Program-controlled switches, the full name of which is stored program control switches, corresponds to cabling logic control switches, referred to as deployment control switches, also known as program-controlled digital switches or digital program-controlled switches.

Usually refers specifically to the switching equipment used in the switched telephone network, which controls the connection of telephones with a computer program. Program-controlled exchange is a telephone exchange that uses modern computer technology to complete control, connection and other work.

The main task of a telephone exchange is to realize the continuity of calls between users. It is basically divided into two parts: telephone equipment and control equipment.

The telephone equipment mainly includes various interface circuits, such as user line interfaces and trunk interface circuits, and switching or connecting networks; The control equipment mainly includes markers and transmitters in the vertical and horizontal switchboard, while in the program-controlled switch, the control equipment is an electronic computer, including a central processing unit, memory and input/output equipment.

In essence, the program-controlled switch is a switch that uses a computer to carry out "storage program control", which programs various control functions and methods, stores them in memory, and uses the scanning data and storage programs of the external state to control and manage the work of the entire switching system.

The basic function of the switching network is to establish a connection path between the calling and the called user through the continuation command of the control part according to the call requirements of the user.

In the vertical and horizontal switch, it adopts a variety of electromechanical connectors, such as vertical and horizontal connectors, coding terminals, flute spring connectors, etc., and in the program-controlled switch, it mainly adopts the air division switching network composed of electronic switch arrays, and the time division connection network composed of memory and other circuits.

The function of the user circuit is to realize the connection between various user lines and switches, usually known as the user line interface circuit, English abbreviation SLIC, full name subscriber_line_inte**ce_circuit.

According to the different switching mechanisms and application environments, there are also many types of user circuits, for program-controlled digital switches, there are mainly analog subscriber line circuits (ALC) connected with analog phones and digital subscriber line circuits (DLC) connected with digital phones, data terminals or terminal adapters.

The digital subscriber line circuit is an interface set up to adapt to the digital user environment, which is mainly used to connect with various data terminal equipment (DTE) such as computers, printers, VDUs, and telex through line adapters (LAM) or digital phones (SOPHO-set).

The access repeater is the interface circuit between the trunk and the switching network, which is used to connect the switch trunk. Its function and circuit are closely related to the standard of the switching system used and the signal mode of the inter-office trunk.

For the analog trunk interface unit (ATU), as the interface between the analog trunk and the switching network, the basic functions generally are:

Transmit and receive the trunk status, such as idle, occupy, answer, release and other line signals; supply of call power and signal tone; The received line signal is provided to the control device.

In the simplest case, if the repeater of one switch is connected to another switch through a solid trunk and uses user loop signaling, the function and function of the analog repeater are equivalent to a "phone".

If other more complex signal methods are used, the repeater should realize the corresponding voice and signaling transmission and control functions.

The function of the digital trunk interface unit (DTU) is to realize the interface between the digital trunk and the digital switching network, and it transmits the trunk signaling through the PCM related time slot, and completes the basic functions that an analog repeater should undertake.

However, due to the fact that the digital trunk transmits the digital signal of the PCM group path, it has some special problems of digital communication, such as frame synchronization, clock recovery, pattern switching, signaling insertion and extraction, etc., that is, it is necessary to solve the connection problems of signal transmission, synchronization and signaling cooperation.

The basic functions of the digital relay interface unit include frame and complex frame synchronization code generation, frame adjustment, even zero suppression, pattern transformation, alarm processing, clock recovery, frame synchronization search and inter-office signaling insertion and extraction, etc., just like the ****orscht of analog user circuits, and the above 8 functions of the digital relay unit can also be summarized as gazpacho.

The control part is the core of the program-controlled switch, and its main task is to execute storage programs and various commands according to the requirements of external users and internal maintenance and management, so as to control the corresponding hardware to realize the switching and management functions.

The main body of the program-controlled switch control equipment is a microprocessor, which can be divided into two categories: centralized control and decentralized control according to its configuration and control working mode.

In order to better meet the requirements of software and hardware modularization, improve the processing capacity and enhance the flexibility and reliability of the system, in the era before Fu Xin's crossing, the degree of decentralized control of the program-controlled switching system has been improved, and partial or fully distributed control methods have been widely adopted.

10,000-door program-controlled switchboard, naturally 10,000-door fully electronic automatic switch.

As early as 1982, Mindu, the provincial capital of Jianfu Province, introduced and opened a 10,000-door program-controlled telephone system, which became a milestone event in the history of China's reform and opening up and communication development. It not only brought about a technological revolution in Jianfu Communications, but also led the great development of the national communications industry.

"To be honest, I really know about a big project, but I just don't know that you don't have the strength to take him next." Fu Zhenbang played a dumb riddle and said mysteriously.

"What big project, as long as it can be followed, there is no strength or not." Fu Xin seemed very interested. He is indeed very interested, at present, Huaxing Industrial has fallen into a bottleneck in the field of electronics industry, and winning this kind of large project is conducive to the development of Huaxing Industrial Development Company.

"Very confident, not bad." Fu Zhenbang's face was full of smiles, and he looked very satisfied, "But can you sit down, I have to say something else, let me tell you what kind of project this is first!" ”

"The current communication situation in our Tay Giang province is relatively backward. According to statistics, as of the end of last year, the province's municipal telephone automatic exchange capacity was only more than 10,000, long-distance circuits were less than 1,000, the capacity was seriously insufficient, the equipment was outdated, there were many obstacles, the smooth rate was low and the standards were different. With the increase in the degree of economic extroversion, the volume of domestic and international telephone services has increased significantly, and the construction of new communication networks cannot be delayed.

Under such a general environment of economic development, the leaders of the Xijiang Provincial Party Committee proposed that Xijiang Province should create conditions for opening up and vigorously develop telecommunications and other infrastructure facilities in various places, and asked the Provincial Post and Telecommunications Administration to vigorously improve its facilities to ensure that telecommunications will not lag behind.

According to the instructions of the Provincial Party Committee and the Provincial Political Axe, after in-depth study, the Provincial Posts and Telecommunications Administration boldly put forward a construction project for program-controlled switching telephones, which will solve the problem of serious shortage of telephone capacity in one step, realize automatic dialing of long and municipal telephones, open up a variety of new telephone services, improve the quality of calls, and accelerate the realization of a plan for the modernization of communications.

According to the preliminary plan, it is planned to build a set of the world's most advanced electronic and fully automatic program-controlled telephone exchange system using time division switching technology in Xunyang, with an initial installation capacity of 10,000 doors. ”

"10,000 program-controlled switching telephones?" Fu Xin asked in disbelief.

Why can't I believe it, because these 10,000 program-controlled switching telephones have just started to be carried out in the coastal provinces, as a province in the central region, Xijiang Province, will start doing it now, which makes Fu Xin feel a little incredible.

But after thinking about it, Fu Xin felt normal again, Xijiang Province is the cradle of the New Chinese Revolution, and the above policies have more or less taken care of here, in addition, Xijiang Province is very rich in rare earth resources, and this rare earth is a sweet spot in the foreign exchange market, so Xijiang Province also has some money.

"You kid is very clear, I talked to you Rory about a bunch of policies, you gave me a nine-word summary, did you listen!" Fu Zhenbang was a little unhappy, Fu Xin's doubts, he felt that his kindness was in vain.

"I listened to it, I listened very carefully, but I couldn't believe it, Wanmen program-controlled switching telephones, this is a new thing in the coastal provinces!" Fu Xin understood Fu Zhenbang's painstaking efforts, and Fu Zhenbang Rory explained the above policies clearly, also so that Fu Xin could better understand the situation of the project, so that he could make decisions on the above policies.

"There is still a little money in the province, and our economic development in Xunyang is very good, your Huaxing Industrial Development Company is a big tax payer, it is said that the province according to the plan, the motorcycle production line introduced from Germany will also be settled in our Xunyang."

"Hmm." Fu Xin nodded, "Our Xunyang is close to Poyang Lake and the Yangtze River, and the geographical conditions are good, otherwise the Tianjin Treaty signed by the cowardly and incompetent Manchu Qing political axe and the British would not have included our Xunyang." ”

"Don't mention the unequal treaty." Fu Zhenbang brought the topic back on track, "For various considerations, the province decided to pilot this 10,000-door program-controlled exchange telephone equipment in Xunyang. ”

"It is said that a set of the world's most advanced and fully electronic and automatic program-controlled telephone exchange system using time division switching technology will be built, with an initial installation capacity of 10,000 doors. In terms of current domestic technology, one cannot be reached, and there are many foreign companies participating in the competition, right? Fu Xin asked.

"Hmm!" Fu Zhenbang nodded, "That's true, Fujitsu and NEC, the United States Xidian, Sweden Ericsson, France TMOSON and CIT, the Netherlands Philips, Belgium ITT and other internationally renowned communication equipment manufacturing companies are very actively involved, one by one rushed to come to us for technical exchanges, and also made many quotations. ”

"The decision has not been implemented and negotiated yet?"

"Nope." Fu Zhenbang shook his head, "It's just a preliminary contact now, and if it is to be implemented, it will be over this year." ”

Fu Xin asked: "Aren't there any domestic companies participating in the competition?" ”

Fu Zhenbang nodded, "At present, no, because domestic companies do not have this technology, I am embarrassed to come to offer ugliness, but there is no provision that foreign technology must be introduced." (To be continued.) )