260 likes | 468 Views
Signal Characteristics Common Signal in Engineering Singularity Function. Section 2.2-2.3. Signal Characteristics. Review Even function Odd function Periodic Signal. Represent x e (t) in terms of x(t). X e (t) X(t)= X e (t)+X o (t) X e (t)=X(t)-X o (t) Xo(t)=-Xo(-t)
E N D
Signal CharacteristicsCommon Signal in EngineeringSingularity Function Section 2.2-2.3
Signal Characteristics • Review • Even function • Odd function • Periodic Signal
Represent xe(t) in terms of x(t) • Xe(t) • X(t)=Xe(t)+Xo(t) • Xe(t)=X(t)-Xo(t) • Xo(t)=-Xo(-t) • X(-t)=Xe(-t)+Xo(-t) • Xe(t)=X(t)-Xo(-t)=X(t)+X(-t)-Xe(-t) • Therefore Xe(t)=[X(t)+X(-t)]/2 • Similarly Xo(t)=[X(t)-X(-t)]/2
Even Function Example(1) • Xe(t)=X(t)+Xo(t) • X(t) is the sum of an even part and an odd part. (X(t)=Xe(t)+Xo(t)) • Let X(t) be a unit step function
Even Function Example(2) X(t) X(-t) (X(t)+X(-t))/2 gives you an even function!
Odd Function Example(1) X(t) X(-t) (X(t)-X(-t))/2 gives you an odd function!
Odd Function Example • Mathemtica function: • Use Exp[-t/2] to represent exponential • Use UnitStep[t] to zero out t<0 • Generate an odd and an even function
Periodic Signal • X(t) is period if X(t)=X(t+T), T>0 • T is the period • To is the minimum value of T that satisfies the definition • A signal that is not period is aperiodic. To
A Systematic Procedure The sum of continuous-time periodic signal is period if and only if the ratios of the periods of the individual signals are ratios of integers Example: x(t)=x1(t)+x2(t)+x3(t)
Is This Signal Periodic? x(t)=x1(t)+x2(t)+x3(t)+x4(t) π is irrational, aperiodic
Common Signals in Engineering X(t)=Ceatoccurs frequently in circuits! C and a can be complex! C and a are real C is complex and a is imaginary C and a are complex
Case 1: C and a are real (Bacterial growth)
Singular Functions • Unit Step Function • Rectangular Function • Impulse Response
Properties of Unit Step Function u(2t-1) u(at-1)=u(t-1/a) u(t-1/2)