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The modulation index (or modulation depth) of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level. It is defined differently in each modulation scheme. Amplitude modulation index; Frequency modulation index; Phase modulation index
Carrier wave - Wikipedia
Frequency modulation and phase modulation are the two complementary principal methods of angle modulation; phase modulation is often used as an intermediate step to achieve frequency modulation. These methods contrast with amplitude modulation , in which the amplitude of the carrier wave varies, while the frequency and phase remain constant.
Waterfall plot of a 146.52 MHz radio carrier, with amplitude modulation by a 1,000 Hz sinusoid. Two strong sidebands at + and - 1 kHz from the carrier frequency are shown. A carrier, frequency modulated by a 1,000 Hz sinusoid. The modulation index has been adjusted to around 2.4, so the carrier frequency has small amplitude. Several strong ...
Angle modulation is a class of carrier modulation that is used in telecommunications transmission systems. The class comprises frequency modulation (FM) and phase modulation (PM), and is based on altering the frequency or the phase , respectively, of a carrier signal to encode the message signal.
Typically the carrier signal is a sinusoidal signal and in various applications. The figures below illustrate a quick example of a 2-D modulation. The original signal from is modulated with a sinusoidal signal to get . The equations and are the real and the imaginary components of the modulated signal.
In telecommunications, the Carson's bandwidth rule defines the approximate bandwidth requirements of communications system components for a carrier signal that is frequency modulated by a continuous or broad spectrum of frequencies rather than a single frequency. Carson's rule does not apply well when the modulating signal contains ...
Single-sideband modulation with full carrier (e.g. as used by CHU) J: Single-sideband with suppressed carrier (e.g. Shortwave utility and amateur stations) K: Pulse-amplitude modulation: L: Pulse-width modulation (e.g. as used by WWVB) M: Pulse-position modulation: N: Unmodulated carrier (steady, single-frequency signal) P: Sequence of pulses ...