Necessity of Telegraph Code and Their Types

Necessity of Telegraph Code and Their Types Points : Necessity of Telegraph Code and Their Types, Telegraph Code Types Necessity of Telegraph Code In sending the information from the source to the destination, it is first converted into codes by the encoder. The received information at the destination is interpreted or decoded for understanding the meaning of the message. This process of encoding and decoding information is two fold: (i) efficient transmission and (ii) secrecy. Telegraphy is the method of transmitting messages by means of signalling codes. Hence telegraph alphabet is made from the set of possible code combinations in a unique pattern for representing each character. The most important features in any code are:

(i). Maximum efficiency in carrying a given amount of information with least number of code elements. So that, its speed should be high and

(ii). Freedom from errors due to signal distortion. Telegraph codes can be classified into, (i) unequal length code and (ii) equal length code. Types of Telegraph Code Types In the unequal length code all the characters are represented by marks and spaces, and the time of transmission is not the same (equal). There is no limit to the number of characters combinations possible from this code. The most common unequal length code is the Morse code.

In the equal length code each character consists of equal number of elements, each having the same duration, which is also the basic time unit of the system. Five-unit code is an equal length code and is most extensively used in machine telegraphy.