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ECE :: Communication Systems

  1. In radar system which of the following is called A scope

  2. A.
    deflection modulation of CRT
    B.
    intensity modulation of CRT
    C.
    computer display
    D.
    none of the above

  3. In a CD the channel separation is

  4. A.
    1 μm
    B.
    1.6 μm
    C.
    2.5μm
    D.
    4 μm

  5. The unit for luminous energy is

  6. A.
    lumens/sec
    B.
    lumens/m2
    C.
    lumen-sec
    D.
    lumen/m

  7. The IF bandwidth of a radar receiver is inversely proportional to

  8. A.
    pulse interval
    B.
    pulse width
    C.
    PRF
    D.
    none of the above

  9. If the radiated power of AM transmitter is 10 kW, the power in the carrier for modulation index of 0.6 is nearly.

  10. A.
    8.24 kW
    B.
    8.47 kW
    C.
    9.26 kW
    D.
    9.6 kW

  11. Satellite communication uses frequencies in the range of

  12. A.
    3 to 6 GHz
    B.
    3-10 MHZ
    C.
    10-50 GHz
    D.
    100-200 GHz

  13. In a channel voice coder, the outputs of sixteen 20 Hz low pass filters are sampled, multiplexed and A/D converted. If sampling is at 40 samples/second and 3 bits/sample represents each voltage sample, the bit rate is about

  14. A.
    1.9 k bits/sec
    B.
    0.95 k bits/sec
    C.
    3.8 k bits/sec
    D.
    7.6 k bits/sec

  15. Super high frequency means more than 3000 MHz.

  16. A.
    True
    B.
    False

  17. Impedance inversion may be obtained with

  18. A.
    half wave line
    B.
    a short circuited stub
    C.
    complex impedance Z connected in series with line
    D.
    quarter wave line

  19. Which of the following can be used to convert PPM into PWM?

  20. A.
    Integrator
    B.
    Astable multivibrator
    C.
    Bistable multivibrator
    D.
    Monostable multivibrator