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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

 

---end---

Ó R. Maybury 1996 2005

 

 


 

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