7E Communications >
Glossary > Glossary Terms Beginning
Glossary Terms Beginning P
0-9 : A
: B : C
: D : E
: F : G
: H : I
: J : K
: L : M
N : O
: P : Q
: R : S
: T : U
: V : W
: X : Y
- Data transmission method that divides messages into standard-sized packets
for greater efficiency of routing and transport through a network.
- 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
- Load carrying capacity; on a rocket launch vehicle, the satellite is the payload.
- Pulse code modulation.
- Perceptual coding
- A coding technique which takes advantage of the imperfections of the human
visual and auditory senses.
- The point of a satellite's orbit where it is closest to the Earth's surface.
- Segment of a flyaway antenna.
- Power flux density: a measure of the satellites illumination of the Earth's
- 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.
- 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.
- Where a reporter gives a news report face to camera.
- Smallest element that is discernible (quantified and sampled) in a picture.
- 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'.
- Geometric plane in which the electromagnetic signals are transmitted.
- Grouping of newsgathering entities, usually for a limited period, to pool
resources to cover a news event.
- Point of presence.
- 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.
- Type of frequency-dependent level boosting/cutting or filtering.
- Satellite service that may be interrupted or displaced by another, higher-priority
service, typically (but not exclusively) during a satellite contingency situation.
- Primary rate ISDN.
- Primary rate ISDN
- PRI: primary rate ISDN provides 30 × 64 kbps (B) data channels and 1 × 64
kbps (D) signalling channel.
- Phase shift key modulation: digital phase modulation.
- Public Switched Telephone Network.
- 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.
- 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.