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What is Signal? Signal is a time varying physical phenomenon which is intended to convey information. OR Signal is a function of time. OR Signal is a function of one or more independent variables, which contain some information. Example:  voice signal, video signal, signals on telephone wires etc. Note:  Noise is also a signal, but the information conveyed by noise is unwanted hence it is considered as undesirable. What is System? System is a device or combination of devices, which can operate on signals and produces corresponding response. Input to a system is called as excitation and output from it is called as response. For one or more inputs, the system can have one or more outputs. Example:  Communication System

Systems are classified into the following categories: Liner and Non-liner Systems Time Variant and Time Invariant Systems Liner Time variant and Liner Time invariant systems Static and Dynamic Systems Causal and Non-causal Systems Invertible and Non-Invertible Systems Stable and Unstable Systems Liner and Non-liner Systems A system is said to be linear when it satisfies superposition and homogenate principles. Consider two systems with inputs as x 1 (t), x 2 (t), and outputs as y 1 (t), y 2 (t) respectively. Then, according to the superposition and homogenate principles, T [a 1  x 1 (t) + a 2  x 2 (t)] = a 1  T[x 1 (t)] + a 2  T[x 2 (t)] ∴ ,  T [a 1  x 1 (t) + a 2  x 2 (t)] = a 1  y 1 (t) + a 2  y 2 (t) From the above expression, is clear that response of overall system is equal to response of individual system. Example: (t) = x 2 (t) Solution: y 1  (t) = T[x 1 (t)] = x 1 2 (t) y 2  (t) = T[x 2 (t)] =...

Operations of CT Signals                    1. Time Reversal y(t) = x(-t)                    2. Time Shifting y(t) = x(t-t d )                    3. Amplitude Scaling y(t) = Bx(t)                    4. Addition y(t) = x 1(t) + x 2(t)                    5. Multiplication y(t) = x 1(t)x 2(t)                    6. Time Scaling y(t) = x(at) There are two variable parameters in general: Amplitude Time The following operation can be performed with amplitude: Amplitude Scaling C x(t) is a amplitude scaled version of x(t) whose amplitude is scaled by a factor C. Addition Addition of two signals is nothing but addition of their corresponding amplitudes. This can be bes...

EC6303          SIGNALS AND SYSTEMS                                 L T P C                   3 1 0 4 OBJECTIVES: · To understand the basic properties of signal & systems and the various methods of classification · To learn Laplace Transform &Fourier transform and their properties · To know Z transform & DTFT and their properties · To characterize LTI systems in the Time domain and various Transform domains UNIT I CLASSIFICATION OF SIGNALS AND SYSTEMS                           9 Continuoustime signals (CT signals) - Discrete time signals (DT signals) - Step, Ramp,Pulse...