In communication theory, coding is to transform the original information symbols according to certain mathematical rules. The purpose of coding is to transmit information to the destination as quickly as possible under the condition of ensuring a certain quality. There are two problems to be solved in communication: one is how to transmit information with as few symbols as possible without distortion or allowing a certain degree of distortion, which is the source coding problem; Secondly, in the case of channel interference, how to increase the anti-jamming ability of signals and maximize the information transmission rate is a channel coding problem. The source coding theorem (Shennong's first theorem) gives the possibility to solve the former problem, and at the same time gives a coding method; The coding theorem of noisy channel (Shennong's second theorem) points out that there is such a coding, which can make the error probability of transmission close to the capacity of the channel, thus giving the possibility of solving the latter problem. Therefore, the use of coding in communication can minimize the influence of distortion and channel interference, and at the same time, information can be transmitted at an information transmission rate close to the channel capacity.

The purpose of information coding

The purpose of information coding is to establish the connection between the data in the computer and the information actually processed, and improve the efficiency of information processing.

Basic principles of information coding

The basic principle of information coding is the most basic requirement for information coding and an important means to ensure scientific and effective information coding. Generally speaking, information coding should follow eight basic principles, namely, uniqueness principle, correctness principle, classification principle, expansibility principle, unity principle, invariance principle, reusability principle and simplicity principle.

The first basic principle of information coding is the principle of uniqueness. One kind of information can only have one information code, and different information has different information codes, and different information codes represent different information. This is the most essential attribute of information coding and the principle that information coding must follow. For example, in order to effectively manage company order information, each order can only have one order code. If different orders have the same order code, the management of order information will be confused.

The principle of correctness means that information coding should be scientific and reasonable, which not only follows the basic principles of information coding, but also conforms to the actual situation of the organization; It can not only meet the needs of the organization itself, but also meet the special requirements of the organization partners; It should not only conform to national standards or regulations, but also conform to international standards or practices as far as possible; The information coding cannot be too long or too short. In many cases, information coding should take a compromise approach.

Classification is the basic way to identify and describe information, and information coding should follow the principle of classification. This principle requires that information be divided into different categories according to reasonable rules, so that the codes of similar information have the same or similar properties in a certain respect, which is convenient for the management and use of management information systems. For example, in order to classify and manage materials, the following coding methods are adopted: raw materials 10, ferrous materials10/,non-ferrous materials 102, metallic aluminum 1023, aluminum rod 10232.

With the development and change of the organization, the management information in the organization will also change. Information coding should not only consider the current information status of the organization, but also consider the future development status and needs of the organization. Information coding should have enough coding resources to meet the growing demand of organizations for information coding. This is the expansibility principle of information coding.

The principle of unity means that all departments in an organization should use a unique code, regardless of whether the information in the organization adopts a unified coding system. The same information can only have one information code. Only in this way can we accurately identify information and fully realize information enjoyment.