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TYPES OF ERRORS



Whenever an electromagnetic signal flows from a point to another, it is subject to unpredictable interference from heat, magnetism, and other forms of electricity. This interference can change the shape or timing of the signal. If the signal is carrying encoded binary data, such changes can alter the meaning of the data.

1. In a single-bit error, a 0 is changed to a 1 or a 1 to 0.

2. In a burst error, multiple bits are changed. For example, a 0.01second burst of impulse noise on a transmission with a data rate of 1200 bps might change all or some of 12 bits of information.




Single-Bit Error

The term single-bit error means that only one bit of a given data unit (such as a byte, character, data unit, or packet) is changed from 1 to 0 or from 0 to 1.

In figure below shows, 00000010 (ASCII STX) was sent, meaning start of text, but 00001010 (ASCII LF) was received, meaning line feed.



Burst Error

A burst error means that two or more bits in the data unit have changed.

In figure below shows, 0100010001000011 was sent, but 0101110101000011 was received. The length of the burst is measured from the first corrupted bit to the last corrupted bit.

Burst error is most likely to happen in a serial transmission. The duration of noise is normally longer than the duration of bit, which means that when noise affects data, it affects a set of bits. The number of bits affected depends on the data rate and duration of noise.