# Fourier series

1. Sep 9, 2007

### sarveshkumarv

We have a periodic signal of period 10 ms and amplitude 2.The signal is a rectangular pulse from -5/2 to 5/2 and 0 from 5/2 to 19/2.This signals fundamental frequency(f0) is 100Hz.It is passed through a filter whose response is 1/(1+jf/f0.I calculated the average power using the trignometric fourier series expansion.I get the average total power for f=100,200 etc.But what will be the average power for f=50Hz.Will there be an average power for a freq less than fundamental frequency.Because we get nf0=f.For f=50Hz n=1/2.But the trignometric fourier expansion talks only about the integer values of n.So wat is the avg power at f=50 Hz???

2. Sep 11, 2007

### antonantal

This signal doesn't have a component at 50Hz. It only has the DC component, the fundamental and the components at positive integer multiples of the fundamental frequency (the harmonics).