit 12 Pulse Generation control circuit

Claims (1)

Claim: What is claimed is: 1. A time difference between a synchronization signal from an upper station and a synchronization signal of the own station is obtained, and this time difference, a synchronization signal of the upper station in the upper station and a synchronization signal from the own station are obtained. In the method of synchronizing the own station's synchronization signal with the synchronization signal of the host station by performing automatic phase control of the own station's synchronization signal based on the comparison result, The time direction of automatic phase control is obtained from the magnitude relationship between the time difference of the station and the time difference of the upper station, and the time direction is obtained when the average value of the time difference of the own station and the time difference of the upper station is larger than a predetermined value. A synchronous immediate pull-in method characterized in that the automatic phase control is performed according to the direction.