University of Pangasinan - ECE 111005619

1)What is the maximum power output of a CB A3E emission?

1. 4 W
2. 10 kW
3. 10 W
4. 3 kW

2.(Nov 1996) The output of a   balanced         modulator       is

           .

1. LSB and USB
2. USB
3. Carrier
4. LSB

3.The purpose of the balances modulator circuits is to eliminate the .

1. Distortion
2. Sidebands
3. Noise
4. Carrier

4.(Apr 1998) Refers to an emission designation for facsimile.

1. A3C and F3C
2. R3E and A3E
3. J3E and F4E
4. A3J and A4E

5.Which produces greater interference, overmodulated positive or negative peaks?

1. Negative
2. neither
3. Positive
4. either

6.(Apr           1997)      Which transmit only sideband?

1. H3E
2. 3AJ
3. A3E
4. 11BE

7.What is the main feature of DSB transmission?

1. Narrow bandwidth
2. High reliability
3. High voltage
4. Carrier is suppressed

8.A 100-V carrier is amplitude modulated by a 1- kHz sine wave. What is the side-frequency amplitude when m=0.75?

a) 75 V

b) 18.75 V

c) 100 V

d) 37.5 V

9. An SSB contains 30 kW. The power content of the carrier is kW.

1. 30
2. 0
3. 20
4. 10

10. What stage in an AM transmitter creates its own sine wave?

1. Buffer
2. Modulator
3. Oscillator
4. Amplifier

11.(Nov1996)  Both frequency and phase modulation utilizes modulation.

1. AM and Fm
2. Phase
3. angle
4. Digital

12.The major difference between FM and PM

1. Lies in the poorer audio response of phase modulation index
2. All of the above
3. Lies in the different definition of modulation index
4. Is too great to make the two system compatible

13.(Apr 1998) The final power amplifier in an FM y=transmitter     usually operates class .

1. B
2. C
3. A
4. AB

14. What          percent  of   the radiated power is in the sidebands                 with                 50% sinusoidal modulation (AM)? a) 16.67%

b) 33%

c) 11%

d) 20%

15. What determine the bandwidth of a transmitted AM signal?

1. The lowest modulation amplitude
2. The highest frequency component of the modulating signal
3. The lowest frequency component of the intelligence
4. The maximum modulation amplitude

16.(Nov 1998) The third symbol radio emission which represent     telephone transmission including sound broadcasting.

1. F
2. C
3. E
4. W

17.  What is the letter-number designation for an FM facsimile? a) F3C

2. A3E
3. C3C
4. F3E

18. An unmodulated carrier is 300 VP-P. Calculate %m when its maximum p-p value reaches 400 V.

a) 100%

b) 33.3%

c) 66.67%

d) 83.3%

19.(Nov 1997) The first symbol in the designation of radio emission under the ITU rules refers to

1. bandwidth
2. type of modulation of the main carrier
3. nature    of     signal(s) modulating the main carrier
4. type of information to be transmitted

20. What           constitutes   the input to an AM transmitter?

1. Mixer and amplifier
2. Mixer and local oscillator
3. Buffer and IF amplifier
4. RF    oscillator    and/or audio amplifier

21. When a carrier is frequency-modulated, what is developed on both sides carrier?

1. Carrier
2. Envelope
3. Noise
4. sidebands

22. If the 500-Hz modulation of a 1-MHz carrier has 3rd harmonic distortion, what is the emission bandwidth?

1. 3 kHz
2. 1 kHz
3. 1500 Hz
4. 1 MHz

23.(Apr       1997)       100%

modulation inn AM means a corresponding increase in total power by .

a) 50%

b) 100%

c) 25%

d) 75%

24.A modulation technique commonly used for low-cost digitization of voice signals.

1. A3
2. F3
3. A5C
4. A0

25. Modulating two waves of the same frequency but with

          . a) 90°

b) 180°

c) 45°

d) 360°

26. For an unmodulated carrier of 1000V and a modulated peak value of 1800 V, what is the modulation index?

a) 0.7

b) 0.8

c) 0.9

d) 0.5

27. What factor determines the modulation index of an FM transmission?

1. Carrier frequency
2. Carrier phase
3. Modulating      signal frequency
4. Carrier amplitude

28.(Mar 1996) Which of the following pulse modulation systems is analog?

1. PCM
2. Differential PCM
3. Delta
4. PWM

29.An FM signal has a frequency deviation of 2000 Hz caused by modulating signal of 500 Hz. What is the modulation index?

1. 2
2. 8
3. 5
4. 4

30.(Apr 1998) Which of the following refers to a double side band full carrier?

1. A3E
2. A3J
3. F3
4. R3A

31. What is the maximum power that can be contained in the sideband without distortion?

a) 50%

b) 25%

c) 66.67%

d) 16.67%

32.(Mar 1996) In AM, the carrier  carries             intelligence.

1. No
2. Distorted
3. Same
4. Difference

33.(Nov 1998) In amplitude modulation technique the unmodulated carrier is referred as having .

1. 50% modulated
2. over modulated
3. 0% modulation
4. 100% modulation

34. modulation envelope is an expression of the amplitude and frequency of the modulation signal.

1. AM
2. FM
3. PCM
4. PM

35.(Apr       1998)    What   is emission C3F?

1. Television
2. Facsimile
3. RTTY
4. Modulated CW

d) 40 kHz

36.A DSB-SC system must suppress the carrier by 50 dB from its original value of 10

W. To what value must the carrier be reduced?

a) 0.1 W

b) 0.001 W

c) 0.0001 W

d) 0.01W

37.What is the following is not a product of overmodulation?

1. Image
2. Spurious signal
3. Buckshot
4. Splatter