The document discusses pulse modulation, defining it as the process of modifying a binary pulse signal to encode information. It covers various types of modulation, including pulse amplitude modulation, pulse width modulation, pulse position modulation, and pulse code modulation, explaining their characteristics and applications. Additionally, it describes companding techniques used to manage signal distortion and noise, focusing on the μ-law and A-law systems.

1. Pulse Modulation
Cervantes, Mary Joy
Neverio, Fulgencio
Estallo, Michael
BSECE-2C

2. DEFINITION
 The process of changing a binary pulse signal to represent the information
to be transmitted
 The variation of a regularly spaced constant amplitude pulse stream to
superimpose information contained in a message signal

3. TYPES OF MODULATION
 Pulse Amplitude Modulation (PAM)
 Pulse Width Modulation (PWM)
 Pulse Position Modulation (PPM)
 Pulse Code Modulation (PCM)

4. PULSE AMPLITUDE MODULATION
 Simplest and least
expensive to implement
 Since the pulses vary in
amplitude, they are far
more susceptible to noise,
and clipping techniques
to eliminate nose cannot
be used because they
would also remove
modulation

5. PULSE WIDTH MODULATION
 The width of the pulse reflects the sampled signal amplitude.
 The position of the leading edge, trailing edge or both may be modified
to reflect the changing duration of the pulse
 also known as: pulse width modulation or pulse length modulation
 PWM is wasteful of energy when the pulses are long, but the information
is only in the pulse transitions

6. PULSE POSITION MODULATION
 The position of the pulse reflects the sampled signal amplitude.
 PPM can be represented as:
where
kp is the sensitivity factor
the adjacent pulses must be strictly non-overlapping

7. PULSE CODE MODULATION
 Most widely used technique for digitizing information signals for electronic data
transmission
 Most basic form of digital pulse modulation
 Elements of pulse-code modulation
1. Transmitter
2. Transmission Path
3. Receiver

8. COMPANDING
 A process of signal compression and expansion that is used to overcome
problems of distortion and noise in the transmission of audio signals
 The most common means of overcoming the problems of quantizing error
and noise

9. COMPANDING
 Two basic types of companding
 the μ-law (pronounced “mu law”) compander
-used in telephone systems in the United States and Japan
 the A-law compander
-used in European telephone networks
The two are incompatible, but conversion
circuits have been developed to convert μ-
law to A-law and vice versa.
The voltage formulas for both are as
follows:

10. SAMPLE PROBLEM
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11. SAMPLE PROBLEM
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