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DOME ECONOMICS
INTRO
Dome cameras are the unobtrusive and
palatable face of CCTV but the Surveyor system from Vicon is much more than
just another discretely enclosed pan-tilt head
COPY
Dome camera technology has undergone
something of a revolution -- no pun intended -- over the past five years. It
has been fuelled by a series of developments, including on-going reductions in
size and improvements in camera performance, mechanical systems and
microprocessor control electronics. Moreover, the argument for dome cameras, as
opposed to traditional open pan-tilt-zoom (PTZ) installations, has become more
compelling with the increased profile of CCTV. Disquiet over the number of
cameras now appearing in public places can be allayed to some extent allayed by
these relatively discrete devices. One strategically mounted dome can replace
several fixed cameras, in some circumstances providing better coverage.
All of these elements have come together in
the Surveyor range from Vicon Industries, dubbed the most advanced dome system
ever! Bold claims, but the specification and features do make impressive
reading. It is very compact, and fast, with the flagship model capable of
panning at 370 degrees per second.
It’s flexible too; housing are available for
in-ceiling or pendant mounting in indoor or outdoor locations. There are three
drive mechanism configurations, with fixed-speed rotation, fixed speed with
continuous rotation, or variable-speed with continuous rotation. There’s a
choice of high resolution colour or black and white cameras and finally three
types of dome, either smoked black, chrome or gold finishes.
However, what really sets this design apart
is so-called ‘distributed intelligence’ which refers to the integrated
programming and control systems built into the dome enclosure. This has a
number of advantages, including being able to remotely program key camera and
control functions, critical settings are retained by the dome unit and are not
erased when it is removed for servicing or cleaning, and it has it’s own
on-board alarm inputs and outputs, which speeds installation, and simplifies
cabling.
The camera can be used in a wide variety of
applications, from a single stand-alone unit, controlled from a hard-wired
joystick CCU, to being part of a sophisticated multi-camera system when
connected to matching keypad units, like the Vicom V1300X-DVX. This particular
device also gives access to a number of additional features, including 79
preset positions and 10 programmable guard tours; it can also switch and
sequence up to 255 cameras.
We have been looking at the top-end system,
comprising the V7UVS variable-speed drive and colour camera, with indoor ceiling
and pendant mounts, plus the V1300X ‘intelligent’ keypad controller.
The exterior housing is an extremely robust
moulding, made from a tough ABS plastic and internally screened with a metallic
coating. Fitting shouldn’t pose too many problems, the unit can be supplied
with a wide variety of mounting hardware, for solid and suspended ceilings, or
wall and ceiling brackets, formed from 1.5-inch steel pipe.
In the base of the housing there’s a set of
interface boards and a quick release mechanism, that latches onto the top of
the drive mechanism. This comprises a large gearwheel, made from what looks
like carbon-fibre, on which is mounted a rotary transformer and a 25-pin D-sub
connector plug that carries power, control signals and the video output from
the camera.
When the camera is inserted into the housing
the plug automatically mates with a socket on one of the interface boards. This
means the drive assembly and camera can be fitted, or removed, in a matter of
seconds. At least, that’s the theory, the unlocking handle is mounted on the
inside of the housing and can only be accessed through a narrow slot, when the
camera head is in the correct position. The slot is very small, and the handle
some way up, installers with short fat fingers take note... It also requires a
fair amount of force to unlock, and a bit of a knack that can only be learned
at the expense of grazed knuckles.
The drive mechanism is suspended beneath the
gear plate on a large bearing; a heavy-duty brass gear on a DC stepper motor
mounted on the all plastic chassis meshes with the larger gear plate on the top
mount, this provides the fast panning motion. The camera is mounted inside the
bell-like chassis, suspended on a pair
of impressively sturdy metal bearings; one side is fitted with a semicircular
gear, engaged by a second stepper motor, to provide the tilting action. Control
electronics for both motors are on either side of the chassis, the camera and
communications circuitry is on a double sided PCB immediately in front of the
camera bay.
The colour camera on our test system has a
1/4-inch CCD interline transfer CCD with 438k pixel display. Low light
sensitivity is 2.2 lux and the quoted resolution is in the order of 450 lines.
It is fitted with a f/1.6 lens that has an 12x (4-48mm) optical zoom. The
magnification can be increased to 96x using a digital electronic zoom facility,
though this has a drastic effect on resolution, with considerable loss of
detail, once the magnification goes much past 30x. Domes fitted with variable
speed drives have proportional pan speed, based on zoom settings. The fitted
lens gives a horizontal angle of view from 47 degrees at the wide-angle
setting, to 4 degrees in the telephoto mode. White balance, focus and iris control can all be controlled
automatically by the camera, the last two can also be adjusted manually, from
the keypad, along with the high speed shutter, which has a range of 1/50th to
1/30,000th second. A snap-fit cable on the underside of the camera platform
connects it to the main interface-control board by a short ribbon cable; this
allows the camera module to be easily replaced, should it become necessary.
Two DIP switches on the control board are
used to set up a range of operating parameters. One controls communications
speed, enables an auto-diagnostic mode and selects camera type, the other one
is used to set up the camera/receiver address, that identifies it to the
external keyboard. The only other controls are a small toggle switch, that puts
the dome into service mode by disabling a tamper alarm. This is activated by
removal of the outer dome. A pair of red and green LED indicate operating
status.
Connections to the dome are made via the
interface board in the top of the housing. On our sample this comprised three
10-way terminal blocks, and a single screw-fit coaxial termination, for the
video output. Two of the connector blocks carry the alarm input and relay
outputs, the third one is for control input and output signals, to the keypad,
and additional communications lines to other domes. A typical installation will
require two screened twisted pairs to carry the telemetry data to and from the
keyboard.
OPERATION
Before we look at what the system can do, a
few words about the instruction and operating manuals. Given the nature of the
system, and the fact that there are so many possible permutations, it’s understandable
that they should be sectionalised. Setting up our very basic test rig involved
consulting no less than four densely-packed booklets, not to mention at least three
bound-in and three loose-leaf addendum’s. However, they all appear to have been
written without reference to one another, which makes life unnecessarily
difficult when it comes to connecting system components together. A simple overview,
detailing various interconnections and a few more diagrams would have come in
very useful, and shortened installation time considerably.
Keypad controllers like the V1300X is part of
the distributed intelligence and unlocks the full potential of the dome camera.
The sloping console includes five banks of buttons, a set of numerical and
alphanumeric displays, and a joystick. Most of the routine functions, like
camera selection, zoom, focus and iris control, and pan/tilt, using the
joystick are self-explanatory. The remaining features are controlled by
on-screen menu displays. They include setting pan and tilt speeds and zoom-scaleable
pan and tilt speed. The programmable camera functions cover adjustments for
auto-iris level, autofocus enable/disable, manual shutter speed setting, AGC,
vertical phase of line-locked cameras, setting titles for the camera, preset
positions and sectors. Other menu-controlled functions include customising the
8 alarm inputs, their reporting and response functions and titles.
Preset positions, stored in the dome cameras
memory, are programmed via the key pad. Up to 79 positions can be set, along
with zoom position, focus, (if the AF is disabled), and title. Up to ten tours
can also be stored in the Surveyor’s memory. A tour can consist of up to 32
‘events’ or actions; tours can also be set to repeat, or chained together in
even longer sequences. Additionally tours can be used to acknowledge or respond
to alarm events.
PERFORMANCE
The logical place to start is with the
housing and drive unit. It is superbly well made and the attention to detail is
impressive. Features like the positive latching mechanism, self-aligning
connector, neatly ordered PCB and wiring are immediately obvious, but smaller
design points are equally important, such as the way they’ve used larger,
heavier grade fixings and components, where lighter duty parts would have done.
Two or three screws, where only one was necessary and thick, high grade mouldings,
where thinner, cheaper plastics or alloys would have sufficed.
Arguably it’s over-engineered, Vicon could
probably have got away with smaller, less powerful motors, and cheaper plastic
gears, but it looks and feels as though it’s going to last. There are other
benefits; precision mechanics enable higher speeds, it positively fly’s around,
yet it is remarkably quiet in action. A gentle whirring noise can just about be
heard close to, but more than metre or so away, with normal levels of
background noise, it’s virtually silent.
There was one brief glitch, when the pan
motor locked up. This turned out to be caused by a magnet, and two small pieces
of metal, that had become lodged in the main gear teeth. They appear to have
become dislodged from one of a pair of magnetic catches, used to hold the dome
in place. The one on the other side would have come adrift too, but for the
fact that it had become attached to the metal casing on the tilt motor.
The camera module is well matched to the
drive in terms of performance. The zoom lens is a familiar modular design and
highly versatile. Automatic functions, such as exposure, focus and white
balance, are fast and reasonably accurate, able to deal with quickly changing conditions, though inevitably
they tend to lag a little way behind the drive. Resolution on our sample was a
little below the manufacturer’s spec, at just under 430 lines, though this is
still a good result. Noise levels are low on well-lit scenes, grain increases
quickly, as light levels, though low-light sensitivity is relatively good and
it’s possible to get a useable image in quite poor conditions. Colour accuracy
is variable, it’s fine in natural and most types of mixed light; tube lighting
on its own produces a slight but noticeable yellow-green caste.
Ergonomics and control logic could do with a
little tidying up on the keyboard. The displays are not that easy to read when
it is on a flat top desk, it does have an extendible tilt stand on the base,
but that’s not a very elegant solution. Frequently-used buttons could have been
better laid out, and it’s easy to invoke error messages if you don’t remember unnecessarily
strict control sequences. Furthermore, our sample emitted a strange intermittent
hissing noise. Initially we suspected it was arcing, coming from a relay or
switch but this wasn’t the case, and despite a thorough internal
investigations, it remains a complete mystery.
CONCLUSION
Speed, accuracy and smoothness of the
mechanics and the general build quality are all very good indeed. They’re
matched by the performance, facilities and flexibility of the camera and
keypad. The most advanced dome system ever? Possibly, at least until something even faster and smarter comes
along!
PRODUCT SPECIFICATION
Power supply 24VAC (mains adaptors for dome and
keyboard supplied
Dimensions 310mm deep x 305mm dia (including dome but not mount)
PSI RATINGS
Product 9
Product design 9
Build quality 9
Ruggedness 9
Operation
General functions 8
CCTV functions 8
Ease of use 7
Instructions 6
Performance
Video quality 9
Speed 9
Response 9
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Ó R. Maybury 1997 1205
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