Analogue versus digital CCTV: should end users have a choice?

There are many industry practitioners who say that analogue systems and products are old-fashioned, not to say obsolete. That said, in the security industry it's perhaps no surprise to find that there remains a strong reliance on analogue, and that new multi-million pound security systems based on the technology are being specified and purchased.

While the cost-per-system ratio of analogue versus digital falls favourably within the realms of the tried and trusted equipment, end users' purchasing decisions need to encompass a good deal more strategic thought about the longer term future (and in particular how digital technology is likely to develop). Only then can purchasers be satisfied that they're receiving value for money, and a surveillance system that will boast the flexibility and development potential to meet the monitoring needs of tomorrow.

Further, digital technology is the route to fully-integrated and automated security systems incorporating a variety of bespoke features designed to meet a client's needs.

Clients are the major driver
The major stumbling block for digital technology is that it isn't in common use so it cannot be proven that it's effective and actually works. Many specifiers and installers aren't familiar with it. In most cases, they are reluctant to work with computer software because they don't fully understand it – and, if the demand from the client isn't there, there's no incentive to invest in additional IT resources or training.

In order to break through the problems associated with the acceptance of new – and largely untried – technology and operating systems, there's a need to involve a far greater number of individuals (and a good deal more professional expertise) in the purchasing process. An obvious candidate to bring on board would be the IT manager, because his or her co-operation (and enthusiasm) would be vital for the project to get off the ground.

Looking at a specific product that will be significantly affected by digital technologies, the future for CCTV is bound up very tightly with the benefits of IT developments. Although analogue images produced by CCTV have improved beyond all recognition in their quality and resolution in recent years, the difference that the digital platform can make is considerable.

First, digital images or recordings transmitted by a digital system remain clear despite the number of times they're transmitted. There is no degradation in the images, which remain in perfect condition.

Second, the toughest feature that a security system must handle is reversing a stored image such that a pictured event can be watched, rewound and watched again (eg to check the actions of a suspect). Difficult and time consuming on a VCR – assuming that a tape was in the machine and set to record correctly in the first place – but the digitally recorded ones and zeros in computer memory banks can handle this.

Many specifiers and installers aren’t familiar with digital technology. In most cases, they are reluctant to work with computer software because they don’t fully understand it – and, if the demand from the client isn’t there, there’s no incentive to inves

For access control, for example, the amount of data passing over a digital network is slow with a low rate of data exchange being no problem. However, the moving images in real-time CCTV need a big 'pipe'. In the past, image compression technology has hampered the use of digital applications, but the arrival of MPEG4 means that just 6 Kbytes of storage space per picture is required as opposed to 17-30 Kbytes on previous MPEG versions. That can be kept on a reasonably-sized hard disk.

End users demand flexibility Really and truthfully, it's in the demand for flexibility of operation that digital overwhelmingly wins out over analogue. The current situation, where separate security systems in the same Control Room are reliant on the vigilance of human reactions, just cannot provide the speed and accuracy offered by a pre-programmed digital system.

With the advent of XML providing the essential translation medium between the various protocols, the security manager will be able to enjoy an intelligent system.

By way of example, a digital fire system can identify not just the presence of a fire but also its exact location. This is based automatically on an XML message to the public address, emergency lighting and access control systems (the first of which will offer pre-recorded messages to direct the occupants away from the blaze via doors that have been opened by the system to provide the safest and quickest escape route).

Furthermore, digital technology operating over a common protocol can make it very straightforward to add further systems or features and operate them as part of an integral system. At the outset, the cost for the initial installation of the digital system can be comparatively expensive with the combination of cabling, routers, bridges and hubs – but once the basic infrastructure is in place, additions are simple and incremental rather than requiring a whole new set of cabling.

The common operating protocol of XML also makes it possible to have a competitive tendering process as there's no need to look for systems compatible with the existing system or go back to the original manufacturer.

It's almost inevitable that digital technology will replace analogue. It's a process that should be well underway in three-to-five years' time. In the meantime, there's likely to be a plethora of hybrid systems emerging as existing end user installations are replaced piece by piece.