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The Silent Witness SWC40 is one of those products that was bound to turn up sooner or later, it's just that we hadn't expected to see it quite so soon… In fact it is so new and unusual that we're not even sure what to call it. The manufacturers have dubbed it 'the first all-in-one CCTV solution', which doesn't really tell you much. Its closest relative, in terms of basic functionality, is a digital still camera, but such similarities as there are, are almost entirely superficial. 


The SWC40 is essentially a black and white surveillance camera with a built in digital still video recording facility, but there are no tapes and unlike a photographic film camera it provides a continuous moving video picture. Still images – up to 1140 of them -- are stored on a solid-state 'flash' memory. Depending upon how it is set up, it can record an event at 0.5 second intervals, lasting up to 1 hour and 35 minutes. Picture quality depends on how the unit has been programmed (recording time, compression level etc.), but all things being equal it should lie somewhere between a low band and high band (VHS/S-VHS) time-lapse VCRs.


Recordings can be triggered in one of two ways, the SWC40 has an external alarm input and an on-board video motion system using a configurable 4 x 4 detection grid. The alarm system is armed remotely using a key fob transmitter, similar to a car alarm switch. It is housed in a very stylish weatherproof, vandal-resistant case and it can be controlled and set up using a simple on-screen display system.


It is a most striking design, quite unlike any conventional CCTV camera in appearance. Far from being discrete or unobtrusive it has been designed to be seen. It comes in two parts, a wall or ceiling mounting base and the actual camera/recorder module. The mount has a moveable arm, on the end is a quick-release connector block that plugs into the back of the camera. Inside the base there is a set of terminals for the DC power feed, video and audio outputs plus a set of external alarm connections.


The camera like the base is made from cream-coloured ABS. When the camera is removed from the connector block the back panel is exposed to reveal a multi-way socket that carries the DC, audio, video and alarm connection, a pair of power and video sockets and four buttons, used to operate the menu-driven on-screen display and recorder functions. At the front of the camera is a removable panel, held in place by two Allen-type security screws. This gives access to the camera lens, there is also another video output socket (it has three video connections in all), a duplicate set of menu/recorder buttons, the microphone, a preset for adjusting audio sensitivity and a mode/status indicator LED.  


The business end of the SWC40 is centred on a black and white board camera module. This uses a 1/3-inch CCD with a maximum off-chip resolution of 410 lines and a low light sensitivity of 0.05 lux. The standard lens is a 3.6mm F1.4 type the package also includes three 'quick-change' lenses with focal lengths of 2.9, 6.0 and 8.0 mm. The lenses are on a bayonet type fixing and can be swapped in a matter of seconds. Exposure is controlled automatically using electronic shuttering (1/60th to 1/100,000th sec), it is possible to adjust the response of the AE system, to compensate for bright or poorly lit areas of the scene using the ILC (intelligent light control) facility, which we'll come to in a moment.


All of the recording system, control and alarm functions are handled by the menu-driven on-screen display. This is called up by pressing a button on the back of the camera or one behind the lens cover. In order to use the rear panel controls the camera has to be removed from its mounting bracket and plugged into the DC power and video leads.


The main menu has six options: record, ILC, Motion, Display, Alarm and Input. Record covers the type of alarm trigger (motion, external trigger, both or off), recording interval (0.5 secs to 5 seconds in 4 steps), recording quality (good, high, super), recording duration (1/50th second to 5 minutes in 6 steps), and overwrite on/off (in off mode recording stops when the memory is full).  


The ILC menu has three options; Mode switches between user designated (tiled) or whole scene (tracking) exposure control, Tile Set-up switches squares on and off in the 4 x 4 target grid and Brightness increases or decreases the luminance level of the video output. The Motion menu also has three options. Tile Set-up brings up the 4 x 4 target grid and allows individual squares to be switched on and off. Sensitivity adjusts the motion sensitivity of the enabled targets and Display superimposes flashing 'X's on the output image that show when a target has been triggered.


The Display menu deals with time and date setting, camera title/ident, title position and display on/off. The SXC40 is year 2000 compliant and during our tests the clock maintained stability to within a 4 or 5 seconds over the period of a week. The Alarm menu controls the external alarm signalling, these include the alarm Source (motion, external trigger, both or off), when an alarm signal is activated, output signal (pulsed or latched), and output delay (instant or 30 seconds). Finally, the Input menu sets the external alarm trigger and arming parameters, the three options cover arming signal switching (high to low or low to high), Arming Delay (instant or 30 seconds) and External Trigger (high level, low level, high to low, low to high or off).      



Installation and set-up shouldn't pose any particular problems. The kit contains all necessary mounting hardware, connecting leads and a compact mains power supply module. The only preliminaries are to fit and adjust the appropriate lens and align the camera, everything else can be carried out from the on-screen display.


Camera mode and status can be determined by watching the indicator LED on the front, a flash every four seconds means it is disarmed, double red flashes every 4 seconds shows a recording has been made, the camera is arming when the LED flashes every second. Continuous red indicated armed or recording and if the LED turns green the camera is too cold to function. 


Recordings can be replayed at any time when the camera is in the disarmed mode. The control buttons on the rear panel (and behind the lens cover) work in a similar manner to VCR transport keys, with real-time play (i.e. at the speed/frequency the recording was made) in either direction, frame by frame replay, and high-speed replay, also in both directions. Recordings are time and date stamped, along with a title or ident. This is the one area where there is room for improvement, in order to access the recording system the camera either has to be dismounted, or the front panel removed, neither of which is very convenient. It is a shame that the remote control facility is limited to arming and disarming. The system's flexibility would have been significantly improved if the recording system and programming facilities could also be controlled remotely.


The manual warns that the flash memory has a limited like, it quotes 100,000 record/rewrite operations, after which an on-screen warning indicator will appear however it goes on to point out that in all probability the memory chip will continue functioning normally.



In the highest quality recording mode our sample was able to resolve a little over 340 lines, though there are a few ifs and buts with digital recording systems and that figure should be regarded as a working average. In all three recording modes the image is quite heavily textured and this can mask detail, on the other hand, unlike analogue tape noise levels are very low and the image has a good dynamic range and the manufacturer's claim that it compares favourably with tape is largely justified. The auto exposure system is quite heavy handed and slow to respond at times; it is worth taking some trouble over the ILC set-up, especially if the scene is likely to experience large or sudden changes in brightness.


Audio is not recorded but it's worth saying a few words about the built-in microphone. The front panel grille is sealed so sounds are a little muffled but it can pick up a conversation two to three metres in front of the lens when background noise levels are reasonably low.



Our only criticism concerns access to the recording controls, it badly needs some form of remote control – wireless or corded, it doesn't matter – that would make it possible to review a recording without dismounting or disassembling the device.

The SWC40 creates any number of new surveillance opportunities many of which would have been impractical or uneconomical using existing technologies. Keeping watch on low-traffic areas that do normally normally warrant full coverage with a time-lapse VCR is one application that springs immediately to mind; you will probably have had half a dozens ideas of your own by now. It's tempting to try and fit innovative new devices like this one into the familiar CCTV pigeon-holes but the SWC40 isn't so easily categorised. Solid-state digital video recording is a fast developing technology and we suspect this is just the beginning.



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                         ****                           



ã R. Maybury 1999 0705



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