Frequency modulation

related topics
{system, computer, user}
{math, energy, light}
{math, number, function}
{rate, high, increase}

Demodulation, modem,

line coding, PAM, PWM, PCM

In telecommunications and signal processing, frequency modulation (FM) conveys information over a carrier wave by varying its instantaneous frequency (contrast this with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant). In analog applications, the difference between the instantaneous and the base frequency of the carrier is directly proportional to the instantaneous value of the input signal amplitude. Digital data can be sent by shifting the carrier's frequency among a set of discrete values, a technique known as frequency-shift keying.

Frequency modulation can be regarded as phase modulation where the carrier phase modulation is the time integral of the FM modulating signal.



Suppose the baseband data signal (the message) to be transmitted is xm(t) and the sinusoidal carrier is x_c(t) = A_c \cos (2 \pi f_c t)\,, where fc is the carrier's base frequency and Ac is the carrier's amplitude. The modulator combines the carrier with the baseband data signal to get the transmitted signal:

Full article ▸

related documents
GE-600 series
Apple Desktop Bus
Exidy Sorcerer
Digital Visual Interface
Wormhole switching
High fidelity
Blue Gene
Signaling System 7
Bally Astrocade
Disk image
Audio amplifier
Magnetic tape
Gigabit Ethernet
Wikipedia:Federal Standard 1037C terms/telephony terms
Video on demand
Internet Message Access Protocol
Computer display standard
Address Resolution Protocol
Distributed computing
LAN switching
Video CD
Digital signal processing
Video codec