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Individual functions of the CCTV system may be specified at a different security grade: for example a system specified generally at grade 1 with a grade 4 storage including a fail-safe image storage.

Any additional functions which are required above the security level may be defined individually in the OR.

The Operational Requirements (OR) document shall be produced. This is a formal written statement of need, justifications and purpose of the proposed CCTV system. The installer should assess and determine whether production of the OR is to be completed before or after the site survey. See 5.2 Purpose of the Operational Requirements for more details.

Once a location has been chosen for a CCTV system installation a site survey should be undertaken. This is to familiarise the system designer with the specifics of the intended site, such as access constraints, siting of key components (cameras, controls, power supplies etc) and environmental factors (see Clause 6 Equipment Selection and Performance for more details).

This should be completed by visiting the location to assess its suitability, and to note any issues for the system design phase.

If the location where the CCTV system is to be installed has not yet been constructed then the site survey may be carried out after a preliminary design has been created.

Once the site survey and OR is completed the CCTV system can be designed and a System Design Proposal and Specification needs to be prepared. The design shall take into account the various requirement and location factors identified in the previous stages. At this stage a site plan should be drawn up, including locations for the various key components e.g. cameras (including field of view), detectors (including range and coverage), control rooms, power supplies, interconnections, etc.

(See Clause 6 'Equipment Selection and Performance' for more details.)

Having designed the CCTV system, a test plan shall be produced to allow any installed system to be suitably proven. This test plan should include all critical aspects of the CCTV system, such as image quality, system interconnectivity, coverage, camera view etc. The purpose is to ensure that the system can be measured against its OR, and proved to be fit for its intended purpose. See Clause 13 Define Testing Plan for more information and 6.11.2 for tamper protection testing.

The Risk assessment, OR and system design (including a site plan) should all be used to help facilitate the CCTV system installation.

Having completed the installation, commissioning tests as specified in the test plan should be completed according to the OR.

Once this has been successfully completed the system can be formally handed from the installer to the owner. See Clause 15 for more details.

Documentation should be completed supporting the design, installing and commissioning phases of the CCTV system. These should be collated and held by the owner as the system references. The risk assessment, OR, testing plan, site survey, system design and site plan (see Clauses 14 and 16) should be included, along with the following documents:

testing results, as built plans/drawings, data interface descriptions;

training, manuals, support documentation, etc.;

maintenance plan including routine inspection cleaning, etc (see Clause 17 for more details).

5. Operational requirements specifications

   1. General

The purpose of the CCTV installation shall be summarized in a document called ‘Operational Requirements’. Further information can be found in the bibliography.

The Operational Requirements states clearly what the customer expects the functions of the system to do. If there is an agreement between system designer and customer, the Operational Requirements could be defined within the System Design Proposal and Specification. If so, this should be clearly stated within the document. The development I design process encourages clear thinking about who will use the CCTV system, where and when it will be used and in particular the purpose of the CCTV system. It is produced by CCTV owners, operators and anyone who intends to use information from the CCTV system. The later stages of development of the OR shall involve those with the necessary skills to convert statements into a technical specification and test procedures.

At appropriate stages checks shall be made to ensure that the proposed implementation will meet the Operational Requirements. Without an Operational Requirement and a matching test procedure there is no practical methodology to assess whether the system can meet its required purpose.

The Operational Requirements shall consist of the following parts:

• Intended purpose(s) of the system (e.g. site monitoring, detection and/or monitoring and/or recording of attacks against individual and property, thefts, robberies or damage).

• Risk assessment, which informs the selection of the required security grade of the system according to EN 50132-1.

• Limitations imposed by legislation, city rules or similar orders.

• Limitations such as privacy areas required by the customer or by the proximity of neighbours.

• Buildings, internal, external or separate areas, etc. which are covered by the CCTV system.

• The intended targets of the system in each part of the site (e.g. unauthorized persons within an area bounded by a perimeter fence; vehicles entering the access driveway, etc.).

• The expected speed of the intended target.

• The intended observation category of the targets from the perspective of the operator (e.g. detection, recognition or identification of a person).

• Whether external detection is required.

• The key performance characteristics of the system and its displayed images (e.g. timescale for operator to view persons and track their movements throughout the scene).

• The degree of image detail required for the purpose which is to be observed in each of the live, recorded and exported views (i.e. it may be desirable or appropriate for a different resolution to be used in the live view than in the recorded view).

• Definition of any image analysis functionality, together with expected accuracy and whether this is to be achieved by the operator or automatically by the system.

• Definition of operating hours for the system (e.g. daily between 21.00 and 08.00 and all day on Sundays and public holidays).

• Definition of environmental conditions, which will apply and/or vary during the monitoring period and are significant in terms of system design, (e.g. illumination of the site, potential obstacles in camera view, maximum and minimum temperatures).

• Definition of the ability of the system to continue operating despite the existence of adverse circumstances (e.g. ability to continue operating during sudden or unexpected loss of power for a significant or defined length of time, absence of single interconnection paths, whether all or parts of the system have the same requirement).

• Definition of where, and by whom, the system shall be monitored and operated.

• Definition of what is to be recorded (e.g. all images for 10 min before and after an event; all camera

views at all times).

• Definition of retention period for recordings and circumstances in which this will change (e.g. all

recorded images to be kept for and erased after 28 days except where they relate to a criminal event).

• Definition of additional (remote) sites where the images shall be available.

• Definition of procedures to be followed when extracting, storing and handling images and data from the system.

• Definition of how images will be exported for short sequences (e.g. a 10 min clip to be exported to WORM media; individual image snapshots exported to USB/IP storage device).

Definition of how images will be exported for long sequences (e.g. network download for full system archive)

• .Definition of required compatibility of exported media (e.g. sequences should be re-playable without the need for any software/codec/hardware that is not considered part of a standard desktop operating system).

• Definition of actions that are required as a matter of normal routine (e.g. the monitoring service shall carry out routine video patrols at 2 h intervals throughout the monitoring period).

• Definition of the person responsible for the response (e.g. key holder, guarding service and/or police).

• Definition of the type of response needed for each potential event (e.g. when a trespasser is observed

the local law enforcement agency is contacted).

• Definition of target times for each response (e.g. Security personnel to attend scene within 3 min of event detection).

• Definition of the number of display screens an operator is expected to monitor.

• Definition of the number of alarm events the operator is expected to manage.

• Definition of the number of live cameras the operator is expected to manage.

• Definition of required training for each role involved in the management and operation of the system.

• Definition of any planned future extensions of the system, indicating any compatibility requirements.

• Definition of method used to connect with other systems.

NOTE If the operational requirement cannot be met with current technology or resources it will be noted in the system design document.

The system operational criteria involve determination of:

• the operational procedures;

• the alarm response;

• the system response times.

The CCTV system shall be designed to enable the operator to analyse the content of the displayed images and take all necessary actions as defined by the O R.

Automatic processing can assist operators allowing them to concentrate on essential tasks.

Automation of the following functions shall be considered:

• Video image switching;

• pre-position of image capture devices;

• equipment monitoring, health check and recording process;

• video content analysis;

• lighting control;

• image storage.

Some of the above functions can be controlled from:

• Alarm conditions,

• externally triggered events,

• time related events,

• operator manual activations.

The signalling indication of an alarm condition to the CCTV system shall have priority over other events.

It should be defined in the OR whether or not the operator shall be able to take manual control of the system, following an alarm condition, regardless of the degree of automation.

Automation of image selection shall consider the following requirements:

• specification for selection of the significant images/sequences in each area where an alarm condition occurs;

• allocation of displays to view the significant images/sequences from the selected image capture devices; on-screen displays with image source identification or animated diagrams of the system can be useful;

• presentation of alarm images on designated displays;

• handling of simultaneous alarm conditions;

• selection of image storage criteria.

The following response times shall be kept to an acceptable I specified minimum:

• time elapsing between the generation of an alarm condition and it being indicated on the CCTV system presentation device;

• switching time for the control centre to acknowledge receipt of an alarm;

• image capture device pre-positioning if functions like zoom and I or pan and tilt are specified;

• display equipment start up time or change from time lapse mode to normal mode if a time lapse

recording is specified;

• change from continuous to alarm recording mode;

• operator’s response time if required.

In order to minimise response times, image capture devices, displays, recording devices, etc. shall be continuously powered and idle, and the system shall not generate more information than the operator can effectively manage.

Operator’s actions and sequences of actions shall generate the expected response.

If the performance is low, due to a high alarm rate or high image flow, the graphic displays shall still appear “normal” and the system shall be able to allocate more resources to keep a proper response to operator’s actions.

Acceptable system response times should be defined in the OR based on the viewing task and operational response for example:

A system response shall always appear within 0 s to 0,2 s (e g. PTZ-Control for tracking targets).

A system response is considered delayed if the time is higher than 0,2 s.

A system response is considered unacceptable if the response time to the operator’s action is longer than 2 s.

Table 1 —System feedback - Responding time, performance and operator

6. Equipment selection and performance

   1. General

It is important to consider not only whether each component is capable of meeting the OR but also whether the components in conjunction with each other, and the system as a whole are able to meet the OR.

Consideration should be given to power consumption of devices particularly for those in continuous operation (see 6.8, 7.1, 12.8 and 12.9).

The lens and camera combination shall be selected such that the image resolution, field of view and low- level light performance are capable of fulfilling the relevant requirements in the OR.

The selection criteria should take into account the following:

• for camera sensitivity and aperture number of the lens, the prevailing and intended worst case light levels and types of light including IR, etc.;

• the color, black and white or thermal sensitivity of the image sensor;

• the focal length of the lens in relation to the size of the image sensor in the camera to give the

required fields of view;

• the resolution of the camera and lens to reproduce the detail to give the necessary information in the fields of view;

• the lens image area should be equal to or greater than the effective diagonal of the imaging device in the camera to avoid vignette.

The camera equipment should satisfy the operational requirement under all anticipated environmental conditions.

The selection criteria shall take into account the following:

• white balance of colour cameras;

• dynamic range and noise of image sensor;

• relevant data protection regulations (e.g. support for masking of private zones);

• long exposure times in relation to movement blur;

• spectral sensitivity in relation to the type of illumination;

• provisions for external synchronisation, line-lock, internal sync, etc.;

• provisions for remote calibration of the imaging properties;

• back-up power supply.

Pan tilt zoom (PTZ) cameras are imaging devices that are controlled either by an operator or by a CCTV system to change the field of view of the camera via mechanical or electronic means. The camera may have any individual function or combination of panning, tilting or zooming.

If a PTZ camera is being used it shall have a home location as defined in the OR. It is desirable to specify a number of preset locations, which provide views designated in the OR. These preset positions shall be annotated in the site plan. Preset positions may include other parameters such as shutter speed, iris setting etc.

PTZ cameras are predominantly mechanical devices, target preset fields of view may alter over time and it is recommended that regular maintenance of the cameras is undertaken.

If the PTZ is required to track moving objects the characteristics of the camera, e.g. rotation speed, shall be assessed to ensure that they can meet this requirement.

Care should be taken to not view areas outside the remit of the installation. If areas fall within the field of view of cameras (either static or PTZ) which are not intended to be surveyed, privacy masking shall be adopted.

Selection of the correct lens type is as important as the camera selection. A poor lens performance can significantly detract from the overall performance of the system.

When selecting the lens the following shall be taken into account:

• the aperture of the lens contributes to the image quality, by controlling the light available to the sensor so a lens with an appropriate aperture or aperture range should be selected and automatic or electronic iris is recommended;

• the lens field of view may be reduced by any overscan in the presentation device in which case a lens with a wider field of view than originally calculated may be required;

• internal lens reflections and flare can significantly impair the image so coated lens elements and/or appropriate housings or hoods should be considered;

• variable maximum aperture zoom lenses may increase the effective aperture number of the lens as the focal length is increased. A lens should be selected which allows sufficient light to fall on the sensor under all anticipated light conditions at all available focal lengths;

• filters to pass selective wavelengths should be specified (e.g. UV cut filter to reduce haze in bright sunlight conditions);

• consideration should be given to the environmental conditions in which the equipment is intended to operate with respect to the additional features which may be implemented into housings i.e. heaters, wipers, etc.;

• housing - All equipment installed shall be suitable to withstand the prevailing environmental conditions according to the environmental classes in EN 50132-1.

NOTE Having selected the camera-lens combination, it is recommended that, for difficult scenes, a camera of the type selected should be evaluated in conditions similar to those to be encountered at the installation.

The location(s) of interest shall be established and documented on the site plan. The level of detail(s) desired for the stated activity (e.g. identify) shall then be established for each location in order that the number of cameras for the whole site can be determined based on the annotated site plan. The actual number of cameras will depend on the types of cameras selected (e.g. Static, PTZ, megapixel etc), lenses required to achieve desired view and any geographical constraints.

The size of an object (target) on the display screen shall have a relation to the operator task, e.g. identification, recognition, observation, detection or monitoring. In digital CCTV systems it is important understand the relationship between the camera resolution and the screen display resolution. If the camera resolution is not equal to the display resolution, the displayed scene may not show the expected amount of detail. If the target is a person and the CCTV system has an installed equivalent PAL (576І) resolution, the recommended minimum sizes of this target are