![ Continuous time (CT) and discrete time
(DT) signals
CT signals take on real or complex values as a
function of an independent variable that ranges over
the real numbers and are denoted as x(t).
DT signals take on real or complex values as a
function of an independent variable that ranges over
the integers and are denoted as x[n].
Note the subtle use of parentheses and square
brackets to distinguish between CT and DT signals.](https://image.slidesharecdn.com/classificationofsignals-160429113057/85/Classification-of-signals-4-320.jpg)
Classification of signals
- 1. Active Learning Assignment Electrical Engg. Dept. oName: Harsh M Shah oEn no:140410109091 oClass:SY Elect. 2 oSubject: Signals & Systems oTopic: Classification Of Signals
- 2. Signals are variables that carry information. It is described as a function of one or more independent variables. Basically it is a physical quantity.It varies with some independent or dependent variables. Signals can be One-dimensional or multidimensional. INTRODUCTION TO SIGNALS
- 3. Types Of Signals 1.Continous & Discrete Time signals 2.Periodic & Non-periodic signals 3.Deterministic & Random signals 4.Symmetrical & Antisymmetrical signals 5.Energy & Power signals
- 4. Continuous time (CT) and discrete time (DT) signals CT signals take on real or complex values as a function of an independent variable that ranges over the real numbers and are denoted as x(t). DT signals take on real or complex values as a function of an independent variable that ranges over the integers and are denoted as x[n]. Note the subtle use of parentheses and square brackets to distinguish between CT and DT signals.
- 5. ANALOG SIGNALS Human Voice – best example Ear recognises sounds 20KHz or less AM Radio – 535KHz to 1605KHz FM Radio – 88MHz to 108MHz
- 6. DIGITAL SIGNALS Represented by Square Wave All data represented by binary values Single Binary Digit – Bit Transmission of contiguous group of bits is a bit stream Not all decimal values can be represented by binary 1 0 1 0 1 0 1 0
- 7. PERIODIC VS. APERIODIC SIGNALS Periodic signals have the property that x(t + T) = x(t) for all t. The smallest value of T that satisfies the definition is called the period. Shown below are an aperiodic signal (left) and a periodic signal (right).
- 8. A causal signal is zero for t < 0 and an non- causal signal is zero for t > 0 Right- and left-sided signals A right-sided signal is zero for t < T and a left- sided signal is zero for t > T where T can be positive or negative. CAUSAL VS. NON-CAUSAL
- 9. BOUNDED VS. UNBOUNDED Every system is bounded, but meaningful signal is always bounded
- 10. EVEN VS. ODD Even signals xe(t) and odd signals xo(t) are defined as xe (t) = xe (−t) and xo (t) = −xo (−t). Any signal is a sum of unique odd and even signals. Using x(t) = xe(t)+xo(t) and x(−t) = xe(t) − xo(t), yields xe(t) =0.5(x(t)+x(−t)) and xo(t) =0.5(x(t) − x(−t)).
- 11. POWER AND ENERGY SIGNALS Power Signal Infinite duration Normalized power is finite and non-zero Normalized energy averaged over infinite time is infinite Mathematically tractable Energy Signal Finite duration Normalized energy is finite and non-zero Normalized power averaged over infinite time is zero Physically realizable • Although “real” signals are energy signals, we analyze them pretending they are power signals!