INTENSITY
MODULATION
TECHNIQUE
SUBMITTED BY:
R ASHOK KUMAR(ECE-2, 25013202810)
GAURAV MITHAS(ECE-2, 14513202810)
AMIT SHAR...
CONTENTS
•
•
•
•
•

MODULATION
MODULATION TECHNIQUES
INTENSITY MODULATION
TYPES OF INTENSITY MODULATION
APPLICATION OF INT...
MODULATION
Modulation is the process of varying
one or more properties of the carrier
signal with a modulating signal whic...
MODULATION TECHNIQUES
INTENSITY MODULATION

• IM: Optical power output of a source is varied in
accordance with some characteristic of the modul...
TYPES OF INTENSITY MODULATION
 Direct intensity modulation(D-IM)

 Subcarrier intensity modulation(S-IM)
 Subcarrier am...
DIRECT INTENSITY MODULATION
• Simplest form of analog modulation for optical fiber
communications.
• The optical output fr...
Fig (a) Analog optical fiber system employing direct intensity modulation.
(b) Time domain representation showing direct i...
SUBCARRIER INTENSITY
MODULATION(S-IM)
• Used for wideband signals.
• Number of baseband channels are multiplexed
onto a si...
Fig. Subcarrier intensity modulation system for analog
optical fiber transmission
Subcarrier frequency modulation(FM-IM)
• The subcarrier is frequency modulated by the
modulating signal.

Subcarrier phase...
SUBCARRIER DOUBLE SIDEBAND
MODULATION(DSB-IM)
• Spectrum translated by direct multiplication of the
baseband message signa...
Fig. Time and frequency domain representations of
double-sideband modulation
PULSE ANALOG TECHNIQUES
• Pulse analog techniques employ pulse
modulation in the electrical regime prior to
intensity modu...
Fig. A PFM–IM optical fiber system employing
regenerative baseband recovery
APPLICATION OF INTENSITY
MODULATION
• Intensity-modulated radiation therapy (IMRT)
Intensity modulation technique using input signal
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Intensity modulation technique using input signal

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Intensity modulation technique using input signal

  1. 1. INTENSITY MODULATION TECHNIQUE SUBMITTED BY: R ASHOK KUMAR(ECE-2, 25013202810) GAURAV MITHAS(ECE-2, 14513202810) AMIT SHARMA(ECE-2, SOURABH KUMAR(ECE-2, 13613202810)
  2. 2. CONTENTS • • • • • MODULATION MODULATION TECHNIQUES INTENSITY MODULATION TYPES OF INTENSITY MODULATION APPLICATION OF INTENSITY MODULATION
  3. 3. MODULATION Modulation is the process of varying one or more properties of the carrier signal with a modulating signal which typically contains information to be transmitted.
  4. 4. MODULATION TECHNIQUES
  5. 5. INTENSITY MODULATION • IM: Optical power output of a source is varied in accordance with some characteristic of the modulating signal. • No discrete upper and lower sidebands as optical sources lack sufficient coherence to produce them. • Recovery of the modulating signal is by direct detection, not heterodyning.
  6. 6. TYPES OF INTENSITY MODULATION  Direct intensity modulation(D-IM)  Subcarrier intensity modulation(S-IM)  Subcarrier amplitude modulation(AM-IM)  Subcarrier frequency modulation(FM-IM)  Subcarrier phase modulation(PM-IM)  Subcarrier double sideband modulation (DSB-IM)  Pulse analog techniques  Pulse amplitude modulation(PAM-IM)  Pulse width modulation(PWM-IM)  Pulse frequency modulation(PFM-IM)
  7. 7. DIRECT INTENSITY MODULATION • Simplest form of analog modulation for optical fiber communications. • The optical output from the source is modulated simply by varying the current flowing in the device around a suitable bias or mean level in proportion to the message. • No electrical modulation or demodulation is required hence, both inexpensive and easy to implement.
  8. 8. Fig (a) Analog optical fiber system employing direct intensity modulation. (b) Time domain representation showing direct intensity modulation of the optical carrier with a baseband analog signal
  9. 9. SUBCARRIER INTENSITY MODULATION(S-IM) • Used for wideband signals. • Number of baseband channels are multiplexed onto a single fiber link. • Provides improvement in SNR. • TYPES:  FM–IM  PM–IM
  10. 10. Fig. Subcarrier intensity modulation system for analog optical fiber transmission
  11. 11. Subcarrier frequency modulation(FM-IM) • The subcarrier is frequency modulated by the modulating signal. Subcarrier phase modulation(PM-IM) • The instantaneous phase of the subcarrier is set proportional to the modulating signal.
  12. 12. SUBCARRIER DOUBLE SIDEBAND MODULATION(DSB-IM) • Spectrum translated by direct multiplication of the baseband message signal with the subcarrier. • frequency domain representation show only two sideband components. • Provides 3 dB degradation in SNR. • Considered inefficient.
  13. 13. Fig. Time and frequency domain representations of double-sideband modulation
  14. 14. PULSE ANALOG TECHNIQUES • Pulse analog techniques employ pulse modulation in the electrical regime prior to intensity modulation of the optical source. • Allows transmission of very narrow pulses. • TYPES: PAM-IM PWM-IM PPM-IM
  15. 15. Fig. A PFM–IM optical fiber system employing regenerative baseband recovery
  16. 16. APPLICATION OF INTENSITY MODULATION • Intensity-modulated radiation therapy (IMRT)
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