## 1. The saving in power in a DSBSC system modulated at 80% is

- Nil
- 80%
- 75.76%
- 50%

**Answer – (4)**

## 2. A 1MHz carrier is amplitude modulated by a 100 µs symmetrical square wave. The frequency not be found in the modulated signals are?

- frequency of 990KHz
- frequency of 1010KHz
- frequency of 1020KHz
- frequency of 1030KHz

**Answer – (4)**

## 3. In which form sound gets modulated in Television Broadcasting?

- VSB
- FM
- SSB
- DSBSC

**Answer – (1)**

## 4. A balance modulator circuit is utilized to discard

- Carrier signal
- LSB signal
- USB signal
- LSB and USB signals

**Answer – (1)**

## 5. The most suitable method for detecting a modulated signal (2.5+5cosω_{c}t) cosω_{c}t is

- The Envelop detector
- The Synchronous detector
- The Ratio detector
- Both (a) and (b) option

**Answer – (4)**

## 6. A carrier is modulated by the two sinusoidal waves of different freqs up to 40% and 60%. The resultant overall modulation index is

- 1.00
- 0.72
- 0.40
- 0.60

**Answer – (2)**

## 7. A 10 Kilo-Watt transmitter is modulated to 80 percent. The avg. sideband power

- 1.8 Kilo-Watt
- 8 Kilo-Watt
- 3.2 Kilo-Watt
- 4.6 Kilo-Watt

**Answer – (3)**

## 8. An AM transmitter radiates power of 10 kilo-watt. The modulation index for carrier’s power is zero.

- 8.24 KW
- 8.47 KW
- 9.26 KW
- 9.6 KW

**Answer – (2)**

## 9. The envelope detector is

- The Synchronous detectors
- The Asynchronous detectors
- The Product demodulators
- The Coherent detectors

**Answer – (3)**

## 10. There are two sine signals. They are in the process of modulation a carrier signal both at a same time. The modulation index is given 0.3, 0.4. the overall modulation index is

- 0.5
- 0.1
- 0.7
- 0.12

**Answer – (1)**

## 11. The intermediate frequency used for a super-heterodyne AM receiver is

- 455 KHz
- 755 KHz
- 545 KHz
- Not an option

**Answer – (1)**

## 12. If the percentage of modulation is 40% for AM wave, find out the change in power.

- 33%
- 2%
- 1%
- 40%

**Answer – (4)**

## 13. What is the maximum transmission efficiency of Amplitude Modulated signal?

- 67.67%
- 50.00%
- 33.33%
- 100%

**Answer – (3)**

## 14. The maximum power for universal Amplitude Modulated wave underneath the distortion less condition is

- 1.5 P
_{c} - P
_{c} - 2P
_{c}/3 - P
_{c}/3

**Answer – (1)**

## 15. A specific Amplitude Modulated broadcasting ratio transmitter radiates 10 Kilo-Watt and the depth of modulation is 60%, the carrier power prerequisite is

- 9 KW
- 7.8 KW
- 8.47 KW
- 9.5 KW

**Answer – (1)**

## 16. The theoretical bandwidth of Freq. Modulated signal is

- Infinity
- 2f
_{m} - 2f
_{m}(1+β) - 0

**Answer – (1)**

## 17. Pre-emphasis in FM signal involves

- Compression technique
- Expansion technique
- Amplification of the lower frequency components only
- Amplification of the higher frequency components only

**Answer – (4)**

## 18. The bandwidth required for transmission of SSBSC signal is

- Greater than AM signal
- Lower than DSBSC signal
- Greater than VSB signal
- Not an option.

**Answer – (2)**

## 19. Varactor diode is used for

- FM generation
- AM generation
- PM generation
- None of these

**Answer – (1)**

## 20. Why pre-emphasis circuit is provided great noise immunity?

- Boost the bass frequency
- Amplify the higher audio frequency
- Pre-amplify the whole audio band
- Convert the PM to FM

**Answer – (2)**

## 21. De-emphasis of FM includes

- Compression technique
- Expansion technique
- Increase of lower frequency signal
- Increase of higher frequency signal

**Answer – (3)**

## 22. If a station is adjusted at 1600 KHz, the image freq. will be

- 1600KHz
- 1145KHz
- 2055KHz
- 2510KHz

**Answer – (4)**

## 23. The typical IF value for an AM receivers is

- The 455KHz
- The 455MHz
- The 108MHz
- 10.7MHz

**Answer – (1)**

## 24. PAM signal may be demodulated by using

- A LPF
- A HPF
- A BPF
- None of these

**Answer – (1)**

## 25. The no. of sidebands in WBFM is

- 1
- More than 1
- Infinity
- None of these

**Answer – (3)**

## 26. Modern FM demodulators uses

- Only quadrature detector
- Only PLL
- Both (1) and (2)
- Diode

**Answer – (3)**

## 27. NBFM is

- Inferior to AM
- Superior to AM
- Same as AM
- Superior to WBFM

**Answer – (2)**

## 28. IF frequency for FM receiver is

- 10.7MHz
- 12.7MHz
- 13.71MHz
- 10.3MHz

**Answer – (4)**

## 29. The Armstrong’s technique is utilized for the

- generation of FM from PM
- generation of WBFM from NBFM
- generation of PM from FM
- All option

**Answer – (4)**

## 30. An FM signal with modulation index of 9 is applied to a frequency triple. Then

- modulation index will become 1
- modulation index will become 30
- modulation index will become 9
- modulation index will become 27

**Answer – (4)**

## 31. Selectivity of a receiver

- Will be changing with incoming signal frequency
- Will be Poorer at higher frequencies
- The elimination of the adjacent channel at the receiver
- All the option

**Answer – (4)**

## 32. Commercial FM has

- 200KHz channel bandwidth and 75KHz deviation
- 150KHz channel bandwidth and 55KHz deviation
- 15KHz channel bandwidth and 75KHz deviation
- None of these

**Answer – (4)**

## 33. In the amplitude modulated wave the majority of the power is

- In the Lower sideband
- In the Upper sideband
- At Carrier
- Not an option

**Answer – (3)**

## 34. Over modulation results in

- Weakens the signal
- Extreme carrier power
- Distortion will occur
- Not an option

**Answer – (3)**

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