ECE 461/561 PROJECT DESCRIPTIONS

Fall 2019

Instructions: Work in teams of 2 people. You are expected to turn in a thorough written project report

that includes analysis, design, simulation, and results discussion. Make sure that graphical data is

presented in such a way that all axes are appropriately labeled with the correct units and legible to receive

full credit. If you use information from books and/or papers, make sure to include a reference list at the

end of the report. Finally, avoid plagiarizing work done by others, as this is considered academic

dishonesty.

Consider an FM modulation system where the transmitted modulated waveform is described by

0

( ) cos 1000 8.7 ( )

t

FMs t t m dπ π τ τ

= +

∫ mV, where 10( ) 150 ( )t sm t t e u t−= V,

where ( )su t is the heavy-side unit step function. Let the communication channel be of the additive white

Gaussian noise (AWGN) type with power spectral density 0 ,

2

N f∀ and zero mean.

Design a second-order phase-lock loop receiver using the same loop filter discussed in class to

demodulate the transmitted FM waveform and assess system performance via computer simulation using

Matlab or Simulink and elementary blocks for several values of signal-to-noise ratio (SNR) in dBs,

starting at 0 and incrementing it in steps of 5 dB, in order to establish the lowest SNR value for which the

quality of the recovered message signal is acceptable. Note that this is a subjective measure of

performance. The idea is for you to use your engineering judgment to determine what is acceptable

performance. You must also show how the noise power and SNR are computed in each simulation and

present your results in terms of both time and frequency domain plots with the appropriate units (units are

extremely important when presenting your design and simulation results). Assume a load impedance of 1

Ohm when you calculate signal power.

To successfully design this receiver, you will need to compute the bandwidth of the message signal mW in

such a way that 99% of the signal energy is contained in that bandwidth, as well as the modulation index

D, in order to establish the threshold value of the minimum SNR required for successful extraction of the

message signal from the frequency modulated waveform. Moreover, you will have to have a good

estimate of the transmission bandwidth TB , in order to design the pre-detection analog bandpass filter

Remember that you will be designing and implementing an analog communication system, which means

that all the system components are continuous-time in nature, namely, do not design and implement

digital filters and other digital components in this project. You must use the nonlinear model of the PLL

to evaluate communication system performance. Use the linear model of the PLL only for design

purposes. Finally, make sure you state your assumptions clearly.

Write a report using the following format:

1. Problem statement

2. Assumptions

3. Analysis (if necessary)

4. Design procedure

5. Simulation setup

6. Simulations results and discussion

7. Conclusions

8. References

9. Appendix which includes your Matlab simulation code and/or the Simulink diagrams.