Synchronous Demodulation Use a square message signal where Am is 0.5, Ac is 1.0, fe is 4 kHz, and the modulating frequen

[answerhappygod]

Synchronous Demodulation Use A Square Message Signal Where Am Is 0 5 Ac Is 1 0 Fe Is 4 Khz And The Modulating Frequen 1 (187.89 KiB) Viewed 15 times

Synchronous Demodulation Use a square message signal where Am is 0.5, Ac is 1.0, fe is 4 kHz, and the modulating frequency is 400 Hz. Using synchronous demodulation, observe the demodulated signal for the three kinds of modulation in both the time and frequency domains. Chose the cutoff frequency and order of the lowpass filter that will yield good results. 10) Do you observe any discrepancies between the original and demodulated signals for any of the three modulating schemes? If so, suggest reasons why this happens. Examine the effects of phase misalignment on synchronous demodulation: shift the phase of the local oscillator by 45° (1/4). (Such a large shift is not required, but it highlights the problem of phase offsets in demodulation. You could try a smaller offset.) 11) Describe the effects on the demodulated signal of the phase discrepancy for each of the three modulating schemes. Compare them to each other and to the theory as seen in class and in the text. Examine the effects of frequency misalignment on synchronous demodulation: shift the frequency of the local oscillator by 50 Hz in either direction (4050 Hz or 3950 Hz). 12) What are your observations for DSBSC ? Compare them to each other and to the theory as seen in class and in the text. Square-Law Demodulation A square-law demodulator will, under certain constraints on the amplitudes, demodulate an AM signal. Use the same square message from above and apply a square-law demodulator to the result. Try using different amplitudes for the information signals and observe the reconstructed signals. 13) What constraint did you have to apply to obtain an acceptable result? Explain why this constraint is necessary for square-law demodulators. Rectifier Detector 14) AM signals without overmodulation can be detected with a rectifier followed by a lowpass filter. On the other hand, a DSBSC cannot. Explore both with the signal from above. Envelope Detector Follow the block diagram to build an envelope detector. 15) How large of a constant did you need to add to the input signal s(t) to make the detected signal visually indistinguishable from the original? Does envelope detection work better for AM? Explain why.