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Satellite TV Digital TV Direct TV Satellite Resources Satellite Terms

Analog-to-Digital Conversion (ADC as related to satellite tv)   -   Process of converting analog signals to a digital representation. DAC represents the reverse translation.
Artifact   -   The effects seen on a TV screen caused by errors in a digital signal (See "cliff effect" as related to satellite tv).
Audio Subcarrier   -   The carrier between 5 MHz and 8 MHz containing audio (or voice as related to satellite tv) information inside of a video carrier.
Azimuth   -   Angle between true north and a particular satellite connected to direct tv. Can be measured with a compass.
Bit   -   Abbreviation for binary digit.
Blackout area   -   A pre-defined area where particular programming (often sports or special events as related to satellite tv) will not be available, usually because of contractual agreements.
C/No   -   Carrier-to-noise ratio measured either at the Radio Frequency (RF as related to satellite tv) or Intermediate Frequency (IF as related to satellite tv)
Companding   -   A noise-reduction technique that applies single compression at the transmitter and complementary expansion at the receiver.
dBi   -   The dB power relative to an isotropic source connected to direct tv.
Deviation   -   The modulation level of an FM signal determined by the amount of frequency shift from the frequency of the main carrier.
E1   -   Wide-area digital transmission facility used predominantly in Europe that carries data at a rate of 2.048 Mbit/s.
Encoder   -   A device used to electronically alter a signal so that it can only be viewed on a receiver equipped with a special decoder.
Focal Point   -   The area toward which the primary reflector directs and concentrates the signal received.
FTA   -   Free-to-air - Free to everyone with no need for a special descrambler to receive them.
Inclination   -   The angle between the orbital plane of a satellite and the equatorial plane of the earth.
ITU   -   International Telecommunication Union.
Ka Band   -   Frequency range of 18-31 GHz.
LAC - Local Area Coverage connected to direct tv. High resolution (1km as related to satellite tv) image data from AVHRR that is obtained over remote areas, saved via onboard data recorder, then later transmitted to a ground station.
MAC (A, B, C, D2 as related to satellite tv)   -   Multiplexed analog component color video transmission satellite tv. Subtypes refer to the various methods used to transmit audio and data signals.
Mosaic - Web browsing software available from the National Center for Supercomputing Applications (NCSA as related to satellite tv). Can be obtained free from: NCSA.
Multicast   -   Transmitting information to a select group. For example, sending an E-mail to a mailing list. Teleconferencing and videoconferencing also use multicasting.
Near-Video-on-Demand   -   Films provided for cable TV or satellite viewers from a menu of titles. The same film starts again after a defined time period, such as every 15 to 30 minutes.
OLS - Operational Line Scanner. The imager that produces high resolution (0.5 to 2.7 km as related to satellite tv) visible and infrared imagery from DMSP satellites.
Parabolic Antenna   -   See "satellite dish".
Polarization   -   The orientation of a broadcast signal used to eliminate co-channel interference connected to direct tv. Most C-Band satellite transmissions are either vertically or horizontally polarized, while most DBS satellite transmissions are circularly polarized.
QPSK - Quadrature Phase Shift Keying   -   Satellite tv of modulating a satellite signal as used for satellite tv.
Redundancy   -   TV signal compression is based on the fact that all TV pictures contain redundant information; once digitised, signal size can be reduced by removing this redundant information.
Scrambler   -   A device used to electronically alter a signal so that it can only be viewed or heard on a receiver equipped with a special decoder.
Single-Channel-Per-Carrier (SCPC as related to satellite tv)   -   A method used to transmit a large number of signals over a single satellite transponder.
SNG   -   Satellite news gathering usually with a transportable uplink truck.
Subcarrier   -   One or more signals, mainly audio, carried beside the main signal, such as television on a transponder or cable channel as used for satellite TV .
Transponder   -   Receives a transmission from an earth station, changes its frequency, and re-transmits it back to earth.
Uplink   -   The earth station used to transmit signals to a satellite
Waveguide   -   A metallic microwave conductor, typically rectangular in shape, used to carry microwave signals into and out of microwave antennas.