Principles of Communication: FM Modulation, Assignments of Electronics

Download Principles of Communication: FM Modulation and more Assignments Electronics in PDF only on Docsity! Principles of Communication Name: _________________________________________________ BSECE II-1 I. IDENTIFICATION. Fill in the blanks. 1. The general name given to both FM and PM is _________ modulation. 2. The amount of frequency shift during modulation is called the ________________. 3. The amount of frequency shift in PM is directly proportional to the __________ of the modulating signal. 4. In PM, the carrier ___________ is varied in proportion to the amplitude of the modulating signal. 5. A varying phase shift produces ___________________ _____. 6. A phase modulator produces a frequency deviation only when the modulating signal is _________. 7. In __________________, the frequency deviation is proportional to both the modulating signal amplitude and frequency. 8. When the modulating signal amplitude crosses zero, the phase shift and frequency deviation in a phase modulator are at _____________________. 9. A phase modulator may use a _______________________ to offset the effect of increasing carrier frequency deviation for increasing modulating frequency. 10. The FM produced by a phase modulator is known as ____________________. 11. An FM signal has a modulation index of 2.5. How many significant pairs of sidebands are produced? _________ 12. What is the relative amplitude of the 4th significant pair of sidebands in an FM signal with a deviation ratio of 4? ___ 13. The amplitudes of the sidebands in an FM signal are dependent upon a mathematical process known as_________. 14. A PM signal has a deviation ratio of 3. The maximum modulating signal is 5 kHz. The bandwidth of the signal is _____kHz. 15. If the maximum allowed deviation is 5 kHz but the actual deviation is 3.75 kHz, the percentage of modulation is _____ percent. 16. A negative sign on the carrier and sideband amplitudes means a__________ _____. 17. The main advantage of FM over AM is its immunity from _____. 18. FM receivers reject noise because of built-in circuits called _________________. 19. The________________ in an FM receiver causes a stronger signal to dominate a weaker signal on the same frequency. 20. Typically FM transmitters are more efficient than AM transmitters because they use class _____ amplifiers. 21. The biggest disadvantage of FM is its excessive use of ___________. 22. Noise interferes primarily with _____ modulating frequencies. 23. The method used to offset the effect of noise in FM transmissions by boosting high frequencies is known as _____. 24. To boost high frequencies, a _______________________ circuit is used. 25. To correct for the high-frequency boost, a ______________________ circuit is used at the receiver. II. PROBLEM SOLVING. Show your solution/s. 1. If a 2-volt instantaneous value of modulating signal amplitude causes a 10-kHz deviation in carrier frequency, what is the deviation sensitivity of the modulator? 2. If a 2-kHz audio tone causes a frequency deviation of 4 kHz, what is the modulation index? 3. What will be the deviation caused by a 3-kHz tone if the modulation index is 3? 4. If the deviation sensitivity of an FM modulator is 2 kHz /V, what will be the modulation index caused by a 1-volt, 1-kHz audio signal? 5. At a modulation index of 2, how much power is in the carrier of a 1000-watt FM transmitter? 6. Using Carson's rule, what is the approximate bandwidth of an FM signal with a modulation index of 2 being modulated by a 5-kHz signal? 7. Using the Bessel chart, what is the bandwidth of an FM signal with a modulation index of 2 being modulated by a 5-kHz signal if we ignore sidebands containing less than 1% of the total power? mdbulos| 1