Earth station

A complete satellite receiving or transmitting station including the antenna, electronics and all associated equipment necessary to receive or transmit satellite signals. Also known as a ground station.

Eb/No

Energy-per-Bit-to-Noise-Power-density ratio. The digital equivalent of C/No.

Eccentricity

Link concentricity, a measure of the center of a conductor's location with respect to the circular cross section of the insulation. Expressed as a percentage of displacement of one circle within the other.

Echo canceller

An electronic circuit which attenuates or eliminates the echo effect on satellite telephone links.

Echo Effect

A time delayed electronic reflection of one's voice caused by an electrical discontinuity in telephone circuit. Echoes are often experienced during satellite-delivered long distance telephone calls.

Eclipse

Period when the satellite passes into the Earth's (or the Moon's shadow, when power must be drawn from storage batteries.

Eclipse-protected

Refers to a transponder that can remain powered during the period of an eclipse.

ED

Energy Dispersal.

Edge of Coverage

Limit of defined service area, typically 3 dB down from beam center, but may be more. Reception is still possible beyond this line.

Effective Isotropic Radiated Power (EIRP)

A measure of the signal strength that a satellite transmits towards the earth below. The EIRP is highest at the center of the beam and decreases at angles away from the boresight.

EIRP (or e.i.r.p.)

Equivalent Isotropically Radiated Power (or Effective Isotropic Radiated Power). Combined result of transmitter (or transponder) RF power, and transmitting antenna gain.

Ekran ("Screen")

Soviet UHF DBS satellite serving the Statsionar - T system. Downlinks at 714 MHz Siberia, but has usable coverage throughout Asia. Located 99 degrees E.

El/Az (El over Az)

An antenna mount providing independent steering in Azimuth and Elevation.

Electromagnetic Spectrum

The entire range of wavelengths of electromagnetic radiation - including visible light - which extend from gamma rays to microwaves and radio waves, all of which travel at the speed of light (186,000 miles per second or 300,000,000 meters per second).

Elevation

Angle between antenna beam and horizontal plane (measured in vertical plane).

Elongation

The fractional increase in length of a material stressed in tension.

EMI

Abbreviation for electromagnetic interference.

Encoder

A device used to electronically alter a signal so that it can only be viewed on a receiver equipped with a special decoder.

Encryption

A satellite TV receiving antenna component that collects the signal reflected from the main surface reflector and channels this signal into the low-noise amplifier (LNA).

Ends

In braiding, the number of essentially parallel wires or threads on a carrier.

Energy Dispersal

A low-frequency waveform added to the baseband signal before modulation to reduce the FM signal's peak power per unit band-width, and thus reducing its interference potential. The modulation of an uplink carrier with a triangular waveform. This technique disperses the carrier energy over a wider bandwidth than otherwise would be the case in order to limit the maximum energy compared to that transmitted by an unclamped carrier. This triangular waveform is removed by a clamp circuit in a satellite receiver.

EOL

End of Life (of a transponder or satellite)

Equalizing Pulses

A series of six pulses occurring before and after the serrated vertical sync pulse to ensure proper interlacing. The equalizing pulses are inserted at twice the horizontal scanning frequency.

Equatorial Mount

Astronomers' term for Polar Mount.

Equitorial Orbit

An orbit with a plane that is parallel to the Arth's equator.

Exciter

The modulator and driver section of a transmitter, as used in an uplink.

Eye Height

A measurement of SNR on a digital bitstream.