Detector Activated CCTV

Guidance Notes & Summary of BS8418 & ACPO Policy 2004

The publication of BS8418 together with the updating of the ACPO Security Systems Policy to version 2004 proved a cornerstone in making CCTV a massively enhanced security tool for many UK businesses.
After a period of police evaluation, formal recognition of the technology of remotely monitored event-driven CCTV as an aid to combating crime has been made.   Now BS8418-compliant systems qualify for a URN, providing other qualifying criteria are also met.  So, such installations are registered with the police and, if a system signals a visually confirmed intrusion, the police will now officially respond to the alarm notification.

Where is this type of system best suited?
Detector activated and remotely monitored CCTV is suited to anywhere where there is security risk.  However, it is mostly intended for risks where either there is an external security risk, or where an early warning of the developing threat of a crime is important.
It is a monitored alarm system with pictures and, rather than a business wait until their building is entered before intruders are detected, response can be instigated sooner and perhaps before a crime ever occurs.
Police may be despatched to site straight away or an audio challenge may proactively scare the criminals away before an incident develops into a crime.

What is BS8418?
British Standard BS8418: 2003 is a code of practice, concerning Detector Activated remotely monitored CCTV systems.  It sets out specific guidelines for the correct design & installation of systems and in respect of the day-to-day operation and the setting/unsetting process.
The establishment of BS8418 has been seen as a significant cornerstone in remotely monitored CCTV, which prior to introduction had police response only on an informal basis.  It provides a ‘best practice’ framework, and particularly determines need for appropriate instruction to be in place at the monitoring centre so that they understand the risks and application needs pertaining to each protected site.

What particular design criteria have to be met?BS8418 focuses on the various key aspects:

  • Detector positioning & areas of coverage
  • Camera positions
  • Camera field(s) of view in relation to detectors
  • Audio challenge equipment
  • Entry route & system setting/unsetting
  • Avoidance of false and unnecessary activations
  • CCTV performance
  • System integrity, incl tamper provision
  • Event logging and recording of activity

Care must be taken to avoid the possibility of detectors overspilling the protected site boundary.  There is an extensive range of detectors available in the marketplace and it is a matter of selecting the most suitable type for each location and risk AND position it to cover space on or within the boundary.

In addition, the field of detection must match the field of view of the associated camera (or preset view in the case of a motorised ‘multi-position’ camera).  Clearly, it is vital that the entire detection area is capable of being viewed in a single image when an alarm activation occurs.  Otherwise, there would be a severe likelihood the monitoring centre Operator may fail to see an intruder who may have triggered the alarm.

Are motorised Pan/Tilt/Zoom (PTZ) cameras best for these systems?
There is a strong bias towards favouring fixed cameras since they ‘guarantee’ viewing their detection field.  However, PTZ cameras clearly can be used, though they should be regarded as multi-position fixed cameras for purpose of event viewing, each with text annunciation of detector or area of view.  They are not to be seen as a camera which may be manually operated to scan & search a protected site to ‘hunt out’ intruders.  Where PTZ cameras are used, it is important not to expect too much of them by having many alarm driven presets.  They can, after all, only look in one direction at a time and therefore risk missing a vital situation.

Is there any particular issue to consider over lighting?
BS8418 states that there should be sufficient lights on site to illuminate the camera’s field of view.  In instances where permanent illumination is not an option, systems can be configured to turn lights on automatically when there is an alarm or they can be relay driven such that the monitoring centre operates them when required.
Alternatively, there are a whole series of day/night fixed cameras now available that incorporate infrared illumination to their field of view.
Lighting conditions are a major issue for all CCTV applications but in the case of these system types, areas of shadow need particular consideration.

Is there a maximum range for a camera and detector?
Technically, the coverage range of the associated alarm detector will dictate the range of view for each camera.  However, the object size of the intruder on screen must be adequate for the monitoring centre Operator to have a capability to clearly see for purpose of the application or risk.
Therefore, BS8418 stipulates that a person 1.6m in height must occupy:
At least 10% of the height of the screen when the application is to verify an event; or
At least 50% of the height of the screen when the application is for recognition.

Must the system have an audio challenge?
Systems must incorporate this feature as standard in order that they satisfy ACPO Policy requirements for purpose of URN registration.
BS8418 stipulates that the audio challenge system should be ‘clearly audible, without undue distortion within the range of all detectors’.  Exceptions are allowed to overcome noise pollution issues, and their use must be discretionary where the system effectiveness may be reduced.

There will be many instances where the broadcast of a challenge will have a successful deterrent effect.  However, staying silent and informing the police of a visually confirmed crime in progress without the criminals being aware of their detection can be significant in helping to achieve an arrest

Where can systems be monitored?
If ACPO Policy is to be satisfied, the monitoring centre (called a Remote Video Response Centre or ‘RVRC’) must be a BS8418 Approved Centre.  Otherwise, no URN can be issued and therefore no formal police response given.
Such a centre therefore must additionally satisfy BS5979 as an accredited Alarm Receiving Centre and be police registered and recognised.