辅导案例-ECE 461/561
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.

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