KALASALINGAM UNIVERSITY(Kalasalingam Acedemy of Research and Education)DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERINGECE305 - Digital Communication QUIZName:Reg.No:Sec:1. What form of modulation is shown here?a. Phase shift keying.b. Amplitude shift keying. c. Frequency shift keying.2. The modulation scheme is an example of _____________________.a. PSKb. ASKc. FSK d. CPFSK3. ____________________ is a technique which transforms an analogue telephone circuit into a digital signal, and involves three consecutive processes: sampling, quantization and encoding. a. Frequency Modulation (FM) c. Pulse Code Modulation (PCM)b. Amplitude Modulation (AM) d. Phase Modulation (PM)4. The figure below shows an example of a modulation system used in digital communication. What is that modulation system?a. PCM Modulation.C. Delta Modulation.b. Sigma Modulation. D . Differential Modulation.5. Error signals associated with the sampling process are calleda. Foldover distortion b. Aliasing c. Nyquist rate d. Foldover distortion and aliasing6. The phase shift of QPSK when symbol change occursa. 2b. c. /2d. 3/27. Which of the following gives minimum probability error?a. ASKb. FSKc. PSKd.DPSK8. The impulse response of a matched filter to a data pulse tg(t) with 0 t T isa. (t)b. g(t)c. g(t T)d. g(T t)9. Which of the following gives maximum probability error? a. ASKb. FSKc. PSKd. DPSK10. The BER of BPSK is

11. The maximum length of a PN sequence that can be generated using a 4-stage shift register is a. 4b. 8c. 16d. 1512. A DSSS system transmitting a binary data at the rate of 10kilobits/sec has PN sequence generators with 5 shift register stages and clock frequency of 1MHz. The processing gain of the system is -------------a. 41dBb. 30 dBc. 20dBd.50dB13. The autocorrelation of the output of a PN sequence generator isa. Randomc. Deterministic and periodicb. Deterministic and nonperiodicd. None of these14. The Shannon-Hartley lawa. refers to distortion b. defines bandwidth c. describes signaling rates d. refers to noise15. The code which provides for parity checks is a. Baudot b. ASCIIc. EBCDIC d. CCITT-2 16. Time-division multiplex a. can be used with PCM only b. combines five groups into a supergroup c. stacks 24 channels in adjacent frequency slots d. interleaves pulses belonging to different transmissions17. Pulse-width modulation system used for telegraphy is a. by differentiating pulse-position modulation b. with a monostable c. by integrating the signal d. with a free-running multivibrator18. In order to reduce quantizing noise, one must a. increase the number of standard amplitudes b. send pulses whose sides are more nearly verticalc. use an RF amplifier in the receiver d. increase the number of samples per second19. Which of the following method is employed in telephony?a. Time division multiplexingb. Both a & bc. Frequency division multiplexing20. True /Falsea) A Jammer is an interference signal which abstracts the signal transmission to the receiver b) The extent of maximum eye opening in the horizontal direction indicates Noise margin.c) The aperture effect in flat top pulses is reduced by using an Equalizer 21. A band limited signal with a maximum frequency of 5 kHz is to be sampled. According to the sampling theorem, the sampling frequency which is not valid is(A) 5 kHz (B) 12 kHz (C) 15 kHz (D) 20 kHz