## SC – U2IP1 – Signal Modulation, Transmitters and Receivers

After you read and made yourself familiar with the following topics, please answer /discuss the following 15 questions. Your answers should have detailed explanations. Topics: Time & frequency domain, AM, FM and PM modulation, Noise in FM, Transmitters, Topologies, SSAM transmitter, Power measurements, Receiver topology, Demodulation and Receiver variations.

Questions:

1) A sine wave carrier has a frequency of 75KHz. A modulation signal has 2 sine waves at 2KHz and 4KHZ. If a signal is applied to a full carrier AM (Amplitude Modulation) transmitter, what are the output frequencies?

2) A sine wave carrier has a frequency of 75KHz. A modulation signal has 2 sine waves at 2KHz and 4KHZ. If a signal is applied to a full carrier DSBSC (Double Side Band Suppressed Carrier), AM (Amplitude Modulation) transmitter, what are the output frequencies?

3) A sine wave carrier has a frequency of 75KHz. A modulation signal has 2 sine waves at 2KHz and 4KHZ. If a signal is applied to a full carrier SSBSC (Single Side Band Suppressed Carrier), USB (Upper Side Band) AM (Amplitude Modulation) transmitter, what are the output frequencies?

4) A sine wave carrier has a frequency of 75KHz. A modulation signal has 2 sine waves at 2KHz and 4KHZ. If a signal is applied to a full carrier SSBSC (Single Side Band Suppressed Carrier), LSB (Lower Side Band) AM (Amplitude Modulation) transmitter, what are the output frequencies?

5) A modulation signal has 3 sine waves at 4KHz, 8KHZ and 12KHz. The carrier frequency is 185KHz. If a signal is applied to a SSBSC (LSB) AM transmitter, what are the output frequencies?

6) How is modulation done in a full carrier AM (time domain) circuit? Do we just add the carrier signal to the modulating signals?

7) Explain the problems caused by overmodulation of an AM signal.

8) It is well known that AM (Amplitude Modulation) is highly effected by noise since noise has effect on signal amplitude and not signal frequency. So, for an AM system, can we say the “envelope” is due to the amplitude of un-modulated carrier signal?

9) Explain what Quadrature AM is and its main problem.

10) What do AM, FM, PM, DSB, DSBSC, SSBSC, NBFM, WBFM stand for?

11) It is known that there are 3 parameters in a sine wave that may be varied for signal modulation. Those are: Amplitude, Frequency and Phase parameters. Explain the relationship between Phase and Frequency of a signal.

12) FM (Frequency Modulation) was originally designed with the idea of having noise immunity compared with AM (Amplitude Modulation). Explain why.

13) An SSB transmitter radiates 500 watts at 100% modulation. What will it radiate with no modulation?

14) Is this a correct statement: The FM modulation index: increases with both deviation and modulation frequency? Why?

15) Explain “Threshold” and “Capture” effects.

### philosophy13

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### FRAMEWORK

Chapter 1 provided a high-level overview of the need for a national framework for protecting critical infrastructure. For some additional reading, take a look at the latest Presidential Order that….