Copper- data is transmitted as electric currents at relatively fast speeds but the signal degrades over long distances (attenuation). This can be solved with a repeater.
Fibre optic- data is transmitted as pulses of light along a glass wire. It is very fast and degrades less than data carried on copper media.
Wireless:
Wi-Fi is the most common method of transmitting data wirelessly. It uses radio waves and transmits on radio frequencies 2.4Ghz and 5Ghz. These frequencies have a number of channels, some of which overlap e.g. 2.4Ghz has 14 channels
Wireless access point (WAP) is additional hardware needed for a wireless network. It converts signals carried along a wired media and converts this signal into radio waves which can be transmitted.
Protocols and Standards
Protocol- set of rules which govern the communication between devices
Physical protocol- rules which apply to the set-up of the communication, e.g. error checking
Logical protocol- to do with the data itself
Protocol layering- allows a developer or manufacturer to make changes to the protocol but they need only be concerned with the layer in question e.g. application layer for a software dev and then make the necessary changes to the interface between layers.
Packet Switching
-Data is split into smaller packets and sent across multiple pathways
-It is reassembled at the receiver end
-It is more secure as the data is split up, so a possible interceptor will only have a small part of the data, which probably won't mean anything on its own.
-Faster
Circuit Switching
-A dedicated pathway is reserved (even if data isn't currently being transmitted)
-All the data is sent in a constant stream
-If data is intercepted, the interceptor will have all of the data
Check digits
Check digits/checksum- used in error-detection algorithms to ensure that data has been transferred/entered correctly
TCP/IP Stack
TCP stands for transmission control protocol, and IP is internet protocol. The TCP/IP stack is split into 4 sections, and is a set of rules for how data is transmitted across a network, to keep the data secure and correct.
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