St. JOSEPH’S INSTITUTE OF TECHNOLOGY
St. JOSEPH’S GROUP OF INSTITUTIONS
OMR, Chennai – 600119
Department of IT Engineering
PROBLEM
SUBJECT NAME :ADC
SUBJECT CODE : EC8394
SL.NOPROBLEM STSTEMENT
YEAR : II
SEM : III
ANSW
ER
1. A Carrier of 6kV is Amplitude Modulated by an audio signal of 3kV.
Find the modulation index.
2. A carrier frequency is frequency modulated with a sinusoidal signal of 2
KHz resulting in a maximum frequency deviation of 5 KHz. Find the
approximate band width of the modulated signal.
3. A signal of 2 sin 2π 5Khz t is modulated with another signal of 20 sin
2π 30Mhz t determine the following when R= 600Ω.
a. modulation index
b. USB,LSB
c. total transmitted power
d. draw the frequency spectrum
e. determine the BW individually for (DSBFC,DSBSC and SSB)
4. A broadcast radio transmitter radiates 5 kW power when the
modulation percentage is 60%. How much is the carrier power?
5. A Carrier of 6kV is Amplitude Modulated by an audio signal of 3kV. Find
the modulation index
6. A 10Kw Carrier wave is amplitude modulated at 80% depth of modulation
by a sinusoidal modulating signal. Calculate the side band power, total
power and the transmission efficiency of the AM wave
7. Derive the equation of an AM wave. Also draw the modulated AM
wave for various modulation index.(ii)The antenna current of an AM
transmitter is 8 ampere when only the carrier is sent. The current
increases to 8.93A when the carrier is modulated by a single sine
wave. Find the percentage modulation.
8. Perfom the Shannon fano code and Huffman code and fin the efficiency
with below data
9. For a BPSK modulator with a carrier frequency of 70 MHz
and an input bit rate of 10 Mbps, determine the maximum
and minimum upper and lower side frequencies, draw the
output spectrum, determine the minimum Nyquist bandwidth,
and calculate the baud.
10. For a QPSK modulator with an input data rate (fb) equal to
10 Mbps and a carrier frequency of70 MHz, determine the
minimum double-sided Nyquist bandwidth (fN) and the baud.
11. For an 8-PSK modulator with an input data rate (fb) equal
to 10 Mbps and a carrier frequency of 70 MHz, determine
the minimum double-sided Nyquist bandwidth (fN) and the
baud.
12. For a standard telephone circuit with a signal-to-noise
power ratio of 1000 (30 dB) and a bandwidth of 2.7 kHz,
the Shannon limit for information capacity is