| M-PEG |
Moving Picture Expert Group. A suite of digital compression tools specifically designed to video images. |
MAC (Media Access
Control) layer |
The protocol that controls access to the physical transmission medium on a LAN. |
| Macro |
Feature allowing you to pre-programme frequent system configurations for selection by a single keystroke or optionally by alarm inputs. |
| Magnetically Encoded |
Coded information that has been recorded on magnetic tape or cards. |
| Matrix Switcher |
A switcher able to route any of its camera inputs to any of its monitor outputs; a name usually reserved for large systems, that often includes telemetry control. |
| Mb |
Megabyte, or one million bytes or characters of information. |
Mechanical Focus
(Back-focus,
racking) |
The mechanical aligning of the imaging device with the focal point of the lens; most important on zoom lenses to ensure the image stays in focus throughout the zoom range. |
| Megabyte (Mb) |
Order of magnitude; 10 6 |
| Micro |
Order of magnitude; 10 –6 |
| Microwave |
Radio frequencies between 1 - 30 GHz used for video transmission over medium/long distance. |
| Milli |
Order of magnitude; 10 –3 |
MMJ (Modular
Modified Jack) |
A modular connection used in DEC systems that has six wires with a locking tab on the side of the connector. |
| Modem |
Used with PSTN telephone lines to connect a fastscan system to the dial up BT network. |
| Modem |
Modulator/demodulator used in data transmission. |
Modem (Modulator-
Demodulator) |
A device used to convert serial digital data from a transmitting terminal to an analogue signal (carrier) for transmission over a telephone channel or to reconvert the transmitted analogue signal to serial digital data for acceptance by a receiving terminal. |
| Monitored |
Senses the state of the door (i.e. open or closed), a door contact is usually used. |
| Monochrome |
Black and white, not colour. |
| Mullion |
Door frame side uprights. (Mullion reader – a reader designed to be mounted on the door frame). |
| Multimode Fibre |
An optical fibre with a core diameter of 50 to 100 microns. Its core causes some distortion and provides less bandwidth than single-mode fibre. |
Multiplex (Time
multiplex) |
Using one carrier to send more than one signal. In video multiplexers, achieving this by sending a different camera’s output in each successive field or frame of a video signal, in a form that can later be retrieved as single camera pictures. |
| Multiplexer |
A device that divides a transmission into two or more sub-channels, either by splitting the frequency band into narrow bands (frequency division) or by allotting a common channel to several transmitting devices, one at a time (time division). |
