What is CCTV and how does it work

CCTV, short for Closed-Circuit Television, plays a vital role in modern surveillance systems. It’s commonly used for home security, traffic management, crowd control, crime prevention, property and employee monitoring, and even wildlife observation. Installing a CCTV system involves connecting a network of cameras to a centralized hub, ensuring comprehensive and secure monitoring across various applications.

With the vast array of CCTV products available today, deciding which to choose can often be overwhelming. This article will explore the different types of CCTV systems and the essential components required for their setup. We’ll also explain how these components form a functional CCTV system.

What is CCTV?

CCTV refers to a network of cameras that transmit video signals to a specific set of monitors. The term “closed circuit” means the video is not broadcast publicly but instead sent to a select set of monitors accessible to a limited number of viewers. While these systems display live footage, they often include a recording feature for reviewing past videos. Modern CCTV systems also offer remote viewing and control via Internet connectivity, allowing access from anywhere.

CCTV systems can be classified in various ways, but the most common method is based on camera technology. The type of installation can also be categorized. Based on camera technology, CCTV systems are classified as follows:

SD CCTV
HD CCTV
HD IP CCTV
Megapixel CCTV
Thermal Imaging CCTV
AI CCTV

SD CCTV systems capture video in standard definition using analog cameras connected with coaxial cables.

HD CCTV systems, on the other hand, capture high-definition video, offering a resolution five times higher than the standard definition. For this reason, it’s typically more costly than SD CCTV. HD CCTV cameras are generally wired using Cat-5 cables, although some technologies allow coaxial cables for wiring.

Three primary HD CCTV technologies use coaxial cables: HD-SDI, HD-CVI, and HD-TVI:

HD-SDI (High-definition serial digital interface) transmits HD video signals digitally over coaxial cables, significantly upgrading analog systems. It’s the most dependable HD CCTV technology for use over coaxial cables, although it does come with a slightly higher cost.
HD-CVI (High-definition composite video interface) is a proprietary analog interface that transmits HD video signals through coaxial cables. It offers good image quality for a reasonable price.
HD-TVI (High-definition transport video interface) is a proprietary hybrid interface using coaxial cables to transmit HD video signals. It balances performance and cost.

In contrast to the limited 500-K pixel resolution of SD CCTV systems, HD CCTV systems offer significantly improved image clarity. With a 1080P resolution (2.1 million pixels), they provide a much sharper and enhanced visual experience.

IP CCTV cameras convert images into data, transmitting them over a network connection (LAN or Internet) without resolution constraints as long as sufficient network bandwidth exists. These systems offer resolutions ranging from 720P (standard definition) to 5K (five times HD quality).

Additionally, IP cameras are powered through Power over Ethernet (PoE), eliminating the need for separate power cables.

Megapixel CCTV systems provide higher resolution than HD CCTV, with video quality ranging from two megapixels (Full HD) to eight megapixels (4K). These systems offer enhanced image clarity, improved digital zoom, and advanced facial or license plate recognition features.

Thermal imaging CCTV systems detect heat signatures, which makes them highly effective for night vision and identifying hidden objects.

AI-based CCTV systems use artificial intelligence algorithms to analyze footage, detect anomalies, and issue alerts.

CCTV systems are also classified based on installation type into the following categories:

Standalone systems: are typically small-scale, featuring a single recording unit that supports a limited number of cameras, usually between four to eight channels.
Hybrid systems: integrate analog and digital cameras, gradually transitioning to IP technology and accommodating 16 or more cameras.
Centralized systems: are designed for large-scale use, and can connect hundreds or even thousands of cameras to a central recording server — with the added advantage of remote viewing through a network infrastructure.

It’s worth noting that the majority of CCTV installations fall into the standalone category, making use of HD CCTV or IP cameras. This widespread adoption underscores the practicality and effectiveness of these two technologies.

Hardware and software for HD CCTV

An HD CCTV system consists of HD cameras connected to monitors via coaxial or fiber-optic cables. The main components that form a complete HD CCTV system are as follows:

HD cameras
Coaxial or fiber-optic cables
Digital video recorder (DVR)
Surveillance hard disk
Power supply
Monitors

In addition to the hardware, CCTV software or video management software (VMS) is necessary to operate the system. Small-scale standalone CCTV setups typically use software running on the DVR, while larger HD CCTV systems require VMS to run on a server. Motion sensors, alarms, and access control systems can be integrated into the HD CCTV system.

The DVR can also be connected to an Internet router via an Ethernet cable, enabling remote viewing, playback, and system control over the Internet. The hardware setup involves connecting HD cameras to a DVR or server using coaxial or fiber-optic cables.

Coaxial cables are suitable for shorter distances and can transmit data and power through a single cable. However, they limit the range and resolution of the system. In contrast, fiber-optic cables can handle longer distances, delivering higher resolution and faster data transfer rates.

The cameras can be powered by a separate power line connected to an adapter or powered directly via the coaxial cable. The video captured by the cameras is transmitted to the DVR, displayed on a monitor via the software. The DVR is also connected to a surveillance hard drive, which stores the video footage for future playback or retrieval. The storage and playback are managed by the CCTV software running on the DVR. The monitor connects to the DVR via an HDMI cable to view the footage.

An IP CCTV system comprises network cameras linked to monitors via Ethernet or Cat-5 cables.

The essential components of an IP CCTV setup include:

IP cameras
Ethernet or Cat-5 cables
Digital video recorder (DVR) or Network video recorder (NVR)
Surveillance hard disk
Power over Ethernet (PoE)
Monitors

The system functions effectively with CCTV or VMS. This software operates directly on the DVR or NVR in smaller, standalone setups. More extensive systems typically require VMS on a server for better scalability and performance.

The IP cameras form a network with the DVR/NVR, transmitting video directly across the network. With sufficient bandwidth, IP cameras offer far superior resolution compared to HD systems. Thanks to its network-based architecture, scaling or expanding an IP CCTV system is easier.

The IP CCTV system seamlessly integrates with Internet infrastructure, enabling remote access to live and recorded video. Thanks to its computer network foundation, it offers advanced features such as data analytics, facial recognition, license plate recognition, and AI integration. Like HD CCTV systems, IP CCTV setups can incorporate motion sensors, alarms, and access control systems for enhanced security.

The hardware setup connects IP cameras to the DVR or NVR via Ethernet or Cat-5 cables through a PoE box, which supplies power to the cameras, and links the cameras to the DVR or NVR. Since video data is transmitted over the network, there are no limitations on video resolution or data rates as long as the Internet bandwidth can accommodate them.

The software on the DVR or NVR displays the video captured by the cameras on a monitor. The NVR could also be connected to a storage device like a surveillance hard disk or network-attached storage (NAS) that stores the camera’s video footage. The CCTV software on the DVR or NVR manages the storage and retrieval of the video footage or its playback. The monitor connects with the DVR or NVR through an HDMI cable.

In conclusion, CCTV systems are integral to modern surveillance, offering enhanced security across various applications. With advancements in camera technology, installation options, and software capabilities, these systems provide high-quality video monitoring, remote access, and data analytics. Whether choosing HD or IP-based systems, the correct CCTV setup ensures comprehensive coverage and improved safety for homes, businesses, and public spaces.