HD-SDI is a new technology in CCTV that offers High Definition 720 and 1080P resolution video over standard Coax cabling. These HD-SDI CCTV products are ideal for upgrading existing analogue CCTV Installations where higher resolution HD images and performance are required.SDI is the transmitting technology through the 75ohm coaxial cable by serializing the video signal that is not compressed.The video signal that is transmitting through SDI is a kind of digital signal. Therefore, contrary to the analog signal which is influenced by the deformation of video signal and the distance of transmit, it is possible to transmit the video signal without limitation of distance and deformation of signal through Equalization and Reclocking of the video signal at intervals.