KR19990060525A - Synchronous Clock Extraction Device for Wireless Data Service System - Google Patents

Abstract

GATE BUFFER and OPEN COLLECT TYPE MODULE are employed in the DITITAL INTERFACE MODULE to extract the synchronous clock signal when connecting to other switching centers. The present invention relates to a network synchronization clock extraction apparatus of a wireless data service system capable of improving normal synchronization extraction. The method for extracting a network synchronization clock signal from a signal transmitted through a transmission path from at least one switching station, thereby enabling system operation in a clock module. A network synchronization clock extracting apparatus of a wireless data service system for generating a clock signal, comprising: a line interface unit for extracting a network synchronization clock signal among signals transmitted through the transmission path and a predetermined gate signal according to a state of the transmission path; Passing the clock signal for network synchronization The clock module may be configured to receive a clock signal for network synchronization through a digital network interface module having a gate buffer, and the clock reproduction of the clock module using the clock signal for network synchronization in a bad state is prevented. Stabilization is ensured, and the flexibility of adding a digital network interface module is ensured.

Description

Network Synchronization Clock Extraction Device for Wireless Data Service System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network synchronization clock extraction apparatus of a wireless data service system, and more particularly, to a gate buffer and an open collect in a digital interface module for extracting a synchronization clock signal when connected to another switching center. The present invention relates to an apparatus for extracting a network synchronization clock of a wireless data service system that employs an OPEN COLLECT TYPE MODULE to improve extraction of normal synchronization in a clock module.

As the basic technology of electricity and electronics is developed, communication technology is also changing drastically, and communication technology started from telegraph technology has recently been developed in various fields to improve transmission speed. Has been popularized, and portable communication terminals such as mobile phones have also appeared and have been generalized for a long time.

Recently, digital communication technology has been developed and commercialized in a wireless data service system, and many exchange stations form a comprehensive digital network for digital communication.

Communication between two different switching stations constituting the digital network is performed through a wireless data service system, and the wireless data service system is configured to extract synchronization for communication between two different switching stations when performing communication in a synchronous manner. In addition, the configuration for synchronous extraction is a plurality of digital network interface module 14 having two line interface units (LINE INTERFACE UNIT) 10, 12 as shown in Figure 1 is one clock module (CLOCK MODULE) ( It is connected to 16).

Each line interface unit 10, 12 provided in each digital network interface module 14 is connected one-to-one with another switching center, and receives a network synchronization clock signal from data transmitted through a transmission path (not shown). Extract.

The network synchronization clock signal is extracted from the line interface units 10 and 12 configured in the digital network interface module 14 described above, and the network synchronization clock signal extracted from the line interface units 10 and 12 is a clock module ( It is inputted in 16) and reproduced as a clock to be used throughout the system. The clock module 16 is provided with a phase locked circuit (PHASE LOCKED LOOP) therein in a system synchronized with the network synchronization clock signal transmitted from the line interface unit 10 (12) of the digital network interface module 14 Generate all clock signals to be used.

However, in the above-mentioned longitudinal data transmission system, the network synchronization clock extracted from the line interface units 10 and 12 is directly transmitted to the clock module 16 to generate all the clock signals to be used in the system.

Therefore, even when the state of the transmission signal is poor and the state of the transmitted signal is abnormal, the line interface unit 10, 12 extracts the network synchronization clock signal and transmits it to the clock module 16. 16) resulted in the generation of clock signals with abnormal or unstable synchronization.

As described above, the clock signal generated by the abnormal or unstable synchronization affects the operation of the entire system, thus degrading the stability of the system.

Since the synchronous clock extracted from the line interface unit is directly transmitted to the clock module, when the number of line interface units increases due to the variable number of connections of more switching stations, additional transmission paths are required as the number of line interface units increased. The drawback of this line interface unit was not flexible.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems as described above, and an object thereof is to achieve abnormal synchronization by blocking transmission of a clock signal for network synchronization from a line interface unit to a clock module in a transmission state of an abnormal signal due to a bad transmission state. The present invention provides a clock extraction apparatus for network synchronization of a wireless data service system that prevents generation of a signal.

Another object of the present invention is to provide an apparatus for extracting a network synchronization clock of a wireless data service system that is flexible to increase and decrease the present line interface unit.

1 is a block diagram showing a network synchronization clock extraction apparatus of a conventional wireless data service system.

Figure 2 is a block diagram showing a preferred embodiment of a network synchronization clock extraction apparatus of a wireless data service system according to the present invention.

* Explanation of symbols for main parts of the drawings

10,12,24 ~ 30: Line interface unit

14,20: Digital Network Interface Module

16,22: Pulse module 32 ~ 38: Gate buffer

40 ~ 60: Open collector type buffer

In order to achieve the above object, the apparatus for extracting a network synchronization clock of a wireless data service system according to the present invention extracts a clock signal for synchronizing a main network signal transmitted through a transmission path from at least one switching station, thereby enabling system operation in a clock module. A clock device for network synchronization of a wireless data service system generating a clock signal, comprising: a line interface unit for extracting a network synchronization clock signal from a signal transmitted through the transmission path and a predetermined gate signal according to a state of the transmission path; Preferably, the clock module is configured to receive a network synchronization clock signal through a digital network interface module having a gate buffer through which the network synchronization clock signal passes.

The digital network interface module includes at least three lines connected to the transmission path including the line interface unit and the gate buffer, and an open collect type buffer is further connected to a rear end of each gate buffer. Preferably, the signal is configured to transmit one of the network synchronization clock signals extracted from the plurality of line interface units to the clock module through one transmission path.

In addition, the gate buffer may be configured to operate as a gate signal for a signal bad state on the transmission line as the gate signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

An embodiment according to the present invention has been applied to a wireless data service system in which a plurality of digital network interface modules 20 and a clock module 22 are combined to perform synchronous operation, and each digital network interface module 20 has four Line interface units 24, 26, 28, and 30 are provided, and each of the line interface units 24, 26, 28, and 30 is connected to one switching center through a transmission line to receive and receive signals. It is configured to extract a clock signal for network synchronization.

In addition, the gate buffers 32, 34, 36, 38 and the open collect type buffers 40, 42, 44 are serially connected to the line interface units 24, 26, 28, and 30, respectively. 46 are sequentially connected, and each of the open collect type buffers 40, 42, 44 and 46 is connected to the clock module 22 through one common transmission path.

Each of the above-described gate buffers 32, 34, 36, and 38 receives a Loss of Signal (LOS) signal having a level corresponding to a state of a corresponding transmission path and receives the corresponding line interface unit ( 24, 26, 28, and 30 are configured to determine the passage of the clock signal for network synchronization, and the level of the above-described loss signal is changed according to a bad or no signal of a transmission path.

In the embodiment according to the present invention configured as described above, the digital network interface module 10 is connected to the digital network interface module of the industrial exchange to receive a signal through a transmission path.

Then, the line interface unit of the digital network interface module 10 extracts a known network synchronization clock signal from the input signal and outputs it to the corresponding gate buffer.

The gate buffers 32, 34, 36 and 38 are operated by the loss signal transmitted according to the state of the transmission path.

An example of a case where a signal is transmitted to a specific line interface unit is described.

When a predetermined signal is transmitted from the digital network interface module of the counterpart switch connected to the line interface unit 20, the currently transmitted signal is input to the line interface unit 20, and a loss signal corresponding to the transmission path state is generated.

If the transmission path connected to the line interface unit 20 is normal and the state of the input signal is good, the gate buffer 32 sends a network synchronization clock signal from the line interface unit 20 to the gate buffer 32 by the loss signal. On the contrary, if the state of the transmission path connected to the line interface unit 20 is abnormal and the state of the input signal is not present or incomplete, the gate buffer 32 outputs the operation of the clock signal for network synchronization by the loss signal. Do not do it.

In the same manner as the operation of the gate buffer 32 described above, other gate buffers 34, 36 and 38 also determine whether the network synchronization clock signal is generated in the signal transmitted from the counterpart switching station according to the state of the transmission path. do.

On the other hand, the open collector type buffers 40, 42, 44 and 46, which are connected to the gate buffers 32, 34, 36 and 38, are connected to the clock module through a common transmission path, respectively. By transmitting only one of the signals input from the gate buffers 32, 34, 36, 38 to the clock module 22, the clock by the signal transmitted from only one upper exchange even if several line interface units are used. Only the signal is reproduced by the clock module 22 and used in the system.

Therefore, when a signal transmitted from a counterpart exchange station is unstable due to a bad or abnormal state of a transmission path, clock reproduction and use using the same are blocked, so that the system can be operated stably.

In addition, since a large number of line interface units are integrated in one digital network interface module, integration of boards constituting a facility is realized, and the adaptability of using a plurality of digital network interface modules is increased.

Therefore, according to the present invention, the clock regeneration in the clock module using the network synchronization clock signal in a bad state is prevented, thereby stabilizing the system, and the flexibility of the addition of the digital network interface module is secured.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (4)

In the network synchronization clock extraction apparatus of a wireless data service system for extracting a clock signal for the network synchronization of the signals transmitted through at least one switching station through the transmission path, thereby generating a system operation clock signal in the clock module, A digital interface module including a line interface unit for extracting a network synchronization clock signal among the signals transmitted through the transmission path and a gate buffer for passing the network synchronization clock signal as a predetermined gate signal according to a state of the transmission path And the clock module is configured to receive a clock signal for network synchronization. The method of claim 1, And the digital network interface module includes at least three lines connected to the transmission path including the line interface unit and the gate buffer. The method of claim 2, An open collect type buffer is further connected to a rear end of the gate buffer to transmit one of the network synchronization clock signals extracted from the plurality of line interface units to the clock module through a single transmission path. Network Synchronization Clock Extractor in Wireless Data Service System. The method of claim 1, And the gate buffer is configured to operate as a gate signal for a signal bad state on the transmission line as the gate signal.