With the rapid development of the news and publishing industry, the long-distance transmission technology for publishing information has also gradually developed. The publication of newspapers in different places is a typical example of this technology. At present, newspapers published in different places in the country have the characteristics of a large number of varieties, high timeliness requirements, many color layouts, and a large amount of information. How to select the appropriate long-distance transmission technology for technology, performance, and price is a problem faced by many organizations. This article will briefly introduce this.

I. Technology development history of newspaper remote transmission

The early printing of newspapers in different places used paper or paper-based transport by airplanes or trains. It was affected by weather and traffic factors, and the publishing cycle was long. It was difficult to guarantee the timeliness of publishing. The emergence of the fourth-generation laser photocopying technology with Huaguang and Founder as the main body in the late 1980s made the computerized information in the newspaper layout a reality. Xinhua News Agency first used manuscripts and texts for remote wireless microwave transmission. The rate was slow and only 2400 baud rate was even lower. In the 1990s, Peking Founder used LANMAM version 1.1 remote dialing software based on the OS2 operating system platform. Transmission of newspaper layout, the maximum transmission rate of 9600 baud rate, but due to the instability of the telephone line, the actual rate can not reach the theoretical speed, and often need to rely on software data breakpoint renewal function to renew documents; 1991 Xinhua News Agency for the first time A one-way satellite transmission technology with a baud rate of 9600 baud is adopted, and the rate is stable. However, due to signal problems and hardware instability of satellite technology, packet loss often occurs. Afterwards, the VAST bit transparency adopted by People’s Daily of the US Hughes Corporation was adopted. Channel bidirectional transmission mode, the speed up to 64K baud rate, the speed is faster, can meet the black and white newspaper layout transmission requirements, but satellite station construction and communication costs are expensive.

Second, the status of wide-area network technology for remote transmission of newspapers

After 1995, the Internet and optical fiber technology developed rapidly, and computer communication technology became more and more mature. Computer communication technology has been fully applied in newspaper transmission. The current newspaper remote transmission technology mainly has the following features.

1. Computer remote dialing

Use point-to-network remote server dialing or point-to-point direct dialing. The use of high-speed modem rates up to 56K baud, easy to set up, convenient transmission, and low cost are the more common transmission methods used by black and white newspapers and weekly newspapers.

2. Internet E-mail transmission method

Use the dedicated or free mailbox provided by the website to establish the E-mail communication method and send the newspaper information as a mail, the rate is generally about 33K baud. However, it is greatly affected by the state of Internet communications and the security performance is poor. This method is easy to set up, convenient to transfer, and low in cost, but it is only suitable for newspapers with a text-based newspaper layout or a longer publishing cycle.

3. High-speed one-way satellite transmission

The high-speed, one-way, full-transparent channel communication method represented by Xinhua News Agency, Liberation Daily, etc., has a rate of up to 128K or 256K baud rate or even higher, which is 2 to 5 times that of the VAST two-way satellite. With fast speeds, satellite stations and communications costs have also dropped significantly. It is different from the early one-way satellite communication. The master station bidirectional check function is added to the hardware, and the software has enhanced the data check of the receiving station. The signal is stable and the error packet rate is low. It is suitable for remote transmission of multi-format, multi-picture color newspapers. It is currently the most popular newspaper remote transmission method.

4. Using ISDN technology for transmission

ISDN is INTERGRADE SERVICE DATA NETWORK, short for Integrated Service Data Network. Technically, it realizes the data transmission, but it adopts data exchange technology at the central office and the rate can reach 128K baud. From the perspective of overall application, ISDN combines the advantages of convenient installation of analog dial-up lines, low cost, stable digital lines, and high speed. However, ISDN convergence between cities and cities still has problems due to the limitations of ISDN throughout the country. Limits the application of ISDN technology for offsite transmission.

5. DDN-based transmission method

DDN, or DIGITAL DATA NETWORK, is an abbreviation of digital data line and is often referred to as LEASED LINE (lease line). It uses a digital, dedicated synchronous line that is logically a direct path connecting two points. Physically and electrically, it passes through digital equipment, thus avoiding the instabilities and slowing of the line caused by past A/D (Analog/Digital) and D/A (Digital/Analog) conversions. Therefore, the overall performance of DDN is very superior. Basically, except for some electrical losses, there is not much loss of bandwidth. While other types of lines are either shared lines, exchange lines, or analog lines, the rate at which they can reach is far lower. In theoretical bandwidth. DDN technology has been widely used in various fields and is a high-speed communication method second only to optical fiber. The Liberation Daily Printing Center took the lead in adopting the DDN technology in the national newspaper transmission at a rate of 512K baud, which is the fastest speed for newspapers at present, and is very suitable for communication between newspaper headquarters and newspaper printing centers in urban areas. It can solve the communication between the newspaper group headquarters and the relevant serial newspapers in the group, and realize the connection between the main newspapers and the serial newspapers in the newspaper group's local area network and wide area network.

6. Communication using optical fiber technology

Optical fiber communication is currently very mature and has broad prospects for development. However, due to its high cost and difficulty in maintenance, the current special technology of optical fiber communication is still less used in the transmission technology of domestic newspapers.

Third, the application of newspaper edition WAN technology in Liberation Daily

Liberation Daily established a large-scale printing base with a total investment of 300 million yuan in 1997. It is now the printing center of the Liberation Daily Newspaper Group. Liberation Daily Newspaper Group has 9 newspapers and 3 periodicals, namely 9 series newspapers and 3 publications. "Liberation Daily" also has printing sites in Beijing, Suzhou, Wuxi, Chongming, and Taizhou. The Group's series of "Newspapers and Digests" has separate printing sites in Xi'an, Wuhan, Shenyang, and Jinan. How to resolve the communication between the newspaper office and the newspaper printing center and solve the communication between the newspaper office and the printing station is a problem that technical personnel must face. Based on the combination of simple and complex, extensive and special cases, and the combination of performance and price, we have fully applied modern communication technologies to solve the problems related to newspaper transmission.

1. Transmission method between newspaper headquarters and newspaper printing center in urban area

(1) Plan selection

When selecting the communication plan between the newspaper headquarters and the newspaper printing center, we focused on researching and inspecting the remote optical fiber communication technology and DDN technology. Finally, we chose the DDN technology with an ideal performance and price. DDN technology currently has two main telephone line + cable, fiber optic cable + cable connection. The former method consists of high-speed data transmission from the terminal to the telecommunications bureau, telecommunications bureau to the terminal's telephone line, and the trunk line is composed of the telecommunication bureau's optical fiber network access. The dedicated telephone line referred to here is a dedicated physical digital line connecting the two ends, which directly realizes the straight-through of the electronic data signal from the terminal to the telecommunication bureau and the telecommunications bureau to the terminal. The latter method is a high-speed fiber-optic data transmission between the terminal and the telecommunications bureau, the telecommunications bureau to the terminal, and the main trunk is composed of a multiplex optical fiber network. Because the latter method requires the construction of two-core fiber optic cables with nearly 5 kilometers at both ends, which is very complicated and has not been adopted, we finally chose a more convenient connection mode between the two-end telephone line and the main line fiber optic network.

In addition, from the theoretical and device hardware performance, we can choose the rate of 64K-2M baud rate. Considering the cost of renting bandwidth and the actual amount of information in color newspapers, we chose a 512K baud rate and a monthly fee of 5,000 yuan. This is currently the fastest domestic newspaper transmission rate, and can be further increased in accordance with the demand for layout information in the future. Transmission rate.

(2) Technology Application

In hardware applications, we mainly use CISCO's 3620 routers and PAIRGAIN's HDSL synchronous modulators, using multi-line automatic backup and automatic recovery technology. Because HDLS may break the wire sometimes, it is critical to ensure that normal transmission of the layout is not affected in the event of a wire break. Therefore, we decided to enable ISDN as a backup line when using DDN technology. Specifically, when an open circuit occurs on the HDSL line, if there is a data signal requesting sending to the other server, the ISDN is automatically started to perform an automatic dial-up connection, which can fully perform the task of emergency transmission. If the HDLS line returns to normal, the ISDN line automatically cuts off the transmission task and returns to the normal HDSL synchronous high-speed line, that is, the DDN technical connection topology.

In the software's system planning, we adopted the TCP/IP network protocol as the basis, the FTP service was the upper application, and the friendly user interface for the convenience of operation was added. The TCP/IP (TRANSPORT CONTROL PROTOCOL/INTERNET PROTOCOL) protocol is a low-level network protocol. It is a network protocol currently used in wide area networks, especially INTERNET. Compared with other network protocols, it has the advantages of convenient management and high efficiency. The FTP (FILE TRANSFER PROTOCOL) service as an upper layer application is currently the main file transfer protocol on the wide area network. We use the FTP service as the basis for file transfer services. Considering reasonable load balancing, FTP service is started on the NT/4.0 server in the Printing Center as a server and as an FTP client in the newspaper headquarters. Based on the above network, we commissioned professional computer companies to develop software that controls the user interface and system file transfer functions. The software is based on the basic FTP graphical interface transfer control and can fully implement related functions, intuitively and simply. Solved complex FTP positioning, operation and other instructions. In addition, the software also includes automatic detection and repair of network and equipment errors, automatic circuit switching and coordination, transmission rate and schedule calculation, and working log records.

In January 1999, the DDN line linking Liberation Daily headquarters with the Printing Service was formally put into use. This was the earliest use of DDN technology in newspaper transmission technology in China, and it is also the fastest rate of transmission in China. After two years of excellent use of signal quality and low failure rate, an average of 4 Mbytes can be transmitted per minute, effectively guaranteeing the publication and printing of "Liberation Daily", "News" and a series of color and black and white newspapers and periodicals. DDN line lease rate is moderate, and the construction cost is low. It should be said that it is the most excellent transmission technology between the newspaper headquarters and newspaper printing companies in the urban area.

2. The transfer method between the printing points and the main station

(1) Plan selection

At the end of 1999, Liberation Daily plans to publish a colorful "Liberation Daily" in Beijing and other places. At that time, the VAST two-way satellite system had been used for four years. Due to its low speed and relatively high rental fees, it has been unable to meet the requirements for large-capacity data transmission of color newspapers. Therefore, we investigated DDN technology, ISDN technology, and high-speed unidirectional broadcast satellite technology. Due to geographical limitations of DDN and ISDN technologies, we finally chose high-speed unidirectional broadcast satellite technology. At that time, we carefully considered whether to adopt the dialing of the phone as a two-way backhaul. Finally, we gave up the two-way backhaul checksum, set up a one-hop two-way backhaul check for the master station, and one-hop software check for the single-hop C-band high-speed one-way broadcast. Satellite system. On the issue of speed At that time, many newspapers chose a rate of 128K. Considering the development of the newspapers in the future, we chose a speed of 256K, which was the highest speed that newspapers used at that time.

(2) Technology Application

In hardware applications, we have adopted EF-DATA's satellite signal modems SDM-300, SDR-54 and power transmission receiving equipment. In order to ensure the continuation of the work of copying in the case of satellite failure, an additional 3COM remote dial-up service equipment was added to establish a terrestrial remote telephone dial-up backup system.

The use of software in the application of Dongze Fei Tianzhuan version of the software, simple and practical, while the establishment of the ground enterprise's own INTRANET, the production of "Liberation Daily" remote dial-up system Web pages, FTP services to achieve the download of each station's layout files.

In November 1999, the second generation of remote satellite copying system of Liberation Daily was put into use. This was the earlier domestic use of 256K speed remote newspaper transmission speed. In addition, the establishment of the company's own INTRANET "Liberation Daily" remote