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PHILIPS LTC 0825/11 AUTODOME CAMERA

 

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Remember those grand old wooden cased wirelesses and radiograms, the ones with huge tuning scales, peppered with names like Hilversum? The tuners on those old radios were miniature masterpieces of engineering with complex pulley systems hauling large illuminated pointers across the dials. We thought the pulley-dial maker’s art was lost to the world of digital push-button tuning, but no, it’s alive and well and living inside Philips AutoDome cameras...

 

Motorised dome cameras are naturally home to some rather weird and wonderful mechanical contrivances but the G3 AutoDome is going to take some beating. The pan/tilt mechanism is ingenious, though at the same time it looks like something out of the Ark with the tilt motion controlled by wires and pulleys. Most manufacturers prefer the direct drive method, whereby the motor that tilts the camera head is mounted on the rotating platform and moves the head with simple gearing. On the AutoDome the tilt motor is on the static chassis/base plate and like the pan motor, it does not move, instead the motion is transferred to the head via a separate gear train, which in turn acts on the pulleys and wires. The most obvious advantage of this system is the significant reduction in weight on the moving camera platform, which reduces inertia and improves acceleration, speed and accuracy.

 

We’ll look at the mechanics in more detail in a moment, but first a quick round-up of the key camera features. Various camera configurations are available but they are all based around a 1/3-inch CCD interline CCD with a 752 x 697 pixel array. This sits behind a 16x optical zoom auto focus lens (F1.2, 4.5 –72mm) and yields a claimed resolution of 425-lines. Low light sensitivity is 0.5 lux with a useable image possible down to as low as 0.08 lux. An electronic zoom increases magnification by a further 6.25x, to 100x.

 

The G3 AutoDome is one of a number of cameras designed to be used with the Philips Allegiant control system (see also review of the LTC 2682/90 video multiplexer/controller PSI XXX), camera and PTZ control is via a standard RS232 serial communications link or telemetry on the video connection. It’s remotely configurable with on-screen displays used to program camera setup and positioning (16 titled sectors, 99 pre-positions). A feature called Auto-Playback stores up to 3 minutes worth of control command.

 

The version we’ve been looking at is the Pendant model encased in an indoor housing, which tips the scales at 3.6 kg. It provides full 360-degrees continuous pan and 0 to 90 degree tilt with an accuracy of +/- 0.5 degrees, moving at up to 360 degrees/sec (pre-position control) and 120 degrees/sec (variable, manual control). A patented Auto-Pivot function rotates and flips the camera to track subjects as they pass under the camera. The outer casing, formed from a light alloy is in two main parts, with the motors and control system in the upper portion, and the clear transparent dome and shroud below, this is a simple push-fit onto the body of the unit, though it’s tight enough to resist casual tampering. The actual dome is made of a surprisingly thin-plastic material, which will deform under finger pressure, but it feels very resilient.

 

The pendant model connects to its support with a tough-looking twist-lock bayonet type fitting and once in place it can be secured with two bolts. All of the power and control connections are routed through the top via a multi-way terminal plug. Video (and telemetry) is carried by a standard BNC connector, also mounted on a plate on the top of the unit. This has a hook for a suspension wire, and there’s a separate suspension wire on the lower dome cover.

 

Compared with some similarly specified dome cameras the mechanical parts look decidedly lightweight in construction but the fact that the motors are mounted on the chassis means there is no need for heavy-gauge components and the whole assembly is surprisingly rigid. The pulley system looks ungainly and possibly a little delicate but it appears to be built to a very high standard using high-grade materials. Philips claim this design has fewer moving parts, which we find hard to believe, but the reduced weight of the camera platform means that there should be less stress on the motors. The camera mount looks and feels finely balanced and hopefully this will have a beneficial impact on reliability and life expectancy.

 

INSTALLATION AND OPERATION

Fitting and setup shouldn’t pose too many problems for most installation engineers; the instruction manual is profusely illustrated and easy to follow. One of the first tasks is to assign the camera an address, when using RS232 communications this has to be set using a rotary DIP switch set into the top of the unit, otherwise it can be configured remotely using the ‘FastAddress’ system.

 

All other settings are carried out from the remote control unit using the camera’s on-screen menu displays. The options cover a lot of ground including auto/manual focus with ‘constant’ or ‘spot’ adjustment (focus only when camera has stopped moving), constant/spot/manual exposure, AGC on/off, white balance (auto, indoor, outdoor, lock), sharpness, electronic zoom and zoom speed. Additionally the menus cover a number of PTZ functions including return to Preset 1 after 3 minutes, AutoPivot on/off, AutoPan, tour period and PTZ speeds.  

 

PERFORMANCE

It’s immediately clear from the on-screen results that the camera is a quality item capable of performing well in a wide range of conditions. Resolution is within a whisker of the manufacturer’s spec, the exposure system copes easily with movement and consequential rapid changes in lighting conditions, noise levels are very low and colour accuracy – in auto white balance mode -- is generally good. In their respective spot modes both focus and exposure adjustments are swift and precise in good light, though there is a tendency to ‘hunt’ at very low illumination levels, at which point it’s a good idea to use the manual overrides. The optical zoom is very smooth, the 100x electronic zoom introduces a lot of processing artefacts as it approaches the limits of the magnification, resolution and stability also take a tumble but it undoubtedly will have its uses.

 

The PTZ is very fast indeed and the lower than average weight almost certainly contributes to the lack of overshoot. It’s very quiet in operation and reasonably discreet with the camera assembly effectively shrouded, making it difficult for a casual observer to see which way the lens is pointing.

 

SUMMARY

Any concerns that the unconventional mechanism and elaborate pulley system would compromise or impair performance are unfounded. AutoDome is a smooth and responsive camera platform that compares very well indeed with the best of the ‘heavy-duty’ systems we’ve looked at. Installation should be a reasonably painless experience and the camera provides a crisp clean image in all but the most adverse situations.  

 

PRODUCT SPECIFICATION

 

Power supply              21-28 VAC 50Hz

Weight                        3.6kg

Dimensions                 344 x 204 mm

 

PSI RATINGS

 

Product                      

Product design             9

Build quality                           8

Ruggedness                            8

 

Operation                  

General functions                     9

CCTV functions                     9         

Ease of use                             8

Instructions                            8

Manuf. support                        ?         

Performance                           9

Video quality                          9

 

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Ó R. Maybury 2000 3010

 

 


 

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