A family of progressive scan analog interfaces for CCTV surveillance systems. Rather than change CCTV systems entirely to IP cameras, HD Analog options were introduced in the 2010 time frame to provide easier upgrade paths. HD Analog cameras support 1080p video but also use the existing coaxial cable network. See network camera, CCTV and surveillance camera resolutions. HD-TVI (Transport Video Interface) An open standard for 720p and 1080p video, HD-TVI is available in numerous analog surveillance cameras using coax up to 1,600 ft. and twisted pair CAT5 up to 700 ft. HD-TVI also supports IP cameras. HD-CVI (Component Video Interface) A proprietary standard for 720p and 1080p video, HD-CVI also supports IP cameras in certain configurations with cable lengths similar to HD-TVI. AHD (Analog High Definition) An open standard for 720p and 1080p video with 1080p cable lengths up to 1,600 ft. and 720p to 492 ft. AHD does not support IP cameras. HD-SDI (Serial Digital Interface) Although a digital interface at 1080p resolution, HD-SDI uses coaxial cable, which allows for integration into existing CCTV systems when hybrid DVRs are installed. However, cable distances are considerably shorter than HD-TVI, HD-CVI and AHD. See HD-SDI, SDI and hybrid DVR.