Glossary of Terms D-2 Glossary of Terms
S412E UG PN: 10580-00318 Rev. P D-7
FM Modulation
Index : In FM modulated systems, the FM Modulation Index is the ratio of the
peak frequency deviation to the maximum modulating frequency. The
higher the index, the greater the received quality. M Modulation Index
= (peak frequency deviation / maximum modulation frequency)
FM Threshold : FM Threshold is the point at which the input signal power is just strong
enough to enable the receiver demodulator circuitry to successfully
detect and recover a good quality television picture from the incoming
video carrier.
GPS : The Global Positioning System (GPS) is a space-based global navigation
satellite system (GNSS) that provides reliable location and time
information in all weather and at all times when and where an
unobstructed line of sight is available to four or more GPS satellites.
The system is maintained by the United States government and is
freely accessible by anyone with a GPS receiver. The Global Positioning
System is making it possible for people using ground receivers to
determine their geographic location within 10 to 100 meters. The
satellites use simple mathematical calculations to broadcast
information that is translated as longitude, latitude, and altitude by
Earth-based receivers.
Graticule : A reticle or grid.
IQ : In-phase and Quadrature (IQ) or (I/Q) IQ is a method of representing
digital modulation. Ll baseband signals can be represented by an I
(In-Phase) portion and a Q (Quadrature-Phase) portion. Vectors
describe the I and Q states (or equivalently the amplitude and phase) of
a signal, so that all possible information about that signal can be
derived from them. I text files contain pairs of I/Q values for signals
that they represent. IQ odulators are 90 degrees out of phase with each
other. IQ dulation combines two channels of information into one signal
and then separates them later.
LMR : Land Mobile Radio
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