Angular Modulation Flashcards
A modulation technique wherein the amplitude of the carrier is kept constant while the angle or the argument of the carrier is varied in accordance with the intelligence signal
Angular Modulation
2 kinds of angular modulation
Frequency Modulation and Phase Modulation
a form of angle modulation where the frequency of the carrier is varied in accordance with the instantaneous value of the intelligence signal.
Frequency Modulation
the amount of change in the carrier frequency produced by the modulating signal.
Frequency Deviation
Frequency Deviation
the amount of change in the carrier frequency produced by the
modulating signal.
In FM, the intelligence amplitude, Em, determines the
amount of carrier frequency change
In FM, the intelligence frequency, fm, determines the
rate of change of the carrier frequency
Ratio of the frequency deviation over modulating frequency
Modulation Index (FM)
Modulation Index (FM)
Ratio of the frequency deviation over modulating frequency
Whenever the maximum allowable frequency deviation and the maximum modulating frequency are used in computing the modulation index.
Deviation Ratio
Expression of the worst case modulation index.
Deviation Ratio
FCC Rules
FM
max carrier deviation = 75 kHz
max intelligence f = 15 kHz
FCC Rules
TV Sound
max carrier deviation = 25 kHz
max intelligence f = 15 kHz
FCC Rules
Public Safety Services
max carrier deviation = 5 kHz
max intelligence f = 3 kHz
FCC Rules
Amateur Band Radio
max carrier deviation = 3 kHz
max intelligence f = 3 kHz