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ECE :: Communication Systems

  1. A telephone channel requires a bandwidth of about

  2. A.

     1 kHz

    B.

     3 kHz

    C.

     10 kHz

    D.

     50 kHz

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  3. Fourier analysis indicate that a square wave can be represented as

  4. A.

     A fundamental sine wave and odd harmonics

    B.

     A fundamental sine wave and even harmonics

    C.

     A fundamental sine wave and harmonics

    D.

     Fundamental and subharmonic sine waves

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  5. If sampling is done at the rate of 10 kHz. The bandwidth required is

  6. A.

     35 kHz

    B.

     70 kHz

    C.

     10 kHz

    D.

     1280 kHz

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  7. Which of the following is an indirect way of generating FM?

  8. A.

     Armstrong modulator

    B.

     Varactor diode modulator

    C.

     Reactance FET modulator

    D.

     Reactance bipolar transistor

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  9. In practical commercial FM system, channel bandwidth is

  10. A.

     150 kHz

    B.

     100 kHz

    C.

     88 MHz

    D.

     108 MHz

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  11. One of the advantages of base modulation over collector modulation of a transistor class C amplifier is

  12. A.

     Improved efficiency

    B.

     Better linearity

    C.

     High power output per transistor

    D.

     The lower modulating power requirement

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  13. Leak type bias is used in plate modulated class C amplifier to

  14. A.

     Increase the bandwidth

    B.

     Prevent over modulation

    C.

     Prevent excessive grid current

    D.

     Prevent tuned circuit damping

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  15. FM transmitting and receiving equipment as compared to AM equipment is

  16. A.

     Costly

    B.

     Cheaper

    C.

     Almost equally costly

    D.

     None of the above

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  17. For AM receivers the standard IF frequency is

  18. A.

     106 kHz

    B.

     455 kHz

    C.

     1.07 MHz

    D.

     10.7 MHz

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  19. A modem is classified as low speed if data rate handled is

  20. A.

     Upto 100 bps

    B.

     Upto 250 bps

    C.

     Upto 400 bps

    D.

     Upto 600 bps

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