1. The document discusses various operations that can be performed on signals including time reversal, time shifting, time scaling, amplitude scaling, signal addition, and signal multiplication.
2. Examples are provided to demonstrate how to graphically represent signals and how the different operations change the signals.
3. Key steps are outlined for performing each operation including reversing the time axis, delaying or advancing signals, compressing or expanding the time axis, amplifying or attenuating signal amplitude, adding or multiplying signal values.
7. Operation on Independent variable
Time Inversion or Time Folding or Time Reversal
Time Shifting
Time Scaling
Operation on Dependent variable
Amplitude scaling
Signal addition
Signal Multiplication
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Signals
8. In Time reversal, signal x(t) is reversed with respect to time
i.e. y(t) = x(-t) is obtained for the given function
Time Folding: By folding the signal x(t) about t=0 (Rotating signal
by 1800 clockwise direction will give mirror image of signal
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i.e x(-t)
25. Multiplying the signal x(t) with A results in output y(t)=A x(t),
where A= Amplitude
• For A ˃ 1, the signal is amplified (Amplitude increases)
• For A < 1, the signal is attenuated (Amplitude decreases)
There is no change in time
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26. 26
y(n) = 2x(n)
Consider the signal x(n).Plot y(n)=2x(n)
Consider the signal x(t).Plot y(t)=2x(t)
27. The addition of two continuous time signals is
obtained by adding the value (amplitude) of two
signals at same instant of time.
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x1(t) x2(t) x1(t)+x2(t)
31. Multiplication of two signals is obtained by multiplying the
value (amplitude) of two signals at same instant of time.
Consider
x1(n) = {1,2,3,4} and x2(n) = {2,1,3,2}
Find y(n) = x1(n) x2(n)
y(n) ={ 1x2, 2x1, 3x3, 4x2}
y(n) = { 2,2,9,8}
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0 1 2 3
y(n)
2 2
9
8
n
32. Multiply the signal values at all time or
specific time
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33. Follow the precedence rule, if Time shifting and
Time scaling , time reversal and amplitude
scaling occurs in same signal.
Rule:
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Amplitude
scaling
Time shifting Time reversal Time scaling