- #1
salman213
- 302
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1. Hi, I'm confused on the method of calculating the power of the sawtooth function.
In my textbook the the general formula for claculating the power is
definition 1. http://img210.imageshack.us/img210/5091/75697758.jpg
where the limit approaches infinity and the limits are -T/2 to T/2.
For periodic function they say this can be simplfiied to just
definition 2. http://img156.imageshack.us/img156/5962/54601684.jpg
so now the T value is actually the period (finite), and the limits are also the finite numbers where the period is from.
For the SAWTOOTH function I know it is periodic so doing with the function equal to f(x) = Ax from for example -1 to 1 (period) and so T = 2
gets the answer that the power is
Px = A^2/3
If i just use the general formula I get infinity!
so for periodic functions is it NECESSARY that you HAVE to use definition 2, and you cannot use definition 1?
example when I use defintion 1 for the saw tooth
i get
lim 1/T A^2 [t^3/3)] limits are from T/2 to - T/2
T-> infinity
so you get
lim 1/T A^2 (T^3/4)
T-> infinity
=
lim A^2 (T^2/4)
T-> infinity
= infinity!
In my textbook the the general formula for claculating the power is
definition 1. http://img210.imageshack.us/img210/5091/75697758.jpg
where the limit approaches infinity and the limits are -T/2 to T/2.
For periodic function they say this can be simplfiied to just
definition 2. http://img156.imageshack.us/img156/5962/54601684.jpg
so now the T value is actually the period (finite), and the limits are also the finite numbers where the period is from.
For the SAWTOOTH function I know it is periodic so doing with the function equal to f(x) = Ax from for example -1 to 1 (period) and so T = 2
gets the answer that the power is
Px = A^2/3
If i just use the general formula I get infinity!
so for periodic functions is it NECESSARY that you HAVE to use definition 2, and you cannot use definition 1?
example when I use defintion 1 for the saw tooth
i get
lim 1/T A^2 [t^3/3)] limits are from T/2 to - T/2
T-> infinity
so you get
lim 1/T A^2 (T^3/4)
T-> infinity
=
lim A^2 (T^2/4)
T-> infinity
= infinity!
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