HD-CCTV system based on HD-SDI transmission technology
There are HD or Megapixel when it comes to recent CCTV market technology. The change from previous SD to HD means not only about change of picture quality but also whole system change. Especially IP solution was demanded and popular in the market to satisfy needs for sending high quality images requiring larger data size of transmission. But sudden change from system using conventional cable into IP system demands high cost and time and it was such a burden on users who run system in small scale. So the HD-SDI transmission method is introduced as suitable solution. There are HD-SDI products being released in the market from this year with the benefit that HD-SDI transmission can be achieved using conventional cable installed in site. Here we need to understand about system with HD-SDI transmission technology and issues about HD-SDI technology.
What is HD-CCTV?
CCTV(Closed Circuit Television) is method to transmit signal to limited monitor of certain place using monitoring camera. The current security market is led by HD leveled sensor and it started to be adopted for CCTV market. Here if we name previous CCTV as SD-CCTV product, we would define HD leveled CCTV system as HD-CCTV system. And we would call CCTV system using HD-SDI transmission technology as HD-CCTV. The reason is that HD-SDI transmission technology is being developed into most reasonable technology to transform conventional CCTV into HD-CCTV which is another way of transmitting HD quality picture being distinguished from IP network transmission.
HD-SDI transmission method
Transmission technology briefly. HD-SDI transmission is achieved throughout Coaxial cable. This means that HD leveled image can be transmitted using conventional SD-CCTV cable installed already in fields. For example, camera has HD-SDI output and DVR support monitoring and recording in a way that conventional SD-CCTV does. In the future, not only images but also Audio, Control signal and Power can be achieved or transmitted via coaxial cable. For reference there are chip solution supplier about HD-SDI transmission technology such as Gennum Corporation, Mindspeed Technologies and National Semiconductor. At this present HD-SDI transmission technology feature is achieved in Logic device(FPGA) and adopted to product. Let’s check about differences of transmission method between HD-SDI and SD method. As you see in below chart, same coaxial cable is being used but there are differences in transmission method between Digital and Analog , differences in frequency and transmission distance. The below picture is one example for various monitoring cameras using HD-SDI transmission technology become whole HD-CCTV system together with HD-SDI DVR. Here HD-SDI camera, repeater, DVR are being used. HD-SDI repeater is being used in between during transmission to make HD-SDI transmission distance longer.