CCTV
Closed Circuit Television (CCTV) is a system in which the circuit is closed and all of the elements are directly connected. We know that, in broadcast television, from the airwaves, any receiver that is correctly tuned can pick up the signal. In CCTV this is different. Systems interconnected via microwave, infrared beams, and other means are examples of directly connected networks.
Figure: CCTV
The camera tube is used to transform light from an item that the camera is focused on into electrical impulses. The lens mechanism focuses light from the object on the light-sensitive surface (called the mosaic or photoconductive material) in the camera tube. An electron gun is housed in the camera tube, which creates and regulates a stream of electrons. The narrow stream of electrons is directed by the cannon in such a way that it crosses (scans) the mosaic line by line. When the beam hits a point in the mosaic, it creates a little electrical impulse that corresponds to the brightness or darkness of that specific small area of the image. The visual amplifier receives the electrical impulses created in this manner.
Control Unit :
In a CCTV, the control unit is considered as the system's heartbeat. This unit links all of the system's other components. Drive pulses are created, and the camera's sweep and blanking signals are developed. The control unit sends synchronizing and blanking pulses to the receiver/monitor.
The camera's video signals are amplified and sent to the receiver/monitor. Vertical and horizontal blanking, sync, and video signals are among the control unit's output signals. The video amplifier, control amplifier, carrier, amplitude modulator, radio-frequency (RF) amplifier, sync generator, and audio controls make up the control unit.
A wide variety of frequencies can be amplified using video amplifiers. The video amplifier amplifies the camera tube's weak electrical impulses and feeds them to a control amplifier.
The control amplifier combines the video, sync, and blanking signals into a single continuous output to the amplitude modulator, all inappropriate order.
Synchronizing (sync) and blanking pulses are generated by circuits in the sync generator. The control amplifier receives these pulses, which constitute part of the broadcast signal. Horizontal synchronization occurs when horizontal scanning at the receiver and horizontal scanning at the camera occur at the same moment. Vertical synchronization keeps the receiver's vertical scanning in sync with the camera's vertical scanning.
The camera circuits also receive synchronization and blanking signals, which are used to generate the appropriate control signals for the electron gun and sweep voltages for the deflection coils (both horizontal and vertical). The main circuit of the carrier is an oscillator that produces a steady, continuous RF signal. Its frequency is set by the relevant civil authorities for the TV station where it is broadcast.
The video, sync, and blanking pulses modify the carrier signal in the amplitude modulator. The R amplifier amplifies the composite (total) signal before feeding it to the antenna for transmission into space.
A frequency-modulated R carrier transmits the sound part of the television broadcast. A microphone picks up the noises, which are then boosted by the audio amplifier and sent to the frequency modulator unit. The frequency of the sound earner is adjusted to match the frequency of the audio signal picked up by the microphone. An R power amplifier then amplifies the frequency modulated signal. The data is then transmitted into orbit through an antenna or a cable system placed throughout the ship.
Receiver/Monitor :
The receiver/monitor unit is the picture-producing unit. The only difference between the receiver and the monitor is the circuitry in each device. The receiver and monitor devices use different types of transmission medium. This discrepancy necessitates the use of extra circuits by the receiver. (Radio waves are used for the receiver, whereas cables are often used for the monitor). The antenna system, tuner, R. The basic TV receiver comprises the same circuits as the monitor, as well as the antenna system, tuner, and R.
Applications of CCTV :
Security systems and applications such as retail shops, banks, and government organizations are among the most well-known uses of CCTV. The real spectrum of possible applications is nearly limitless.
Examples are:
• Focusing on traffic on a bridge.
• Record the inside of a bake oven to figure out what's wrong.
• A makeshift technique for conducting a traffic study in a city center.
• For the animation of plasticizing puppets, the time-lapse recording was used.
• Used by a show's stage manager to see hidden sections of the set.
• Its widespread use in football stadiums.
• Vandalism was controlled by hiding in buses.
• Observing a gorilla's birth at a zoo.
• Using a big model helicopter to create a wildlife program.
• Replicating a goldfish's infrared eyesight!
• Photographs taken from a hot air balloon.
• Factory production control.