A suitable case for networking?

Imagine this scenario …You are discussing a new CCTV installation with a potential customer. He wants to be able to view the pictures from the system on a screen in his office, and he wants his operations manager, who works in another building, to be able to view them at the same time.

Your customer also wants pictures of the car parks and the front door to be viewable at the reception desk. Finally, he wants all of the images produced by the system to be recorded in a secure central location. Until recently, your response as a security installer would undoubtedly have been to offer a conventional analogue system.

Conventional systems do, however, have a number of unavoidable disadvantages. The first is expense, particularly when the cost of connecting the operations manager in a separate building is considered. The second is that installing the system is time consuming and disruptive, and the third is that all users need a dedicated monitor on their desk to watch the CCTV images, even if they already have a monitor for their PC.

The networked alternative
All of these shortcomings can be overcome by offering a solution which distributes the CCTV images via an Ethernet network, particularly if much of the necessary network cabling already exists. A network solution is, therefore, likely to be very attractive to the customer, so let’s have a look at ways in which it could be implemented.

Survey results
So that we can examine the network options in more detail, we need more information about the installation. Let’s agree that, for our installation example, a site survey and customer discussions have produced these results (see Fig 1):

• 11 external cameras, all of them fixed, will be needed.
• 5 internal cameras, also all fixed, will be needed.
• Event-driven digital recording, capable of storing images for at least two weeks, is required.
• There must be a facility for exporting images to a CD or other permanent storage medium.
• While in his office (Location A) the general manager needs to be able to view pictures from any of the cameras at any time. He would also like to explore the possibility of viewing pictures from home.
• The operations manager needs to be able to view images from all of the cameras while in his office (Location B).
• The receptionist (Location C) needs to be able to see the front door, and the car park areas.
• A digital recorder will be installed in a locked cupboard in the main building.
• All images will be distributed via the existing network installation.

The preliminary meeting
With the survey complete – but before any design work is carried out – a preliminary meeting with the customer is necessary. It is absolutely essential that the customer’s IT department is represented at this meeting.

This is because the IT department will almost certainly have the final say about whether the CCTV equipment can be connected to the network. It is also because the success of the installation, as we shall see later, depends critically upon the support and co-operation of the IT department.

Network Capacity
At this meeting, the IT department will primarily be concerned about whether the existing network has sufficient capacity (bandwidth) to handle the CCTV images without seriously affecting its performance. With modern, fast networks, bandwidth is not a major issue but, with older networks, it may be the factor that decides whether or not a networked CCTV installation is possible.

To make a decision on network capacity, the IT department will need you, as the installer, to provide information about the number, rate and file size of the images produced by the system. Supplying this information should not be a problem, however, as it will be readily available from the manufacturer of the CCTV equipment.

The bandwidth required will be influenced by the number of cameras, the resolution of the images, and the type of file compression algorithm used. As an aside, it is worth mentioning that these same factors dictate the amount of digital storage needed for the images. Once again, the equipment supplier should be able to provide a good estimate of the necessary storage capacity.

Making the connections
After reaching agreement with the IT department, the next step is to consider how the CCTV equipment is going to be physically connected to the network. While use will be made of the existing network infrastructure, some additional cabling is almost always going to be needed. Installing this new cabling and the associated network points is well within the scope of most CCTV installers.

It is important, however, that whoever carries out the work has had proper training on the installation of CAT5 UTP cables. This training, which is an excellent investment, is necessary as there are standards involving, for example, cable bunching and minimum bending radius, which must be observed. It is also worth bearing in mind that the IT department will undoubtedly check the performance of new cabling before it can be linked to the existing installation.

Now, let’s take a look at some of the ways our example system could be implemented.