Essay
BTEC LEVEL 3 - Unit 10 - Communication Technologies
- Institution
- PEARSON (PEARSON)
Assignment 3 P4 P5 P6 M2 D2- Data transmission
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Data ElementsData elements are terms that we use to describe functions carried out in the computational
process such as over networks. As with protocols it is important to define these processes
so that some standardization of these functions can take place across various networks.
The cyclic redundancy check, or CRC, is a technique for detecting errors in digital data, but
not for making corrections when errors are detected. In the CRC method, a certain number
of check bits, often called a checksum, are appended to the message being transmitted. The
receiver can determine whether or not the check bits agree with the data. If an error
occurred, the receiver sends a “negative acknowledgement” (NAK) back to the sender,
requesting that the message be retransmitted.
A sequence is a collection of items or characters which appear in a particular order often
referred to as a string. They are used for identification and error correction.
A datagram is a single transmission that stands by itself. They are often known as unreliable
datagrams because there is no guarantee that they will reach their destination. It is up to a
higher protocol or application to verify that a datagram reaches its destination. Streaming
media (audio/video/voice) often use datagrams because it doesn't really matter if a few are
lost in transmission
Computer networks do not dedicate a single wire to each pair of communicating computers.
Instead, the computers share the hardware. To avoid delays, networks limit the amount of
data that a computer can transmit on each turn. This is called packet switching, and the unit
of data that can be transferred is called a packet.
A checksum is the outcome of running an algorithm, called a cryptographic hash function, on
a piece of data, usually a single file. Comparing the checksum that you generate from your
version of the file, with the one provided by the source of the file, helps ensure that your
copy of the file is genuine and error free.
Signal Theory
In a computer network in order to send data a digital signal needs to be sent to the receiving
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