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ECE :: Communication Systems

  1. 24 telephone channels, each band limited to 3.4 kHz are to be time division multiplexed using PCM. If sampling frequency is 10 kHz and number of quantization levels is 128, the required bandwidth of PCM is

  2. A.
    1.68 MHz
    B.
    240 kHz
    C.
    81.6 kHz
    D.
    3.072 MHz

  3. Resonant circuits are used in

  4. A.
    audio amplifiers
    B.
    RF amplifiers
    C.
    both audio and RF amplifiers
    D.
    none of the above

  5. The bandwidth of DSB suppressed carrier modulation system when the modulating frequency varies between 500 Hz and 5 kHz is

  6. A.
    555 kHz
    B.
    505 kHz
    C.
    500 kHz
    D.
    9 kHz

  7. Linear diode detector utilizes

  8. A.
    linear portion of static characteristics of diode
    B.
    linear portion of dynamic characteristic of diode
    C.
    square law portion of dynamic characteristics of diode
    D.
    rectification property of diode

  9. In the equivalent circuit of a moving coil cone type loudspeaker, the mass of the moving system is represented by

  10. A.
    a resistance
    B.
    a capacitance
    C.
    an inductance
    D.
    a conductance

  11. Assertion (A): In India we use CCIR-B standard

    Reason (R): Video signals are frequency modulated.

  12. 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

  13. CATV stands for

  14. A.
    Common Antenna Television
    B.
    Community Antenna Television
    C.
    Cable Antenna Television
    D.
    Channel Antenna Television

  15. Household tape recorders use

  16. A.
    separate motor for each operation
    B.
    only one motor for all operations
    C.
    one motor for capstan and another for take up reel
    D.
    a total of 3 motors

  17. A 400 W carrier is modulated to a depth of 75 percent. The total power in modulated wave will be

  18. A.
    38.5 W
    B.
    400 W
    C.
    512.5 W
    D.
    615.5 W

  19. A geostationary satellite

  20. A.
    is located at a height of 358, 00 km
    B.
    appears stationary over earth's magnetic pole
    C.
    is motionless in space but keeps spinning
    D.
    orbits the earth within a 24 hour period