Frequency or phase of message signal is varied according to the message signal.The amplitude is kept constant.

1. ANGLE MODULATION
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2. TOPICS COVERED
• Introduction
• Concept of Angle Modulation : Basic Definition
– Phase Modulation (PM) Definition
– Frequency Modulation (FM) Definition
• Frequency Deviation
• Relationship between Phase Modulation (PM)
and Frequency Modulation (FM)
• Single Tone Frequency Modulation
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3. INTRODUCTION
• Frequency or phase of message signal is
varied according to the message signal.
• The amplitude is kept constant.
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4. Concept of Angle Modulation :
Basic Definition
DEFINITION
Total phase angle of the carrier wave is
varied according to the instantaneous
value of the modulating signal keeping the
amplitude constant.
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5. TYPES OF ANGLE
MODULATION
• Depending upon the ways in which we can
vary phase angle ‘Ǿ’, the types are:
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6. APPLICATIONS OF ANGLE
MODULATION
• Radio Broadcasting
• Two way mobile radio
• Microwave communication
• TV sound transmission
• Cellular radio
• Satellite communication
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7. ADVANTAGES AND
DISADVANTAGES
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8. PHASE MODULATION
Phase angle Ǿ is varied in accordance to
baseband or modulating signal.
The mathematical representation of the
same can be shown as:
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9. DIKSHA PRAKASH

10. DIKSHA PRAKASH

11. FREQUENCY MODULATION
• It is a type of angle modulation in which
the instantaneous frequency varied
linearly in accordance to baseband or
modulating signal.
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12. FREQUENCY MODULATION
Negative
Deviation
Positive
Deviation
FIGURE: Illustration of Frequency Deviation
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13. Frequency Relationship between
PM and FM
Expression for PM wave is:
Expression for FM wave is:
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14. • In PM, the phase angle varies linearly with
base band signal x(t).
• In FM, the phase angle varies linearly with
the integral of baseband signal x(t).
Thus, FM can be obtained from FM and
the converse is also true.
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15. FM using PM
FM signalAn
Integrator
Phase
Modulator
Carrier
Generator
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16. PM using FM
A
Differentiator
Frequency
Modulator
Carrier
Generator
PM Signal
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17. SINGLE TONE FREQUENCY
MODULATION
• General expression for FM wave:
Equation shows non-linear modulation
process.
Hence to avoid complexity, we use single
tone frequency modulation.
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18. DIKSHA PRAKASH

19. INFERENCES
• Frequency of carrier wave is varied
according to x(t).
• Maximum amplitude of the carrier wave is
kept constant.
•
• This deviation is called ‘Frequency
Deviation’
• Amount of deviation depends upon
amplitude of x(t)DIKSHA PRAKASH

20. • For FM, the modulation index is denoted
by:
or,
The modulation index maybe greater than
unity.
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21. MATHEMATICAL EXPRESSION
& NUMERICALS
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