| MAGNIFICATION RATIO | | | | consists of a photo sensor plus its |
| | | | associated control gates. |
| The ratio between the focal length of a lens | | | | |
| and the focal length of a standard angle | | | | PLUMBICON |
| lens. Indicates the magnification of the | | | | |
| image when compared to an image from a | | | | Thermionic vacuum tube developed by Philips, |
| standard angle lens. | | | | using a lead oxide photoconductive layer. It |
| | | | represented the ultimate imaging device up to |
| MANUAL IRIS | | | | the introduction of CCD chips. |
| | | | |
| Type of lens that requires manual focusing. | | | | POLARISING FILTER |
| | | | |
| MATRIX SWITCHER | | | | An optical filter that transmits light in |
| | | | only one direction (perpendicular to the |
| Advanced type of switcher in which a signal | | | | light path), out of 360° possible. The |
| from any input can be switched to any number | | | | effect is such that it can eliminate some |
| or combination of outputs. Generally used in | | | | unwanted bright areas or reflections, such as |
| larger and more complex systems the matrix | | | | when looking through a glass window. In |
| will usually also incorporate a range of | | | | photography, polarising filters are used very |
| additional advanced features. | | | | often to darken a blue sky. |
| | | | |
| MICROWAVE TRANSMISSION | | | | POTS |
| | | | |
| A method of transmitting signals using a | | | | Plain Old Telephone Service, ie. the |
| microwave frequency link. Not affected by | | | | telephone service in common use throughout |
| adverse weather but requires direct line of | | | | the world today. Also known as PSTN. |
| site. A licence may be required to operate a | | | | |
| microwave frequency system. | | | | PRESET POSITIONING |
| | | | |
| MODEM | | | | A function of a pan and tilt unit, including |
| | | | the zoom lens, where a number of certain |
| Derived from the term Modulate-Demodulate. A | | | | viewing positions can be stored in the |
| modem is used to convert between analogue and | | | | systems' memory (usually this is in the PTZ |
| digital signal to then transmit and receive | | | | site driver) and recalled when required, |
| the signals over the PSTN network. | | | | either upon an alarm trigger, programmed or |
| | | | manual recall. |
| MOIRÉ PATTERN | | | | |
| | | | PRINCIPLE POINT |
| An unwanted effect that appears in the video | | | | |
| picture when a high frequency pattern is | | | | An optical term that refers to one of the two |
| looked at with a CCD camera that has a pixel | | | | points that each lens has along the optical |
| pattern close (but lower) to the object | | | | axis. The principle point closer to the |
| pattern. | | | | imaging device (CCD chip in our case) is used |
| | | | as a reference point when measuring the focal |
| MULTIPLEX VIDEO RECORDING | | | | length of a lens. |
| | | | |
| The condensed recording of more than one | | | | PSTN |
| video signal on a single videotape, or hard | | | | |
| disk drive. | | | | Public Switched Telephone Network usually |
| | | | refers to the "plain old telephone" service. |
| MULTIPLEX | | | | Also known as POTS. |
| | | | |
| The concept of transmitting several signals | | | | PTZ SITE DRIVER |
| on a single channel. | | | | |
| | | | (PTZ site receiver, or decoder). An |
| MULTIPLEXER | | | | electronic device, usually a part of a video |
| | | | matrix switcher, which receives digital, |
| A device that combines a number of signals | | | | encoded control signals in order to operate |
| into one. Often used in CCTV to describe a | | | | pan, tilt, zoom and focus functions. |
| device that is primarily used to multiplex | | | | |
| several video signals into one for the | | | | QUAD COMPRESSOR |
| purposes of recording or microwave | | | | |
| transmission. It can also refer to a fibre | | | | (Also split screen unit). Equipment which |
| optics multiplexer which combines a number of | | | | simultaneously displays parts or more than |
| video signals into one in order to transmit | | | | one image on a single monitor. It usually |
| all of them via a single fibre cable. | | | | refers to four quadrants display. |
| | | | |
| N/C AND N/O ALARMS | | | | RAID |
| | | | |
| Refers to Normally Closed and Normally Opened | | | | Redundant Arrays of Independent Disks. This a |
| contacts. It is usually used to describe | | | | technology of connecting a number of hard |
| alarms in CCTV. | | | | drives into one mass storage device, which |
| | | | can be used, among other things, for digital |
| NA | | | | recording of video images. |
| | | | |
| Numerical Aperture. A measure of the angular | | | | RAM |
| acceptance of light incoming into a fibre | | | | |
| optics cable, in the form of a cone. It is | | | | Random Access Memory. An electronic chip, |
| expressed as the square root of the | | | | usually known as "memory", holding digital |
| difference of the squares of the indices of | | | | information while there is power applied to |
| the core and the cladding. | | | | it. Its capacity is measured in kilobytes. |
| | | | |
| NBS | | | | RANDOM INTERLACE |
| | | | |
| National Bureau of Standards (USA). | | | | A term describing a camera that has a free |
| | | | running horizontal sync as opposed to a 2:1 |
| ND FILTERS | | | | interlace type which has the sync locked and |
| | | | therefore has both fields in a frame |
| Neutral Density filters are optical filters | | | | interlocked together accurately. |
| that attenuate the light a number of times. | | | | |
| This attenuation is equal for all the | | | | REMOTE CONTROL |
| wavelengths therefore it does not change the | | | | |
| colour balance of an image, hence the term | | | | A transmission and receiving of signals for |
| neutral. | | | | controlling remote devices such as pan and |
| | | | tilt units, lens functions, wash and wipe |
| NIT | | | | control and similar. |
| | | | |
| A photometric unit for measuring luminance. | | | | RETMA |
| One nit is equal to one candela per square | | | | |
| metre of a projected surface area. | | | | Former name of the EIA association. Some |
| | | | older video test charts carry the name "RETMA |
| NOISE | | | | Chart". |
| | | | |
| An unwanted signal produced by all electrical | | | | RF SIGNAL |
| circuits working above the absolute zero. | | | | |
| Noise cannot be eliminated but only | | | | Radio frequency signal that belongs to the |
| minimised. | | | | region up to 300GHz. |
| | | | |
| NTSC | | | | RG-11 |
| | | | |
| National Television System Committee, an | | | | A video coaxial cable with 75 Ohms impedance |
| American committee that set the standards for | | | | and much thicker diameter than the popular |
| colour television as used today in USA, | | | | RG-59 (of approximately 12 mm). With RG-11 |
| Canada, Japan and a few other countries. | | | | much longer distances can be achieved (at |
| | | | least twice the RG-59), but it is more |
| O/P | | | | expensive and harder to work with. |
| | | | |
| Output. Objective. The very first optical | | | | RG-58 |
| element at the front of a lens. | | | | |
| | | | A coaxial cable designed with 50 Ohms |
| OCULAR | | | | impedance, therefore not suitable for CCTV. |
| | | | Very similar to RG-59, only slightly thinner. |
| The very last optical element at the back of | | | | |
| a lens (the one closer to the CCD chip). | | | | RG-59 |
| | | | |
| OSCILLOSCOPE | | | | A type of coaxial cable that is most common |
| | | | in use in small to medium size CCTV systems. |
| (Also CRO, from "Cathode Ray Oscilloscope"). | | | | It is designed with an impedance of 75 Ohms. |
| An electronic device that can measure the | | | | It has an outer diameter of around 6 mm and |
| signal changes versus time. A must for any | | | | it is a good compromise between maximum |
| CCTV technician. | | | | distances achievable (up to 300 m for |
| | | | monochrome signal, and 250 m for colour) and |
| PAL | | | | good transmission. |
| | | | |
| Stands for Phase Alternating Line, which | | | | RMS |
| describes the colour phase change in a PAL | | | | |
| colour signal. | | | | An abbreviation for Root Mean Square. All AC |
| | | | voltages are measured with multimeters that |
| PAN AND TILT HEAD | | | | show the RMS value of the signal (not the |
| | | | peaks). For a sine wave signal such as the |
| (P/T head). A motorised unit permitting | | | | mains, the RMS value happens to be 1.41 times |
| vertical and horizontal positioning of a | | | | (square root of 2) below the peak values. |
| camera and lens combination. Usually 24 VAC | | | | |
| motors are used in such P/T heads, but also | | | | ROM |
| 110 VAC, ie. 240 VAC units can be ordered. | | | | |
| | | | Read Only Memory. An electronic chip, |
| PAN UNIT | | | | containing digital information that does not |
| | | | disappear when power is turned off. |
| A motorised unit permitting horizontal | | | | |
| positioning of a camera. | | | | RS-232 |
| | | | |
| PHOT | | | | A format of digital communication where only |
| | | | two wires are required. It is also known as a |
| A photometric light unit for very strong | | | | serial data communication. The RS-232 |
| illumination levels. One phot is equal to | | | | standard defines a scheme for asynchronous |
| 10,000 luxes. | | | | communications, but it does not define how |
| | | | the data should be represented by the bits, |
| PHOTODIODE | | | | ie. it does not define the overall message |
| | | | format and protocol. It is very often used in |
| A type of semiconductor device in which a PN | | | | CCTV communications between keyboards and |
| junction diode acts as a photo sensor. | | | | matrix switchers, or between matrix switchers |
| | | | and PTZ site drivers. The advantage of RS-232 |
| PHOTO-EFFECT | | | | over others is in its simplicity and use of |
| | | | only two wires. |
| Also known as photoelectric effect. This | | | | |
| refers to a phenomenon of ejection of | | | | RS-422 |
| electrons from a metal whose surface is | | | | |
| exposed to light. Photon. A representative of | | | | This is an advanced format of digital |
| the quantum nature of light. It is considered | | | | communication when compared to RS-232. The |
| as the smallest unit of light. | | | | basic difference is in the need for four |
| | | | wires instead of two as the communications is |
| PHOTOPIC VISION | | | | not single-ended as with RS-232, but |
| | | | differential. In simple terms, the signal |
| The range of light intensities, from 105 lux | | | | transmitted is "read" at the receiving end as |
| down to nearly 10-2 lux, detectable by the | | | | the difference between the two wires without |
| human eye. | | | | common earth. So if there is noise induced |
| | | | along the line, it will be cancelled out. The |
| PINHOLE LENS | | | | RS-422 can drive lines of over a kilometre in |
| | | | length and distribute data to up to 10 |
| A fixed focal length lens, for viewing | | | | receivers. |
| through a very small aperture, used in | | | | |
| discrete surveillance situations. The lens | | | | RS-485 |
| normally has no focusing control but offers a | | | | |
| choice of iris functions. | | | | This is an advanced format of digital |
| | | | communications compared to RS-422. The major |
| PIXEL | | | | improvement is in the number of receivers |
| | | | that can be driven with this format, and this |
| Derived from picture element. Usually refers | | | | is up to 32. |
| to the CCD chip unit picture cell. It | | | | |