Terms to Know
- BEACON
- Modulated oscillator, usually containing telemetry.
- BEAM
- Uplink or downlink channel. May cover a wide area, or be
focused on a particular location (spot).
- BENT PIPE
- Big repeater in the sky. Simply repeats uplinked signal on downlink
side, with amplification.
Also called non-processing.
- BIRD
- Your target.
- DOWNLINK, UPLINK
- Downlink is signal from satellite to ground station.
Uplink is signal from ground station to the satellite.
- EOL
- End of Life. Satellite lifetimes, barring accident or other
damaging incident, are determined by the amount of manuevering fuel
(typically hydrazine) on-board. When the fuel runs out the satellite
can no longer be maneuvered to stay in it's assigned orbital location.
The orbit then becomes inclined. Current satellites have an
expected life of 10 - 15 years.
- ECLIPSE
- Satellite's solar panels are blocked by the earth (22 days before
and after spring and autumn equinox, maximum of 70 minutes) or
the moon (irregular).
- EIRP
- Effective Isotropic Radiated Power. A measure of satellite
transmitter strength, usually in dBw (decibels above one watt).
- FDMA, TDMA, CDMA, DAMA
- Modulation schemes to allow resource (bandwidth) sharing.
Frequency Division Muliple Access: standard for video.
Time Division Multiple Access: standard for telephone, most data.
Code Division Multiple Access: spread spectrum, originally military.
Demand Assign Multiple Access: shared data systems, including VSAT.
- FOOTPRINT
- Geographic area on the earth covered by a particular satellite beam.
- INCLINED ORBIT
- When maneuvering fuel runs out. Requires tracker at ground station.
Traces a figure-eight pattern above and below the equator over 24 hours.
- INMARSAT
- International Maritime Satellite Organization.
Covers Atlantic (AOR East and West), Pacific (POR) and Indian (IOR) Oceans.
Has spares in orbit, not always in contact with TT&C.
- PSEUDOLITE
- Pseudo-satellite. Ground station emitting satellite-like signals.
- TRANSPONDER
- Discrete frequency slot assigned to an uplink/downlink.
- TT&C
- Telemetry, Tracking and Command. Ground Station monitoring and
controlling satellite operation.
- TWT
- Traveling-Wave Tube amplifier. Has nearly flat response
across a wide bandwidth. Newer satellites are using solid state
amplifiers.
- VSAT
- Very Small Aperature Terminal. Usually dedicated data links in
a star configuration. Popular with gas stations for credit card
verification; car dealers for sales information.