Data Transmission
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When discussing data transmission, people usually make reference to two particular types of transmission: analogue and digital.
Analogue data transmission (or analogue signal transmission) utilises physical carrier waves to transport data around. These waves transmit this data through modulations (or changes in the wave) of one of the three parameters: amplitude, frequency or phase. Examples of analogue data include sound waves. Analogue transmission of digital data consists of combining the analogue data wave to be transmitted and the carrier wave to form a combinatory wave consisting of both simultaneously. When the receiver receives this wave, the carrier wave is taken out again so that the original data can be accessed. The diagram below shows how the analogue wave and the carrier wave are combined.
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Digital transmission of analogue data requires a codec to convert the analogue signals into digital signals before it gets transmitted. Codec is a contraction for coder/decoder, and is mainly used to compress analogue data into a digital form so that it can be transmitted.
Digital transmission of digital data is not as simple as you may think, either. Different devices can have different encodings of binary, where the two-state signals are interpreted in a separate way (eg. NRZ Encoding, NRZI Encoding, Manchester Encoding, etc.). This is because data has to travel through different physical mediums which some codings work better than others.
In digital data transmission, there are two main methods of data transfer, serial and parallel transmission. Each has their own advantages/disadvantages.
It is important to note that these transmission methods are used because of peripherals, that is, any additional auxiliary hardware used in conjunction with the computer (eg. graphic cards, USBs, webcams, loudspeakers, etc.). When using such peripherals, there must be some physical way that the device and the computer can communicate with each other. This is usually in the form of a physical wire which transmits digital data to and fro from the computer so that they can communicate. Serial and parallel transmission methods are the two main ways these occur.
Serial and Parallel Transmission
Serial transmission is whereby the data is transmitted over only a single wire. Data here is sent sequentially, that is one after another. Here, the data is transmitted one bit at a time along the wire, thus where the name originates from. Also, the data is arranged in a particular way so that the data is sent as a unit and disassembled at the receiving end.
Digital transmission of digital data is not as simple as you may think, either. Different devices can have different encodings of binary, where the two-state signals are interpreted in a separate way (eg. NRZ Encoding, NRZI Encoding, Manchester Encoding, etc.). This is because data has to travel through different physical mediums which some codings work better than others.
In digital data transmission, there are two main methods of data transfer, serial and parallel transmission. Each has their own advantages/disadvantages.
It is important to note that these transmission methods are used because of peripherals, that is, any additional auxiliary hardware used in conjunction with the computer (eg. graphic cards, USBs, webcams, loudspeakers, etc.). When using such peripherals, there must be some physical way that the device and the computer can communicate with each other. This is usually in the form of a physical wire which transmits digital data to and fro from the computer so that they can communicate. Serial and parallel transmission methods are the two main ways these occur.
Serial and Parallel Transmission
Serial transmission is whereby the data is transmitted over only a single wire. Data here is sent sequentially, that is one after another. Here, the data is transmitted one bit at a time along the wire, thus where the name originates from. Also, the data is arranged in a particular way so that the data is sent as a unit and disassembled at the receiving end.
Parallel transmission is when the data is transmitted through several wires or channels simultaneously alongside each other within one cable. The bits of data are transferred alongside each other, timed to do so by a clock. Each wire has the capability to hold (send) one bit at a time; thus, if a parallel cable has enough wires, more data can be sent during the same time.
Considering the diagram shown, it is clear to notice that parallel transmission will get the byte of data transferred in one ‘click’, while serial communication will take say 8 ‘clicks’ before the entire byte gets through and is processed. Parallel transmission transmits data at a faster rate than serial transmission. This is why parallel transmission is used for CPUs, where a group of parallel ‘bus lines’ send data rapidly from CDs, ROMs or keyboards to the CPU. However, parallel transmission requires additional hardware (more wires) over which the data transfers and thus is more costly to implement than serial transmission. Subsequently, it is very inefficient to transfer information over distances larger than a few centimetres.
Serial transmission can seem quite useless in comparison to parallel transmission; they are generally slower than parallel transmission and rely on only one line to transfer information. Despite this, technology advancements have improved transmission so that gigabytes of data can be transferred per second via serial transmission. In other words, data transmission technologies have improved enough for serial transmission to transfer data as quick as some parallel transmissions. Along with this, it is more easy to implement into certain peripheral systems that require quick plugging in (eg. earphones, MP3 players).
Serial transmission can seem quite useless in comparison to parallel transmission; they are generally slower than parallel transmission and rely on only one line to transfer information. Despite this, technology advancements have improved transmission so that gigabytes of data can be transferred per second via serial transmission. In other words, data transmission technologies have improved enough for serial transmission to transfer data as quick as some parallel transmissions. Along with this, it is more easy to implement into certain peripheral systems that require quick plugging in (eg. earphones, MP3 players).