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: using dedicated cable transmission media: coaxial cable; twisted pair cable; fibre optic cable; 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. using analogue high-resolution video interfaces: VESA and VGA; using digital uncompressed high-resolution video interfaces: HDMI; DVI. This European Standard specifies the minimum requirements for the specification and testing of the performance of a video transmission channel involving transmitter, receiver or intermediate devices associated with the selected transmission media, for use in CCTV surveillance systems. Video transmission equipment may be combined with additional functions, e.g. for audio or data transmission. These functions are not included in this European Standard. This European Standard covers the transmission of colour and black and white video signals in accordance with the former CCIR Report 624-4, 625 lines, 50 fields per second and today ITU-R Report BT.624-4. IP based video transmission is covered in EN 50132-5-1 and EN 50132-5-2.