How analog CCTV systems work

The concept of traditional analog CCTV systems is quite simple, a camera must be connected directly to a monitor through coaxial cables that can carry the analog signal.

The first analog CCTV cameras was a very low-resolution model. It was impossible to observe the details of objects and people with such a camera.

Resolution on analog CCTV systems is measured in TV lines, which represents the number of lines generated and displayed on a monitor. This type of system will cease to exist in the next few years.

Traditional analog CCTV system

The idea of a CCTV system is to generate, store and display the videos on a monitor, the diagram below exemplifies this concept on the 3 blocks. 

The CCTV cameras generate the images, a recorder stores the footage and finally, a monitor displays the video from the camera or tape recorder.

On old CCTV systems, the videos from the cameras were recorded in analog format by using a VCR (Video Cassette Recorder).

To date, this VCR recording technology is obsolete, but decades ago that equipment was manufactured to ensure high-quality recording.

It was very common to discuss which were the best VCRs, many of the best ones were developed and manufactured in Japan with the latest technology.

Now it's not easy to find VCRs being used on CCTV systems because have changed from analog to digital.

CCTV on tapes

Cassette tapes for VCRs were produced on a large scale for use throughout the world in residential and industrial systems, but the technology has many limitations in terms of quality and practicality.

The first recording systems were composed of low-resolution cameras that generated black and white images for display on monitors and store on simple recorders with VHS tapes.

Recording on cassette tapes was done in a linear manner, which made it very difficult to search for recorded evidence since it was necessary to "run the tape" until reaching the point of interest where the event was recorded.

Another major problem with cassettes for to CCTV footage was the quality deterioration of new copies of the tapes.

Monitors and joysticks for CCTV

Nowadays it is very common to find LCD and LED monitors displaying high-resolution images. But that was not the case for old CCTV systems. 

In traditional CCTV systems, it was common to use VCRs connected directly to analog monitors

The idea is to bring the signals from the cameras to the VCR to record the footage and display it on analog monitors with the maximum number of lines, which means the system has high-resolution.

Some camera mounts have an internal motor that allows controlling the movement of the camera directly from the surveillance room by using a joystick.

Even in an analog CCTV system, it is possible to use cameras with advanced features. Those cameras can be controlled remotely from the surveillance room by sending commands from a joystick. Those camera models are known as PTZ (Pan, Tilt, and Zoom), have a built-in motor to control horizontal, vertical and zoom movement,

There are several models of CCTV cameras with analog technology, but with different protection housings to meet specific installations. Sometimes it is necessary to use domes or bullet cameras with infrared.

In large CCTV projects, it is possible to find a mix of CCTV camera models, most of them have a fixed viewing angle and other models such as the PTZs mentioned above are used for patrolling the area.

Currently, the number of CCTV cameras scattered throughout cities and commercial establishments is scary. Due to the low cost of new electronic security products such as cameras and recorders, there has been a proliferation of security camera installations in all countries.