ECT 263

Homework

Chapter 4, questions 1, problems 21, 26, 28, 33 and 37.

1. What two types of modulation are included in the term angle modulation?

21. An FM signal has a deviation of 10 kHz and a modulating frequency of 2Khz. Calculate the modulation index.

Modulating Index = derivative/B

26. A 10 kHz signal modulates a 500 MHz carrier, with a modulation index of 2. What are the maximum and minimum values for the instantaneous frequency of the modulated signal?

28. A PM signal has a modulation index od 2, with a modulating signal that has an amplitude of 100mV and frequency of 4 kHz. What would the effect onn the modulation index of:

a. Changing the frequency of 5 kHz?

b. Changing the voltage to 200 mV?

33. An FM signal has a deviation of 10kHz and is modulated by a sine wave with a frequency of 5kHz. The carrier frequency is 150 MHz, and the signal has a total power of 12.5W, operating into an impedance of 50 ohms.

a. What is the modulation index?

b. How much power is present at the carrier frequency?

c. What is the voltage level of the second sideband below the carrier frequency?

d. What is the bandwidth of the signal, ignoring all components that have less than 1% of the total signal voltage?

37. Use Carson’s rule to compare the bandwidth that would be required to transmit a baseband signal with a frequency range from 300 Hz to 3 kHz using:

a. NBFM with maximum deviation of 5 kHz

b. WBFM with maximum deviation of 75 kHz