CCTV Explained

What is CCTV?

Closed Circuit Television (CCTV) is a system in which all elements – from the cameras to the recording devices – are directly connected in order to keep the video from being broadcast over public airwaves and on a closed circuit. Since its development in 1942, CCTV has undergone drastic changes. Whereas once upon a time, the technology could only be used to observe live footage, it quickly developed into a recording system that allowed users to both view and preserve data. This made it the ultimate security technology. Today, property owners everywhere utilize CCTV technology to build simple to comprehensive security camera systems for their safety and peace of mind.

Types of CCTV Systems

Analog – Use Bayonet Neill-Concelman (BNC) connectors on coaxial cables to transmit continuous video signals. They are relatively low resolution but cheap and effective. There are more peripherals in an analog system, e.g., standard coaxial cables do not usually transmit audio. Analog signals can be digitized, making it more cost-effective to go digital even with older equipment. The images require a video capture card and can be stored on a PC or tape recorder. A step up, analog HD enables increased resolution over traditional systems (1080 pixels) and are backwards compatible with analog cameras and BNC.

See Dahua Analogue Bullet/Dome Camera Varifocal

See Dahua Analogue Bullet/Dome Camera 700TVL

Network or IP – Used with analog or digital cameras, these systems utilize a video server to stream footage over the internet. The advantages are the possibility of Wi-Fi and audio, Distributed Artificial Intelligence (DAI) for analysing image footage, remote access, Power Over Ethernet (POE) and better resolution.

How Does CCTV Work?

Analog and digital systems work quite differently but modern CCTV networks use conversion software and hardware to convert analog to digital. This process is called retrofitting. A traditional CCTV system comprises of:

• One or more cameras (analog or digital), each with a lens equipped with an image sensor
• A recorder – Either a standard video tape recorder for analog systems, or a Direct Video Recorder (DVR) or Network Video Recorder (NVR) for digital systems
• Cables – Either Ethernet for digital or coaxial for analog
• One or more monitors to which the images are transmitted

A CCTV system works as follows:

1. A camera records images through the lens using image sensors.
2. These images (and often audio too) are transmitted to the recorder or tape, either wirelessly or by cable. Recorders may use analytical software and other smart technologies to scan the data and send automated alerts to either humans, or other systems and devices. This Video Management Software (VMS) records, stores and analyses video feeds. The software is often self-learning, using machine learning (ML) algorithms that utilize functionality like motion detection, face recognition, people counting, etc.
3. Monitor(s) can be passively (through software) or actively (by people) monitored. CCTV networks can, and should, themselves be monitored.

CCTV Applications

Crime Management

CCTV surveillance can deter potential criminals. When a crime does occur, video footage can help law enforcement to investigate and later provide evidence for prosecution in a court of law. Used in conjunction with CCTV, audio, thermal and other types of sensors can alert officials to occurrences that are out of the ordinary, e.g., a fire or gun shots at a location. For businesses, CCTV cameras can detect and monitor in-house criminal activities. Prisons may use video surveillance to prevent drones delivering drugs and other contraband to prisoners. Cameras are able to monitor areas that are not easily accessible, e.g., roof tops.

Disaster Management

Using CCTV cameras, emergency services and rescue workers are able to assess and monitor events in real time to relay a “situation” via video to disaster management teams, e.g. from inside a burning building, from a cave or from a helicopter flying over a scene.

City and Community Traffic Monitoring

Law enforcement agencies use security cameras to monitor traffic at intersections and on busy roads. The footage, which can be viewed by an officer at any time, allows law enforcement to identify drivers that run red lights, speed, or otherwise drive recklessly, and to penalize those drivers while preventing more serious crime elsewhere.

Medical Monitoring and Diagnosis

There are about 43 facial muscles that express people’s thoughts and feelings. Smart software can identify these expressions, e.g., pain or anxiety, from images more easily that people can. CCTV cameras can also monitor patients – for instance children or the elderly – to identify potential medical crises, e.g., a stroke, or an epileptic or asthma attack.

Behavioural Research

CCTV used to research suicide found that 83 percent of people attempting to throw themselves in front of a train showed specific behaviours. These were later analysed from CCTV footage and are now used to alert monitor watchers to potential suicides. Surveillance networks are also used by researchers to record crowd activities in public places and prevent anti-social behaviours. For instance, cameras have been used at schools for security, and to record bullying or playground incidents.

Retail Intelligence

Market intelligence garnered from video surveillance of customers is being used to analyse buying trends and enable enhanced strategizing, e.g. how do people shop, which aisles do they traverse the most, how likely are they to respond to calls to action within different store layouts. Heat maps can show the highs and lows of shopper traffic at specific locations in a store, helping stores to identify peak buying times, preferred promotion types, and staffing requirements for peak shopping periods.

Analog CCTV vs. Digital (IP) CCTV Systems

Analog Security Cameras

Advantages

• Cost: Analog cameras tend to cost less, sometimes even a lot less, than their digital counterparts on a per camera basis.
• Simplicity: DVR is easier to set up and understand for most. It is one unit with one cost, and the installation is a bit more straightforward.
• Lower Bandwidth Requirements: Analog recorded video files tend to be smaller, and they are transmitted to the DVR over coax instead of LAN, so transmitting them doesn’t take as much bandwidth and doesn’t tax your network as much. Plus, DVRs also usually only transmit the information and use bandwidth when someone is viewing the video, rather than on a more constant basis.
• More Design Options: With a wider variety of analog camera designs, you may have an easier time finding a camera model with all of the features you need at a lower cost.

 Disadvantages

• Cabling: Because the cameras need to be connected to both the power supply and the DVR via cables, you tend to have a lot of wiring to handle, even if you use cables that bundle video and power. Furthermore, coax cables are usually more expensive on their own than the Cat 5 or 6 counterparts used for digital systems.
• Image Quality: The image quality on analog cameras is pretty low. Most smartphones today have higher resolution. As a result, details at a distance may be grainy, making it difficult to identify potential suspects in an incident with a high degree of confidence. Moreover, there’s no digital zoom. If you try to zoom in on something on analog video, you’ll likely get an image that is even more blurred and grainy.
• Coverage Area: Typically, analog surveillance cameras have a much narrower field of view than their digital counterparts, so you may need more of them to cover the area you need.
• Positioning Limitations: Because analog cameras need to be connected to the DVR, you have to keep these cameras within a reasonable range of the device, or you risk diminishing the reliability of the connection. As a result, you become more limited on where you can place your cameras.
• Port Limitations: DVRs have only so many ports on them, so you can only connect a limited number of cameras to them. If you want to exceed this number, you’ll probably have to get a second DVR.
• Wireless Capability (or Lack Thereof): The reality is that analog wireless systems don’t work very well due to government regulations regarding analog frequencies and signal strength. As a result, other wireless devices and even fluorescent lighting can interfere with and distort the video signal.
• Encryption: Analog signals can’t be encrypted, typically speaking, meaning that it could be easier to for unwanted eyes to view the signal.

Digital Security Camera Systems

Advantages

• Image Quality: The image quality from digital security cameras is significantly higher than analog, with many cameras capable of recording and transmitting high-definition video. Plus, digital cameras are more likely to have digital zoom features, which can have zoom distances over 100ft.
• Coverage Area: A single digital camera can cover an area that would require three or even four of its analog counterparts. As a result, you may require fewer cameras and be able to maintain security surveillance over a wider area.
• Fewer Cables Needed: Instead of individually wiring each camera with power and then cabling each camera to the DVR, digital systems can have multiple cameras connected to a switch, and then all of those cameras on the switch can be connected to the NVR with a single cable.
• Positioning or Port Limitations: Because cameras merely need to be connected to your LAN network in order to connect to your NVR, you are no longer limited by the distance between cameras and the video recorder. As the NVR is software-based and does not have ports, you also eliminate that limitation as well.
• Power over Ethernet (PoE): Power over Ethernet switches enable your signal cables to provide power to the cameras as well, reducing the need for those additional cables.
• Wireless Capability: Digital security camera systems are very good at operating within a wireless network. They are not susceptible to the same kinds of interference that affect their analog counterparts, so you can easily view a live feed from more remote locations if desired.
• Encryption: A lot of digital security cameras have encryption built in, so your data is safer from the beginning of its journey to its end.

 Disadvantages

• Setup Complications: If you don’t have the network set up already and the switches in place, these can increase the cost and labor involved in your CCTV installation, regardless of the fact that you’d need fewer cables overall.
• Higher Initial Cost: The cameras and equipment (aside from cables) tend to cost more on an individual basis compared to their analog counterparts (though you might need fewer of them, so the costs may balance out).
• High Bandwidth Requirements: IP security camera systems usually require a lot more bandwidth than analog ones. Between the higher resolution and higher frame rate, even with compression, you’re looking at around 720Kbps, and that’s before considering the newer cameras that have megapixel resolution. As a result, this could drive your costs up.
• Storage Requirements: Higher resolution and higher frame rates mean larger files, so you’ll need a lot more storage space on your hard drive to accommodate them.