《信号与线性系统分析基础 》 课件 1.2 信号的分类

信号与系统SignalsandSystems吉林大学FundamentalConceptsofSystemsFundamentalconceptsofsystems1.Definition:Asystemisaninterconnectionofcomponentswithterminalsoraccessportsthroughwhichmatter,energy,orinformationcanbeappliedorextracted.Asystemisamathematicalmodelforaphysicalprocessthatrelatestheinputtotheoutput.Fundamentalconceptsofsystems2.Blockdiagramrepresentation:ScalarmultiplierUnit-delayelementFundamentalconceptsofsystemsSummator/adder/subtracterIntegratorFundamentalconceptsofsystems3.Classification:(1)CausalsystemNoncausalsystem(2)Continuous-timesystemDiscrete-timesystem---Describedbyalgebraicequationsordifferentialequations.---Describedbydifferenceequations.Fundamentalconceptsofsystems(3)Time-varyingsystemTime-invariantsystem---Describedbydifferentialequationswithvariablecoefficients.---Describedbydifferentialequationswithconstantcoefficients.Fundamentalconceptsofsystems---Describedbyordinarydifferentialequations.---Describedbypartialdifferentialequations.Distributedparametersystem(5)Lumpedparametersystem(6)StablesystemUnstablesystem(Boundedinputboundedoutput,BIBO)(4)InstantaneoussystemDynamicsystem---Describedbyalgebraicequations.---Describedbydifferentialequations.Fundamentalconceptsofsystems(b)Superposition/Additivity(a)Homogeneity(c)Decomposition(8)LinearsystemNonlinearsystem(7)ReversiblesystemIrreversiblesystemInitialcondition信号与系统SignalsandSystems吉林大学DeterminationofSystemCharacteristicsDeterminationofsystemcharacteristics[Example]Determineifthesystemdescribedbyislinear,time-invariant,causalandstable.Linearornonlinear?(1)Time-invariantortime-varying?(2)Let?DeterminationofsystemcharacteristicsCausalornoncausal?(3)Stableoru