KALASALINGAM UNIVERSITY(Kalasalingam Acedemy of Research and Education)DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERINGECE305 - Digital Communication QUIZ1. 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. Phase Shift Keyingc. Frequency Shift Keyingb. Amplitude Shift Keying d. Continuous-Phase Frequency Shift Keying3. ____________________ 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 c. Aliasingb. 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 4 8 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 -------------41dB 30 dB 20dB50dB13. The autocorrelation of the output of a PN sequence generator isRandom Deterministic and periodicDeterministic and nonperiodic None of these14. The acoustic channel is used for which of the following? UHF communications single-sideband communication television communications person-to-person voice communications15. Digital signals do not provide a continuous set of values represent values as discrete steps can utilize decimal or binary systems all of the above 16. The Shannon-Hartley law refers to distortion defines bandwidth describes signaling rates refers to noise17. The code which provides for parity checks is Baudot ASCII EBCDIC CCITT-2 18. Broadband long-distance communications were made possible by the advent telegraph cables repeater amplifiers Geostationary satellites 19. Time-division multiplex can be used with PCM only combines five groups into a supergroup stacks 24 channels in adjacent frequency slots interleaves pulses belonging to different transmissions20. The number of repeaters along a coaxial cable link depends on whether separate tubes are used for the two directions of transmission the bandwidth of the system the number of coaxial cables in the tube the separation of the equalizers 21. In order to separate channels in a TDM receiver, it is necessary to use AND gates bandpass filters Differentiation integration 22. Pulse-width modulation system used for telegraphy is by differentiating pulse-position modulation with a monostable by integrating the signal with a free-running multivibrator23. Quantizing noise occurs in time-division multiplex frequency division multiplex pulse-code modulation pulse-width modulation 24. In order to reduce quantizing noise, one must increase the number of standard amplitudes send pulses whose sides are more nearly vertical use an RF amplifier in the receiver increase the number of samples per second25. Companding is used to overcome quantizing noise in PCM in PCM transmitters, to allow amplitude limited in the rece ivers to protect small signals in PCM from quantizing distortion in PCM receivers, to overcome impulse noise 26. The aperture effect in flat top pulses is reduced by using an ---------------27. The sampling rate (fs) of value 2w samples per second for a signal bandwidth of w.Hz is often referred to as ------------------ 28. Which of the following method is employed in telephony?Time division multiplexing Frequency division multiplexingBoth a & b Only a29. True /FalseA Jammer is an interference signal which abstracts the signal transmission to the receiver The extent of maximum eye opening in the vertical direction indicates Noise margin