Lab report 4_Swinburne PDF

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Swinburne University of Technology Faculty of Information and Communication Technologies ASSIGNMENT AND PROJECT COVER SHEET Unit Code:

TNE30003

Unit Title:

Lab number and title: 4 Pulse Modulation Lab group Day:

Time:

Communications Principles Due date: Demonstrator:

To be completed if this is a group assignment We declare that this is a group assignment and that no part of this submission has been copied from any other student's work or from any other source except where due acknowledgment is made explicitly in the text, nor has any part been written for us by another person. ID Number 101110641

Name

Signature

Rukshan Mudliyer

Rukshan Mudliyer

Marker's comments:

Total Mark:

Extension certification: This assignment has been given an extension and is now due on Signature of Convenor:

Student id:

Name:

EXPERIMENT 4 PULSE MODULATION.

Results 1. Spectrum of Pulse Train

Observed (Frequncy domain

Observed (Time domain)

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2. Spectrum of a Sampled Signal

Observed Sampled Signal (Time domain)

Sampled Signal (frequency domain) 1) Describe the observed time domain waveform and its spectrum. Do your results agree with theory?  Yes, the result agrees with our prediction.

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3. Recovery of Baseband Signal by Filtering

Observed (Time Domain)

Observed (Freqency Domain)

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2) Explain the effect of varying the cutoff frequency of the filter.  The carrier frequency was removed when the cut-off frequency was lowered. Because every component passes at higher frequencies, the message will be recovered.

4. Aliasing Effects. 3) What is the lowest frequency needed for aliasing to occur? Compare with the theoretical value stated above. fs=8.3kHz, fm needs to be equal or greater than 1.732 kHz to have an aliasing occur. 4.1. Why is the frequency of the recovered signal different from the original message? 



Because of the alising effects that occur during the sample, the frequency of the recovered signal differs from the message signal.

5. Time Division Multiplexing

sampled signal at 500Hz

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sampled signal at 5000Hz Results 5-1 Time Division Multiplex signal 5.1. Comment on your results 

As the frequency is increased, aliasing occurs, causing the image to become more distorted.

6. Conclusion This lab provided a thorough review of the concepts covered in the previous week's lecture on Pulse Modulation. The lab assists us with concepts such as Pulse Period and Pulse Width, as well as the Pulse Strain spectrum. The following topic was Natural Sampling for sampling a Sinusoidal Signal. IN the third part Baseband Signal Recovery was covered, in which a low pass filter is used to recover the message and we were required to change the cut-off frequency and observe the results. The Aliasing Effects is discussed next, and we must evaluate the lowest frequency where the aliasing occurs.

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