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PDFAngle modulation is a class of analog modulation that involves varying the angle of a carrier wave according to the amplitude of the modulating baseband signal (the information signal). The amplitude of the carrier is kept constant throughout. Angle modulation methods provide better protection against channel noise than Amplitude Modulation and is less susceptible to non-linear distortion and power loss. However, this is at the cost of increased bandwidth requirements.
Phase Modulation and Frequency Modulation are the two main types of angle modulation. Their digital equivalents are called Phase-Shift Keying (PSK) and Frequency-Shift Keying (FSK), respectively.
Angle modulation can be expressed using the following equation:
where:
fc is the carrier frequency
Kf is the frequency deviation constant in Hz/V
fm is the frequency of the information signal
Am is the amplitude of the information signal
Refer to the RF & Communications Resources page for additional information about RF terminology, fundamentals, and National Instruments RF products.
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