In this article, you find the answer to the question "What is CCTV?" and not only that, you will also understand the essential details about surveillance systems.
Modern technology helps to secure places with the use of access control and modern security cameras. Perhaps you already saw the term "CCTV" while researching around, but you don't know what it means.
What is CCTV?
CCTV stands for Closed-Circuit Television. It's a video surveillance system used for security purposes. The first CCTV system with analog cameras was used in 1942 in Germany to monitor rocket launch and later evolved to a more sophisticated system that uses digital surveillance cameras with video analytics capabilities.
There are many modern CCTV cameras that can be used for different applications, even for home security.
Many modern CCTV cameras can be used for different applications, even for home security. Let's take a look at some of them.
Applications for CCTV
CCTV cameras are used mainly in the following places:
- Police Station
- Commercial Centers
- Vehicles (Truck, buses, car, trains)
- Train station
- Bus station
How do CCTV systems work?
Suppose you install security cameras in malls, shops, schools, businesses, or other locations and take the cables from each of the cameras to a recording and monitoring center. In that case, you will have your Closed Circuit Television, which can record footage from the cameras.
At first, security systems could not be monitored remotely; operators were required to look at the screens for something suspicious and react according to some security protocol.
Security systems help on crime prevention
One of the ideas of using cameras to help law enforcement avoid or reduce the incidence of crimes, since cameras are installed in closed or public places, there is a tendency to minimize crimes because the area is being watched, the criminal thinks twice before acting.
It's hard to say with 100% certainty whether you are being monitored when walking through public places. With the massive production of new security cameras, it is easy to find them installed in many areas.
Traffic and accident control
You will hardly drive on the road from one city to another without being monitored by at least one security camera. Nowadays, it is very common to find them installed on poles along great highways and even on streets and avenues of small and large cities.
Security systems have become essential tools for traffic and accident control in various locations around the world. From a surveillance center, it is possible to view images from all the cameras.
CCTV security systems for business
Factories, banks, and many other types of companies use security cameras to monitor manufacturing processes and products; some even use them to control activities performed by employees to record what is happening during working hours.
It is common to have recorded evidence of employees' misbehavior to be used in lawsuits. Sometimes the footage can also benefit the employee. It all depends on what is on the CCTV footage of the video recorders.
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 were a very low-resolution model. It was impossible to observe the details of objects and people with such a camera.
With the resolution measured in TV lines, representing the number of lines generated and displayed on a monitor, this type of system will cease to exist in the next few years.
Traditional security systems
A CCTV system's idea is to generate, store, and display the videos on a monitor. The diagram below exemplifies this concept on the three blocks.
The cameras generate the images, record the footage, and finally, a monitor displays the video from the camera or tape recorder.
The videos from the cameras were recorded in analog format by using a VCR (Video Cassette Recorder) on old CCTV systems.
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 argue about what are the best VCRs. Many of the best ones were developed and manufactured in Japan with the latest technology.
It's not easy to find VCRs being used on such systems because they have changed from analog to digital.
Recording with tapes
Cassette tapes for VCRs were produced on a large scale throughout the world in residential and industrial systems. Still, 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 linearly, 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.
Monitors and joysticks
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 camera's movement directly from the surveillance room by using a joystick.
Even in analog systems, 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, known as PTZ (Pan, Tilt, and Zoom), have a built-in motor to control horizontal, vertical, and zoom movement.
There are several 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 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 cameras scattered throughout cities and commercial establishments is scary. Due to the new electronic security products' low cost, there is a proliferation of such a device in many countries.
Evolution of video surveillance systems
Over time, analog systems have evolved into digital recorders known as DVRs. The acronym is original from the name Digital Video Recorder.
When using a DVR to record the footage from security cameras, there is a conversion of the analog to digital signals before recording and transmission over the local network or Internet.
Usually, the footage is recorded based on motion detection to save storage space, which is very useful in modern video surveillance systems.
This recording method is standard among systems with analog or IP cameras.
Modern security cameras
In addition to analog systems' evolution to the hybrid version that uses DVRs for digital recording, new technologies have also emerged from analog systems that can provide higher resolution and thus better image quality.
These technologies are known as HD-TVI, HT-CVI, and AHD. To learn more about such technologies, read the article: HD-TVI, HD_CVI and AND comparison
It's also common to use IP cameras for the new security projects.
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Claudemir Martins is a former Samsung Engineer with 18+ experience in the surveillance industry. He has been traveling around 17 different countries to teach people how to design, and install CCTV systems.