Modulation Formats

Optical Communications

This set of Optical Communications Multiple Choice Questions & Answers (MCQs) focuses on “Modulation Formats”.

1. _____________ is essentially a crude form of Amplitude shift keying.
a) Analog modulation
b) Digital intensity modulation
c) Photodetector
d) Receiver structure

2. Almost _________ of the transmitter power is wasted in the use of external modulators.
a) Half
b) Quarter
c) One-third
d) Twice

3. The line width in the range ________ of bit rate is specified for ASK heterodyne detection.
a) 8%
b) 2 to 8%
c) 10 t0 50%
d) 70%

4. ______________ is also referred to as on-off keying (OOK).
a) FSK
b) DSK
c) PSK
d) ASK

5. ________ does not require an external modulator.
a) FSK
b) DSK
c) PSK
d) ASK

6. The frequency deviation at frequencies above 1 MHz is typically ____________
a) 10 to 20 mA-1
b) 100 to 500 mA-1
c) 1000 to 2000 mA-1
d) 30 to 40 mA-1

7. ___________ offers the potential for improving the coherent optical receiver sensitivity by increasing the choice of signalling frequencies.

8. Eight level FSK and binary PSK yields an equivalent sensitivity.
a) False
b) True

9. External modulation for ________ modulation format allows the most sensitive coherent detection mechanism.
a) FSK
b) DSK
c) PSK
d) ASK

10. _________ can potentially provide spectral conservation through the use of multilevel signalling.
a) M-ary PSK
c) ASK

11. The digital transmission on implementation of polarization modulation which involves polarization characteristics of the transmitted optical signal is known as _____________
a) Frequency shift keying
b) Amplitude shift keying
c) Phase shift keying
d) Polarization shift keying

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