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ECE310 – Lecture 3. Transformation of Functions 01/17/01. CTF vs. DTF. Continuous-time function g(t) t can be any real number Discrete-time function Sampling rate is T s g(nT s ) g[n]. CTF g(t) = 3+t 2 -2t 3 g(2t) g(1-t) g(2x) = 5e -20x g(x) g(x 2 ). DTF g[n] = 3+n 2 -2n 3
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ECE310 – Lecture 3 Transformation of Functions 01/17/01
CTF vs. DTF • Continuous-time function • g(t) • t can be any real number • Discrete-time function • Sampling rate is Ts • g(nTs) g[n]
CTF g(t) = 3+t2-2t3 g(2t) g(1-t) g(2x) = 5e-20x g(x) g(x2) DTF g[n] = 3+n2-2n3 g[2n] g[1-n] g[2n] = 5e-20n g[n] g[n2] The Argument of Function
CTF Amplitude scaling g(t) Ag(t) Time shifting g(t) g(t-t0) Shifting g(t) to the right by t0 units Time scaling g(t) g(t/a) Expands the function horizontally by a factor of a If a is negative, the function is also time-inverted DTF Amplitude scaling g[n] Ag[n] Time shifting g[n] g[n-n0] Time scaling g[n] g[n/n0] Transformation of Function
Amplitude scaling by A General Transformation • g(t) Ag((t-t0)/a) • g(t) Ag(t) Ag(t/a) Ag((t-t0)/a) • g(t) Ag(t) Ag(t-t0/a) Ag(t/a-t0/a) Time scaling by a Time shifting by a Time shifting by t0/a Time scaling by a
Exercises -1 1 2 -1 1 2 0 2 2 -1 0