Glossary Terms Beginning P

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Packet-switching: Data transmission method that divides messages into standard-sized packets for greater efficiency of routing and transport through a network.
Panning-up: Process of accurately aligning satellite uplink antenna to the satellite.
Parabolic antenna: Antenna with a reflector described mathematically as a parabola; essentially an electromagnetic wave lens which focuses the radio frequency energy into a narrow beam.
Payload: Load carrying capacity; on a rocket launch vehicle, the satellite is the payload.
PCM: Pulse code modulation.
Perceptual coding: A coding technique which takes advantage of the imperfections of the human visual and auditory senses.
Perigee: The point of a satellite’s orbit where it is closest to the Earth’s surface.
Petal: Segment of a flyaway antenna.
PFD: Power flux density: a measure of the satellites illumination of the Earth’s surface.
Phase noise: Phase interference in the wanted digital signal which can cause the digital signal to fail to be demodulated correctly.
Phase stability: Characteristic that is important in digital transmission components – lack of phase stability can cause the digital signal to fail to be demodulated correctly.
Phase-combiner: Multi-port microwave device which ensures that the individual outputs from two HPAs are combined together so that the outputs are added inphase.
Phase-locked loop: PLL: type of electronic circuit used to demodulate satellite signals.
Piece-to-camera: Where a reporter gives a news report face to camera.
Pixel: Smallest element that is discernible (quantified and sampled) in a picture.
Pixellation: Aberration of a digitally coded television picture where the individual digitally coded samples can be seen.
Pointing loss: Loss due to misalignment of boresight of antenna towards satellite, and movement of satellite within its station-kept ‘box’.
Polarization: Geometric plane in which the electromagnetic signals are transmitted.
Pool: Grouping of newsgathering entities, usually for a limited period, to pool resources to cover a news event.
POP: Point of presence.
POR: Pacific Ocean Region: describes coverage area of a satellite.
Power density: Density of radiated power from an antenna, measured in W/m2 (mW/cm2).
Precipitation loss: Loss due to rain attenuating the signal, particularly in the Kuband, and further dispersing the signal as it passes through the drops of water.
Precipitation zone: To aid in calculating the effect of precipitation loss, the world is divided into precipitation zones or rain climatic zones, each of which has a numerical value defined by the ITU, used in the calculation of a link budget.
Pre-emphasis: Type of frequency-dependent level boosting/cutting or filtering.
Pre-emptible: Satellite service that may be interrupted or displaced by another, higher-priority service, typically (but not exclusively) during a satellite contingency situation.
PRI: Primary rate ISDN.
Primary rate ISDN: PRI: primary rate ISDN provides 30 × 64 kbps (B) data channels and 1 × 64 kbps (D) signalling channel.
PSK: Phase shift key modulation: digital phase modulation.
PSTN: Public Switched Telephone Network.
PTC: Piece-to-camera.
PTO: Public telecommunications operator; power take-off: where a generator may be driven through a vehicle’s road engine and transmission system while the vehicle is at rest.
PTT: Post, telephone and telegraph administration: national telecommunications agencies directly or indirectly controlled by governments, in charge of telecommunications services in most countries of the world.
Pulse code modulation: PCM: time division modulation technique in which analogue signals are sampled and quantized at periodic intervals into digital signals – typically represented by a coded arrangement of 8 bits.