space communications, Time & frequency domain, Noise in communications, Signal fidelity, Frequency Division Multiplexing and Time Division Multiplexing

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) In a SWAM (Short Wave AM) radio signal, does a shorter wavelength means lower frequency?

2) Can an analog signal to be effected by noise? Why? If yes, can the noise be easily removed by a LP (Low Pass filter)?

3) Does the "envelope" of an AM (Amplitude Modulation) signal resemble the carrier signal?

4) Define the wavelength of a radio signal.

5) How do you cancel unwanted feedbacks?

6)  A sine wave signal has a frequency of 60MHz. What is its wavelength (in meters)?

7) What is a Crystal controlled oscillator made of, and what is its main advantage?

8) In communication systems, where is the shot noise generated?

9) A communication signal mixer, has two sinusoidal inputs with frequencies of 7 KHz and 80KHZ. What is the output frequency (or frequencies)?

10) In a balanced mixer, two sinewaves are mixed (with frequencies of 44MHz and 4MHz). At the output, there are present 4 sinewaves with frequencies of 4MHz, 40MHz, 44MHz and 48 MHz. Are these correct frequencies?

11)  How is a Signal-to-Noise ratio determined?

12) Explain a resonant circuit and where it is used in signal communications.

13) A power amplifier has a decibel gain of 27 dB. What is the absolute power gain?

14) What does a spectrum analyzer do?

15)  An amplifier has a signal-to-noise ratio of 80dB at the input and 45dB at the output. Determine, NF (Noise Figure), both in ratio and dB.