There are various types of detection devices and features that may be incorporated. The type and number of detectors will
be specified by our company surveyor.
Detectors and Beams
External movement detectors or beams can be used on a site so that if movement is detected a PTZ camera can be panned round
to the scene and an alert sent off. Particularly useful on unmanned sites and in conjunction with a monitored system.
Video Motion Detection
Works a bit like detectors and beams but no hardware is involved. Instead the software in the NVR is set to notice a change
in the scene or when a virtual line in the image is crossed. The software can also be set to notice objects that have
been left, for example a bag that has been left in an airport which could be suspicious. In some cases, this works
well but unlike a movement detector which will pick up a solid object moving, the software is looking at a change of
scene so can without proper adjustment be prone to false alarms. For example, the sun going behind a cloud will cause
a shadow on the ground to disappear causing an activation. Movement and beam detectors are of course unaffected by
these changes.
ANPR
Automatic Number Plate Recognition again uses software built within the NVR to recognise number plates and can even keep
a database of valid number plates. These systems can further be interfaced with access control systems to say automatically
open gates or barriers if the vehicle is on the database such as an employee’s car or raise an alarm if the vehicle
is not on the database.
Monitors
Whilst NVRs now can connect to the internet and be viewable across devices remotely, it is often required that on site
monitors are used. These can vary from a simple flat screen computer type 17” monitor to a complete array of large
wall mounted screens viewing different areas both locally and remotely. Monitors are now High Definition (HD) or even
4K.
Public Address and audio Challenge
Where a monitored CCTV system is installed, both detection and audio challenge are required so that when the monitoring
stations operator detect a potential crime in place they can speak to the culprit warning them to leave site before
the police are called. The system requires several speakers or PA horns and an on‐site amplifier which is connected
to the NVR.
Infra-Red (IR) Lighting
Most Cameras these days have their own in built infra‐red however these are limited to perhaps 10 or 12 metres. It
is possible to flood light a complete area with infra‐red lighting. The advantage is that to the naked eye the
area can be pitch black, making it harder for intruders to see valuables but to the camera or cameras the scene is
brightly lit thanks to IR lighting
Towers and Columns
Cameras can be fitted to buildings and structures but in some cases such as large yards there are no buildings within the
vicinity of the area that needs covering. Or perhaps the camera needs to be positioned higher than the building. Towers
and columns come in various heights and features.
