What our experts say …
With so many new and unfamiliar names adorning the sides of CCTV cameras these days (and in some instances no names at all) the Baxall logo is a reassuringly familiar sight. In fact if CCTV cameras were cars Baxall’s products would lie somewhere between Volvo and Jaguar in terms of brand awareness, perceived reliability and performance.
Baxall cameras are almost instantly recognisable and no matter what the spec might be, virtually all recent and current models are housed in a distinctive cream case with a lightly sculptured front and gently curved edges. This uniformity continues with the recently-launched X Series.
We have been taking a close look at the CDX9714, one of two models in the range, the principal difference being the type of power supply. The 9714 is mains powered (98 – 260v AC) while its stablemate the CDX9714L/V requires an 11 – 40v DC or 12 – 30v AC supply.
The key features are above average low-light sensitivity and resolution plus extensive use of digital signal processing (DSP), which together mean the camera can function in a wide range of conditions including difficult situations where most regular general purpose models would not be able to cope.
We will begin the tour with the image sensor and this particular mode uses a 1/2-inch Sony Exview HAD device with a claimed minimum sensitivity of 0.4 lux (f1.2). Resolution is towards the high end of the performance range at 480 lines. Exposure options include an electronic iris, switchable AGC, configurable backlight compensation, adjustable gamma correction, four-mode white balance, auto/manual shutter and connections for an auto-iris lens.
There are some interesting extras too, such as Peak White Inversion (PWI) and ‘flickerless’ operation, when the camera is used in some types of tube lighting.
The 9714 has a standard C/CS mounting thread at the front of the case with back focus adjustment handled by a pair of screws on the top and side of the case. This is very convenient if, for example, access to one of the screws is hindered by a wall or ceiling. On the right side of the unit there is a standard square four-pin socket for an auto iris lens and a hinged flap that opens to reveal three banks of miniature DIP switches, a push button switch for displaying the backlight compensation ‘window’ and two rotary presets for auto-iris lens level and PWI threshold.
DIP switch 1 (SW1) covers AGC (on/off), line-lock phase (fixed/adjustable), sync (internal/line-lock) and the position and shape of the backlight compensation window. Three DIP switches provide eight permutations or patterns – shown by an opaque window, temporarily superimposed on the image – covering the central area, top and sides of the picture.
DIP switch 2 (SW2) is used to set manual shutter speeds and flickerless mode; the four switches provide eight speed settings, from 1/50th to 1/10,000th second. The first two positions on SW3 are used to set colour balance mode (auto, fluorescent, indoor & outdoor), position 3 is for gamma correction (normal 0.45/linear 1.0) and the fourth switch enables Peak White Inversion.
When PWI is switched on, very bright areas of the image are displayed as black. This can be used to help overcome exposure problems when using some types of auto-iris lens which can react to excessive scene brightness by closing down, resulting in a loss of detail in darker parts of the image.
The back of the camera is recessed by around a centimetre. This is very neat touch as it stops the sockets and connectors protruding, reducing the overall length of the camera when it is installed, and at the same time providing some protection for the connections. Two panel-mounted BNC sockets carry the composite video output and an input for external synch (genlock).
A separate Y/C (S-Video) socket is also provided in the shape of a standard four-pin mini DIN connector. A two-way spring terminal carries the connections for a voltage controlled type auto iris lens and there is a recessed preset for adjusting line-level phase (when the camera is powered from an AC source).
A green LED indicator shows power on and the captive main lead emerges from a collet close to the bottom right hand corner of the back panel.
The top and bottom halves of the case are lightweight but very tough alloy extrusions; the end caps are plastic mouldings. It is quite busy inside the case with the shielded mains supply module taking up around a third of the available space. The absence of a bulky transformer and the wide mains voltage operating range suggests it is an efficient switched mode type supply. This appears to be confirmed by the fact that there are no hot spots and the camera body never becomes more that slightly warm to the touch.
There are five other circuit boards inside the case, attached to a steel sub-frame. The two on the right are concerned with video processing and the various DSP functions. One at the front – mounted on the back focus adjustment mechanism – supports the CCD image sensor. A board in the base of the camera acts like a motherboard providing connection to the other PCBs and finally there is one in the back of the case, which handles the rear panel connections.
Overall it appears to be very well constructed with a minimum of wiring. In fact the only visible connections are the three mains wires and a ribbon cable from the image sensor board to the video processor PCB. It is very stable too and the image never missed a beat when subjected to a healthy dose of the Bench Test intermittency test, courtesy of the workshop rubber mallet.
Set-up & operation
In most cases installation should prove relatively painless. Mechanically there are no problems and standard quarter-inch threaded mounting bosses are built into the top and bottom panels on the case.
The back focus adjustment is quite smooth; unusually there is no provision for locking the mechanism but this does not appear to be a problem and the setting remains stable and unaffected by physical shock or vibration.
The only potential trouble spot is likely to be the miniature DIP switches. They are very small indeed, verging on the microscopic, and quite deeply recessed so that adjusting them in situ could pose problems when the side of the camera is mounted close to a wall.
All of the set-up operations are reasonably straightforward and outlined in a fair amount of detail in the instructions. The booklet is generally well presented, though for some reason it makes no mention of the back panel layout. Nor will novice installers find much in the way of explanation for the function and operation of features such as gamma correction or the electronic shutter.
Performance
Resolution on our sample was within a whisker of the manufacturer’s specs and in good light the image is packed with fine detail, so it would be well suited to systems using high performance monitors and recording equipment.
Low light performance is good but largely dependent on the AGC being enabled, which then has an impact on scene brightness and noise levels at higher lighting levels.
There doesn’t seem to be a happy medium and some experimentation may be necessary to get a well-balanced image when there is a wide variation in scene brightness. Image quality in good light is fine; there is plenty of sharp detail with very little noise and colours are crisply defined and natural looking.
The auto colour balance system responds well to change in lighting type though scenes lit exclusively by tube lighting can have a slightly yellowish tinge, even when the white balance system is set to fluorescent.
The auto iris system is fairly agile and reacts quickly to sudden changes in scene illumination. The Peak White Inversion feature looks as though it could have applications over and above the ones suggested. It could prove useful in locations with areas of high level lighting, with which the backlight compensation facility cannot cope.
<b>What the manufacturer says …</b>
The CDX series from Baxall is a range of feature-rich cameras, which have proven so popular that the CDX 9714 model was nominated for an IFSEC award. Building on the technology and feature set of the highly popular CDSP range, the CDX cameras offer extra features and more configurable options to choose from.
These include S-VHS video output for exceptionally high resolution colour images, variable peak-white inversion to display a pre-specified level of white light as black and genlock – which is now available on the colour models in addition to the monochromes – to prevent images from ‘rolling’. The peak white inversion feature is ideal for external night-time applications as it allows extra detail to be seen, such as number plates which would normally be impossible to read due to the car headlamps blinding the camera.
The CDX cameras also feature eight Back Light Compensation (BLC) window configurations. In situations where people are entering a building, they are often seen in silhouette by a camera as it tries to compensate for the varying brightness. BLC addresses this by instructing the camera and lens to ignore certain areas and stop trying to compensate for them. The CDX cameras allow the installer to select the best window configuration from eight options, for maximum efficiency.
In addition to these advanced features, the CDX camera range also comes with all the standard features you would expect from a Baxall camera, including AGC and gamma for flexibility, back focus mechanism for ease of installation and four white balance modes to provide optimal colour rendition across a vast range of illumination conditions and light source types.
There are three half inch models in the CDX range: a DSP colour camera, an infrared DSP monochrome camera and a colour/monochrome camera which automatically switches between the two so that it can be used in both daylight and night-time conditions.
All the CDX cameras have been designed by Baxall with the EXview imaging chip for increased infrared sensitivity for use in low light conditions, and support all lens options including C and CS, auto iris and direct drive. The CDX cameras are suited to specialist applications where high performance or complex profile changes for radically changing lighting conditions are required.
