Anna University Regulation 2013 CSE CS6304 ADC 2marks 16marks is provided below. Download link for CSE 3rd SEM CS6304 Analog and Digital Communication Short answers, Question Bank are listed down for students to make perfect utilisation and score maximum marks with our study materials.

### UNIT I–Fundamentals of Analog Communication

#### PART-A

1. What is modulation?
Modulation is the process of changing any one parameter (amplitude, frequency or phase) of a relatively high frequency carrier signal in proportion with the instantaneous value of the modulating signal or message signal.
2. Define amplitude Modulation.
Amplitude Modulation is the process of changing the amplitude of a relatively high frequency carrier signal in proportion with the instantaneous value of the modulating signal.
3. Give the expression for AM modulated wave.
4. Define Modulation index and percent modulation for an AM wave.
Modulation index is a term used to describe the amount of amplitude change present in an AM waveform .It is also called as coefficient of modulation.
Mathematically modulation index is m = Em/ Ec
where m = Modulation coefficient, Em = Peak change in the amplitude of the output waveform voltage. Ec = Peak amplitude of the unmodulated carrier voltage.
Percent modulation gives the percentage change in the amplitude of the output wave when the carrier is acted on by a modulating signal.
5. Give the bandwidth of AM?
Bandwidth (B) of AM DSBFC is the difference between highest upper frequency and lowest lower side frequency. fm(max) – maximum modulating signal frequency.
6. Draw the spectrum of AM signal.
7. Give the expression for modulation index in terms of Vmax and Vmin.
m = Vmax – Vmin / Vmax + Vmin
8. Give the formula for AM power distribution.
9. Give the expression for total current.

10. Give the types of AM Modulation.
DSBSC-Double sideband suppressed carrier.
SSBSC- Single sideband suppressed carrier.
DSBFC- Double sideband full carrier
VSBSC-Vestigial sideband suppressed carrier.
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