The document discusses modulation, the process of converting digital signals into analog signals, which is crucial for bandpass mediums. It explains different types of modulation such as Amplitude Modulation (AM), Frequency Modulation (FM), and Phase Modulation (PM), highlighting their characteristics and bandwidth requirements. Each modulation type has its advantages, with AM being simple to implement and FM requiring higher bandwidth.

1. A N A L O G T O A N A L O G
C O N V E R S I O N
NETWWORING

2. MODULATION
The process of changing the
digital signals into Analog Signals
is called Modulation.
Change Analog information by
analog signals is also known as
Modulation.

3. WHY TO MODULATE ANALOG
SIGNAL?
Modulation is needed . . .
• If the medium is Bandpass in nature.
• BANDPASS - the range of frequencies
which are transmitted through
bandpass filter.

4. BANDPASS FILTER
An electronic device or circuit.
• Allows signals between two specific
frequencies to pass.
• Prevents signals at unwanted
frequencies.
• Example – Radio

5. ANALOG To ANALOG
CONVERSION
Analog signals are modified to
represent analog data.
• Also known as Analog Modulation.
• Required when BANDPASS is used.

6. TYPES

7. AMPLITUDE MODULATION
Process of changing the amplitude of
high frequency carrier wave in
accordance with intensity of signal is
called AM.
• Amplitude of the carrier wave :
amplitude of the signal being
modulated.

8. AMPLITUDE MODULATION

9. WHY WE NEED MULTIPLIER
Has two analog inputs .
• Output proportional to the product of
the two amplitudes
• Ex. MICROPHONES

10. AMPLITUDE MODULATION
If the modulation signal frequency
increases, the amplitude of the carrier
changes at a greater rate.
• B
AM =2 B
• BAND WIDTH of AM Signal = TWICE
the BANDWIDTH of MODULATING
Signal

11. ADVANTAGES
• It is simple to implement.
• It can be demodulated using a
circuit consisting of very few
components

12. Frequency Modulation
5.12
 The modulating signal changes the freq. fc of
the carrier signal
 The bandwidth for FM is high
 It is approx. 10x the signal frequency

13. 5.13
The total bandwidth required for FM can be determined from the bandwidth
of the audio signal: BFM = 2(1 + β)B. Where  is usually 4.
Note

14. 5.14
Frequency Modulation

15. 5.15
FM Band Allocation

16. Phase Modulation (PM)
5.16
 The modulating signal only changes the phase
of the carrier signal.
 The phase change manifests itself as a
frequency change but the instantaneous
frequency change is proportional to the
derivative of the amplitude.
 The bandwidth is higher than for AM.

17. 5.17
Phase Modulation