Section 1-1
1. Define modulation.
In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted.
*2. What is carrier frequency?
The frequency generated by an unmodulated radio, radar, carrier communication, or other transmitter, or the average frequency of the emitted wave when modulated by a symmetrical signal. Also known as center frequency; resting frequency. 3. Describe the two reasons that modulation is used for communications trans- missions.
1) Signal integrity 2) Power savings
4. List the three parameters of a high-frequency carrier that may be varied by
In testing this system, the noise of a 100-k resistor is applied to its input. Calculate the input and output noise voltage and power and the system noise figure. (19.8 m V, 0.206 mV, 9.75 10 16 W, 1.4 10 10 W, 3.6 dB)
Section 1-5
32. Calculate the minimum signal power needed for good reception for the re- ceiver described in Problem 31 if the signal-to-noise ratio must be not less than 100 : 1. (5.52 10 13 W)
37. Define information theory.
Information theory is a branch of applied mathematics, electrical engineering, and computer science involving the quantification of information.
38. What is Hartley's law? Explain its significance.
Transmission of Information,” in which he proved "that the total amount of information that can be transmitted is proportional to frequency range transmitted and the time of the transmission.
40. What is the seventh harmonic of 360 kHz? (2520 kHz)
The first harmonic is the fundamental f1 = 360 kHz. The seventh harmonic f7 = 360,000 Hz × 7 = 2,520,000 Hz = 2520 kHz.
49. Define resonance and describe its use. resonance is the tendency of a system to oscillate with greater amplitude at some frequencies than at others. Resonant systems can be used to generate vibrations of a specific frequency (e.g., musical instruments), or pick out specific frequencies from a complex vibration containing many frequencies (e.g., filters).
55. Define the quality factor (Q) of an LC bandpass filter. Explain how it relates to the