Sunday, July 10, 2011

Table of Laplace and Z Transforms

Entry Laplace Domain Time Domain (note) Z Domain
(t=kT)
unit impulse      unit impulse
unit step   (note)
ramp
parabola
tn
(n is integer)
exponential
power b to the k, Z
time
multiplied
exponential
Asymptotic
exponential
double
exponential
asymptotic
double
exponential
asymptotic
critically
damped
differentiated
critically
damped
sine
cosine
decaying
sine
decaying
cosine
generic
decaying
oscillatory
generic
decaying
oscillatory
(alternate)


    (note)
Z-domain
generic
decaying
oscillatory
Generic second order, Discrete Time

(note)
Prototype Second Order System (ΞΆ<1, underdampded)
Prototype
2nd order
lopass
step
response
 
Prototype
2nd order
lopass
impulse
response
   
Prototype
2nd order
bandpass
impulse
response
 


Using this table for Z Transforms with discrete indices

Commonly the "time domain" function is given in terms of a discrete index, k, rather than time.  This is easily accommodated by the table.  For example if you are given a function:
Since t=kT, simply replace k in the function definition by k=t/T.  So, in this case,
and we can use the table entry for the ramp
The answer is then easily obtained
source:http://lpsa.swarthmore.edu/LaplaceZTable/LaplaceZFuncTable.html

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