Peak detection of a signal & frequency b/w 2 peaks?

hi all, i want to find frequency between 2 peaks of a continuous signal. the signal is like a ECG signal but no -ve values. In my signal i have only positive peaks and i want to find frequency b/w peaks. The frequency b/w peaks is not const. So i want to find 2 successive peaks and frequency b/w them.. I have tried using FFT but but i want to know abt amplitude data.. Could anyone plz help me in developing algorithm...

[Niki]

if you explain what you exactly want with an example, one might be able to help you out

[LAKSHMAN]

i have an aperiodic impulse train.. but most samples are periodic in general and few samples might lag or lead.. I want to find the frequency b/w samples which is repeating mostly... ant that samples amplitude..