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    Tutorial 2A

    Uploaded by

    Yuki Yap Zhi Xuan
    This document contains information and questions about amplitude modulation (AM) communication systems. It includes questions about: (1) deriving the modulation index formula; (2) calculating information/carrier voltages, modulation percentage, sideband amplitudes/frequencies/power from an oscilloscope trace of an AM signal; and (3) determining the output equation, frequencies, powers, and spectrum for an example AM transmitter. It also asks the reader to: (4) calculate envelope voltages and modulation coefficients for an AM modulator; and (5) identify the best performing receiver for rejecting image frequencies based on preselector Q-factors, IF frequencies, and tracking error ranges given in a table.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    Tutorial 2A

    Uploaded by

    Yuki Yap Zhi Xuan
    9 views2 pages
    This document contains information and questions about amplitude modulation (AM) communication systems. It includes questions about: (1) deriving the modulation index formula; (2) calculating information/carrier voltages, modulation percentage, sideband amplitudes/frequencies/power from an oscilloscope trace of an AM signal; and (3) determining the output equation, frequencies, powers, and spectrum for an example AM transmitter. It also asks the reader to: (4) calculate envelope voltages and modulation coefficients for an AM modulator; and (5) identify the best performing receiver for rejecting image frequencies based on preselector Q-factors, IF frequencies, and tracking error ranges given in a table.

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    This document contains information and questions about amplitude modulation (AM) communication systems. It includes questions about: (1) deriving the modulation index formula; (2) calculating information/carrier voltages, modulation percentage, sideband amplitudes/frequencies/power from an oscilloscope trace of an AM signal; and (3) determining the output equation, frequencies, powers, and spectrum for an example AM transmitter. It also asks the reader to: (4) calculate envelope voltages and modulation coefficients for an AM modulator; and (5) identify the best performing receiver for rejecting image frequencies based on preselector Q-factors, IF frequencies, and tracking error ranges given in a table.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    9 views2 pages

    Tutorial 2A

    Uploaded by

    Yuki Yap Zhi Xuan
    This document contains information and questions about amplitude modulation (AM) communication systems. It includes questions about: (1) deriving the modulation index formula; (2) calculating information/carrier voltages, modulation percentage, sideband amplitudes/frequencies/power from an oscilloscope trace of an AM signal; and (3) determining the output equation, frequencies, powers, and spectrum for an example AM transmitter. It also asks the reader to: (4) calculate envelope voltages and modulation coefficients for an AM modulator; and (5) identify the best performing receiver for rejecting image frequencies based on preselector Q-factors, IF frequencies, and tracking error ranges given in a table.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 2

    FAKULTI KEJURUTERAAN ELEKTRIK

    SUBJECT: COMMUNICATION SYSTEM BEKC 3633

    Tutorial 2

    Vmax  Vmin Vm
    (a) Prove that modulation index, ma  
    Vmax  Vmin Vc

    (b) A high frequency carrier signal with frequency of 8MHz is amplitude


    modulated by 10 x 104 MHz low frequency modulating signal. The AM
    signal is then applied to 0.12 kΩ load. By using the oscilloscope, AM signal
    shows the maximum and minimum amplitude of modulated signal as 41 V and
    21 V respectively, determine:

    i. Information signal voltage and carrier signal voltage

    ii. The amount that the carrier signal is modulated in percentage.

    iii. Lower and upper sideband amplitude

    iv. The sideband power and the total power of the signal

    v. Upper and lower sideband frequency as well as its bandwidth

    vi. The trigonometric equation of the above signal

    vii. Sketch the AM signal above

    (c) HOT.AM Radio Station transmits an AM wave with a carrier signal of 5


    sin (6283185.31t) is fed with an information signal of 2 sin (628.32t) and the
    load resistance of the antenna is 50Ω. Determine

    i. The equation for the AM output signal

    ii. The upper and lower sideband frequencies and the bandwidth

    iii. Modulation coefficient and percentage modulation

    iv. The power absorbed by the carrier, total sideband power and the
    transmitter power

    Tutorial 2 TOPIC: CHAPTER 2 – AMPLITUDE MODULATION


    GROUP: DATE: PAGE: - 1 -
    FAKULTI KEJURUTERAAN ELEKTRIK
    SUBJECT: COMMUNICATION SYSTEM BEKC 3633

    v. The output frequency spectrum

    Note: AM- Amplitude Modulation

    (d) One input to an AM DSBFC modulator is a 500 kHz carrier with an amplitude
    of 35 Vp-p. The second input is a 10 kHz modulating signal whose
    amplitude is sufficient to produce a 14 VP change in the amplitude of the
    envelope and the load resistance of the antenna is 10 Ω. Determine

    i. The maximum and minimum positive AM envelope voltage.

    ii. The coefficient of modulation and percent modulation.

    iii. The total transmitted power.

    (e) Table (1) shows three superheterodyne receiver using high side injection that
    are receiving an AM DSBFC broadcasted signal from a radio station with RF
    carrier of 800 kHz and maximum modulating signal frequency of 5 kHz.
    Based on the given value of certain parameters for each receiver,

    i. Identify which receiver gives the best performance in tem1 of rejecting an


    image frequency signal from an undesired radio station.

    ii. How you relate the factor of distance between RF frequency and image
    frequency to your answer in i) ?

    iii. As the receivers are tuned to several other radio stations, identify which
    receiver will be facing a problem in tracking each station carrier frequency if the
    maximum IF bandwidth is 15kHz.

    Table (1)

    Parameter Receiver A Receiver B Receiver C


    Preselector
    Q -factor 60 90 100
    IF center frequency
    (kHz) 550 455 350
    Tracking error range
    (kHz) ±2.5 ± 1.5 ±3.5

    Tutorial 2 TOPIC: CHAPTER 2 – AMPLITUDE MODULATION


    GROUP: DATE: PAGE: - 2 -

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