| M |
| Magnetic Variation |
| The difference between true north and the north indication of a compass. |
| Master Antenna TV (MATV) |
| Broadcast receiving stations that use one or more high-quality centrally located UHF and/or VHF antennas which relay their signals to many televisions in a local apartment/condo or group- housing complex. |
| Match |
| The condition that exists when 100% of available power is transmitted from one device to another without any losses due to reflections. |
| Matching Transformer |
| A device used to match impedance between devices. A matching transformer is used, for example, when connecting a 75 ohm- coax to a television 300 ohm input terminal. |
| MegaHertz (MHz) |
| One millions cycles per second. |
| Microprocessor |
| The central processing unit of a computer or control system, either on a single integrated (IC) circuit chip or on several ICs. |
| Microwave |
| The frequency range from approximately 1 to 30 GHz and above. |
| Mixer |
| A device used to combine signals together. |
| Modulator |
| A device that modulates a signal, for example an analog signal or an MPEG-2 transport stream onto a radio frequency carrier |
| Modulation |
| A process in which a message is added or encoded onto a carrier wave. Among other methods, this can be accomplished by frequency or amplitude modulation, known as AM or FM, respectively. |
| Monochrome |
| A black and white television picture. |
| Mount |
| The structure that supports a receive dish. Polar and az-el mounts are the most common variety. |
| MPEG-2 |
| Motion Pictures Expert Group-Two MPEG-2 Transport Stream - A data stream resulting from a Multiplexing process according to MPEG-2 |
| Multiple Analog Component (MAC) Transmissions |
| A video/audio/data transmission method that separates the data, chrominance and luminance components and compresses them for sequential relay over one television scan line. There are a number of systems in use and under development including A-MAC, B- MAC, C-MAC, D-MAC, D2-MAC, E-MAC and F-MAC. |
| Multiple Unit Dwelling |
| MUD Microwave Multipoint Distribution Services - MMDS - A system for distributing television programs via terrestrial microwaves to very small receive dishes |
| Multiplexing |
| The simultaneous transmission of two or more signals over a single communication channel. The interleaving of the luminance and chrominance signals is one form of multiplexing, known as frequency multiplexing. MultiChoice transmissions use time division multiplexing (TDM) whereby data streams are divided in time into interspersed data packets. |
| Multiplexer |
| MUX - A device that takes the outputs from a number of encoders and multiplexes them together to form one data stream |
| MUX Controller |
| A computer that controls the functions of a specific multiplexer pair in a compression system |
| MUX Interface Room |
| The space where input program switching to the various compression sys |
| MUX Room |
| Space where compressors and multiplexers reside tems is accomplished |
|
| N |
| N-Connector |
| A low-loss coaxial cable connector used at the elevated microwave frequencies. |
| NTSC |
| The National Television Standards Committee which created the standard for North American TV broadcasts. |
| NTSC Color Bar Pattern |
| The standard test pattern of six adjacent color bars including the three primary colors plus their three complementary shades. |
| Negative Picture Phase |
| Positioning the composite video signal so that the maximum level of the sync pulses is at 100% amplitude. The brightest picture signals are in the opposite negative direction. |
| Negative Picture Transmission |
| Transmission system used in North America and other countries in which a decrease in illumination of the original scene causes an increase in percentage of modulation of the picture carrier. When demodulated, signals with a higher modulation percentage have more positive voltages. |
| Network Operator |
| The Network Operator is responsible for transmitting one or more services. This person operates the headend and uplink equipment and is also responsible for satellite dishes, microwave equipment and all other components used to broadcast the services |
| Network Information Table |
| NIT - A table that describes the transport medium for services on the currently demodulated and other multiplexes |
| Noise |
| An unwanted signal which interferes with reception of the desired information. Noise is often expressed in degrees Kelvin or in decibels. |
| Noise Figure |
| The ratio of the actual noise power generated at the input of an amplifier to that which would be generated in an ideal resistor. The lower the noise figure, the better the performance. |
| Noise Temperature |
| A measure of the amount of thermal noise present in a system or a device. The lower the noise temperature, the better the performance. |
| Non-Serialized Products |
| Any generic or non-uniquely identified product or device made available by the SMS-operator for release into the marketplace |
|
| O |
| Odd Field |
| The half frame of a television scan which is composed of the odd numbered lines. |
| Offset Feed |
| A feed which is offset from the center of a reflector for use in satellite receiving systems. This configuration does not block the dish aperture. |
| OSD |
| On-Screen Display |
| Orthomode Coupler |
| A waveguide, generally a three-port device, that allows simultaneous reception of vertically and horizontally polarized signals. The input port is typically a circular waveguide. The two output ports are rectangular waveguides. |
|
| P |
| Packet Identity - PID |
| A 13-bit number that identifies transport stream packets containing data from a single data stream |
| Packetizer |
| An entity that breaks a stream up into discrete units of data and, usually, encapsulates each packet with extra information used to allow the packets to be reliably re-assembled into the continuous data stream |
| Packetized Elementary Stream - PES |
| An elementary stream that is divided into typically large packets of defined structure before being further packetized for the MPEG transport process |
| PAL - Phase Alternate Line. |
| The European/African color TV format which evolved from the American NTSC standard. PAL-I version used in South Africa. |
| Pad |
| A concrete base upon which a supporting pole and dish can be mounted. |
| Path Loss |
| The attenuation that a signal undergoes in traveling over a path between two points. Path loss varies inversely as the square of the distance traveled |
| Parabola |
| The geometric shape that has the property of reflecting all signals parallel to its axis to one point, the focal point. |
| Pay-Per-View |
| Pay-per-view is a method of purchasing programming on a per-program basis. |
| Pay-per-View (PPV) Event |
| A PPV event is similar to a "normal" event, except that the subscriber is charged for viewing. In this respect, it is similar to a product. However, there can be many PPV events in a short time and registering them all as products is not practical |
| Pay-TV Transactions |
| Access control transactions such as enable, hold, etc... |
| Persistence of Vision |
| The physiological phenomena whereby a human eye retains perception of an image for a short time after the image is no longer visible. |
| Phase |
| A measure of the relative position of a signal relative to a reference expressed in degrees. |
| Phase Distortion |
| A distortion of the phase component of a signal. This occurs when the phase shift of an amplifier is not proportional to frequency over the design bandwidth. |
| Picture Detail |
| The number of picture elements resolved on a television picture screen. More crisp pictures result as the number of picture elements is increased. |
| Polar Mount |
| A dish mount that permits all satellites in the geosynchronous arc to be scanned with movement of only one axis. |
| Polarisation |
| A characteristic of the electromagnetic wave. Four senses of polarisation, determined by the direction of the electric field, are used in satellite transmissions: horizontal; vertical; right-hand circular; and left-hand circular. |
| Positive Picture Phase |
| Positioning of the composite video signal so that the maximum point of the sync pulses is at zero voltage. The brightest illumination is caused by the most positive voltages. |
| Preamplifier |
| The first amplification stage. In a terrestrial receive system, it is the amplifier mounted adjacent to an antenna to increase a weak signal prior to its processing at the headend |
| Pre-emphasis |
| Increases in the higher frequency components of an FM signal before transmission. Used in conjunction with the proper amount of de- emphasis at the receiver, it results in combating the higher noise detected in FM transmissions. |
| Pre-Enabling |
| Making subscription products available on the decoding device before release into marketplace |
| Presentation Time Stamp - PTS |
| A 33-bit field indicating when the packetised elementary stream (PES) packet should be presented to the user (90 kHz base reference) |
| Primary Colors |
| Red, green and blue. |
| Prime Focus Dish |
| A parabolic dish having the feed/LNA assembly at the focal point directly in the front of the dish. |
| Product |
| A product is a billable service, group of services, programs or events. The SMS Operator is mostly concerned with products, for which customers can be charged. Products are important to the CDTV systems because the correct ECMs have to be broadcast for each one. The same service, program or event can be marketed under different |
| Product/Program Provider |
| Any establishment producing or providing video and audio material for broadcasting |
| Product Management |
| A sub-system on the BS managing all product related information such as prices, deviations, durations, marketing areas and availabilities |
| Program |
| A program is an identifiable unit of broadcast material such as a movie, one episode of a soap opera or even a news bulletin. Each program has a name, for example. "Terminator 2", and descriptive information, such as a list of actors, a short description of the item, the year it was created, etc... It can be broadcast more than once and may also be broadcast by different services |
| Program (Technical) |
| A collection of elementary streams locked to the same time base, making up an event or sequence of events Program Association Table - PAT - A program specific (PSI) table associating the program maps tables, by the packet identity (PI) of their data streams, to program numbers, i.e. to services |
| PID |
| Program Identification |
| Program Clock Reference |
| PCR - A counter based on a 27 MHz time-base used to synchronize the presentation of data arriving in different data streams on the multiplex (asynchronouly). The PCR is split into two sections when supplied - 33 bits giving 1/90 kHz resolution and a 9-bit extension to fine-tune to 27 MHz |
| Program Map Table - PMT |
| A table that identifies the data streams that comprise a service and provides other data used for decoding these services |
| Program Specific Information - PSI |
| Information provided in a format defined by MPEG to convey the essential data a decoder must have to receive one or more services make up of elementary streams. It consists primarily of the program association table (PAT), program map table (PMT) and conditional access table (CAT), although it also introduces the network informat |
| Programme Stream - PS |
| An MPEG 2 multiplex with variable length packets that are typically large - intended for low error rate transport media with only a single programme, for example CD-ROM ion table (NIT) |
|
| Q |
| Quadrature Phase Shift Keying - QPSK |
| A modulation technique used on satellite transmissions that uses phase shifts of a carrier wave to relay 4 symbols per cycle |
| Q Signal |
| One of two color video signal components used to modulate the color subcarrier. It represents the color range from yellowish to green to magenta. |
|
| R |
| Radio Frequency (RF) |
| The approximately 10 kHz to 100 GHz electromagnetic band of frequencies used for man-made communication. |
| Raster |
| The random pattern of illumination seen on a television screen when no video signal is present. |
| Reed Switch |
| A mechanical switch which uses two thin slivers of metal in a glass tube to make and break electrical contact and thus to count pulses which are sent to the dish actuator controller. The position of the slivers of metal is governed by a magnetic field applied by a bar or other type of magnet. |
| Reference Signal |
| A highly stable signal used as a standard against which other variable signals may be compared and adjusted. |
| Return Loss |
| A ratio of the amount of reflected signal to the total available signal entering a device expressed in decibels. |
| Retrace |
| The blanked-out line traced by the scanning beam of a picture tube as it travels from the end of any horizontal line to the beginning of either the next horizontal line or field. |
