Introduction to frequency modulation

TITLE:       Introduction to frequency modulation

Introduction:.

 Frequency modulation (FM) is the standard technique for high-fidelity communications as is evident in the received signals of the FM band (88-108 MHz) vs. the AM band (450-1650 KHz). The main reason for the improved fidelity is that FM detectors, when properly designed, are not sensitive to random amplitude variations which are the dominant part of electrical noise (heard as static on the AM radio). Frequency modulation is not only used in commercial radio broadcasts, but also in police and hospital communications, emergency channels, TV sound, wireless (cellular) telephone systems, and radio amateur bands above 30 MHz.

Mathematically, an FM signal is written as:

where A = the amplitude of the signal

ωc = center frequency (frequency for no modulation signal)

ωm = modulation frequency

mf = FM modulation index = δ/fm

δ = maximum frequency shift caused by the modulation signal

fm = frequency of the modulation signal.

Following are the main formulae that are used in frequency modulation in lab view

y(t)=Asin(2πfct+Isin(2πfmt)),

where the parameters are defined as follows:

• fc= carrier frequency (Hz)
• fm= modulating frequency  (Hz)
• I= modulation index=

Block diagram

Front panel

CONCLUSION:

In this lab I have learned some basic concept of frequency modulation that

How frequency modulation occur.  I notice that carrier signal has

Higher value than message signal because carrier signal need high power

Because on the message signal have to travel on message signal and I have

Learned the overall behavior of frequency modulation.