IP Masterclass [Part 1] - Getting to grips with the IP revolution | Archive Titles

The basics of bits and bytes
Table of Units
Basic Units
Unit Abbreviated	Unit in Full	Explanation	Example
b	bit	bit stands for binary digit – a 0 or a 1. The basic volume unit of all computer operations	A single bit has no useful meaning in the context of CCTV – a computer can neither store nor send a single bit
B	Byte	a byte is made up of eight bits	One byte stores a single pixel of an image, or a single character in a text document
Storage Units – measured in Bytes
Unit Abbreviated	Unit in Full	Explanation	Example
KB (often spoken of as just “kay”)	Kilobyte	1000* bytes	a single image, or a small video image, takes tens or a few hundreds of KB
MB (often spoken of as “meg”)	Megabyte	1000* KB, and therefore 1 million* bytes	big images or an average video sequence may take a few MB to store
GB (often spoken of as “gig”)	Gigabyte	1000Megabytes, thousand million bytes	storage media such as disks are measured in GB. PCs have storage capacity in low GB (such as 40).
TB	Terabyte	1000* Megabytes, and therefore 1* million million bytes	dedicated storage devices can have capacities up to a few TB
Communications Units – measured in bits
Unit Abbreviated	Unit in Full	Explanation	Example
Kbps	Kilobits per second	1000* bits (or 125* bytes) per second	slower line speeds such as PSTN, allow speeds of around 56 Kbps. Broadband Internet allow speeds of Mbps
Mbps	Megabits per second	1000Kbps, which is 1 million bit per second	Local Area Networks and some Public Data Services work at speeds in Mbps – for example Ethernet LANs operate typically at 10 Mbps, although 100 and 1000 Mbps are available
Communications systems do not yet use giga- or tera- speeds, so the terms are not used
* Purists know that the multiples from Byte all the way up to TB are not truly 1000 but 1024 (strictly 1KB = 1024B). Engineers rarely need to take account of this 2 per cent difference