Glossary of CCTV Terms
CCTV Term Definition
AC adaptor Also called a power supply. All CCTV devices needs power of some sort. Each device has its own power requirements (usually 12 volts with a minimum amperage). The power coming out of the wall (in the US) is 110 to 120 AC. The adaptor converts the AC power to DC power and will adjust it to a specified amperage. The power supply should be included with each item - you usually don't have to buy these separately.
alarm input An input connection to a security VCR or DVR that triggers the unit to start recording if the alarm is triggered.
analog There are two main ways of doing things electronically, analog or digital. An analog signal can be represented as a series of sine waves. The term originated because the modulation of the carrier wave is analogous to the fluctuations of the human voice or other sound that is being transmitted.
analog system Most cameras used in cctv applications are analog. Security VCRs, switchers, multiplexors and quads also are analog devices. Any cctv system that consists of analog devices are considered analog systems. Compare to 'digital systems'.
angle of view For security cameras, this refers to the angular range in degrees that you can focus the camera on without distorting the image. When focusing close up, you can generally see a wide angle of view. If the focus is distant, the angle of view is smaller or narrower.
aperture The opening of a lens which controls the amount of light let into the camera. The size of the aperture is controlled by the iris adjustment. By increasing the f stop number (f1.4, f1.8, f2.8, etc.) less light is permitted to pass into the camera.
armor dome camera These cameras are designed to resist vandalism by using a hi-impact reinforced polycarbonate dome casing.
audio Most cameras capture 'video' only (what you can see) - some come with audio too (sound). You can add a microphone to a security system to capture audio if needed. To record the sound, your recording device needs to support audio (must have at least one audio input).
auto electronic shutter The ability of the camera to compensate for moderate light changes in indoor applications without the use of auto iris lenses.
auto iris control A lens in which the aperture automatically opens or closes to maintain proper light levels on the faceplate of the camera pickup device.
auto gain control An electronic circuit used by which the gain of a signal is automatically adjusted as a function of its input or other specified parameter.
auto white balance A feature on color cameras that constantly monitors the light and adjusts its color to maintain white areas.
back light compensation A feature on newer CCD cameras which electronically compensates for high background lighting to give detail which would normally be silhouetted.
bullet camera A type of camera with a bullet like shape. Can be used inside or out. Some come with infrared lighting.
c-mount camera C-Mount cameras are designed to accomodate custom lenses. The lenses can be removed and replaced.
cable The wiring used to connect electronic devices. Cables tranmit different kinds of signals such as video, power, data, and audio signals. Refer to plug and play cable and RG59 siamese cable for more information.
ccd Stands for "charge-coupled device". First invented in the 1970s, this technology uses a shift register combined with photodiodes to create the modern day imaging device. Used in cameras, scanners, fax machines, etc. The size of the CCD chip is normally 1/4", 1/3" or 1/2". As a rule of thumb, the larger the size, the higher the quality of the image produced and the higher the price. However some of the higher density 1/4" and 1/3" CCD chips can now produce as good an image as many of the 1/3" or 1/2" chips.
cctv Closed-circuit television.
compression Refers to taking an incoming signal or image, which can be analog or digital, and compressing the data so it can be stored or transmitted faster and using less resources. There are many different algorithms and techniques that are used to compress data.
covert A covert application refers to a situation where you don't want the person to know that they are being watched or recorded. Also known as 'hidden' cameras.
day / night camera "Day/Night Cameras" are regular cameras with an especially sensitive CCD chip that allows a good image to be captured in very low ambient lighting (regular lighting - not infrared). Do not confuse these cameras with "Night Vision" cameras which is another name for infrared cameras.
digital There are two main ways of doing things electronically, analog or digital. The digital method is to consider a circuit either on or off. A digital voltage or signal refers to the discrete nature of digital voltage potentials in digital circuits. TTL (Bipolar Transistor-Transistor Logic) defines 0.0 Volts as a logic 0 or low, and 5.0 Volts as a logic 1 or high; These are single values for clarity - there are actually ranges of voltage potentials around 0.0V and 5.0V which are recognized as low and high logic levels, respectively.
digital system CCTV systems are just lately coming into the digital age. Most security cameras are still analog. There are some digital cameras available but they are extremely expensive. Where digital technology is really making ground in CCTV is with digital video recorders (or DVRs). Any CCTV system that includes a DVR is considered a digital system.
digital video recorder (dvr) A digital video recorder is basically a computer that converts the incoming (analog) signal from the cameras to digital, and compresses it, and stores it. The DVR replaces the function of a multiplexor (or quad or switcher) and a security VCR. There are many advantages of digital video recorders over their analog counterparts.
dome camera A type of camera with a dome like shape. Usually used inside only. Some come with infrared lighting and some are designed to be tamper-proof.
duplex A duplex device can transmit data into and out of the electronic device at the same time. For example, a full duplex digital video recorder can continue capturing and recording images even while a different image is being displayed.
frames per second (fps) In digital video applications, refers to the number of video images that can be captured, displayed, or recorded in a second. Also referred to as the 'frame rate' or 'refresh rate'.
housing Special covering or container to protect a camera from extreme temperatures or weather conditions.
infrared The region of the electromagnetic spectrum bounded by the long-wavelength extreme of the visible spectrum (approximately 0.7 m) and the shortest microwaves (approximately 0.1 mm).
infrared camera Infrared cameras (aka night vision cameras) have special infrared lights installed around the perimeter of the camera lens. This provides special light that the camera uses to capture a good picture even in total darkness.
iris The iris (on some lenses) controls how much light is let into the camera lens.
jpeg (or jpg) Pronounced "jay-peg" and stands for "Joint Photographic Experts Group" who designed the standard. This is a standard way of compressing images which works particularily well for photographic images (as opposed to graphic art).
lens The lens of the camera determines the angle of view and the focus of the captured image. There are many different lens options.
low light Refers to very dim lighting, even 'normal' darkness. Complete darkness is 0 lux. Infrared cameras work well in very low light conditions.
lux Refers to the amount of light required for a camera to capture a good image. Infrared cameras have very low lux.
micro camera Very small cameras designed to work in covert applications where you don't want people to know that the camera is there. Also called 'hidden cameras'.
monitor Security monitors are used to display the images from your cameras (or captured on your recording device). There are two basic kinds used today in CCTV applications. Analog or composite video monitors are used to display images in analog systems. They are just like a TV screen without the TV receiver. These are the monitors we have for sale on our site. Digital or VGA monitors (just like on your computer) are used with digital devices like the Digital Video Recorders. We don't include the monitor with our digital video recorders because you can pick one up more affordably at your local computer store (and not have to pay the shipping cost for such a heavy item).
motion detection Refers to the feature in some VCRs and DVRs to only record video if something in the image moves or changes. Therefore you don't have to look through hours of taped video looking for something to happen. It also saves a lot of space on the tape or hard drive.
mounting bracket Various different kinds of mounting brackets are used to install cameras to the wall or ceiling.
mpeg (or mpg) Pronounced "em-peg" and stands for "Motion Picture Experts Group" who designed the standard. This is a standard way of compressing audio and video files. (It's also the technology behind the now world-famous MP3 music files.)
multiplexor A device that can accept a number of camera inputs and almost simultaneously display them on a single monitor and/or record them. Multixplexers can also be used to transmit multiple cameras over the same transmission medium.
outdoor camera Outdoor cameras come in special weatherproof housings that allow them to stand up well in tough weather and temperature conditions.
pan-tilt-zoom (PTZ) cameras PTZ cameras allow you to adjust the position ('pan' is side-to-side, 'tilt' is up-and-down) and focus ('zoom') of the camera using a remote controller. Due to this added functionality, these cameras tend to cost much more than non-PTZ cameras
pin-hole camera Pin-hole cameras have a very small lens that can see through a small hole. These types of cameras are used in covert applications. A disadvantage of pin-hole cameras is that they require more lighting than normal cameras to capture a good clear picture.
plug and play cable A cable that makes wiring cameras easy. Each camera needs to have a power wire and video wire (and sometimes an audio wire too), plus the connectors at the end of the wire to plug it in. The plug and play cables have all three wires built into one cable with the connectors already attached. The only disadvantage of plug and play cable is that the signal tends to degrade if run distances. For DVRs - plug and play cables can be run reliably up to 100 ft. For analog systems - plug and play cable can be run up to 400 ft. If you need to run longer distances then you need to use the RG59 siamese cable.
power supply Also called an AC adaptor. All cctv devices needs power of some sort. Each device has its own power requirements (usually 12 volts with a minimum amperage). The power coming out of the wall (in the US) is 110 to 120 AC. The power supply converts the AC power to DC power and will adjust it to a specified amperage. The power supply should be included with each item - you don't have to buy these separately.
quad An analog device used to display 4 cameras simultaneously on a single monitor.
RG59 siamese cable This type of cable combines the power wire with the video wire. You have to add your own connectors to each end of the cable. Use this type of cable when you need to run distances longer than 100 ft with a digital system, or more than 400 ft. with an analog system (see the plug and play cable above). The RG59 siamese cable can be run reliably up to 1000 ft.

real-time recording In digital video applications, 30 frames per second per camera (see above) looks just like real-time. There is no hesitation or jerkiness in the video.
remote surveillance The ability to view your cameras from a remote location. Information is transmitted via phone line or internet.
resolution Refers to how much detail can be captured on a camera or displayed on a monitor. Cameras typically capture about 380 horizontal lines of resolution. High resolution cameras may capture 450 lines of resolution or more. The higher the resolution, the more detail that can be captured in a picture. The monitors and recording devices can generally handle at least as much resolution as the cameras can capture.
Smart Search This is a feature of our digital video recorders that allows you to search for changes in a particular area of an image over time. For example, if a wallet was stolen off of a table, you could go to a point on the video where the wallet is there, draw a virtual box around that area, then search the video recording for changes to that particular area. This would allow you to locate the exact point on the video where the wallet was removed.
s/n ration signal to noise ratio; this number represents how much signal noise the camera can tolerate and still provide a good picture. The higher the number the better.
switch A switch will take multiple camera inputs and will show them on the monitor one at a time. Unlike a quad it will not display them all at once, instead it sequences through them showing one camera at a time. It will also allow you to select a particular camera to view.
time-lapse VCR A VCR that can be set to slow down its recording rate in order to extend the length of time that can be recorded on a standard tape up to as much as 960 hours. This is possible by recording one frame at time at set time intervals. Most units have an alarm input signal so it can be automatically switched to real time mode in case of an alarm.
transformer A device used to transfer electric energy from one circuit to another, especially a pair of multiply wound, inductively coupled wire coils that effect such a transfer with a change in voltage, current, phase, or other electric characteristic.
varifocal lens A camera lens in which the focus is not fixed, it can be manually or automatically adjusted.
VCR Videocassette recorder; an electronic device for recording and playing back video images and sound on a videocassette.
video capture card Computer cards that you can install on the motherboard of your own computer to create your own video recording computer. Due to compatibility issues with this type of device, we do not sell these separately.
video gain An increase in video signal power by an amplifier, expressed as the ratio of output to input. Also called amplification.
video input A connection in a video controller or recording device that you can plug a camera into. The more video inputs (also called camera inputs) available on a device the more cameras you can connect to it.
watch dog timer circuit protection If problems are detected in the DVR computer the system will automatically reboot to correct the problem.
waterproof A device that can be immersed in water and still function properly.
weatherproof A device that is weatherproof can be installed outside and stand up to harsh weather conditions and temperatures. However, it does not mean that it is waterproof.
wireless camera Wireless cameras allow the transmission of video and audio data to be transmitted to the receiver without having to run wires (using radiowaves).