7E Communications
   

Glossary Terms Beginning H

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 : Z

H.221
Framing protocol used as part of H.320 (ITU-T standard).
H.230
Control and indication protocol used as part of H.320 (ITU-T standard).
H.242
Communications procedure protocol used as part of H.320 (ITU-T standard).
H.261
Audio compression algorithm standard (ITU-T standard).
H.263+
Further refinement of H.320 to improve performance (ITU-T standard).
H.320
Specification for video-conferencing over ISDN (ITU-T standard).
HDTV
High definition television: television system with approximately twice the horizontal and twice the vertical resolution of current 525-line and 625-line systems, with component colour coding, picture aspect ratio of 16:9 and a frame rate of at least 24 Hz.
Hertz
Hz: term for the basic measure of an electromagnetic wave completing a full oscillation from its positive to its negative pole and back again in what is known as a cycle; thus 1 Hertz is equal to one cycle per second.
Hop
A single Earth-satellite-Earth path.
Horn
See Feedhorn.
HPA
High-power amplifier.
HSD
High-speed data.
Hz
Unit of frequency, where 1 Hz describes one cycle per second; 1 kHz = 1000 Hz (1 103 Hz); 1 MHz = 1000 000 Hz (1 106 Hz); 1 GHz = 1000 000 000 Hz (1 109Hz).