Kilobits per second. Thousand bits per second. Also written as kbps.

Potion of electromagnetic spectrum commonly used in satellite and microwave applications with frequencies in the 390 MHz to 1550 MHz range. The GPS (global positioning system) frequencies are in the L-Band. GPS uses 1227.6 MHz and 1575.42 MHz

Retention that occurs in a video image when rapid motion of the camera or viewed object leaves a trail.

A source of exceptionally pure light which can consist of a single wavelength concentrated into a straight beam, used to transmit IR lighting through fibre optic cable.

The approximate size of a lens projected image. In most cases the lens will project a image slightly greater than the designated image size to insure the pickup device is completely covered. It is recommended that camera and lenses are the same format size. A lens a larger format size can be used on a smaller format camera, however a smaller format lens should never be used with a larger format camera.

Follower Pots are installed on lens that allows feedback to the controller information relevant to zoom and focus positioning allowing the controller to quickly adjust to a preselected scene and arrive in focus at the proper focal length automatically.

Refers to the lens aperture or its ability to transmit light. This is measured in F-stops.

Used to set the auto-iris circuit to a video level desired by the user. Turning the level potentiometer towards the HIGH position will open the iris allowing more light to pass through the lens, towards the LOW will close the iris allowing less light to pass through the lens.

An amplifier for audio or video signals that feeds a transmission line; also called program amplifier.

There are a variety of proprietary names for this latest advance in video storage technology. The principle is that a series of video frames is compressed and stored in digital form, in what is likened to a continuous loop. This records, for instance, 200 frames and then records over the top again and carries on doing this until an alarm signal is received. When this happens, the equipment carries on recording for (say) 150 frames and then stops. This means that 50 frames BEFORE the event causing the alarm and 150 frames after the event are captured. It eliminates the tedious searching through hours of dubious quality video recording and concentrates the reviewing on the period of real activity. There are currently systems that can record four or eight cameras simultaneously using this technique.

Also called looping. The method of feeding a series of high impedance circuits (such as multiple monitor/displays in parallel) from a pulse or video source with a coax transmission line in such a manner that the line is bridged (with minimum length stubs) and that the last unit properly terminates the line in its characteristic impedance. This minimizes discontinuities or reflections on the transmission line.

Distortion effects which occur at low frequencies. In television, generally considered as any frequency below the 15.75-kHz line frequency.

The unit of luminous flux. It is equal to the flux through a unit solid angle (steradian) from a uniform point source of one candela or to the flux on a unit surface of which all points are at a unit distance from a uniform point source of one candela.

A unit of incident light. It is the illumination on a surface one square foot in area on which a flux of one lumen is uniformly distributed, or the illumination at a surface all points of which are at a distance of one foot from a uniform source of one candela.

The brightness of a video signal.

Used to specify how sensitive cameras are to light (measured in lumens/sq metre).
e.g a camera with a LUX Level of 0 can see in pitch black. The lower the LUX Level the better the camera will see in the dark.

A term used with regard to lenses and has evolved to be the same as "power" when describing the size of a zoom lens.

(METROPOLITAN AREA NETWORK) - A high-speed network designed to link together sites in a metropolitan or campus area.

A lens with a manual adjustment to set the iris opening (aperture) to a fixed position. This type lens is generally used in fixed lighting conditions.

A combination or array of electromechanical or electronic switches which route a number of signal sources to one or more designations.

Communications network comprising many hundreds of individual communication channels.

Mega Pixel resolution refers to video resolutions now achievable using IP Cameras. Unlike Analogue cameras, whose resolution is usually limited to around 752 x 582 (0.4 Mega Pixels), a Mega Pixel IP Camera can achieve far greater resolutions such as 1280 x 1024 (1.3 Mega Pixels) or 1600 x 1280 (2 Mega Pixels). This increase in resolution produces far better image quality than a traditional analogue camera could ever achieve.

The mechanical aligning of the imaging device with the focal point of the lens, most often on zoom lenses, to ensure the image stays in focus throughout the zoom range that the system has been set to.

Megahertz, a measure of frequency in millions (mega) of cycles per second.

The closest distance a given lens will be able to focus upon a object. Generally the smaller the focal length the shorter the M.O.D. This distance can be altered with use of extension tubes.

The process, or results of the process, whereby some characteristic of one signal is varied in accordance with another signal. The modulated signal is called the carrier. The carrier may be modulated in three fundamental ways: by varying the amplitude, called amplitude modulation; by varying the frequency, called frequency modulation; by varying the phase, called phase modulation.

Metal Oxide Semiconductor - a form of CCD imager used in some CCD cameras.

Method of sending video signals and/or data over free space, longer distances than IR transmission can be achieved. Licencing is usually required.

This compression standard generally refers to JPEG images shown at high frame rate, generally 30 frames per second. It gives high quality video images, but the comparatively large file sizes of each individual image does put demands on the transmission bandwidth.

Multipoint Multi-channel Distribution Service. MMDS is a way of distributing cable television signals, through microwave, from a single transmission point to multiple receiving points. Often used as an alternative to cable-bases cable TV. An MMDS service, "in digital form, will provide more than 100 channels to a radius of approximately 40 miles from the transmitter. The MMDS transmitter delivers video to homes that are in its 'line of sight.' MMDS transmissions are limited by the terrain and foliage of a given market. The microwave signal is received by an antenna on the subscriber's home, then sent down coaxial cable to a box atop the customer's TV set. The box decodes and decompresses the digital signal." MMDS is increasingly being called "Wireless Cable."

In monochrome television, a signal wave for controlling the brightness values in the picture. In color television, that part of the signal wave which has major control of the brightness values of the picture, whether displayed in color or in monochrome.

The transmission of a signal wave which represents the brightness values in the picture, but not the color (chrominance) values.

Recording method for digital surveillance systems. When someone walks in front of a camera, the pixels change and the DVR defines this as motion. The surveillance system will then record these images to the hard disk. This is a popular recording setup as every event recorded is actually motion driven as opposed to a static image if the system was set to record 'round-the-clock'.

Motion Picture Experts Group - a video compression technique for video images MPEG-4 has fast become the Digital CCTV standard recording compression format.
MPEG-2 is used for DVD Recording quality.

Mean Time Between Failure - the average time between equipment or component failure.

Mean Time To Repair - the average time it takes to repair a piece of equipment.

An optical fibre that allows the signal carrying light to travel along more than one path.

A Multi Screen CCTV device that allows input of 4, 9, 16 etc cameras and provides a 'Mutli-Plexed' (or split screen) display of those cameras.

National Association of Broadcasters

A filter that attenuates light evenly over the visible light spectrum. It reduces the light entering a lens, thus forcing the iris to open to its maximum.

A graduated filter fitted to the centre of a lens, restricting the amount of light that can effectively pass through to the image sensor.

Powerful software used in motion detection to teach the computer to learn object sizes and shapes.

An unwanted signal produced by all electrical circuits working above the absolute zero.
Noise cannot be eliminated but only minimized.

A video signal that is complete, except for the synchronisation information.

SMPTE time code format that continuously counts a full 30 frames per second. Because NTSC video does not operate at exactly 30 frames per second, non-dropframe time code will count 108 more frames in one hour than actually occur in the NTSC video in one hour. The result is incorrect synchronization of time code with clock time. Drop-frame time code solves this problem by skipping or dropping 2 frame numbers per minute, except at the tens of the minute count.

The process of scanning whereby every line in the picture is scanned during the
vertical sweep.

A number that defines the light gathering ability of a specific fiber. The numerical aperture is equal to the sine of the maximum acceptance angle.

National Television System Committee. American committee that set the standards for color television as used today in the US, Canada, Japan and parts of South America. NTSC television uses a 3.57945 MHz sub-carrier whose phase varies with the instantaneous hue of the televised color and whose amplitude varies with the instantaneous saturation of the color. NTSC employs 525 lines per frame and 59.94 fields per second.

Output.

The very first optical element at the front of a lens. Ocular. The very last optical element at the back of a lens (the one closer to the CCD chip).

The unit of resistance. The electrical resistance between two points of a conductor where a constant difference of potential of 1 V applied between these points produces in the conductor a current of 1 A, the conductor not being the source of any electromotive force.

An antenna having an essentially non-directional pattern in azimuth, and a directional pattern in elevation.

(Also CRO, from cathode ray oscilloscope) An electronic device that can measure the signal changes versus time. A must for any CCTV technician.

The impedance a device presents to its load. The impedance measured at the output terminals of a transducer with the load disconnected and all impressed driving forces taken as zero.

A video monitor condition in which the raster extends slightly beyond the physical edges of the CRT screen, cutting off the outer edges of the picture.