Then you have to provide for power distribution: analog CCTV cameras and other devices such as multiplexers and DVRs all need individual power supplies, which require cabling, AC outlets and wall warts, which in turn means involving electricians in the installation. Uninterruptible power supplies (UPSs) will be required at each device for mission critical systems, or a separate UPS reticulation system must be provided, in case of power failure.
Power over Ethernet (PoE), sometimes referred to as Power over LAN, allows IP-based surveillance systems to realise savings of up to 80% on traditional analog installations. PoE is a revolutionary technology that integrates data, voice and power over standard LAN infrastructure. It works across standard Ethernet network cabling (ie, CAT-5) to supply power directly from the data ports that the networked devices are connected to. Standard CAT-5 Ethernet cables have four twisted pairs, but only two of these are used for 10Base-T and 100Base-T data. The other two pairs can be used to deliver power to networked devices: with one pair delivering positive current and the other negative, a versatile power supply can be provided through use of DC/DC converters. Over two million PoE ports are already installed, and PoE came of age with the introduction of the IEEE standard 802.3af in June 2003.
802.3af enables the safe transmission of electrical power to networked devices without any degradation of network performance. It defines how to deploy PoE across multiple networked devices including network IP cameras, and vendors of laptops, Voice over IP terminals, mobile phones, IP surveillance systems as well as integrated building management systems are already looking to pre-install it.
Understandably, those that watch this technology predict massive growth in its use. This article will look at the benefits of PoE for surveillance systems: unlike traditional CCTV, IP surveillance can take full advantage of PoE to reduce installation and management costs dramatically.
The immediate and most obvious cost saving is in the physical cabling and its installation. Ethernet cable is cheaper and easier to install and is often either already present or going to be installed for other network purposes anyway. Multiple cameras can share cabling, so the number of individual cable runs is reduced, and peripheral functions such as voice and control signals can also be carried on the same cables; and of course, power cabling is eliminated, further reducing cable run count and cost. There are, however, still further benefits to be had.
First, PoE has evolved to the point where it is a more intelligent power source than traditional ones are, out of the box. The power sourcing equipment (PSE) within PoE is capable of providing a high level of system management using existing system management protocols such as Simple Network Management Protocol (SNMP). This makes it possible to monitor, report on, and even shut down power centrally through the network for maintenance, for example.
Second, PoE makes it easier and more cost effective to make the power supply to IP surveillance systems highly robust. Most computer networks of more than a few PCs already have a central UPS: the centralisation of power through PoE hubs (often called Mid-spans) means that PoE-based systems piggyback on the central UPS without additional cabling or special reticulation. This ensures that any power outages, which we are told will be more likely in the future, will not affect the integrity of the IP surveillance system.
Third, PoE hubs or mid-spans let security managers shut down or reset devices remotely. Malfunctioning networked devices can be identified and reset at the touch of a button. Devices being replaced can simply be isolated from power, a new device installed and then re-powered up.
Fourth, centralisation of power supply control eliminates the security vulnerability so often created by the 'vacuum cleaner effect', where someone carrying out a service such as cleaning or building work carelessly unplugs a power point used by a camera. It is not uncommon for vulnerable organisation such as hospitals to lose surveillance capability at specific times of day while cleaning is in operation. Any regular events like this, which can be spotted by a criminal, could easily be exploited over time.