The present invention relates to systems which provide power over a communication or transmission line or medium, such as over coaxial cable, to remotely located equipment and devices.
Increasingly, remote devices are being provided with the ability to be accessed virtually. For example, security cameras are migrating from black and white closed circuit analog devices to digital devices with connectivity to the World Wide Web. It is cost advantageous to continue to use the installed infrastructure of coaxial cable for the new digital cameras. In addition to sending of digital data full duplex over the coaxial cable it is also advantageous to send power over the cable from the data collection side (local) to the camera (remote). This power can then be used in place of mains alternating current (AC) power for powering the camera. This allows more flexibility for the installer to move the camera without the need for an electrician to also move or add AC mains power. Newer devices other than cameras can also benefit from being provided power over installed coaxial cable, or alternatively being provided power over a pair of copper wires routed along with a fiber optic cable.
The injection of direct current (DC) power into an infrastructure that previously had no applications using this type of energy can have several unintended consequences if the DC current were to be arbitrarily applied to the coaxial cable or to the copper wires routed with a fiber optic cable. The first being damage to legacy equipment that may still be connected to the coaxial cable or fiber optic cable. Particularly true of coaxial cable, a second consideration is the coaxial cable at the remote end may also be unterminated with bare wire that could possibly arc and create a combustion source if the cable were to come in contact with a metallic object or some other electrical device.
In order to eliminate such possibilities, it is prudent to first determine that there is equipment at the remote end of the cable that can be positively identified (classified) as being able to operate with a DC current before the local equipment injects a DC current onto the coaxial cable or pair of wires routed with a fiber optic cable.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.