For a given optical fiber communication system, P(e) = 10-9, Zm = 20.7, f = 2.9×1014, η = 1. Find the minimum pulse energy or quantum limit.

= 10-9, Zm = 20.7, f = 2.9×1014, η = 1. Find the minimum pulse energy or quantum limit.a) 3.9×10-18b) 4.2×10-18c) 6.2×10-14d) 7.2×10-14

FOR_A_GIVEN_OPTICAL_FIBER_COMMUNICATION_SYSTEM,_P_(E)_=10-9,ZM=_20.7,_F_=_2.9‚ÄÖ√†√∂‚ÀÖ‚Â•1014,_‚ÂÀ√≠‚ÄÖ√†√´=_1._FIND_THE_MINIMUM_PULSE_ENERGY_OR_QUANTUM_LIMIT.?$#

4.2‚Äö√†√∂‚àö‚â•10-18

3.9‚Äö√†√∂‚àö‚â•10-18

4.2‚Äö√†√∂‚àö‚â•10-18

6.2‚Äö√†√∂‚àö‚â•10-14

7.2‚Äö√†√∂‚àö‚â•10-14

The incident optical power required to achieve a desirable SNR is 168.2nW. What is the value of incident power in dBm?$

‚Äö√Ñ√∂‚àö√ë‚àö¬® 34 dBm

Internal noise generation can be reduced by keepin?

Both input and output lead length short

Mention a scheme to reduce the effect of electrical noise on ICs?

Use of compensating networks near ICs

Isolating ICs on different boards

Use of compensating networks near ICs

The factors that determine the amount of noise induced is

Rate of change of current per unit time

Type of coupling between two circuits

Rate of change of current per unit time

Which among the following is not a source of internal noise?

AC random voltages generated within conductors

Identify the external noise sources

Switching of rotating machinery

39 + Mcqs in Noise in Optical Communication Page 1 McqOptions

1.	If a matched attenuator with a loss of 3.2 dB is placed between the source and the amplifier’s input, what is the operating spot noise figure of the attenuator amplifier cascade if the attenuator’s physical temperature is 290 K?
A.	9 db
B.	11.3 db
C.	10.4 db
D.	13.3 db
Answer» E.

Discussion

2.	What is the maximum average effective input noise temperature that an amplifier can have if its average standard noise figure is to not exceed 1.7?
A.	203 K
B.	215 K
C.	235 K
D.	255 K
Answer» B. 215 K

Discussion

3.	What average operating noise figure results when the amplifier is used with an antenna of temperature 30 K?
A.	9.54 db
B.	10.96 db
C.	11.23 db
D.	12.96 db
Answer» B. 10.96 db

Discussion

4.	If the amplifier is sold to engineering public, the noise figure that would be quoted in a catalog is
A.	0.46
B.	0.94
C.	1.83
D.	2.93
Answer» D. 2.93

Discussion

5.	A system has three stage cascaded amplifier each stage having a power gain of 10 dB and noise figure of 6 dB. the overall noise figure is
A.	1.38
B.	6.8
C.	4.33
D.	10.43
Answer» D. 10.43

Discussion

6.	A mixer stage has a noise figure of 20 dB. This mixer stage is preceded by an amplifier which has a noise figure of 9 dB and an available power gain of 15 dB. The overall noise figure referred to the input is
A.	11.07
B.	18.23
C.	56.43
D.	97.38
Answer» B. 18.23

Discussion

7.	A resistor R 1 k is maintained at 17C. The rms noise voltage generated in a bandwidth of 10 kHz is
A.	16 x 10(-14) V
B.	0.4 µV
C.	4 µV
D.	16 x 10(-18) V
Answer» C. 4 µV

Discussion

8.	In a receiver the input signal is 100 V, while the internal noise at the input is 10 V. With amplification the output signal is 2 V, while the output noise is 0.4 V. The noise figure of receiver is
A.	2
B.	0.5
C.	0.2
D.	None of the mentioned
Answer» B. 0.5

Discussion

9.	In the equation given below, what does τstands for?
A.	Velocity
B.	Time
C.	Reflection
D.	Refractive indexView Answer
Answer» C. Reflection

Discussion

10.	The incident optical power required to achieve a desirable SNR is 168.2nW. What is the value of incident power in dBm?
A.	-37.7 dBm
B.	-37 dBm
C.	– 34 dBm
D.	-38.2 dBm
Answer» B. -37 dBm

Discussion

11.	An analog optical fiber system operating at wavelength 1μmhas a post-detection bandwidth of 5MHz. Assuming an ideal detector and incident power of 198 nW, calculate the SNR (f = 2.99×1014Hz).
A.	46
B.	40
C.	50
D.	52
Answer» D. 52

Discussion

12.	For a given optical fiber communication system, P(e) = 10-9, Zm = 20.7, f = 2.9×1014, η = 1. Find the minimum pulse energy or quantum limit.
A.	3.9×10-18
B.	4.2×10-18
C.	6.2×10-14
D.	7.2×10-14
E.	= 10-9, Zm = 20.7, f = 2.9×1014, η = 1. Find the minimum pulse energy or quantum limit.a) 3.9×10-18b) 4.2×10-18c) 6.2×10-14d) 7.2×10-14
Answer» B. 4.2×10-18

Discussion

13.	A digital optical fiber communication system requires a maximum bit-error-rate of 10-9. Find the average number of photons detected in a time period for a given BER.
A.	19.7
B.	21.2
C.	20.7
D.	26.2
Answer» D. 26.2

Discussion

14.	The probability of zero pairs being generated when a light pulse is present is given by which of the following equation?
A.	P(0/1) = exp(-Zm)
B.	P(x) = exp (Zm)
C.	P(y) = x (0) + x(1)
D.	P(z) = P(-Zm)
Answer» B. P(x) = exp (Zm)

Discussion

15.	A small leakage current still flows from the device terminals even if there is no optical power incident on the photo detector.
A.	True
B.	False
Answer» B. False

Discussion

16.	AN_ANALOG_OPTICAL_FIBER_SYSTEM_OPERATING_AT_WAVELENGTH_1‚ÂÀ√≠¬¨‚À´MHAS_A_POST-DETECTION_BANDWIDTH_OF_5MHZ._ASSUMING_AN_IDEAL_DETECTOR_AND_INCIDENT_POWER_OF_198_NW,_CALCULATE_THE_SNR_(_F_=_2.99‚ÄÖ√†√∂‚ÀÖ‚Â•10¹⁴HZ)?$#
A.	46
B.	40
C.	50
D.	52
Answer» D. 52

Discussion

17.	HOW_TO_CHOOSE_AN_IC_FOR_A_HIGH_ELECTRICAL_NOISE_ENVIRONMENT??$
A.	Low degree of noise immunity
B.	High degree of noise immunity
C.	Low degree of noise reduction
D.	High degree of noise reduction
Answer» C. Low degree of noise reduction

Discussion

18.	FOR_A_GIVEN_OPTICAL_FIBER_COMMUNICATION_SYSTEM,_P_(E)_=10^-9,Z_M=_20.7,_F_=_2.9‚ÄÖ√†√∂‚ÀÖ‚Â•10¹⁴,_‚ÂÀ√≠‚ÄÖ√†√´=_1._FIND_THE_MINIMUM_PULSE_ENERGY_OR_QUANTUM_LIMIT.?$#
A.	3.9‚Äö√†√∂‚àö‚â•10<sup>-18</sup>
B.	4.2‚Äö√†√∂‚àö‚â•10<sup>-18</sup>
C.	6.2‚Äö√†√∂‚àö‚â•10<sup>-14</sup>
D.	7.2‚Äö√†√∂‚àö‚â•10<sup>-14</sup>
Answer» B. 4.2‚Äö√†√∂‚àö‚â•10<sup>-18</sup>

Discussion

19.	In the equation given below, what does ‚âà√¨‚àö√´stands for?$#
A.
B.	Velocity
C.	Time
Answer» C. Time

Discussion

20.	The incident optical power required to achieve a desirable SNR is 168.2nW. What is the value of incident power in dBm?$
A.	-37.7 dBm
B.	-37 dBm
C.	‚Äö√Ñ√∂‚àö√ë‚àö¬® 34 dBm
D.	-38.2 dBm
Answer» B. -37 dBm

Discussion

21.	Which_among_the_following_has_best_immunity_to_induced_noise?$
A.	Non-inverting amplifier
B.	Inverting amplifier
C.	Differential amplifier
D.	Voltage follower
Answer» D. Voltage follower

Discussion

22.	Internal noise generation can be reduced by keepin?
A.	None of the mentioned
B.	Input lead length short
C.	Both input and output lead length short
D.	Output lead length short
Answer» D. Output lead length short

Discussion

23.	A digital optical fiber communication system requires a maximum bit-error-rate of 10^-9. Find the average number of photons detected in a time period for a given BER?
A.	19.7
B.	21.2
C.	20.7
D.	26.2
Answer» D. 26.2

Discussion

24.	Mention a scheme to reduce the effect of electrical noise on ICs?
A.	Isolating ICs on different boards
B.	Add a filter near ICs
C.	Physical shielding of ICs
D.	Use of compensating networks near ICs
Answer» D. Use of compensating networks near ICs

Discussion

25.	The Te is
A.	70 K
B.	110 K
C.	149 K
D.	240 K
Answer» D. 240 K

Discussion

26.	The minimum pulse energy needed to maintain a given bit-error-rate (BER) which any practical receiver must satisfy is known as ___________
A.	Minimal energy
B.	Quantum limit
C.	Point of reversed
D.	Binary signaling
Answer» C. Point of reversed

Discussion

27.	Which type of noise is produced when the op-amp has wider bandwidth?
A.	1/f noise
B.	Schottky noise
C.	Thermal noise
D.	Radiant noise
Answer» C. Thermal noise

Discussion

28.	The probability of zero pairs being generated when a light pulse is present is given by equation ‚Äö√Ñ√∂‚àö√ë‚àö¬®$
A.	P (0/1) = exp(-Z<sub>m</sub>)
B.	P(x) = exp (Z<sub>m</sub>)
C.	P(y) = x (0) + x(1)
D.	P (z) = P(-Z<sub>m</sub>)
Answer» B. P(x) = exp (Z<sub>m</sub>)

Discussion

29.	The factors that determine the amount of noise induced is
A.	Type of coupling between two circuits
B.	Rate of change of current per unit time
C.	Speed of operation of circuit
D.	All of the mentioned
Answer» B. Rate of change of current per unit time

Discussion

30.	___________ distribution provides the description the random statistics of light emitted in black body radiation.
A.	Poisson
B.	Cumulative
C.	Probability
D.	Bose-Einstein
Answer» E.

Discussion

31.	The type of noise phenomena that increases with increase in temperature is
A.	None of the mentioned
B.	1/f noise
C.	Schottky noise
D.	Thermal noise
Answer» E.

Discussion

32.	A small leakage current still flows from the device terminals even if there is no optical power incident on the photo detector. State whether the given statement is true or false.
A.	True
B.	False
Answer» B. False

Discussion

33.	Which among the following is not a source of internal noise?
A.	AC random voltages generated within conductors
B.	Lightning
C.	Switching of circuits
D.	None of the mentioned
Answer» C. Switching of circuits

Discussion

34.	A resistor R 1 k is maintained at 17C. The rms noise voltage generated in a bandwidth of 10 kHz is
A.	16 x 10<sup>(-14)</sup> V
B.	0.4 ¬¨¬®¬¨¬µV
C.	4 ¬¨¬®¬¨¬µV
D.	16 x 10<sup>(-18)</sup> V
Answer» C. 4 ¬¨¬®¬¨¬µV

Discussion

35.	______________ is caused due to thermal interaction between the free electrons and the vibrating ions in the conduction medium.
A.	Thermal noise
B.	Dark noise
C.	Quantum noise
D.	Gaussian noise
Answer» B. Dark noise

Discussion

36.	Identify the external noise sources
A.	Switching of rotating machinery
B.	Control circuits
C.	Ignition system
D.	All of the mentioned
Answer» C. Ignition system

Discussion

37.	A receiver is operated at a temperature of 300 K. The transistor used in the receiver have an average output resistance of 1 k. The Johnson noise voltage for a receiver with a bandwidth of 200 kHz is
A.	1.8 ¬¨¬®¬¨¬µV
B.	8.4 ¬¨¬®¬¨¬µV
C.	4.3 ¬¨¬®¬¨¬µV
D.	12.6 ¬¨¬®¬¨¬µV
Answer» B. 8.4 ¬¨¬®¬¨¬µV

Discussion

38.	How many types of noise are observed because of the spontaneous fluctuations in optical fiber communication systems?
A.	One
B.	Four
C.	Two
D.	Three
Answer» E.

Discussion

39.	_____________ refers to any spurious or undesired disturbances that mask the received signal in a communication system.
A.	Attenuation
B.	Noise
C.	Dispersion
D.	Bandwidth
Answer» C. Dispersion

Discussion

Explore topic-wise MCQs in Optical Communication.

If a matched attenuator with a loss of 3.2 dB is placed between the source and the amplifier’s input, what is the operating spot noise figure of the attenuator amplifier cascade if the attenuator’s physical temperature is 290 K?

What is the maximum average effective input noise temperature that an amplifier can have if its average standard noise figure is to not exceed 1.7?

What average operating noise figure results when the amplifier is used with an antenna of temperature 30 K?

If the amplifier is sold to engineering public, the noise figure that would be quoted in a catalog is

A system has three stage cascaded amplifier each stage having a power gain of 10 dB and noise figure of 6 dB. the overall noise figure is

A mixer stage has a noise figure of 20 dB. This mixer stage is preceded by an amplifier which has a noise figure of 9 dB and an available power gain of 15 dB. The overall noise figure referred to the input is

A resistor R 1 k is maintained at 17C. The rms noise voltage generated in a bandwidth of 10 kHz is

In a receiver the input signal is 100 V, while the internal noise at the input is 10 V. With amplification the output signal is 2 V, while the output noise is 0.4 V. The noise figure of receiver is

In the equation given below, what does τstands for?

The incident optical power required to achieve a desirable SNR is 168.2nW. What is the value of incident power in dBm?

An analog optical fiber system operating at wavelength 1μmhas a post-detection bandwidth of 5MHz. Assuming an ideal detector and incident power of 198 nW, calculate the SNR (f = 2.99×1014Hz).

For a given optical fiber communication system, P(e) = 10-9, Zm = 20.7, f = 2.9×1014, η = 1. Find the minimum pulse energy or quantum limit.

A digital optical fiber communication system requires a maximum bit-error-rate of 10-9. Find the average number of photons detected in a time period for a given BER.

The probability of zero pairs being generated when a light pulse is present is given by which of the following equation?

A small leakage current still flows from the device terminals even if there is no optical power incident on the photo detector.

AN_ANALOG_OPTICAL_FIBER_SYSTEM_OPERATING_AT_WAVELENGTH_1‚ÂÀ√≠¬¨‚À´MHAS_A_POST-DETECTION_BANDWIDTH_OF_5MHZ._ASSUMING_AN_IDEAL_DETECTOR_AND_INCIDENT_POWER_OF_198_NW,_CALCULATE_THE_SNR_(_F_=_2.99‚ÄÖ√†√∂‚ÀÖ‚Â•1014HZ)?$#

HOW_TO_CHOOSE_AN_IC_FOR_A_HIGH_ELECTRICAL_NOISE_ENVIRONMENT??$

FOR_A_GIVEN_OPTICAL_FIBER_COMMUNICATION_SYSTEM,_P_(E)_=10-9,ZM=_20.7,_F_=_2.9‚ÄÖ√†√∂‚ÀÖ‚Â•1014,_‚ÂÀ√≠‚ÄÖ√†√´=_1._FIND_THE_MINIMUM_PULSE_ENERGY_OR_QUANTUM_LIMIT.?$#

In the equation given below, what does ‚âà√¨‚àö√´stands for?$#

The incident optical power required to achieve a desirable SNR is 168.2nW. What is the value of incident power in dBm?$

Which_among_the_following_has_best_immunity_to_induced_noise?$

Internal noise generation can be reduced by keepin?

A digital optical fiber communication system requires a maximum bit-error-rate of 10-9. Find the average number of photons detected in a time period for a given BER?

Mention a scheme to reduce the effect of electrical noise on ICs?

The Te is

The minimum pulse energy needed to maintain a given bit-error-rate (BER) which any practical receiver must satisfy is known as ___________

Which type of noise is produced when the op-amp has wider bandwidth?

The probability of zero pairs being generated when a light pulse is present is given by equation ‚Äö√Ñ√∂‚àö√ë‚àö¬®$

The factors that determine the amount of noise induced is

___________ distribution provides the description the random statistics of light emitted in black body radiation.

The type of noise phenomena that increases with increase in temperature is

A small leakage current still flows from the device terminals even if there is no optical power incident on the photo detector. State whether the given statement is true or false.

Which among the following is not a source of internal noise?

A resistor R 1 k is maintained at 17C. The rms noise voltage generated in a bandwidth of 10 kHz is

______________ is caused due to thermal interaction between the free electrons and the vibrating ions in the conduction medium.

Identify the external noise sources

A receiver is operated at a temperature of 300 K. The transistor used in the receiver have an average output resistance of 1 k. The Johnson noise voltage for a receiver with a bandwidth of 200 kHz is

How many types of noise are observed because of the spontaneous fluctuations in optical fiber communication systems?

_____________ refers to any spurious or undesired disturbances that mask the received signal in a communication system.

AN_ANALOG_OPTICAL_FIBER_SYSTEM_OPERATING_AT_WAVELENGTH_1‚ÂÀ√≠¬¨‚À´MHAS_A_POST-DETECTION_BANDWIDTH_OF_5MHZ._ASSUMING_AN_IDEAL_DETECTOR_AND_INCIDENT_POWER_OF_198_NW,_CALCULATE_THE_SNR_(_F_=_2.99‚ÄÖ√†√∂‚ÀÖ‚Â•10¹⁴HZ)?$#

FOR_A_GIVEN_OPTICAL_FIBER_COMMUNICATION_SYSTEM,_P_(E)_=10^-9,Z_M=_20.7,_F_=_2.9‚ÄÖ√†√∂‚ÀÖ‚Â•10¹⁴,_‚ÂÀ√≠‚ÄÖ√†√´=_1._FIND_THE_MINIMUM_PULSE_ENERGY_OR_QUANTUM_LIMIT.?$#

A digital optical fiber communication system requires a maximum bit-error-rate of 10^-9. Find the average number of photons detected in a time period for a given BER?