FREQUENCY MODULATION

FREQUENCY MODULATION

Frequency modulation is the transfer of information signals with the varies frequency carrier wave

Frequency modulation is a form of analog angle modulation in which the baseband information carrying signal, typically called the message or information signal m(t), varies the frequency of a carrier wave.

FM is considered an analog form of modulation because the baseband signal is typically an analog waveform without discrete, digital values

Frequency modulation is a method of impressing data onto an alternating-current (AC) wave by varying the instantaneous frequency of the wave. This scheme can be used with analog or digital data.

Frequency modulation uses the information signal, V_m(t) to vary the carrier frequency within some small range about its original value. Here are the three signals in mathematical form:

• Information: V_m(t)
• Carrier: V_c(t) = V_co sin ( 2 p f_c t + f )
• FM: V_FM (t) = V_co sin (2 p [f_c + (Df/V_mo) V_m (t) ] t + f) 
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Frequency Modulation (FM) is a form of modulation in which changes in the carrier wave frequency correspond directly to changes in the baseband signal

A spectrum represents the relative amounts of different frequency components in any signal.

The efficiency of a signal is the power in the side-bands as a fraction of the total. In FM signals, because of the considerable side-bands produced, the efficiency is generally high.

 

MODULATION

Modulation is the process of varying one or more properties of a periodic waveform (a carrier signal) with a modulating signal that typically contains information to be transmitted

Modulation is the addition of signal information to an electronic carrier. Modulation can be applied to direct current (mainly by turning it on and off), to alternating current, and to optical signals.

The information signal can rarely be transmitted as is, it must be processed. In order to use electromagnetic transmission, it must first be converted from audio into an electric signal.

The conversion is accomplished by a transducer. After conversion it is used to modulate a carrier signal.

Transmitter

Transmitter is the sub-system that takes the information signal and processes it prior to transmission. The transmitter modulates the information onto a carrier signal, amplifies the signal and broadcasts it over the channel

Channel

Channel is the medium which transports the modulated signal to the receiver. Air acts as the channel for broadcasts like radio. May also be a wiring system like cable TV and internet.

Receiver

Receiver is the sub-system that takes in the transmitted signal from the channel and processes it to retrieve the information signal. The receiver must be able to discriminate the signal from other signals which may using the same channel

Signal of information can be encoding in a carrier wave by varying instantaneous frequency of a wave in such with analog signal the instantaneous and frequency of the carrier is directly proportional to the instantaneous value of input-signal amplitude.

Data can be encoding and transmitted through a carrier wave by shifting the carrier frequency into the set of predefined frequency this sends radio teletype and Morse code by using of modems and fax modems

FM radio uses the electrical image of a sound source to modulate the frequency of a carrier wave. At the receiver end in the detection process, that image is stripped back off the carrier and turned back into sound by a loudspeaker

FM radio uses the electrical image of a sound source to modulate the frequency of a carrier wave

The change in frequency, which is greatly exaggerated here, is proportional to the amplitude of the signal. An FM radio carrier around 100 MHz is limited to modulation of +/- 0.1 MHz

The FM band of the electromagnetic spectrum is between 88 MHz and 108 MHz and the carrier waves for individual stations are separated by 200 kHz for a maximum of 100 stations.