Angle displays the phase spectrum xeeet signals and systems laboratory

School of Engineering

EEET2369 – Signals and Systems 1 (Laboratory 3)
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Learning Outcomes

Upon successful completion of this laboratory exercise you will be able to:

Introduction to the laboratory

Continuous-time (or analogue) systems are used to process analogue signals and together they make up the area known as analogue signal processing (ASP). Analogue systems generally consist of circuitry such as resistors, capacitors and inductors as well as active components such as operational amplifiers (op amps) to process an incoming signal in some way.

Generally, we can consider a system’s frequency response to be the Fourier transform of that system’s impulse response:

𝑍𝑅 = 𝑅complex impedance of resistor

𝑍𝑐 =	1

Learning outcomes:

Also use the method described on the previous page to find the transfer function of this filter. Contrast these two forms of the frequency response.

Now use MATLAB to plot this system’s frequency response using the freqs() function. See Table I: Some useful MATLAB functions for syntax example. Make sure to label your x and y axes appropriately for these graphs.

-	Confirm that the behaviour of this system to inputs of frequencies 0 Hz (i.e. DC) and 5 kHz are consistent with your results from last week.

School of Engineering

Exercise:

A passive, RC high-pass filter shown in figure 4 is now to be analysed in MATLAB.

- What do these graphs show you about the response of this new system to different frequency inputs?

- Use the graphs to confirm the cutoff frequency of this filter. Use the

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EEET2369 – Signals and Systems 1 (Laboratory 3)
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Other useful functions
	Performs convolution on the functions x and h. h is usually the impulse response of an LTI system while x is the input signal to that system.
fft(x)	Performs a Fast Fourier Transform (FFT) on the variable x.
fftshift(X)	Rearranges the FFT in array X so negative frequency regions can be displayed correctly.
	num is an array containing the numerator coefficients from the system’s transfer function. den is an array containing the denominator coefficients from the system’s transfer function.

EEET2369 – Signals and Systems 1 (Laboratory 3)
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EEET2369 – Signals and Systems 1 (Laboratory 3)
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