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ECE :: Communication Systems

  1. Frequency shifting keying is basically a method involving

  2. A.
    amplitude modulation
    B.
    frequency modulation
    C.
    phase modulation
    D.
    none of the above

  3. Which of the following codes provides parity checks?

  4. A.
    CCITT-2
    B.
    EBCDIC
    C.
    ASCII
    D.
    Baudot

  5. PA radar means

  6. A.
    Phased Array radar
    B.
    Pulsed Array radar
    C.
    Pulse Amplitude radar
    D.
    None of the above

  7. Dynamic range of hi-fi system is at least

  8. A.
    150 dB
    B.
    120 dB
    C.
    80 dB
    D.
    40 dB

  9. A band limited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through

  10. A.
    an RC filter
    B.
    an envelope detector
    C.
    a PPL
    D.
    an ideal low pass filter with the appropriate bandwidth

  11. The seven segment display used in watches and clocks generally uses

  12. A.
    LED
    B.
    LCD
    C.
    Photodiode
    D.
    FET

  13. If e = 10 sin(108 t + 3 sin 104 t) then modulating frequency is

  14. A.
    159 Hz
    B.
    1590 Hz
    C.
    1.59 MHz
    D.
    15.9 MHz

  15. When a signal is quantized such that the step size S is small in comparison with the peak to peak range of the signal, the mean square quantization error is equal to

  16. A.
    S2
    B.
    C.
    D.

  17. Assertion (A): Many times a radar cannot detect 'grounding hopping' military aircraft.

    Reason (R): Ground interference limits the range of radar.

  18. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R are correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    A is wrong but R is correct

  19. Entropies associated with an extremely unlikely message and that with an extremely likely message are respectively

  20. A.
    0 and 0
    B.
    1 and 1
    C.
    1 and 0
    D.
    0 and 1