The ABC of IP (Part 1)

IP technology is now used in a wider range of applications than ever before. IP products in our homes can be addressed and accessed from anywhere with a connection to the Internet – which is never any further away than our mobile phones.

We will soon be able to make sure that our central heating is turned off if we are unexpectedly delayed at the office, and then turned on before we get home. Fridges will know what food is available, if it is still in date, and will automatically re-order as it is used. It will also be able to suggest recipe ideas with the ingredients you have available.

Constant monitoring systems can detect water leaks or sudden rises in temperature and alert the homeowner if there is a problem as soon as the fault occurs, giving peace of mind when away from home. Although it may seem to be a long way off, this type of Internet home is closer than you might think … and security installers are well placed to take advantage of this new business opportunity.

This level of control and interaction has been made possible by using Internet based technologies. In the same way that our homes can be automated and monitored when we are away, a company's security system can also use this technology.

In a corporate environment IP surveillance shows cost savings for companies in several areas. In many cases, security equipment can be added to the existing IT infrastructure requiring very little additional cabling to be installed, representing a cost benefit to your customer and causing much less disruption.

Unlike passing video along a single coaxial cable, as with traditional systems, information is sent across a network of devices - a network, in its simplest form, being two or more devices interconnected.

Benefits of sharing

When a large number of devices are connected to a network the benefit becomes clear. This ability to share a 'channel' allows many devices, each with their own specific application to co-exist on the same network and, when necessary, communicate with each another.

No longer do organisations need to rely on a individual to preserve evidence at a site ... control can be from anywhere

Equipment can be added or removed from the network, normally without disrupting existing network members, meaning that a single network has the ability to cater for a much wider range of solutions that may be changed constantly, unlike a closed system.

For all these devices to operate correctly they need to communicate with each other efficiently and securely even if they are not within close proximity. Each device also needs its own unique identity address.

This addressing issue is handled by the Internet Protocol (IP), the purpose of which is to route information across a network. Each device is given a number unique to that network known as an IP address. When a device has information to be sent across the network, it breaks the information down into small, manageable 'chunks', known as an IP packets or datagram's. These packets are labelled with important information which includes the address of both the sending and destination devices.

It is only in the past few years that IP technology has become accepted as a viable alternative to traditional CCTV-style surveillance. Unlike its closed counterpart, IP surveillance opens the security system to a wider audience, allowing remote monitoring of systems.

Controlled from anywhere

No longer do organisations need to rely on an individual to preserve evidence at a site, instead this control can be taken from anywhere on a company's network, or even the Internet. Recordings from a remote site can be transmitted across the network to be reviewed and passed on to the relevant authorities as evidence.

A total IP solution is not practical for all organisations, for the most part existing cameras may not require replacement, or cabling is already installed and operational. On the other hand, existing security equipment may be non-existent or under-resourced, in this case a different system may be considered. IP systems can form a smaller part of the overall solution, known as a hybrid solution. This is where the system is primarily analogue and at some point this information is transmitted over the network.

Although very basic in its operation, ‘pinging’ is invaluable for checking a network for a new device

The diagram (Fig 1 on previous page) shows a comparison between IP solutions and traditional CCTV solutions, the hybrid solution uses a combination of the two.

Digital recording and codecs

Digital recorders are an example of how we can use hybrid systems to further enhance existing systems. In the example (Fig 2) the digital recorder uses a composite video signal from a standard camera to record. Images from the camera are displayed on a PC connected to the network, using the digital recorder to process the information.

This solution is complementary to a system where the cameras are using analogue video signals. Therefore, a recorder that accepts this signal is required. However, if a Network Video Recorder (NVR) is used in place of a digital time lapse recorder, the images from the camera can be transmitted over the network to the recorder. A video codec device (Fig 3) is used to convert the analogue signal produced by the camera to a format suitable for the network.

Unlike the previous example, this solution puts a much higher, continuous load on the network, as video is being transmitted across the network almost all the time, not just when an operator reviews footage. The design of the network must be considered when adding cameras and recorders. Most offices and buildings use Category 5e (Cat 5e) cable to form communication between network devices, whether this is PCs on employees desks, IP telephones for voice over IP, (VoIP) or network enabled printers. Devices on a network connect to a central location in a star configuration, normally to a switch or hub. The role of this equipment is to pass data only to the relevant device on the network. For example (Fig 4), if A has information that it needs to send to D, the switch ensures that the data is only sent from A to D, reducing unnecessary information being passed across the network.

Making larger networks

These network switches can be joined together to provide a larger network of devices. Each switch on the network forms a segment of the LAN. A high speed link is made between these switches. Again, data is only sent from one device on the network to its intended location, reducing in the amount of traffic on a single switch considerably. As the network increases in size and becomes more heavily populated, this has enormous benefits.

In the diagram (Fig 5) there are four devices attempting to communicate with one another, A to F and B to C. Only the data from A is passed across the link to the second switch. Therefore, data from B is only handled by its local switch.