Security Installer

HomeSoftwareArchiveTop TipsGlossaryOther Stuff





Dome cameras are becoming an increasingly attractive alternative to conventional pant-tilt-zoom (PTZ) systems. They’re relatively discrete -- an important consideration these days with the proliferation of CCTV becoming a subject of  public concern -- yet they afford as much, in some circumstances more, effective coverage than a PTZ installation.


The technology has progressed at a rapid pace, thanks largely to advances in servo motor design, microprocessor control, telemetry, camera optical and digital video processing systems. Vicon Industries have combined all of these developments, and a few more besides, into the Surveyor dome camera. It’s arguably the most sophisticated system currently available; in addition to being unusually compact -- the dome is only 7.5 inches in diameter -- the mechanism is very fast indeed. The model we’ve been evaluating can pan through 360 degrees in less than second and tilt at 120 degrees a second.


Specifiers and installers can choose from a variety of configurations, including indoor and outdoor housings, with pendant or in-ceiling mounting options, fitted with gold, chrome or black domes. The drive units are available with variable or fixed-speed rotation and colour or black and white camera modules. On the version we’ve been looking at pan/tilt speed can be configured to be proportional to zoom position.


One of the key design features however, is what Vicon call ‘distributed intelligence’. In a nutshell this means that instead of the Surveyor simply being a ‘dumb’ enclosed PTZ mechanism and camera, connected to a ‘smart’ controller, the housing also contains microprocessor-based  programming, control and telemetry systems, plus eight local alarm inputs and replay outputs. This means the control unit or keypad can be a simpler design, though it does place some restrictions on using the dome with other, similarly featured systems. The on-board electronics are also used to store camera settings, generate on-screen set-up menus and idents. The net result is a highly flexible system, that’s easier to install and service. 


The specifications for the colour camera in our test system are impressive. The module is housed inside a light alloy shroud, coloured black, in common with all other surfaces that would be visible through the dome. The camera is based around an 0.25 inch interline CCD with a 500 x 582 pixel display. This is coupled to a f/1.6 zoom lens (4-48mm) giving 12x magnification and a horizontal field of view extending from 4 to 47 degrees. This set-up has a quoted low-light sensitivity of 2.2 lux and a resolution of 460 horizontal lines. Digital processing circuitry can extend the optical zoom to a maximum of 96x, though resolution at higher magnification levels drops off drastically.


Most camera functions can be adjusted remotely or left to operate automatically, these include focus, iris white balance and high-speed shutter. In addition to PTZ controls a suitable external keypad also gives access to AGC, vertical phase, idents and titles via a series of on-screen menus. Dedicated control panels such as the Vicom V1300X-DVX ‘intelligent’ keypad enable access to additional programming features, such as 10 programmable guard tours, built up from 79 preset positions, moreover it can sequence and switch a further 255 cameras. 


The camera is mounted on a pair of strong bearings,  inside the hub of a sturdy, vaguely bell-shaped chassis. Tilt motion is controlled by a hefty-looking DC stepper motor, acting on a semi circular gear plate. The chassis is mounted on a central rotary bearing, attached to a large gear wheel. A gear-shaft on a second stepper motor meshes with the larger gear for the panning action. Control PCBs for both motors are located either side of the chassis. A third double-sided PCB, is responsible for movement programming, camera control and communications is mounted ahead of the camera bay. All settings are stored in a non-volatile memory, that is retained even if the camera drive unit is removed from the housing for cleaning, servicing or adjustment.


The whole assembly locks into the housing using three extension feet that are held in place by a rotating metal latch. All power and control feeds to and from the drive unit are carried by a self-aligning 25-pin D-Sub plug and socket system, that mate together when the assembly is inserted into the housing. The unit can be released by a small handle inside the case, after two arrows on the drive assembly and housing have been lined up.


Inside the top of the housing, behind a removable metal plate, are all of the interconnections for the power supply, control and alarm inputs and outputs. They’re mounted on two PCBs and take the form of three 10-way screw terminal blocks, and a coaxial terminal, for the video output. The unit is compatible with both Vicoax and Nova control systems and protocols. A pair of Miniature DIP switches on the main drive unit circuit board pre-select auto-diagnosis mode, communications speed and camera type and address. One other small switch selects service mode, to override a small tamper switch that senses when the dome has been removed.


The cylindrically shaped housing is made from a tough heavy-grade plastic, that’s coated internally with a metallic RF screen. It is supplied with one of a range of mounting systems for walls and ceilings (solid or suspended).  



Build quality is outstanding, in fact it’s fair to say that some components are a lot stronger than they need to be, though that’s obviously going to benefit reliability and longevity. There are a couple of relatively minor niggles: the drive unit release handle is quite hard to get at, almost impossible for anyone with fat or shorter than average fingers.  The instruction manuals are not especially installer-friendly; there’s rather a lot of them, (3 manuals and several addenda), moreover presentation and accessibility could be improved. 


The drive unit is incredibly agile, smooth and very quiet in action, thanks to the precision gears and high-grade stepper motors. The camera works well too.  Resolution on our sample, in good daylight conditions, was in excess of 430 lines, with commendably low levels of picture noise. Colours were natural and accurately registered. In moderate to poor light there was a steep increase in noise and grain but the image continued to be useable down to dusk-level conditions. Colour accuracy deteriorated slightly under tube light, which resulted in a light green-yellow tint.



Mechanical design, camera performance, control facilities and flexibility are all excellent. Limitations, such as they are, are mainly confined to the unit’s reliance on compatible control systems to get the most out of it, so it’s probably unwise to regard it as a stand-alone component. The Surveyor is a most impressive piece of equipment, especially when you see it in action. It’s almost a shame to hide it beneath the dome, watching it fly around is almost guaranteed to scare the pants off any villain...



Design and design features              *****

Circuitry and components                  *****

Ease of installation and wiring    ****   

Range and variety of functions            ****   

Accompanying instructions                   *****                            

Technical advice and backup            ****     

Value for money                         ****




Ó R. Maybury 1997 2005



[Home][Software][Archive][Top Tips][Glossary][Other Stuff]

Copyright (c) 2005 Rick Maybury Ltd.