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VICON SURVEYOR DOME CAMERA
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WHAT OR EXPERTS SAY...
Dome cameras are becoming an increasingly
attractive alternative to conventional pant-tilt-zoom (PTZ) systems. They’re
relatively discrete -- an important consideration these days with the
proliferation of CCTV becoming a subject of public concern -- yet they afford as much, in some circumstances more,
effective coverage than a PTZ installation.
The technology has progressed at a rapid pace,
thanks largely to advances in servo motor design, microprocessor control,
telemetry, camera optical and digital video processing systems. Vicon
Industries have combined all of these developments, and a few more besides,
into the Surveyor dome camera. It’s arguably the most sophisticated system
currently available; in addition to being unusually compact -- the dome is only
7.5 inches in diameter -- the mechanism is very fast indeed. The model we’ve
been evaluating can pan through 360 degrees in less than second and tilt at 120
degrees a second.
Specifiers and installers can choose from a
variety of configurations, including indoor and outdoor housings, with pendant
or in-ceiling mounting options, fitted with gold, chrome or black domes. The
drive units are available with variable or fixed-speed rotation and colour or
black and white camera modules. On the version we’ve been looking at pan/tilt
speed can be configured to be proportional to zoom position.
One of the key design features however, is
what Vicon call ‘distributed intelligence’. In a nutshell this means that
instead of the Surveyor simply being a ‘dumb’ enclosed PTZ mechanism and
camera, connected to a ‘smart’ controller, the housing also contains
microprocessor-based programming,
control and telemetry systems, plus eight local alarm inputs and replay
outputs. This means the control unit or keypad can be a simpler design, though
it does place some restrictions on using the dome with other, similarly
featured systems. The on-board electronics are also used to store camera
settings, generate on-screen set-up menus and idents. The net result is a
highly flexible system, that’s easier to install and service.
The specifications for the colour camera in our
test system are impressive. The module is housed inside a light alloy shroud,
coloured black, in common with all other surfaces that would be visible through
the dome. The camera is based around an 0.25 inch interline CCD with a 500 x
582 pixel display. This is coupled to a f/1.6 zoom lens (4-48mm) giving 12x
magnification and a horizontal field of view extending from 4 to 47 degrees.
This set-up has a quoted low-light sensitivity of 2.2 lux and a resolution of
460 horizontal lines. Digital processing circuitry can extend the optical zoom
to a maximum of 96x, though resolution at higher magnification levels drops off
drastically.
Most camera functions can be adjusted
remotely or left to operate automatically, these include focus, iris white
balance and high-speed shutter. In addition to PTZ controls a suitable external
keypad also gives access to AGC, vertical phase, idents and titles via a series
of on-screen menus. Dedicated control panels such as the Vicom V1300X-DVX
‘intelligent’ keypad enable access to additional programming features, such as
10 programmable guard tours, built up from 79 preset positions, moreover it can
sequence and switch a further 255 cameras.
The camera is mounted on a pair of strong
bearings, inside the hub of a sturdy,
vaguely bell-shaped chassis. Tilt motion is controlled by a hefty-looking DC
stepper motor, acting on a semi circular gear plate. The chassis is mounted on
a central rotary bearing, attached to a large gear wheel. A gear-shaft on a
second stepper motor meshes with the larger gear for the panning action.
Control PCBs for both motors are located either side of the chassis. A third
double-sided PCB, is responsible for movement programming, camera control and communications
is mounted ahead of the camera bay. All settings are stored in a non-volatile
memory, that is retained even if the camera drive unit is removed from the
housing for cleaning, servicing or adjustment.
The whole assembly locks into the housing
using three extension feet that are held in place by a rotating metal latch.
All power and control feeds to and from the drive unit are carried by a
self-aligning 25-pin D-Sub plug and socket system, that mate together when the
assembly is inserted into the housing. The unit can be released by a small
handle inside the case, after two arrows on the drive assembly and housing have
been lined up.
Inside the top of the housing, behind a removable
metal plate, are all of the interconnections for the power supply, control and
alarm inputs and outputs. They’re mounted on two PCBs and take the form of
three 10-way screw terminal blocks, and a coaxial terminal, for the video
output. The unit is compatible with both Vicoax and Nova control systems and
protocols. A pair of Miniature DIP switches on the main drive unit circuit
board pre-select auto-diagnosis mode, communications speed and camera type and
address. One other small switch selects service mode, to override a small
tamper switch that senses when the dome has been removed.
The cylindrically shaped housing is made from
a tough heavy-grade plastic, that’s coated internally with a metallic RF screen.
It is supplied with one of a range of mounting systems for walls and ceilings
(solid or suspended).
PERFORMANCE
Build quality is outstanding, in fact it’s
fair to say that some components are a lot stronger than they need to be,
though that’s obviously going to benefit reliability and longevity. There are a
couple of relatively minor niggles: the drive unit release handle is quite hard
to get at, almost impossible for anyone with fat or shorter than average
fingers. The instruction manuals are
not especially installer-friendly; there’s rather a lot of them, (3 manuals and
several addenda), moreover presentation and accessibility could be
improved.
The drive unit is incredibly agile, smooth
and very quiet in action, thanks to the precision gears and high-grade stepper
motors. The camera works well too.
Resolution on our sample, in good daylight conditions, was in excess of
430 lines, with commendably low levels of picture noise. Colours were natural
and accurately registered. In moderate to poor light there was a steep increase
in noise and grain but the image continued to be useable down to dusk-level
conditions. Colour accuracy deteriorated slightly under tube light, which
resulted in a light green-yellow tint.
OVERALL ASSESSMENT
Mechanical design, camera performance, control
facilities and flexibility are all excellent. Limitations, such as they are,
are mainly confined to the unit’s reliance on compatible control systems to get
the most out of it, so it’s probably unwise to regard it as a stand-alone
component. The Surveyor is a most impressive piece of equipment, especially
when you see it in action. It’s almost a shame to hide it beneath the dome, watching
it fly around is almost guaranteed to scare the pants off any villain...
PRODUCT ASSESSMENT
Design and design features *****
Circuitry and components *****
Ease of installation and wiring ****
Range and variety of functions ****
Accompanying instructions *****
Technical advice and backup ****
Value for money ****
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Ó R. Maybury 1997 2005
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