What does coding mean in information transmission?

The three elements of an information transmission system are similar to vehicles and roads in a traffic system. There are loading and unloading processes in transportation, and there are also problems of "loading" and "unloading" in information transmission. "Installation" is to convert the information to be transmitted into a signal form suitable for channel transmission; "Offloading" refers to converting the signal sent by the channel into a form that can be received by the sink. In information systems, the former is called "encoding" and the latter is called "decoding".

When sending a message, the sender (source) first drafts what he wants to express into a telegram, and the operator converts the telegram into a code through a machine or keys. This is called "coding". The "code" here refers to the sequence of symbols arranged according to certain rules. After encoding, messages (information) evolve into signals. In the actual information transmission process, information often has to be encoded several times before it can be sent to the channel for transmission.

After the coded signal is transmitted to the receiving end through the channel, the receiving end first receives the electric signal, and then restores the coding to a message, which is called "decoding". Decoding is actually the inverse transformation of coding. After conversion, the receiver (the receiver) can understand what the sender wants to express. This is the process of transmitting information by telegraph. Not only telegrams, but also all information transmission processes, but the specific sources, channels and destinations, as well as the ways and means of encoding and decoding may be different.