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ECE :: Communication Systems

Communication Systems - Section 1
Communication Systems - Section 2
Communication Systems - Section 3
Communication Systems - Section 4
Communication Systems - Section 5
Communication Systems - Section 6
Communication Systems - Section 7
Communication Systems - Section 8
Communication Systems - Section 9
Communication Systems - Section 10
Communication Systems - Section 11
Communication Systems - Section 12
Communication Systems - Section 13
Communication Systems - Section 14
Communication Systems - Section 15
Communication Systems - Section 16
Communication Systems - Section 17
Communication Systems - Section 18
Communication Systems - Section 19
Communication Systems - Section 20
Communication Systems - Section 21
Communication Systems - Section 22
Communication Systems - Section 23
Communication Systems - Section 24
Communication Systems - Section 25
Communication Systems - section-26
Communication Systems - Section-27

  1. A sinusoidal carrier voltage, having frequency 1000 Hz is amplitude modulated by a sinusoidal voltage of frequency 15 kHz. The frequency of upper and lower sidebands will be

    2. A.
    1015 kHz and 985 kHz
    B.
    1030 kHz and 970 kHz
    C.
    13 kHz and 17 kHz
    D.
    14 kHz and 16 kHz

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  2. Identical telephone numbers in different parts of a country are distinguished by their

    3. A.
    area codes
    B.
    office codes
    C.
    access digits
    D.
    language codes

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  3. Consider the following statements as regards pulse repetition frequency

    1. Pulse interval should be as large as possible so that a pulse returns before next pulse is transmitted
    2. Greater the number of pulses reflected from a target, greater is the probability of distinguishing it from the noise
    Which of the above are correct?

    4. A.
    1 only
    B.
    2 only
    C.
    both 1 and 2
    D.
    neither 1 nor 2

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  4. Which gives minimum probability of error?

    5. A.
    ASK
    B.
    FSK
    C.
    PSK
    D.
    DPSK

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  5. Which SNR denotes excellent picture quality in TV?

    6. A.
    50 dB
    B.
    30 dB
    C.
    15 dB
    D.
    5 dB

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  6. In amplitude modulation

    7. A.
    the amplitude of carrier varies in accordance with the amplitude of the modulating signal.
    B.
    the modulating frequency lies in the audio range
    C.
    the amplitude of the carrier remains constant
    D.
    the amplitude of the carrier varies in accordance with the frequency of the modulating signal.

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  7. At f = 7 GHz, a 120 cm dish antenna gives a gain of about

    8. A.
    50
    B.
    500
    C.
    5000
    D.
    50000

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  8. PIL colour picture tube has the main advantage that

    9. A.
    it is cheap
    B.
    it ensures purity in colour
    C.
    it is self convergent
    D.
    both (a) and (b)

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  9. What is the frequency of the modulated carrier wave?

    10. A.
    1000 Hz
    B.
    2000 Hz
    C.
    1000 kHz
    D.
    2000 kHz

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