Power communication PCM device

1. Power communication PCM device application

The power dispatching communication network is one of the important dedicated communication networks in China, and it is the most important component of the power system communication private network. The power dispatching communication network includes a large-scale communication private network connecting various power supply stations, substations, dispatching centers, etc. The mainstream networking scheme adopts SDH device and PCM device to realize optical fiber transmission and 2M access. This will elaborate on the functional requirements of power users for PCM device systems and the characteristics of various types of services in PCM power communication.

2. The PCM system principle description

PCM is used to graft an analog signal (such as voice) onto a 64 kbps digital bit stream for transmission. The PCM converts continuous analog signals into discrete digital signals. In digital audio the pulse coding development method, so-called PCM, is commonly used. PCM coding is the abbreviation of Pulse Code Modulation, also known as pulse code modulation. It is one of the coding methods of digital communication. The main process of coding is to sample the analog signals such as voice and image at regular intervals to discretize them. The sampled values are rounded up and rounded in hierarchical units, and the sampled values are represented by a set of binary codes to represent the amplitude of the sampled pulses. The biggest advantage of PCM coding is that the sound quality is good.

The PCM digital communication process mainly includes three parts: the first part is the analog/digital conversion of the transmitting end, which has the sampling, quantization and encoding process; the second part is the channel, including the channel transmission and the regenerative relay; the third part is the number of the receiving end. The /mode conversion part mainly refers to the reproduction, decoding, and low-pass filtering smoothing process.

3. Power users' requirements for PCM device

A. System function application of PCM communication in power system

The PCM equipment should have multi-service integrated access functions such as data and voice. In the transmission, parallel digital switching technology and flexible time slot cross-connection technology are used to complete service scheduling of different flows. It mainly relies on MSTP (Integrated Service Transmission Platform), 2M the electrical interface provides power system users with SCADA (Supervisory Control And Data Acquisition) real-time data communication, telecontrol signals and other data services; and dispatching telephone, administrative telephone, hotline and other voice services, and user terminal services convergence convergence at the access layer and efficient and secure transmission in the optical transport network.

B. Many type voice interface

It can provide various voice interfaces including user analog interface, loop relay interface, billing telephone (polarity reversal) interface, E/M trunk interface, 2/4 line audio interface, magnet interface, hot line interface and so on.

C. Complete data interface

Such as standard E1 interface, 64K co-directional data interface (G.703), low-speed data interface (RS232/485/422), N×64K synchronous data interface (V.35), 10BaseT Ethernet interface, etc., to meet user terminal equipment access to data.

D. Safe and reliable

The important boards of the PCM device, such as the ringing disk, the power disk, and the main control disk, should have 1+1 redundancy protection. To ensure the safe operation of each service, when the 64K service branch and 2M lines fail, the service can be automatically switched; the optical transmission network provides protection methods such as ring network protection and line protection to meet the high reliability requirements of the power system

E. Line protection

For the important service, the main service transmission channel and the auxiliary transmission channel form two 1:1 protection channels. When the 2M line fails, the service protection dedicated channel can realize automatic switching; when the main service transmission channel is disconnected, the main service is automatically switched to the auxiliary transmission channel. When the main service transmission channel is normal, the primary service is automatically restored to its original state to implement restorative switching.

F. Device compatibility

It can communicate and schedule services with other brand PCM devices

G. Intelligent network management

Provide clear network management graphic interface, and easy to operate, easy to learn; establish and delete cross-connection between any two time slots when connecting services; system clock setting and change; detailed display of fault alarm information, query, etc. Operation and archiving; network element operation and maintenance functions, such as security management functions such as local loops and remote loop settings and deletion of E1 interfaces.

4. ZMUX-3300 PCM device in power communication solutions

A. Introduction to ZMUX-3300

ZMUX-3300 is an integrated service communication device. It adopts the frame + tributary board design to provide users with various service interfaces such as voice, audio, serial port and Ethernet, and realizes voice, data and other on the same line with service crossover, multiplexing, and switching functions. It also provides PDH optical disk and E1 interface disk to meet various access environments and aggregation requirements. The product is managed by the V3.0 unified network management platform of the network management monitoring station of Yinxun Communication Co., Ltd., which can conveniently carry out local and remote management and setting, and support the management and maintenance of the equipment during operation.

B.Solution of  ZMUX-3300 in the power communication access layer

*Communication access network overall solution PCM+SDH optical transceiver

In the current power system communication, the PCM device networking is required to be a chain structure and a ring network structure, and the communication service can be up, down or straight through at any network element node, and the service flow for protecting the dedicated PCM can be unidirectional on the channel single or double transmission. At present, the power PCM service flow connection is mainly a star structure,each station to the central office of the dispatching bureau. The access of 2M data mainly relies on SDH optical transmission equipment to realize long-distance transmission of voice and service data by power users.

ZMUX-3300 rack PCM multiplexing equipment, combined with SDH equipment to form a local optical fiber communication network networking diagram is as follows: