The bench test 2: Competent performer

What our experts say …

Generally speaking, video surveillance cameras are incredibly reliable, and this is even more impressive when you consider how complex they have become.

Faults, when they happen, tend to occur when cameras approach the end of their service lives, or very occasionally in the first few hours of use, so we don’t get the chance very often to get our hands dirty, as it were.

Even when we do, most recent models have few replaceable or serviceable parts, other than the power supply circuitry, and it’s often more economical to replace the whole unit rather than attempt a repair.

Nevertheless the opportunity to practice our troubleshooting skills and poke around the innards of a brand new camera arose with the Asset Security AST9024, which after connection to the Bench Test power supply produced a decidedly shaky black and white picture with what looked like a serious synchronisation problem.

Normally we would immediately seek a replacement, but curiosity got the better of us, and since the fault appeared to be intermittent in nature there was a very fair chance it was a connection problem.

This proved to be the case, and it was quickly traced to a badly seated ribbon cable linking the image sensor board to the main PCB.

We also discovered a couple of loose screws inside the camera, one holding an escutcheon plate and the other securing a PCB. Not a very good start, but for the moment let’s be charitable and put it down to a momentary lapse in quality control...

The AST9024 is billed as a specialist high-res day/night colour ‘traffic’ camera. We can only assume that ‘specialist’ and ‘traffic’ are used in their loosest sense since there don’t appear to be any special features specific to observing vehicular movement.

That aside, the manufacturer’s specs quotes resolution at 480 lines and 580 lines for day and night modes respectively, with a low light sensitivity of 0.075 lux from the 1/3-inch CCD image sensor.

The camera’s performance is enhanced by a motorised IR filter, which slides out from in front of the image sensor when the camera switches to monochrome night mode.

Despite appearances to the contrary, the AST9024 has a fair number of manual exposure and configuration adjustments, including auto/manual day/night switching, auto/manual shutter (1/50th to 1/10,000th sec), switchable gain (22/30dB), switchable gamma correction (0.45/1), backlight compensation, auto/manual white balance, picture sharpness (high, mid, low), camera ID (one line of up to 16 characters), DC or Video control for auto iris lenses and external control and access to additional functions by dedicated control box or PC via a RJ-45 cable.

In stand-alone mode everything is controlled from a menu-driven on-screen display, using a set of three recessed buttons on the left side of the camera body.

Here too are presets for DC iris level, V-phase adjustment, and a three-position switch for selecting DC and Video auto iris or Auto Electronic Shutter (AES) exposure modes.

On the opposite side is a standard 4-pin socket for an auto iris lens, and on the front there’s a threaded mounting collar (CS lenses only) with a lockable back focus adjustment using a small thumb-operated lever set into the top of the front panel.

On the back of the camera there’s a BNC socket for the video output, an RJ-45 socket and a spring terminal for the 12 volt DC/24 volt AC power supply connection. (A mains powered version of the camera is also available).

An LED ‘power on’ indicator mounted on the main PCB is visible through a small hole on the back plate.

Sturdy design

The camera body is a one-piece alloy extrusion; the two end caps are also metal so it feels quite solid.

It’s a simple, sturdy design, though no effort has been made to weatherproof the case or indeed provide any protection from dust, moisture or even quite large insects, so consideration needs to be given to its location or housing if it is going to be used in anything other than a clean environment.

Inside the case there are four PCBs. The smallest one holding the CCD image sensor and its associated circuitry is mounted on the back-focus mechanism. The two largest PCBs, responsible for video processing and the power supply, are bolted either side of a simple metal chassis that runs the length of the unit. The fourth PCB handles the onscreen display and control functions and this is attached by a strip connector to the main processor board.

Considering the range of functions, the designers have done a reasonably good job of squeezing the controls and adjustment into just three buttons. For the most part it works reasonably well, though setting the camera ID can be a slow business.

The main menu is displayed by holding down the centre button for a couple of seconds; this brings up nine sub-menus covering day/night switching functions and sensitivity, shutter mode and speed, gain, sync, gamma correction, backlight correction and white balance.

The backlight control steps through four fixed sensitivity ‘masks’ covering the top, bottom, centre and bottom centre portions of the screen. The white balance sub menu includes two auto tracing settings for indoors and outdoors, full auto and manual, with independent red and blue adjustments.

The second menu page has four options for setting picture sharpness, pre-determined shutter speed (PREDTMSP), camera ident and ID position. The PREDTMSP setting allows an external controller to switch the camera to a preset shutter value for reasons that are not fully explained in the somewhat vague instruction manual.

There is a third menu page for external control settings, and this appears when the up arrow button is pressed and held for more than a couple of seconds.

There are five options covering the camera address (001 to 199), protocol (Pelco D, Pelco P and ERNITEC), on-screen display menu (English, French or German), bit rate (1200, 2400, 4800 and 9600 bps) and the software version.

The additional functions available from the optional control box are dealt with in a fairly cursory manner, but include the previously mentioned pre-determined shutter speed and day/night switching.

There’s also a passing mention of PC control software and an RS-485 to RS-232 interface converter, but no details of how it is used.

Performance

We found the resolution on our sample slightly below that of the manufacturer’s figures, but not by a large enough margin to cause any serious concern.

Low light sensitivity figures might also be a little optimistic, and at the extremes of operation noise levels are perhaps just a tad higher than some similarly specified day/night cameras we’ve seen recently.

Day/night switching is quite relaxed and there is a need to avoid spurious changeover from colour to mono mode.

In situations where there is a sudden change in light level – when the lights are switched off for example – it can take from a few seconds to half a minute or more to react.

The auto exposure systems cope well enough with gradual variations in lighting level, though again it wasn’t especially lively and it can take several seconds to respond to sudden change.

Colour accuracy is good, and the auto white balance system handles the normal range of natural, artificial and mixed lighting without any problems.

Once the ribbon cable had been properly seated and the chassis screws tightened, the camera passed our intermittency tests without any further problems.

What the manufacturer says ...

This is a high-spec, highly adaptable camera for demanding applications. It is not only suitable for all general applications, but as a major advantage it complies with local authority requirements for a traffic camera.

It has pre-selectable shutter speeds, and the speed can be changed using a remote contact. This means that the camera can run normally, then have the shutter speed altered by closing the contact, to allow effective capture of number plates. On releasing the contact the camera returns to normal surveillance mode.

As one would expect from a product of this calibre, all parameters can be set to suit the specific application. Adjustable elements include shutter speed, sync, gain, gamma level, BLC, white balance, aperture, etc. The camera also features four white balance modes.

It incorporates a ½” Sony ExView HAD CCD, capturing more light and offering maximum sensitivity. It offers excellent IR performance for night time surveillance.

Users can set the parameters using on-board menu buttons or via a PC – it features an OSD menu (in several languages).

The parameters for up to 250 cameras can be set remotely via the PC, allowing users to adjust each camera following installation. Each camera is given a 16 character alpha-numeric ID, allowing maximum flexibility and control from the PC.

It is available in two versions. One is a 230VAC model (AST9200P) and the other is a 12VDC/24VAC model (AST9024P). It is the latter that many local authorities are specifying.

The product has also been approved and is being used by a major installer on highways in France.