Intro to Electronic Communications & RF Circuit

Answer /discuss the following 15 questions. Your answers should have detailed explanations. Topics: Elements of space communications, Time & frequency domain, Noise in communications, Signal fidelity, Frequency Division Multiplexing and Time Division Multiplexing.

Questions:

1) Name 3 basic elements of a communication system.

2) Any amplifier can be made to oscillator if a portion of the output is fed back to the input in such a way that two criteria are satisfied.  Explain those two criteria.

3) How is the frequency of an oscillator controlled? 

4) Compare LC controlled oscillators with Crystal-controlled oscillators from "Frequency stability" point.

5) What is "Excess Noise"? 

6) In signal modulation, usually the carrier is a sine wave, which parameters of the sine wave can be changed when dealing with modulation? 

7) What does 'Fidelity" mean? 

8) Define FDM (Frequency Division Multiplexing) and TDM (Time Division Multiplexing).

9)  What are Mixers in signal communication? What is the different between summing and mixing?

10) How are Signal to Noise power ratios calculated in dB? 

11) What is impedance matching for two electrical circuits?  

12) In a communication system, the output frequencies of a mixer are 200, 230, 30, 170 KHz. What are the frequencies of two sinusoidal inputs? 

13) How are frequency and wavelength of a signal related? 

14) What is "White Noise" in signal communication?

15) Explain the Fourier series.