Traditionally, the camera, using power from the power outlet in the cab ceiling, views the lift compartment and transmits the image via very flexible travelling coaxial or fiber optic cable in the lift shaft to a fixed junction box half way up the shaft. From this box, standard cable is used down to the lobby or monitoring room.
One company claims, however, to be able to cut the difficulties and cost of lift CCTV installation using the latest laser-based technology described as "ideal" for signal transmission. Vector Technology has introduced an optical transmission system based on lasers that is designed for passenger and freight lifts that currently run unmonitored.
Hours, not days
Lift-Master is said to be fitted or retro-fitted in hours rather than days. System maintenance is also reduced as cable wear in the lift shaft is eliminated. The technology is based on the visible wavelength laser diode, now used in many industries. A unique feature of this is that its light output can be modulated at very high frequencies using quite simple electronic circuits. Modulated signals are far easier to see than on a constant beam and this makes them far easier to distinguish even in difficult lighting conditions.
"This makes the technology ideal for signal transmission applications in areas such as security CCTV and sound monitoring," says Ken Owen, MD of Vector Technology.
Monitoring centres are provided with real time "broadcast quality" pictures and sound.
The system – said to be compatible with all cameras and monitors and requiring no operating licence – is suitable for low-rise and high-rise buildings up to 30 floors. It uses a modulator to transfer outputs from the lift-mounted camera and microphone on to a carrier signal. The signal is then fed into a laser transmitter mounted to the top or the underside of the lift car. The beam from the laser is directed at an optical receiver located at the top or bottom of the lift shaft and is said to be effective in excess of 100m.
The receiver converts the beam back into an electrical signal that is then transmitted by cable to a demodulator at the monitoring station, which can be located up to 500 metres from the receiver.
As well as the time and cost savings in installation, maintenance (with no cable wear involved) is said to be a simple case of wiping the glass of the receiver! In one installation in a public building, the Lift-Master also monitors the critical functions of the lift in a preventative maintenance programme.
Another installation called for a lift which gave access only to specific floors in a building with the use of a swipe card. Instead of complicated electronics in each lift, a single remote computer handles requests from several lifts and provides a log of all card requests.
Other possibilities now being considered for this technology includes the transmission of CCTV and audio signals over point links between buildings, particularly where other systems would require prohibitively expensive excavation of roads. Also being developed is signal capability with remote pan-and-tilt mechanisms.
Beat the lift vandals
Maintenance (with no cable wear involved) is said to be a simple case of wiping the glass of the receiver!
To combat increasing vandalism, Consilium Security Systems plc provides a vandal-resistant lift camera housing constructed in stainless steel and Lexan, secured with vandal-resistant screws.
The Consilium full-width Lift Housing is manufactured to any length in a standard width of 310mm and will fit any lift. The housing can also take a Corner Mount Lift Speaker Housing that gives two-way communication with the lift occupants or covert audio monitoring within the lift. It can be fitted and maintained from within the lift and is said to be easy to assemble and install.
No tampering in the lift
Suitable for lift security, GBC's vandal-resistant corner mount camera, the CM-300VR/A is said to be easily installed with 'tamper-proof' features.
The miniature camera is encased in a strong, powder-coated steel housing designed to fit neatly into the corner of a lift or room and is available in 250-plus colours.
It has a 4mm Lexan shatterproof window set at an angle to maximise viewing and the camera inside is mounted on an adjustable steel cradle for precise positioning. The camera is factory-fitted with a pre-focused lens and no bracket is required for installation. Concealed apertures allow wiring to be channelled directly into a wall or ceiling without the danger of disconnection.
… and at the sharp end
Writing in CCTV Surveillance, a classic textbook on the subject published by Butterworth Heinemann, Herman Kruegle gives this advice on lift camera siting:
In an overt system, a wide field of view lens/camera in an unobtrusive housing should be viewable on the monitor screen with facial characteristics able to be identified. A warning label could deter a would-be offender. The camera system should have a 90 deg horizontal, and 70 deg (approx) vertical field of view and a camera/lens optical axis directed 45 deg from each wall and 45 deg down from the ceiling.
The housing should be vandal-proof. It should preferably have a locked, hinged cover giving easy access for maintenance, a removable, unbreakable window port made of polycarbonate or tempered glass and an easily removable camera/lens assembly for servicing.
Other camera/lens/housing configurations mount directly into the ceiling corner of the elevator cab with the front of the housing projecting out as little as possible into the interior. Wide angle lenses – 4.8mm focal length for a 2/3 inch camera format, 3.5mm FL for a ½ inch camera - are used. Either combination achieves approx 90 deg horizonal/70 deg vertical field of view.
Immediate apprehension by a guard is more probable with a covert system. If covert security is required a small (1 ¼ x 1 ¼ x 2 1/8 inches) camera can be installed inside the lift cab wall or ceiling with only the lens showing. A remote head camera can also be used (the camera is mounted in the cab wall or ceiling with only the wide FOV lens in view in the cab).
Source
Security Installer
