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Introduction to Microprocessors and MicrocontrollersTry instead, walking in and saying ‘Lunch will consist of burgers’. Everyone would understand your message. The first attempt was very efficient in terms of the number of words used but is probably likely to be inefficient communication since many people will not receive the message. In the second attempt, we have used five words to make sure that the one important one gets through. This is called adding ‘redundancy’. The more redundancy we add, the more certain is the message but the slower and less efficient becomes the communication system. Data being returned from space probes use very high levels of redundancy, over 96%, which allows for correction of really scrambled signals due to the extremely low power levels involved. We can use parity for alerting us to the possibility of an error in a stream of data or, in some cases, we can detect and correct the error. In its simplest form, we take a group of bits in a transmission, 4 or 8 bits are normally used though the idea is applicable to other values ...» |
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