C.C.T.V. terminology and Information
What is CCTV?
CCTV consists of at least one camera………… and that’s it! That one camera can be connected to the internet or via a WiFi signal and viewed on your phone, tablet or computer, from anywhere nearby or anywhere in the world with an internet connection.
A CCTV system would consist of one or more camera’s that are connected back to a recorder prior to being connected to the internet. The recorder will record all the video from all the cameras with date and time stamps so that the footage can be easily checked later. The recorder can also be connected to a TV or computer monitor via a cable so that the camera’s can viewed in real time. Recorders usually come with a remote control so you can control how you view the cameras.
Larger CCTV systems may be connected on a network system and controlled by computer software. These systems are common in commercial applications.
Cameras
Bullet A bullet CCTV camera is a wall-mount or ceiling-mounted unit that is typically designed for indoor use, but can also be fill some outdoor applications. The camera derives its name from its sleek, thin cylindrical shape. Many bullet cameras also tout themselves as being waterproof. The camera is not typically designed to have pan/tilt/zoom control but instead to capture images from a fixed area. The unit is mounted pointing at a particular area.
Dome: A dome cameras get their name from the dome-shaped housing in which they sit. These housings are designed to make the cameras unobtrusive… not covert or hidden. Typical applications are retail, where the camera is designed to be unobtrusive, but visible.
These units serve a dual purpose: “bad guys” will know the facility is being watched and patrons will feel at ease knowing the facility is being protected. Units that allow the camera to spin quickly within the housing are often referred to as “speed domes.”
Covert/Desktop/Board Cameras: These tiny cameras are well suited for desktop use for Skype and other low-resolution teleconference applications.
Discreet Cameras: It’s clock… it’s a smoke detector… it’s motion sensor. The real answer is none of the above. These are just some of the disguises for covert cameras. Of course, covert cameras can also be characterized by conventional cameras placed in discreet locations.
Infrared/Night Vision: These night-vision cameras have the ability to see images in pitch black conditions using IR LEDs. In some cases they are for mobile applications.
Outdoor: The key to outdoor cameras is the housing itself, which must be impenetrable to moisture, insects, dust and other elements.
Day/Night: Day/night cameras compensate for varying light conditions to allow the camera to capture images. These are primarily used in outdoor applications where the security camera is positioned for an outdoor parking lot, for example. In many cases, units are dubbed as having a wide dynamic range to function in glare, direct sunlight, reflections and strong backlight 24/7.
Varifocal: A camera with a varifocal lens allows the operator to zoom in or out while still maintaining focus on the image.
Network/IP: These cameras, both hardwired and wireless, transmit images over the Internet, often compressing the bandwidth so as not to overwhelm the web. IP cameras are easier to install than analog cameras because they do not require a separate cable run or power boost to send images over a longer distance.
Wireless: Not all wireless cameras are IP-based. Some wireless cameras can use alternative modes of wireless transmission. But no matter what the transmission method, the primary benefit to these units is still the same: extreme flexibility in installation.
PTZ/Speed Domes: Pan/tilt/zoom cameras give the surveillance operator the ability to move the camera left or right (pan); up and down (tilt); and zoom the lens closer or farther. These are relegated to surveillance situations where there is an actual live guard or surveillance specialist monitoring the images. There are cameras that have automated pan/tilt/zoom functionality where the camera is moving on a timed basis. These are many times used to cover a wide area with only one camera, or to avoid poor light conditions, such as a setting sun.
High-Definition Cameras: Ultra high-definition cameras are often relegated to niche markets, such as casinos. These give the operators the ability to zoom in with extreme clarity (to look at poker players, for example, who might have something up their sleeve). In the past, these cameras were tube-based analog cameras, but today’s digital technology has displaced those older units. The cameras can also transmit their images using HDcctv.
Understanding Digital Video Recorders
The practice of recording CCTV images in digital format is now widely accepted and there are many manufacturers and resellers of what is generically known as the DVR (Digital Video Recorder).
However, whilst it is convenient to think about a “DVR” as if it is a commodity item, the truth is that these products differ wildly in their capabilities, performance, quality, reliability, support, compatibility and price.
The Technology employed in these devices has changed significantly in the last ten years, and is still evolving, so it’s wise to understand what is being offered and, perhaps more importantly, what you need.
Historically, the camera signals connected to a recorder would be analogue, and usually connected with a BNC connector. These days, it is increasingly likely that the camera signal will arrive in a digital format, via a network connection. In fact, there are devices, generically known as NVR’s (Network Video Recorders) which will only accept network connected cameras.
This section is specifically about what I will describe as“High end” DVR’s”. These devices are usually of a hybrid design, accepting analogue and digital camera signals, and being capable of a wide range of functions. These are the products that you will usually find in larger systems and higher security applications.
High end video recorders have particular characteristics that make them suited to more demanding applications. These characteristics will usually include:
- Higher resolution recording to give better playback quality
- Higher capacity to allow many sources to be recorded for long periods at high frame rates and high quality
- The ability to be integrated into large CCTV systems, often with high level interfaces to control and auditing systems
- A robust build quality with features ensuring system integrity, even if components fail..
- A means to analyse, copy and transmit bulk footage in the event of a major incident.
- Analytic or advanced search facilities, allowing days weeks or months of video recording to be filtered down to the required events very quickly.