How does a CCTV Camera Work

At first, IP and analog cameras may seem more alike than they are different. Both cameras employ an analog image sensor, which is either CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor). Virtually, all analog cameras use a CCD sensor and IP cameras can utilize either type. The analog signal from the sensor is then converted to digital form by an analog-to-digital converter and further processed by the camera’s on-board digital circuitry (DSP).

For an IP camera the image is then compressed internally (encoded) and transmitted via an IP protocol (Ethernet) and is either stored in the camera or on a network video recorder (NVR). For an analog camera, the image is then converted back to analog by a digital-to-analog converter so the image can be transmitted to a video monitor or a digital video recorder (DVR), where the image is encoded and stored.

At this point, it seems the difference between the two types of cameras is negligible. Primarily, the difference is where the video is compressed and what components it utilizes. There are, however, significant qualitative differences between CMOS and CCD sensors, with CCD holding a demonstrable advantage in image quality over CMOS.