The purpose of the transmission system in a closed circuit television (CCTV) installation is to provide reliable transmission of video signals between the various CCTV equipments in security, safety and monitoring applications. Along with high-resolution video interfaces and transmission, the analogue video signals are still in use today for video transmission and offer interlaced scanning and the film aspect ratio of 4:3. The complexity of a video transmission system varies in accordance with the requirements of the installation. Examples of the different types of video transmission systems covered by this European Standard are as follows: a) using dedicated cable transmission media: - coaxial cable; - twisted pair cable; - fibre optic cable; b) using wireless transmission methods: - microwave; - infrared; - radio transmission; NOTE 1 These transmission methods apply to non-compressed video signals. NOTE 2 Multiple analogue video signals may be combined in one physical transmission path using multiplexing techniques. c) using analogue high-resolution video interfaces: - VESA and VGA; d) using digital uncompressed high-resolution video interfaces: - HDMI; - DVI.