Home / ECE / Communication Systems :: Section 18

ECE :: Communication Systems

  1. Transit time is considered as significant at

  2. A.
    HF
    B.
    MF
    C.
    LF
    D.
    all of the above

  3. In a colour TV receiver, AGC adjusts the gain of

  4. A.
    RF stage only
    B.
    IF stage only
    C.
    RF stage and one or two IF stages
    D.
    none of the above

  5. In pulse transmitter the ratio of time on to time off is called

  6. A.
    efficiency
    B.
    duty cycle
    C.
    base
    D.
    bandwidth

  7. In figure the output v(t) is

  8. A.
    phase modulated signal
    B.
    amplitude modulated signal
    C.
    frequency modulated signal
    D.
    none of the above

  9. A MASER is a

  10. A.
    low noise device
    B.
    high noise device
    C.
    medium noise device
    D.
    may be either high or medium noise device

  11. Which one of the following is correct?

  12. A.
    Coding reduces the noise in the signal
    B.
    Coding deliberately introduces redundancy into messages
    C.
    Coding increases the information rate
    D.
    Coding increases the channel bandwidth

  13. A paraboloid reflector has mouth diameter D meters, wavelength λ meters. Its beam width φ is equal to


  14. A balanced modulator circuit uses

  15. A.
    two identical diodes with same V-I characteristics
    B.
    two triodes with different V-I characteristics
    C.
    two diodes with different V-I characteristics
    D.
    a diode and a triode

  16. In a television camera tube, scanning of a picture is done

  17. A.
    line by line from left to right
    B.
    line by line from right to left
    C.
    line by line from top to bottom
    D.
    line by line from bottom to top

  18. In communication receivers the fidelity is provided by

  19. A.
    audio stage
    B.
    detector range
    C.
    mixer stage
    D.
    all of the above