The bench test 1: The dome-maker's art

The range of options is sufficiently diverse to cover most applications and includes both indoor and outdoor models with a selection of housings, mounting configurations and camera modules. The dome featured in this test comprises a VPD-VR-P vandal-resistant pendant with a seven-inch clear dome plus a VPD-3 colour camera with pan/tilt mechanism.

The PTZ assembly is remarkably agile with speeds of up to 400 degrees/second between preset positions; accuracy between presets is an impressive 0.01 degrees. Under manual control it's a little more leisurely, moving at between 1.5 and 120 deg/sec. A total of 128 preset positions can be stored with titles; these can be used in four tours of up to 64 presets, or an AutoPan mode.

In addition it has four 'Learn' tours, three lasting one minute and one lasting three minutes. These are programmed by storing manual PTZ actions in real time. There is provision for storing up to 24 privacy zones or masks, eight of which can be in use at any one time and preset positions can be associated with up to 16 external alarm inputs.

Additional facilities include auto-follow or 'quick spin' to track subjects and objects as they pass beneath the dome. The camera has a freeze-frame facility, used to display a still image as the camera moves between presets and there is a 'coordinate display', which shows the camera's azimuth and rotational angle, in degrees, relative to a user-set bearing or position such as North.

The camera is a high performance day/night model with a mechanically switched infrared filter. In colour mode low light sensitivity is quoted at two lux. Switching to monochrome night-time operation is automatic, or manually from the keyboard controller, at which point sensitivity falls to just 0.08 lux. The manufacturer claims resolution figures of 470 lines for colour images and 570 lines monochrome.

The 4.1-73mm lens has an 18x optical zoom and this is supplemented by a 12x digital zoom, with proportional control of pan/tilt speed. It's bristling with exposure options, including full manual control of the iris and shutter speed from the keyboard and that is in addition to the usual auto options. There is also manual lift/gain control, external sync, white balance plus manual focus. A 20-character camera title can be positioned on any one of 11 horizontal rows on the left, right or centre of the screen. The camera module is available with either coaxial or unshielded twisted pair video outputs, the latter being used to send video though standard CAT5e cable, without significant degradation over distances of up to 1km.

Standard RS485 comms protocols are used, enabling the dome to communicate with a wide variety of devices. It is also designed to smoothly integrate with other surveillance systems, including Vista's range of Columbus Triplex hard disk recorders. It is obvious from the outside that the cast alloy upper housing and the dome are very well engineered. It looks and feels solidly built and the attention to detail is impressive. It is highly unlikely that anything is going to get past the heavy-duty seals between the dome and the housing. Inside, two small fans blow air onto the inside surface of the dome. A flat heating element mounted next to the fan inlets is controlled by a temperature sensor on the smaller of two PCBs, which also handles the power (24v AC), video and telemetry connections with the outside world.

Cables pass through a central hole in the top of the housing; a soft rubber gland provides extra weatherproofing. The connector board is hard to get at and the plug for a coaxial video connection can be a swine to fit. The second larger PCB is mounted in the top of the housing and this is responsible for communications, configuration and connections to the camera module.

Everything about the housing and the internal components looks as though it is made to last, which instills a great deal of confidence, until you get to mounting the camera module and the so-called 'quick-fit' connector system. Here the designers seem to have suffered a mild brainstorm and devised a mechanism that Heath Robinson would have been proud of.

It's worth looking at the design of the PTZ head assembly. The camera is mounted on a vertical arm, formed from high density plastic, and connected to a beefy-looking stepper motor immediately below with a simple toothed belt and pulley arrangement. The arm is mounted on a rotary transformer and bearing. It's turned by a second stepper motor, belt and pulley, mounted on a lightweight alloy chassis. It's simple and effective. There are two PCBs, one on the outside of the vertical arm and one beneath the main platform, both encrusted with microchips and tiny delicate surface mount components, which is part of the problem mentioned.

The mounting system looks deceptively straightforward. On the platform supporting the rotating camera arm are four large protruding pins. The idea is that they fit into four socket holes in alloy plates mounted inside the housing. In order to locate the pins two of the sockets are mounted on a sprung plate that has to be pushed back (with some force) to allow the pins to fit into the holes.

The camera module therefore has to go in at an angle, both to orientate the pins and to allow a locating hook to engage in a slot in the mounting plate. There are two basic problems. It is fiddly and it can be difficult to align the camera module, a third hand would be an advantage, and that's with the dome inverted, in good light, on a bench.

Secondly, enormous care has to be taken to make sure the PCB on the camera arm doesn't come into contact with one of the cooling fans or any other protrusions inside the dome as it is angled in to fit because there is a fair chance that components on the board might be damaged. The mounting system does what it is intended to do and provides a strong positive fixing for the camera but the rigmarole of inserting and extracting the camera, allied to the potential for damage and the awkwardness of the design, gives us cause for concern. Heaven help the installer 20 feet up a ladder in foul weather or poor light trying to fit or exchange a module! Set-up & operation
Entering a four-digit PIN into the keyboard accesses the dome's extensive menu system. This has to be done using the joystick, using it to point a cursor at a row of numbers, rather than by simply tapping the PIN into the numeric keypad alongside. A status display appears showing version data for the software, comms address and installation date. Pressing the Enter button advances the display to the main menu, which has five options. Item 1 is the set-up menu with seven selections for password change, memory clear, set install date, camera title, title position (vertical and horizontal) and configuration status, showing all current settings. The title is composed using the joystick and like the PIN number uses it to move a cursor along rows or characters and symbols.

The second sub menu deals with Control Options, for setting Auto Pan speed (fast medium or slow), setting the Home position, preset speed (four steps), proportional zoom (on/off), Quick Spin (on/off), maximum pan and tilt speeds, reset action (go to Preset, Preset Tour, Learn Tour, AutoPan or disable). There is an on/off switch and position control for the Coordinate display.

   Camera Options are covered on the third sub menu and these include day/night switching and level, electronic zoom (1x, 4x, 8x & 12x), Iris control (manual or man/auto), Lift & Gain control (eight and 31 steps respectively), shutter (AI, EI and 1/3 to 1/10000 sec in seven steps), still shot (on/off), Sync, Phase and White balance (auto or red/blue manual). Menu 4 is for setting Presets, Tours and the Learning Tours. Option 1 is to set a position preset and selecting this brings up the camera image. The camera and zoom are positioned as required and the settings stored using the Enter button. The preset is then assigned a number using the now familiar (and increasingly annoying) joystick wiggling method. Areas can be defined from the second menu item. The camera is moved to set the top left and bottom right hand corners of the area, after which the system 'maps' it out, which can take up to two minutes. The next menu covers programming the four Tours and have data entry fields for preset position number (up to 64), dwell time, speed, zoom and title. The Learn menu simply requires the operator or installer to move the camera and set the zoom in a manual tour while all actions are recorded in the allotted one or three-minute period. If required a Learn Tour can be edited.

The last item on this sub menu is for creating and editing titles, for Presets, Areas, Tours and Learn Tour and the Privacy Masks. The latter is set using a moveable square 'target' which is positioned on the upper left and bottom right-hand corners of the area to be obscured, by a grey block.

The fifth and last item on the main menu is for programming the dome's 16 alarm inputs, designating the preset position to move to in the event of activation.

   On the bench with the dome removed, picture quality is excellent with resolution close to the manufacturer's claims. In good natural light the image is crisp, clean and well balanced across a wide range of lighting conditions. Noise only becomes an issue at very low lighting levels but even then it is still some way below the average.

Rapid changes in lighting level are handled smoothly and colour accuracy is fine in natural light and only a shade or two off in mixed or predominantly artificial lighting conditions.

However, as soon as the dome is fitted there is a noticeable drop in clarity at higher zoom levels. This is mostly due to internal reflections and some optical distortion, though the effects may be exaggerated by our fully transparent sample dome. Where there is any possibility of direct or reflected sunlight, it would be wise to investigate the tinted and mirrored alternatives.

What the manufacturer says ...
Vista powerdome is a range of 19 high-speed PTZ domes for internal and external use in a wide variety of commercial and industrial environments.

The VPD-3 series in the range has been designed to offer the ultimate in external surveillance. Featuring a high resolution (570/470TVL), high sensitivity 18:1 colour/monochrome (0.7/0.02 lux) camera, it is suitable for effective 24-hour day/night surveillance and, with the option of a vandal resistant housing, it is suitable for use in harsh environment or where the unit is prone to attack.

The VPD-3 series also benefits from the ability to display 24 dynamic privacy zones, with up to eight on screen at any one time, enabling certain areas of an image to be blocked out to ensure privacy in sensitive areas. The unit accommodates up to 16 local alarm inputs.

The range can be ordered with one of two video transmission options: coaxial or unshielded twisted-pair via NVT, which can transmit real-time colour video over standard UTP CAT5e cable over distances of 1km.

All are simple to install with a quick-release connector that facilitates removal of the camera yoke assembly. Available housings include pendant, wall, drop ceiling and external options. Internal dome bubble options include clear, tinted, smoked, gold, silver and chrome with clear and smoked options available for external mounting.

The range provides a full range of pan, tilt and zoom movements that can be controlled with speeds up to 400 degrees per second between preset positions, with a preset accuracy to 0.01 deg. With the ability to be controlled from either RS485 or FSK coaxial telemetry and on-board HF lift and gain, the PowerDome lends itself to the vast majority of installation requirements.

As well as new installations, the speed dome is an ideal replacement for existing worn out PTZ cameras. It leads the market in price performance.