SME
College · Engineering
Signals & Systems
5 topics
Electrical
Before this course
Topics
Continuous and discrete signals
Main lesson
Time shift and scaling
Use this for “x(t) peaks at t = 2 s. Where does y(t) = x(2t − 4) peak?”
Period of a discrete cosine
Use this for “Find the fundamental period of x[n] = cos(3πn ÷ 4).”
Energy and power of a signal
Use this for “Find the energy of x(t) = 2e⁻⁴ᵗu(t) and the average power of 2 cos(10t + 30°).”
Linear and time-invariant systems
Use this for “Is the system y(t) = t·x(t) linear? Is it time-invariant?”
Convolution
Fourier series and transforms
Main lesson
Time scaling and delay in the spectrum
Use this for “x(t) has a part at 5 kHz. Where is it in y(t) = x(2(t − 25 μs)), and what phase does the delay add there?”
Spectrum of a rectangular pulse
Use this for “A 2 V pulse lasts 1 ms. Find its spectrum at 0 Hz and at 500 Hz, and the first frequency where it is zero.”
Laplace and z-transforms
Main lesson
Final and initial value
Use this for “Find the final value of x(t) when X(s) = 10 ÷ (s(s + 5)).”
Step response of a difference equation
Use this for “Find y[3] and the final value when y[n] = 0.5y[n − 1] + x[n] and x[n] is the unit step.”
Pole positions: dies out, oscillates or grows
Use this for “X(s) has poles at s = −1 ± j2. Does x(t) die out, oscillate forever or grow?”
Sampling
Main lesson
Quantization: levels, step and SQNR
Use this for “An 8-bit quantizer covers 2 V. Find the number of levels, the step size and the SQNR.”
Data rate and file size of sampled audio
Use this for “CD audio is sampled at 44.1 kHz with 16 bits in 2 channels. Find the bit rate and the size of one minute.”
DFT bin spacing
Use this for “A 256-point DFT is taken of samples at 1 kHz. How far apart are the bins, and where does 100 Hz fall?”
Course test
See what you know: 10 questions on this course
New questions each time. Pass to mark it complete.