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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.

 

Itís 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. Thereís 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 Ďdistributed intelligenceí 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 itís 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 Ďintelligentí keypad controller.

 

The exterior housing is an extremely robust moulding, made from a tough ABS plastic and internally screened with a metallic coating. Fitting shouldnít 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 thereís 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, thatís 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, itís 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 addendumís. 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 Surveyorís memory. A tour can consist of up to 32 Ďeventsí 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 theyíve 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 itís over-engineered, Vicon could probably have got away with smaller, less powerful motors, and cheaper plastic gears, but it looks and feels as though itís going to last. There are other benefits; precision mechanics enable higher speeds, it positively flyís 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, itís 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 manufacturerís 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 itís possible to get a useable image in quite poor conditions. Colour accuracy is variable, itís 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 thatís not a very elegant solution. Frequently-used buttons could have been better laid out, and itís easy to invoke error messages if you donít 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 wasnít 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. Theyíre 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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R. Maybury 1997 1205

 


 

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