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Guide to Closed Circuit TV (CCTV)

So would you like to play "Spot the CCTV Camera?". Eagle eyed visitors may recognise the profusion of street furniture, surrounding a single heritage dome camera keeping watch over part  of Londons' prestigious Oxford Street shopping area.

So you want to know more about Digital,
the predicted future for CCTV ....?

A General Introduction to 'Digital' CCTV

Before we look at the three main levels of 'digital' CCTV, it might be worth Doktor Jon briefly explaining exactly what digital is (for the uninitiated).
Well first off, a conventional 'analogue' signal (which in the world of CCTV is described as a CVBS or "Composite" signal) can be displayed on a test bench oscilloscope ( a type of TV used by engineers as a measuring and display device) as a complex and continuous waveform.
Now if you imagine the word digital as a piece of "joined up" writing, this would be an "analogue" representation.

Now when computers were first being developed, it quickly became obvious that a piece of electronic machinery can handle simple code at very high speeds, in fact much more easily than complex signals; in practice it's a bit like having the worlds fastest Morse Code operator.

So in time, each individual letter, character and number was then assigned an individual 'universal' (Binary) code which could be quickly read by a computer. This code used eight "bits", a bit being a very simple state where it's either 'on' with a very low voltage present (perhaps 5 volts DC), or 'off' with no voltage present at all. The 'On' state is represented by the number '1', and 'off' by '0'. So for example, where the word 'digital' has seven letters, each letter is made up of its own unique code using 8 bits, which collectively are known as a 'byte'.

In practice, the "digital" binary code (7 bytes) for the word " D i g i t a l " would be:-

Whilst older computers used to have 8 on / off bit state processing, modern computers have through vastly increased microprocessor speeds jumped from 16, through 32, 64, to 128 bit processing. The idea is that as the 'chips' have rapidly increased in speed to a point where they can process millions of bits per second, by increasing the number of bits in the code, this makes for much greater accuracy in processing data.

So if this is the basis of 'digital' operation, how does it relate to the use of digital techniques in developing new CCTV equipment...?

What exactly is 'Digital' CCTV? >>

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