ANALOG COMMUNICATION SYSTEMS
1. A
PLL can be used to demodulate FM
signals.
2. A
PAM signal can be detected by using an
integrator.
3. The
image channel rejection in a super heterodyne receiver comes from detector, RF and IF stages.
4. SSB analog modulation scheme requires the minimum
transmitted power and minimum channel bandwidth.
5. In
a super heterodyne AM receiver, the image channel selectivity is determined by the pre selector and RF stages.
6. A
Hilbert transformer is a time varying
system.
7. Te
maximum power efficiency of an AM modulator is 50%.
8. For
a message signal m(t)=cos(2π
t) and carrier of frequency
, cos[2π(
+
)t]
represents a single side band signal.
9. The
DSB-SC scheme has signal to noise ratio is 2.
10. Ring
modulator behaves like
linear time variant circuit.
11. AM
SSB-SC wave form in time domain can be described by using Hilbert transform.
12. Increases gain, Isolate LO, Increase selectivity are the functions of RF amplifier.
13. Linear
modulation is used
in AM DSB-SC.
14. Del square/12 general formula for normalized noise power.
15. What is synchronous detection?
Ans: The local carrier generated at the
receiver is phase locked with carrier at transmitter is called synchronous
detection or coherent detection.
16. Define
coupling efficiency?
Ans: Ratio of
power coupled into fibre to the power emitted from source n=pf/ps.
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