HD-SDI (High Definition Serial Digital Interface) provides high resolution digital video over coaxial cables. These surveillance cameras can capture 720p or 1080p resolution video and transmit it 100 meters or more over a standard coaxial cable. These security cameras are also sometimes referred to as HD CCTV. They provide high resolution video but still transmit over coaxial cables. HD-SDI’s resolution and transmission range rivals that of IP systems but it is much easier to upgrade CCTV systems to HD-SDI than to IP. The HD-SDI surveillance cameras are the ideal choice for users looking to upgrade their existing CCTV system to high definition.