BOOT CAMP 367 (08/03/05)

CAUGHT ON (WEB) CAMERA, part 2

Following on from our introduction to IP surveillance last week we conclude this short series with a look at the hardware and software you will need to set up your own home video security system.

The first and most important component is the PC and this can be any reasonably recent model with an 800MHz or faster processor and at least 128Mb of RAM (obviously more is better in both cases). This is a perfect application for a redundant PC, however, it’s not a good idea to use your main work or home PC as it needs to be left on all of the time and video recording swallows up a lot of resources so it’s better to dedicate the PC to this single task.

It is important to have plenty of free hard disc space but rather than try and cram everything onto a single drive the trick is to install a second slave drive. This will leave the main drive free to run Windows and the security software with the images from the cameras recorded on the slave drive. The size of the slave drive determines recording times so the bigger the better. As a very general rule of thumb continuous video recording from three or four cameras, say, will use between 5 and 10Gb of space per day, so a 80Gb drive would be a good starting point.

Next the cameras. It’s tempting to use cheap and cheerful USB ‘webcams’ but these have a number of limitations, not least relatively poor image quality and lenses that are intended for close-ups. Webcams are also more difficult to use in a multi-camera set-up and there’s a restriction on cable lengths of around 10 metres.

Domestic ‘analogue’ video security cameras are ideal for this application; they’re relatively inexpensive (prices start at around £40 from DIY stores), most models are weatherproof, image quality is generally very good, they have better low-light performance and more flexible exposure systems, moreover, cable lengths of 100 metres or more are possible.

Using analogue video cameras also makes it easier to upgrade to more specialist types with superior picture quality, better lenses and ‘zero lux’ or ‘day/night’ models that produce a useable image in total darkness or near dark conditions. Wireless cameras are also available for installations where it’s difficult or impossible to run a cable.  

The final link in the chain is the interface between the PC and the cameras and the most flexible option is a plug-in PCI video ‘capture’ card. There are plenty to choose from (see Tip of the Week) and I suggest starting with a 4-port design which can be used with up to four cameras, Additional cards can usually be added if and when you want to expand your system. Some capture cards also have an audio input, so you can record sound as well. This is a worthwhile extra, many domestic security cameras have built-in microphones and the sounds captured during a burglary may provide valuable evidence.

Most capture cards come with all of the software you will need to display images on a PC monitor -- usually a choice of a single camera view or multi-screen ‘quad’ format. The software also handles the picture (and sound) playback and recording, with a choice of record quality and compression settings that determine recording duration.

Many capture cards have motion detection facilities. Each camera image is divided up into a grid of variable-sensitivity ‘targets’. These can be selectively enabled or disabled to avoid false alarms by ignoring movement, such as small animals or a tree or bush blowing in the wind, and concentrate on areas of the image where no movement would normally be expected.

Depending on the type of card motion detection may be used in a number of ways. Virtually all systems imprint a ‘flag’ on the recording in response to an activation, making it easier to review or locate specific ‘events’ during replay. Most systems can also be set to sound an audible alarm, display an on-screen message and trigger an external alarm.

Capture cards with dial-up Internet connectivity are usually quite easy to set up and can be programmed to send an email alert with a captured still image as an attachment, or an ‘alarm’ text message to a mobile phone. Several inexpensive capture cards also have network capabilities and live images from the cameras can be viewed, via a standard browser, on another PC connected to the network (by cable or Wi-Fi).

On some models it’s also possible to upload still or moving video images over a network or the Internet to a web site (your own, or space provided by a monitoring company) and allow PCs on the Internet to view live ‘streamed’ images. However, both facilities normally require a broadband connection, preferably with a fixed IP address. Most domestic broadband installations have ‘dynamic’ IP addresses that change with each time a new connection is made. That means it will be impossible to access the remote PC if, for any reason, the connection is broken or unreliable.

One final word of warning. Some capture card manufacturers glibly assume that their customers are well versed in the intricacies of networking, file transfer protocols, configuring Firewalls and the inner workings of Windows. This reflects the fact that this technology is still quite new and has only been available on the consumer market for a relatively short time. The more advanced capture cards and best avoided by complete novices but even old hands should check that both the supplier and card manufacturer provide lots of free support, you will almost certainly need it!

Next Week -- Ten things to do with an old PC, part 1

JARGON FILTER

PCI

Peripheral Component Interconnect - high-speed expansion/connector system used on most current PCs for sound, video, and network adaptor cards, etc.

QUAD DISPLAY

Split screen monitor display showing four simultaneous camera images

ZERO LUX

Video camera capable of operating in little or no visible light, using either very high sensitivity image sensors and advanced processing circuitry or viewing a scene lit by ‘invisible’ infra-red light

TIP OF THE WEEK

Four-port PCI video capture cards with bundled software are widely available from a number of UK suppliers; prices start at under £60. The software included with budget cards will have recording and playback facilities and in some cases motion detection as well. Cards with features like network connectivity and email notification generally cost a little more. Recording quality tends to be fairly good on the cheaper cards but for more demanding applications requiring higher resolution images and additional networking or remote access facilities you can expect to between £150 to £200.

Useful web links:

www.teamsolutions.co.uk/winnov/tsvid4100.html

www.edgarsson.co.uk/vidcap.htm

www.mediaatlantic.com/product.php/657/1327/

www.grandtec.com/prod05.htm

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