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BISCHKE TRI-Q Colour Camera
INTRO
Multi-role surveillance cameras are by their
nature something of a compromise but the Bischke TRI-Q suggests it is possible
to strike a balance between price and facilities, without necessarily sacrificing
performance
COPY
Town centre surveillance is one of the most
demanding roles for a video camera, placing considerable strains on the
technology, not to mention local authority and customer finances. Bischke have
sought to address these problems with a range of cameras and systems, tailored
to this application.
Traditionally it’s been a job for monochrome
cameras, which can cope with the exceptionally wide range of lighting
conditions, from bright sunlight to near or total darkness. The cost and low-light
sensitivity of colour cameras has, until recently limited their use in this
market, even though colour imaging has a clear advantage in the critical
identification of targets, especially in crowded locations. Bischke claim their
cameras meet the performance criteria, particularly with regard to low-light
and infra-red capability, moreover their products are competitively priced, giving
customers the flexibility they require to specify the components that best suit
their needs, remain in budget and avoid compromising a system’s effectiveness .
The relevant Bischke range includes three high-performance
colour/mono and monochrome cameras, available as stand-alone devices, or
configured as part of a system. They are the TRI-Q 2012-P IR-sensitive colour
camera with automatic mono switching, CCD-2012-P, which is a colour camera, without
the extended IR sensitivity but retaining the colour/mono switching facility,
and the CCD 4012-P high-performance monochrome IR-sensitive camera.
We’ve been looking at the TRI-Q 2012-P,
configured as a system camera, fitted with a Syka 8x motorised zoom lens
(numerous other options are available), built inside in a weatherproof housing and
fitted with Bischke ASK modular telemetry. Key camera features include a 0.5-inch
interline CCD with 580k pixels, giving a quoted resolution of 570-line TV lines.
It has bottom-loaded backlight compensation, which overcomes the effects of a
bright skyline on the upper portion of the image. A variable-speed electronic
shutter -- from 1/50th to 1/100,000th second -- helps preserve detail in
fast-moving targets (car number plates etc.). Low noise levels yield improved resolution
in poor light levels, allied with automatic switching from colour to black and
white, when illumination levels fall below 3 lux.
However, IR performance is likely to be one
of this camera’s main selling points. The extended spectral response is stated
to be from 380 to 1,000nm, (visible light lies between 400 and 700nm) making it
suitable for use with a broad range of IR illumination systems, including those
marketed by Derwent Lighting, which Bischke recommended for use with their
cameras.
The camera electronics are housed within a
compact cream-coloured alloy case measuring 130 x 66 x 66mm. Inside there are
four glass-fibre PCBs. The PCB at the front supports the CCD image sensor plus allied
microchips; two boards in the top half of the case contain the video processing
and control circuitry, on the back panel there’s a set of control presets,
sockets and connectors. The camera has both composite and Y/C outputs and operates
on a 12 volt DC supply. There’s a fair amount of space in the lower half of the
camera case, presumably for a power supply module on mains driven variants.
User accessible adjustments on the back panel include red and blue gain control
presets, V-phase, automatic, manual or pre-set (3200 degrees k) white balance,
plus manual or automatic shutter and manual iris.
At the front there’s a standard C/CS lens
mount. On system cameras, lens back-focus is factory set. This is an important
consideration on IR cameras; not only does it help speed up installation but
the adjustment is different to the setting required for visible light, due to
the characteristics of the optics under these conditions. The standard of
construction of the camera is generally very good and the high proportion of
surface mount components on the PCBs bodes well for long-term reliability.
The system camera housing supplied with our
test sample measured 345 x 95 x 95mm. Inside the beige-coloured weatherproof
housing, fabricated from extruded aluminium, the camera is mounted on a ABS
tray, bolted to the bottom half of the case. Behind the camera there’s a small
PCB containing all of the connections for the video signal, power supply and
lens control telemetry. These are brought together on a 26-way socket, that connects
to a pre-fabricated system camera cable. The rear section of the housing on our
sample was somewhat cramped; connectors on the back of the camera are
uncomfortably close to components on the interface board, moreover the leads
for the auto iris and motorised zoom lens could have done with being cut to
length as they have to be bunched tightly together in order to fit into the
space available. The bolts holding the tray on to the underside of the case are
rather inaccessible and this could make field disassembly, testing and/or
repair quite tricky. Inside the front of the housing -- immediately below the
lens -- there’s a thermostatically-controlled 10 watt heater; a sunshield is
available as an optional extra.
PERFORMANCE
In order to fully assess the camera we’ve divided
the performance checks into three sections: normal daylight; low-light
conditions simulating dusk, and near-dark conditions using a small (50 watt) infra-red
lighting rig.
In good natural light the camera produces a
clean, sharp and well-defined image resolution is close to the manufacturers quoted
figure, our sample managed a little over 540 lines under normal test
conditions. Noise levels are very low, colour fidelity is satisfactory though in
the auto white balance mode colour balance is quite heavily weighted in favour of
reds in particular, and to a lesser extent, blue as well. The exposure system is very responsive to
sudden changes in lighting level and the white balance system copes reasonably well
with artificial and mixed lighting. The unusual backlight compensation is quite
effective at dealing with bright scene illumination at the top of the screen,
though the system can be a little choppy, resulting in sudden changes in
brightness and contrast.
Low light performance at and around the point
when the camera switches to monochrome operation is most impressive. The image
remains coherent with plenty of detail and a good dynamic range. Again the auto
exposure systems work efficiently. At the changeover point there is a small but
noticeable increase in grain and image brightness. At low light levels, whilst
the image is in colour, red/blue emphasis remains quite significant.
Finally, in near total darkness, using infra-red
illumination, noise levels are still elevated but there is only a comparatively
small reduction in resolution and the image is generally clean, with plenty of useful
detail. A car number plate, for example was readable at a distance of 25 metres,
with only IR illumination. Contrast and dynamic range in the image are not as
wide as that available in bright natural light, though in practice much will depend
on the illumination and reflectance of the scene and target. Bright lights
within the scene area can cause flaring but the exposure systems work hard to
minimise their impact, highlighting the importance of matching optics the
optics to the camera and the need for careful alignment.
SUMMARY
Compared with video surveillance market as a
whole, only a relatively small proportion of camera systems -- mostly from the larger
and better known manufacturers -- have been specifically developed or targeted
at exacting applications such as town centre surveillance. The Bischke range effectively
increases the choice available to installers and end-users. Furthermore their competitive
pricing structure is significant, taking into account the effect the cost of these
products can have on the scope and flexibility of multi-camera systems.
SPECIFICATIONS
Make/model Bischke
TRI-Q 2012-P
Line standard 625/50 CCIR
Image sensor 0.5-inch
interline CCD, 568k pixels
Spectral response 380 -
1000 nm
Horizontal resolution 570-lines
Min. exploitable sens 0.3-lux
Min. sensitivity 0.5 lux
S/N ratio (min AGC) 62dB
Gamma correction 0.45
Backlight compensation bottom-loaded, 50/50% to 25/75%
High speed shutter 8-speeds (1/50 -
100,000 th sec)
Cameras dimensions 130 x 66 x
66mm
Weight 0.45kg
Lens mount C/CS
PSI RATING
Product
Product design 8
Build quality 8
Electronics quality 9
Installation
Ease of installation 9
Set-up functions 8
Instructions 8
Manufacturer’s support ?
Operation
Functions 8
Ease of use 8
Performance
Image quality 9
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Ó R. Maybury 1996 2005
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