RAKAN KONGSI INFORMASI

A Closed Circuit Television (or CCTV) system is used for

visual (and frequently audio) monitoring and recording

events in a defined area

Generally categorised for the following requirements:

Deter criminal activity Assist in the detection of crime To instil confidence in staff/visitors/customers that

they are in a safe and secure area Provide management intelligence for health &

safety or commercial use

1. What is a CCTV System?

2. CCTV Principles Basic Components of a CCTV System

(Analogue) Old style system with analogue video recording

from a multiplexer. Usually a maximum of 16 cameras per system

Basic Components of a CCTV System (Analogue) Old style system with analogue video recording

through a quad. A maximum of 4 cameras per system.

2. CCTV Principles

Basic Components of a System (Digital)New style system using a DVR to digitally record and playback, usually up to 16 cameras. No multiplexer or quad is required as the DVR performs these functions, amongst others.

CCTV Principles

The Camera CDD Image Sensor (Charged-Coupled Device)

• A group of optical detector integrated circuits • Light is ‘sensed’ by individual photo-diodes (rows & columns of which = ‘pixels‘) • Pixels develop a charge proportional 1/3 inch CCD

to the light level, which are then processed by the camera’s electronics

2. CCTV Principles

There are 3 main types of CCTV camera lens: - Fixed Focal Length (The focal length of the lens cannot be altered) - Varifocal Length (manual zoom length) - Motorised Zoom (Focal length can be automatically adjusted using, for example, a keyboard controller or DVR) >

The greater the focal length, the smaller the angle of view; therefore the image viewed will be larger

Angle of View

Iris Control Methods Auto Iris Features integral circuitry which will vary

the size of lens aperture according to changes in light

Direct Drive Lens control circuitry is within the camera,

rather than the lens (Direct Drive specific lenses and cameras required)

Fixed/Manual Iris No electronic control over the iris

Monitor

Camera housings are designed to protect the camera from weather, dust, vandalism, damage, etc…

Types of Housings :‘IP rated’ Weather Proof Vandal Resistant With or without brackets With or without internal heaters Wash & Wipe

‘IP ratings’ are a measure of resistance to the penetration of solid objects (e.g. dust) and liquids (e.g. rain!)

A product considered to be ‘weatherproof’ would have a rating of IP65 and above

-‘IP’ stands for Ingress Protection - The first number (in this case 6) is the protection against solids (0~6, 6 being dustproof) - The second number (in this case 5) is the protection against liquid (0~8, 8 being protected gainst constant submersion )

Cameras and housings with heaters will require power, mains or low voltage depending upon the product you have chosen.

Where low voltage PSUs are required there are various choices.

24v AV 500MA up to 4A 12v DC 750MA up to 4A

Early CCTV systems used analogue time-lapse VCRs CCTV systems now use DVRs (Digital Video

Recorders) with a huge range of benefits over old analogue technology

Many existing installations, therefore, are upgrading their recording system from analogue VCR to DVR

The benefits of DVRs: Digital image quality No need for tapes (changing / storage of) Fast, easy image search & retrieval •

Remote viewing & control capabilities Never stops recording • Up to 400 images

per second (IPS) record rate Up to 1.5TB storage Easily providing in excess of 31 days storage Less mechanical components to service >

Main factors for consideration in choosing the

correct DVR: Number of cameras Record rate (images per second) HDD size (amount of data storage) Remote viewing / control Fixed / Mobile Data transfer/storage media formats

Choosing recording frame rate:

Each DVR has a maximum IPS rate (100, 200, 400)

The IPS rate is normally divided by the number of channels ie. 400 IPS, 16 channel recorder would record @ 25 IPS per camera

High quality DVRs allow control of IPS rate per camera channel

How long does the customer require to retain the images/video on the DVR?Record duration is the ‘data lifetime’ of the recorded images / video on the DVR Data lifetime will be determined by customer’s

specific requirements and rules of the Data Protection Act

Longer data lifetimes require larger HDD space

Estimating record duration, the following all

Need to be considered:

Number of camera channelsHard Drive size IPS rate Compression type

Multiplex (Simultaneous functionality) :Simplex: The ability to record or playback but not at the

same time. For live view it is only possible to see a single camera on the monitor, multiple camera view is possible during playback.

Duplex: The ability to record and playback simultaneously. Multiple live screen is possible. However, the monitor will only display live images or recorded images.

Triplex: The ability to record and playback simultaneously. Multiple live screen is possible and unlike Duplex operation the monitor will display both live images and recorded images simultaneously.

Angle of view Internal or external Static or PTZ Colour or Monochrome High or Low resolution Available / Changing light

levels Site orientation Power availability Data Protection Act

Alarm Inputs send telemetry signals via the DVR to automatically control / preset camera position, record rate, image resolution, etc…

Alarm Inputs triggered via:

• External detection devices • Panic Button • Access Control Equipment

Lamps are usually Tungsten Heat generated by the bulb’s wasted

energy Aluminium-plated reflector Short life High power consumption / High cost of

ownership Range = various angles – Wide /

Medium / Narrow

Use solid state technology Long life Better performance & efficiency Gold-plated reflector Low power consumption Need IR sensitive cameras Range = 10° ~ 60° / 20m ~ 175m >

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