How can linear phase shift give undistorted output?

[A.Anand Srinivasan]

i studied that linear phase shift ensures undistorted output how is that possible when each frequency is shifted differntly

 

[electronics_kumar]

Re: linear phase shift

linear phase shift means same phase shift for all frequency of the signal which is equal to delay in time domain ie we will get the output after delay
If it is nonlinear means in the frequency domain it will produce different phase shift for different frequencies of same signal which when displayed in time domain ,we will get a distorted signal..
hope it helps

 

[Kral]

Re: linear phase shift

A.Anand Srinivasan,
Linear phase shift means that the phase shift varies linearly with frequency. Under these conditions, a signal that conatins multiple frequencies (such as a pulse) will be delayed in time, but not distorted. Visualize a wave that consists of a fundamental and a third harmonic. If the phase shift of the third harmonic is exactly three times the phase shift of the fundamental, then the phase shifted output waveform will be undistorted. Try drawing this or plotting this in Excel. It is not possible to obtain perfect phase linearity in an analog system, but it can be attained digitally. Simply run the sampled signal through a FIR filter whose coefficients are symmetrical with respect to the middle coefficient. This guarantees perfect phase linearity.
Regards,
Kral