Lab: Baseband Pulse Modulations

Objectives: After finishing this lab you will be able to:

• Implement baseband pulse modulations of PAM, PWM and PPM.
• Use time domain and frequency domain to identify the characteristics of these baseband pulse modulations.

Part A - Pulse Amplitude Modulation

Experiment A1: Run the simulation and look at the oscilloscope screen. Describe your observation briefly.

Experiment A2: Increase the duty cycle of the pulse source, which is connected to the pin 13 of the 4066 chip, from 10% to 50%. Describe your observation.

Experiment A3: Return the duty cycle of the square wave to 10% and look at the spectrum of the PAM. You need to adjust the spectrum analyzer for this reason. To do so, after connecting the PAM signal to the IN input of the spectrum analyzer follow these steps:

1. Double click on spectrum analyzer to bring it up

2. Click on stop button

3. Select 0 Hz as the Start frequency

4. Select 3 kHz as the End frequency (roughly 3 times of the pulse frequency)

5. Click on Enter button of the spectrum analyzer

6. Then change the frequency resolution option of the spectrum analyzer to Hz and then select a small value (for instance 10 Hz).

7. Click on Start button on and then start the simulation.

Wait for about 1 or 2 minutes to let the spectrum analyzer's algorithm converges and shows you an accurate result.

Task: Place the snapshot of the spectrum analyzer's screen in here and describe your observation briefly. You may use the spectrum analyzer's probe.

Experiment A4: Based on your observation in previous task, briefly write how you can reconstruct the original signal.

Part B - Pulse Width Modulation

Experiment B1: Run the simulation and look at the oscilloscope screen. Describe your observation briefly.

Experiment B2: Place the snapshot of the spectrum analyzer's screen in here and describe your observation briefly. You may use the spectrum analyzer's probe.

Experiment B3: Based on your observation in previous task, briefly write how you can reconstruct the original signal.

Part C - Pulse Position Modulation

Experiment C1: Run the simulation and look at the oscilloscope screen. Describe your observation briefly.

Experiment C2: Place the snapshot of the spectrum analyzer's screen in here and describe your observation briefly. You may use the spectrum analyzer's probe.

Please place the snap of the spectrum analyzer on the next page.

Experiment C3: Based on your observation in previous task, briefly write how you can reconstruct the original signal.

Lab Conclusion:

Describe PAM, PWM and PPM in three lines.

Based on your observations in frequency domain, please shortly explain how to demodulate PAM, PWM and PPM.

Attachment:- Assignment Files.rar