Door Phone Camera Transmission System Using Simple PVC Pair Cable

A residential door phone camera system usually employs the use of a multi-wired cable, including a coaxial one, to connect the indoor and outdoor units. Concurrently, interphone systems generally use a pair of PVC (Poly Vinyl Chloride) insulated wires. Therefore, for the purpose of converting this interphone system cable (which is already installed) into cable for a TV door phone system, a method using cable composed of PVC-coated parallel wires (each 0.5 mm in diameter and 100 m in length) has been examined under various conditions. This enables the multiplexed transmission of two-way simultaneous voice and picture signals, which are superposed on DC power, to be fed to an outdoor unit comprised, of a TV camera and processors.