| Earth segment | the part of a satellite communications system consisting of the earth stations and the interfaces with the terrestrial telecommunications infrastructure |
| Echo | the time delayed electronic reflection of a signal to its source within a communications system |
| Echo canceller | an electronic circuit which attenuates echo on satellite links; today these are largely replaced by echo suppressers |
| Echo check | an error checking tequnique in which data sent to a receiver is sent back to the sender for verification |
| Echo suppressor | a device which reduces the echo in a communications channel |
| Edge of coverage | limit of a satellite's defined service area |
| Element set | a data file which defines a satellite's orbit |
| Elevation | angular altitude of the satellite above the horizon at the earth station |
| Encapsulation | the process of wrapping a data set in a protocol header; also a method of bridging dissimilar networks in which the entire frame from one network is simply enclosed in the header used by the link layer protocol of the other network |
| Encryption | the technique of modifying the form or structure of a transmission so that, without a decoder and the appropriate key, the signal is unintelligible |
| Encryption algorithm | a mathematical process (such as DES and RSA) which can be used to scramble and descramble a data stream |
| Enterprise network | large network connecting most major points in a company; differs from a WAN in that it is typically private and contained within a single organisation |
| Equalisation | method of compensating for the distortion introduced during the transmission of a signal through a channel with different gain at different frequencies |
| Equatorial Orbit | an orbit with inclination i=0°, ie and orbit in the same plane as the Earth's equator |
| Error control | the technique of detecting and correcting, if possible, errors introduced during transmission |
| Event timer | programmable timer built into a receiver to switch on and change channels for unattended video recording |
| Event TV | televising of one-off events to the business community |
| Extended IF | the enlarged receiver IF tuning range (950 - 2050 MHz) to enable it to use the whole frequency range supported by triple band LNBs |
