On the CCTV network

In essence, a conventional analogue transmission system is what's known as a 'point-to-point' system, with central points of control. A digital network, on the other hand, can have multiple points of image presentation (ie many cameras transmitted independently to many control stations). The digital network removes the need for a traditional matrix system as the network and the CCTV application can perform the matrix function.

A function of the digital network is the capability to record in high quality. There are other benefits to be had as well, though. For instance, increased and easier access to the video allows multiple points of control to be set up to the same images. Airport security management teams will often have a requirement to view the images simultaneously as several 'agencies' (including the police, the immigration services and HM Customs and Excise) may need to watch the same video stream at the same time.

Given that the British Transport Police has several control centres located around the M25, when a given centre is occupied in responding to an incident those officers at other centres can now monitor the remaining cameras at the same time. Similarly, blue chip companies operating across multiple sites around the UK may be more flexible, efficient and effective with the operation of their guarding teams (ie the officers can be centralised at night and then dispersed during the day).

Greater flexibility is another advantage of the digital medium. The network is scaleable, making it easier and faster to either add or remove cameras and viewing stations. This also reduces any disruption caused by installing dedicated cables to the system. In addition, an analogue CCTV system with more than one control system and/or multiple cameras is quite complex and cumbersome to cable, manage and operate.

A digital network allows simplified cabling and easier connectivity – good news for you and your installer. Don't forget that digital systems are also capable of carrying other systems including telephone and data networks, although dialogue with your IT manager will be essential here.

Higher system resilience is a further benefit. A digital network is capable of routing data in different ways to ensure that it reaches its destination. Analogue systems, on the other hand, operate solely on the aforementioned point-to-point basis with no fallback if there's a failure. An analogue system can completely fail from a single point (eg if a fuse blows on a matrix) whereas the digital network has the capability to use hot back-ups (thus images will still be available even if multiple failures occur).

In this sense, the choice between analogue and digital surveillance is (to a degree, at least) dependent on how crucial the system is to your security operation. Many teams at airports and other high security installations may not be able to perform with any degree of authority if the system should fail.

Signals, fibres and multi-service
Even though ISDN systems have been used for many years for remote manned guarding operations, transmission over longer distances is much easier using a digital video stream than it is an analogue signal. A digital network enables a quicker initial connection and, as long as the bandwidth is available (remember to talk to your IT manager!) the images will be of a superior quality and boast a far higher update or refresh rate.

Analogue systems can easily transmit CCTV images around a large site using either fibres or co-axial cable, but there are drawbacks with that over longer distances. Without going into too much technical detail and blinding you with science, the digital signal is easier to regenerate without errors – rendering them capable of transmitting video files over very long distances with no discernible differences in quality. A great boost to security managers responsible for a host of dispersed sites.

The amount of data that may be transmitted through cables is always growing. Currently, it's possible to send 10 Gbits per second (10 billion bits per second) of data if you're using the latest transmission equipment. In other words, you can fit 1600 camera feeds along a fibre pair using a digital signal. Paradoxically, analogue techniques can only support around four cameras.

A major advantage of most digital systems is their capability for using the fibre optic infrastructure more efficiently. This will reduce the cost of installations quite dramatically, owing to the lower requirement for fibre. Good news for the security professional who has been dealt what they might feel to be a low systems budget for the New Year.

In truth, the cost benefits here would be most readily apparent in road and rail security and surveillance applications, where available fibre is limited and the distances to be covered are vast. It then becomes quicker – and more cost-effective – to install a high data rate network on the existing fibre infrastructure than to lay new fibres for a system expansion.

Of course, end user organisations are always looking to improve the performance of their existing systems and infrastructures (usually by employing, wherever possible, the very latest technologies). CCTV is but one of those systems and, rightly or wrongly, is often low on the list of corporate requirements for Boards of Directors who are, shall we say, less well educated in security as a discipline.

Having said that, the ability to provide multi-service networks that can incorporate other systems (including CCTV) is bound to harness their interest.

Advantages for the end user
As we've seen, networks can carry all manner of communication systems while analogue CCTV systems are dedicated. Additionally, analogue set-ups will often require separate cables for the video to enable the transmission of data to control PTZs.

Digital networks go much further than that, with the ability to transmit almost every type of data for all types of system (eg data for computer systems, printers, telephony, access control, Public Address, the Internet and CCTV). This data transmission is also standardised under the auspices of Institute of Electrical and Electronic Engineers' guidelines – meaning that it's not proprietary, and clients cannot be locked into a non-standard system.

In a nutshell, then, there are several advantages to be gained by end users 'going digital'. There'll be reduced installation costs as less standard cabling equipment is needed. Lower maintenance costs will result, too, as fewer specialists will be needed for what is a multi-service system. In addition, there's a greater reliability in network topology such that all systems carried will benefit.

For those looking for integrated solutions, look no further… Digital systems allow the CCTV system to work more efficiently within the organisation. For example, the input of an alarm from the surveillance unit can then initiate a generation of wider communications from e-mails and SMS text messages through to sending video images directly to a hand-held PC via a wireless Local Area Network. Thus, security officers can be situated at a remote site (or at any location that links to the network) allowing a reduction in end users' on-site security costs. As stated, sites can be managed locally during the day, and then centrally from a remote location during the night.

As codecs remain highly priced in relation to analogue technologies, the cost benefits (for the moment) only really occur for larger systems where more applications are brought onto the network. However, as the costs begin to fall so too the size of system required to demonstrate a cost benefit will reduce in scale.

Traditionally, remote sites have always been protected by guard patrols and on-site officers monitoring CCTV images in the Control Room. Both approaches have drawbacks. They can be expensive, and offer limited effectiveness. After all, security officers can only be in one place at a time, and will not always be 100% alert. Officers are prone to attack, and it can actually be the quality of the personnel employed on site that makes up nine tenths of your security problem.

Remote connectivity to remote camera systems offers flexibility in terms of system management, as there's less need to have multiple people to hand who are capable of understanding the requirements of the system (as it can be controlled on a central basis). Also, this may help in maintaining police response if there is a major problem on site.

As many of you will doubtless be aware, the Association of Chief Police Officers' (ACPO) 'Security Systems Policy 2000' alters the way in which the police services respond to alarms, preferring systems that offer visual confirmation of a need for that response.

Think of the overall solution
All of these benefits are only benefits if the end user perceives them as being useful and applicable to a given situation. Both analogue and digital systems must be compared as overall solutions and not on a product-by-product basis. Potential customers should concentrate only on the overall business objectives of the system rather than on which products to put in.

In conclusion, there are far too many misconceptions in the marketplace (certainly among consultants and installers) concerning networked CCTV. Those misconceptions are generally based on either a lack of knowledge or indeed on presumed knowledge.

Although they're not a panacea for all surveillance ills, that should not stop end users from trying IP-based systems for size.