Re: difference between power and energy
sorry if i am replying to late to this post...
i have read all junk here...,, An energy of a signal refers to integration of square of the signal over a period from - inf to +inf ,, at the same time if we say the same signal exists for some finite limits, then the same square of signal integrated between that period would give power of the signal and would be a power signal. physically a signal that lasts for a long interval of time( tends to inf) is an energy signal and one which has limits definable easily is a power signal..
why do we need to create all this thing? energy and power signal?
let us consider a signal v(t). Now let us be in a condition that we need to tell someone, how our signal is..? big small, wide, short etc.... we cud do this by telling him in terms of amplitude phase etc but for how much time...,? what if it is a varying signal. so to make quantisation simple we take energy into consideration. square of v(t) ensures as well that all the negative part of the signal is considered positive. so we could easily tell, how much energy is there in our signal (ofcourse integrating b/w -inf to +inf) and same if it is a small signal,, may be a small pulse , we could tell power of it..(integrated b/w -t to +t) ., physically both terms do not have any DIFFERENCE. DONT CONFUSE IT WITH ENERGY=POWER/T . it is a communication analogy.