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JVC TK-C675 COMBINATION CAMERA
STANDFIRST
The market for compact dome cameras is expanding at an
unprecedented rate, JVC have reacted to the demand with the highly
sophisticated and flexible TK-C675 combination camera
COPY
Dome cameras are one of the fastest moving sectors of the
surveillance market. This reflects the fact that these versatile devices solve
a number of problems that fixed cameras and conventional PTZ systems fail to
address. The key feature in this sector is the compact enclosure, designed for
discreet ceiling mounting. In that respect the JVC TK-C675 is not significantly
different to half a dozen other devices on the market. It measures 154 x 185mm,
with the main unit easily detachable from its mounting plate, but there the
similarities mostly end.
The most obvious physical difference is the moving dome,
whereas most other designs the camera moves around inside a static dome, the
whole assembly on the TK-675 rotates. The camera inside tilts through a range
of 90 degrees, seeing through a transparent window on the opaque black coloured
dome.
All camera movements and functions are remotely controlled,
JVC have opted for as wide a compatibility as possible; our test sample was
supplied with a serial communications link, driven from Windows 95 based
software, but this is only one of a number of options. You can take it as read
that the unit supports all of the most frequently used video facilities and movement
programming routines. The motorised mount has a full 360 degree panning range,
the speed is selectable in five increments, (2, 4, 12, 80 and 240 degrees/sec),
making it one of the fastest movers in the business. Tilt speed can also be
varied, again in five stages (1, 2, 6, 60 and 120 degrees sec), so it's no
slouch in the horizontal plane either. A switchable 'auto-flip' facility spins
the camera around when it reaches the limit of the downward tilt, so that it
can follow a subject as it passes beneath the dome.
The camera we've been testing is a colour model, based
around a 1/3-inch interline transfer CCD with a 440k pixel array. Horizontal
resolution is claimed to be in the order of 470 lines and low light sensitivity
is just 3 lux. It has a motorised zoom lens (x16, 4.5 to 72mm), with an aperture
of F1.2. Maximum focussing and zoom speeds are 1 and 2 seconds respectively.
Shutter speed can be left under automatic control, or set to one of five
presets (1/60th to 1/10,000th sec.) The camera has a
built-in character generator. This is used to superimpose camera setting data
on the video output and it can also be used to assign a camera ident of up to
16 characters.
SET UP AND USE
A single multi-way plug and socket on the mounting plate and
the underside of the camera module carry all electrical connections to the
camera. Communications, video output and power feeds on the mount are handled
by a six way screw terminal, plus a coaxial termination for the composite video
output. Once the dome unit has been aligned with the plate it is turned a few
degrees and latches into place, a single screw locks the module into position.
This is not a particularly secure method and it would be relatively easy to
remove the unit. A drop-prevention wire secures the camera to the mount.
The dome is held in place by a simple collar and three
screws; inside it is immediately apparent that JVC have put a lot of thought
into the design. The camera, motors and virtually all of the ancillary
electronics are mounted on a tough-looking steel and cast alloy chassis. That
includes both pan and tilt motors, which means that just about everything
swivels around with the camera. This kind of one-piece modular construction
means there's far fewer moving cables and connections than normal, which must
be a good omen for reliability. It also makes it easier to get at the major
components, though none of the parts look as though they're designed for
on-site maintenance.
The actual camera is housed in a lightweight alloy casing;
it's fully self-contained with all of the focus, zoom and exposure adjustments
carried out internally. All of the camera electronics are inside the module as
well. Control and communications are handled by a second PCB mounted on the
right side of the camera, whilst the power supply and motor control devices are
on a circular printed circuit board in the base (top) of the dome.
All of the mechanical moving parts appear to have been built
to a very high standard. The motors are linked to the pan and tilt drives by
toothed belts, this makes it very quiet and undoubtedly has something to do
with the high pan and tilt speeds. It looks durable and great care seems to
have been taken with any cables and connections subject to movement. A tiny fan
inside the base extracts excess heat, it operates continuously emitting a
low-level whine.
PERFORMANCE
Resolution on our sample was within spitting distance of the
stated 470 lines. It produces a clean, sharp image with very low levels of
picture noise. Colour accuracy depends to a large extent on the prevailing
lighting conditions. With white balance set to automatic we found it coped well
with natural and mixed light. Tube lighting produced a slight colour caste,
though this could be minimised using the manual WB adjustments. Low light
sensitivity was as advertised, noise and grain only start to increase when
light levels fall towards the minimum illumination level.
The motorised mount is very fast indeed yet it remains
controllable using the slow acceleration setting. It is also very smooth, with
negligible overshoot. The amount of control is impressive too, at the lowest
speed it is possible to adjust the camera in increments of a degree.
SUMMARY
The TK-C675 looks and feels as though it has been designed
from the ceiling down, and not assembled from a collection or parts, or cobbled
together from other systems. JVC have chosen to defy several conventions, which
may or may not be a problem, depending on the type of installation. The most
obvious one is the rotating dome, which immediately draws attention to it,
making it obvious which way the lens is pointing. The other minor concern is
the nature of the fixing, and the ease with which the whole unit can be
removed. A simple, concealed locking mechanism would be preferable to a single
cross head screw, which if not tightened, will allow the dome to be detached
from its mount with a simple flick of the wrist.
We have no complaints with the performance, mechanical or
electronic. The camera is a well-specified unit, it's perfectly suited to this
kind of application and up to JVC's usual very high standard of performance and
construction. So too is the motorised mount, it's fast, agile and responsive,
with an excellent range of control and motion facilities, though ultimately
this will depend on the control system it is used with.
PRODUCT SPECIFICATION
Power supply 24 VAC 50Hz
Weight 2.0kg with mount
Dimensions 154 x 185mm
PSI RATINGS
Product
Product design 9
Build quality 9
Ruggedness 9
Operation
General functions 9
CCTV functions 9
Ease of use 8
Instructions 8
Manuf. support 8
Performance
Video quality 9
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R. Maybury 1998 2005
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