Line coding is the process of converting binary data, a sequence of bits to a digital signal. For example data, text, numbers, graphical images, audio and video that are stored in computer memory are all sequences of bits. Line coding converts a sequence of bits to a digital signal. Some line coding schemes leave a residual direct-current (DC) component (zero-frequency). This component is undesirable for two reasons. First, if the signal is to pass through a system (such as a transformer) that does not allow the passage of a DC component, the signal is distorted and may create errors in the output. Second, this component is extra energy residing on the line and is useless.
To correctly interpret the signals received from the sender, the receiver's bit intervals must correspond exactly to the sender's bit intervals. If the receiver clock is faster or slower, the bit intervals are not matched and the receiver might interpret the signals differently than the sender intended. Self synchronization is one of the characteristics of line coding. A self synchronization digital signal includes timing information in the data being transmitted. This can be achieved if there are transitions in the signal that alert the receiver to the beginning, middle or end of the pulse. If the receiver's clock is out of synchronization, these alerting points can reset the clock.
To correctly interpret the signals received from the sender, the receiver's bit intervals must correspond exactly to the sender's bit intervals. If the receiver clock is faster or slower, the bit intervals are not matched and the receiver might interpret the signals differently than the sender intended. Self synchronization is one of the characteristics of line coding. A self synchronization digital signal includes timing information in the data being transmitted. This can be achieved if there are transitions in the signal that alert the receiver to the beginning, middle or end of the pulse. If the receiver's clock is out of synchronization, these alerting points can reset the clock.
