TELECAM CCTV CAMERA SYSTEM
WHAT OUR EXPERTS SAY...
Over the past five years advances in video
camera technology have had a tremendous impact on the security and surveillance
industry, that have been felt far beyond its traditional bounds. One
development in particular -- the sub-miniature ‘board’ camera -- has created
several new and thriving niche markets for covert and concealed cameras, and is
helping to ‘domesticate’ CCTV.
Tiny, low-cost board cameras, where the CCD
imaging chip, control electronics and usually a ‘pin-hole’ lens are integrated
together onto one postage-stamp sized circuit board, are now being produced in
vast numbers in the Far East. They’re simple to use, requiring only a
low-voltage DC supply, and a connection to the composite video input of any
video monitor or TV. Suggestions that that cameras can be purchased in bulk,
direct from the manufacturers, for less than £30 each, are probably not far
from the truth!
One thing is clear though, they’re
responsible for changing public perceptions, that CCTV is a complex and
expensive technology, used more or less exclusively by commercial, industrial
and governmental organisations. Now low-cost door observation systems, some packaged
for home installation, are being sold in DIY ‘sheds’, through mail order
advertisements, and even featured on the QVC satellite home shopping channel.
Whilst some installers and security specialists may regard these products as a
threat to their business, others see them as an exciting new opportunity, helping them to reach the
much broader, and so far, largely un-tapped consumer market.
Most of the systems that have appeared so far
follow a fairly predictable pattern. They’re being pitched at security-conscious
householders, enabling them to see who is at their front door, on their
living-room televisions. The cameras included in these packages come in a
variety of guises, styled to look like miniature surveillance cameras, or
hidden away, inside PIR detectors, door-bell boxes, porch lights or
anonymous-looking black-plastic domes.
The Viewmate Telecam System, (rrp £129.99)
which is the subject of this month’s Bench Test, is slightly different. Billed somewhat inaccurately as the worlds
‘smallest’ video camera (Matshushita might have something to say about
that...), it is nevertheless remarkably compact, so small and inconspicuous in
fact, that virtually no attempt has been made to disguise it, or make it look
like a security camera. The housing is a purely functional encapsulation,
protecting the electronics and optics from mechanical shock and the weather.
The rest of the system has a familiar ring to it, though. The 15 metre cable,
that carries both power plus video and audio signals -- to and from the camera
-- connects to a small black box interface module. This contains an RF
modulator, and power supply regulator.
The Viewmate box, which is a little thicker
than a pack of 20 cigarettes, has four sockets. Two of them are standard
co-axial connectors, for the aerial lead bypass to the TV. There’s a 6-pin mini
DIN socket for the camera lead, and a DC power socket, for the plug-in mains
Normally the interface unit connects between
the aerial downlead and the TV (and VCR, if one is included in the aerial
chain). The output on our sample was factory set to UHF channel 36. This will
almost certainly require re-adjustment as that clashes with the default channel
on a lot of VCRs and some satellite tuners, which in turn can cause problems in
areas where there are Channel 5 broadcasts. The RF output is variable, between
channels 29 to 39; the adjusting screw can be accessed through a hole in the
casing. The modulator (an ALPS module, similar to those used on VCRs and
satellite receivers etc.), also has a simple two-bar tuning pattern generator.
This is enabled from a small switch, in a recess next to the camera socket.
The camera module is incredibly small,
measuring approximately 25 x 25 x 18mm, with the lens barrel adding a further
15mm to the depth. To put that into perspective, the profile just a little
larger than a fifty-pence piece, it will fit snugly inside a matchbox! The
housing is completely sealed, the only opening is for the electret microphone,
on the underside of the module. There are no controls (accessible from the
outside), other than a simple twist-focus adjustment. Te focusing range is from
just a few millimetres in front of the lens, to infinity.
The lens is a 5-element, wide-angle type,
giving a 45 degree angle of view. The image sensor is an IR responsive VLSI
CMOS type, producing a monochrome image with a claimed low-light sensitivity of
1 lux. Gain control and electronic shuttering are both fully automatic.
There are two mounting options, based on a
simple bracket, held in place by two screws; this comes with interchangeable straight or right-angle ball
fittings, that clip into a moulded socket on the back of the camera. They’re a
good tight fit, allowing the camera to be easily positioned. However, this fitting method is far from
secure, and the camera easily detaches from its mount, with just a slight tug.
Fortunately, being small and unobtrusive, the camera is easily hidden and can
be discretely positioned above eye-level, where it will almost certainly remain
unnoticed by most casual observers.
Despite the fact that Telecam has been
designed for DIY installation, the instruction leaflet glosses over the
practicalities of fitting the mounting bracket and camera to wood or brickwork,
drilling holes through brickwork or masonry, running and securing cables.
Clearly some expertise is required, a useful cue for installers, to offer their
expert services, to customers put off fitting the system themselves. There’s helpful diagrams, showing how the
system connects together. It also mentions the fact that the cable can be
extended, to up to 50 metres, though the suggestion that ‘a four-core screened
cable with mini DIN connectors’ is required, will mean little to most
end-users; a pin-out diagram for the connector would have been useful. There’s
a fair amount of information, about how to tune in the TV, some helpful hints
and tips, for aligning the camera, and a troubleshooting guide, but with such a
simple system, and the almost complete lack of user adjustments , it doesn’t
stray much beyond the plainly obvious checks, that it is switched on, and
everything is plugged in.
Comparisons with other types of video camera
are difficult as this system uses RF modulation, rather than a straightforward
composite video feed to the monitor, so the image can be viewed on a normal
living-room television. However, using our standard test procedures, the camera
managed to resolve a little over 350 lines, using the RF connection, which is
about par for the course. However, noise levels were rather high, giving the
image a fairly grainy appearance, that no amount of re-tuning of the modulator
or TV could resolve. This is almost certainly due to the modulator, as the
off-camera signal is reasonably clean. If our sample is typical increasing the
length of the cable much beyond the 15 metres supplied would almost certainly
lead to a rapid deterioration in image quality.
The dynamic range is average, the exposure
system, optics and gamma correction appear to have been optimised for low-light conditions.
Low-light sensitivity is fair and it will produce a useable image with a normal
porch light. The lens produces some barrelling at the edges of the image,
though this is a reasonable trade-off, given the wide angle of view.
Audio from the built-in microphone is crisp,
and picks up incidental sounds within a metre or so of the camera, with no
difficulty. The output level appears to be on the low side, though, and on our
sample the TV volume control has to be set somewhat higher than normal
broadcast channel levels.
A slight intermittency on our test camera
resulted in the image and sound being lost. This was eventually traced back to
the camera, and twisting the cable slightly, where it enters the camera
housing, restored the signal. Since both picture and sound disappeared together
it’s likely the fault lay with the DC supply connection.
It’s difficult not to be impressed by the
small size of the camera, it’s performance less so, and we suspect the picture
could and indeed should be a lot cleaner. Noise levels on our sample were
bordering on the unacceptable. However, assuming that the noise and
intermittency problems are confined to our sample, it’s possible to see that
the system can work very well indeed. We’re a little sceptical about its DIY
credentials, though that could be resolved with better instructions, and maybe
a few little extras, even something as simple as a pack of cable clips would
help. The connecting cable could do with being a little longer, 20 metres would
be a good starting point. However, in the end it’s the tiny camera and
attractive price that sets this system apart form the crowd; it should help
spread the word and bring the benefits of CCTV to a much wider domestic market.
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 ****
Ó R.Maybury 1997 1202