# Constant phase for each frequency?

FFT of some signal $x$ has two parts: $|x|$, which is the magnitude spectrum and $arg(x)$, which is the phase spectrum. I want each frequency to have the same phase. Is there a way to accomplish this?

• Forcing each frequency to have the same phase will result in a counter-intuitive signal. Why do you need to do that? – Peter K. Oct 21 '13 at 16:24
• Why it would be counter-intuitive? – user5741 Oct 21 '13 at 16:30
• Each phase the same relative to what point in time? 2 different frequencies will have 2 different phases most of the time. – hotpaw2 Oct 21 '13 at 16:42
• Because it's a generalization of saying the phase must be zero (i.e. the signal's FFT has to be real-valued). That means that the signal will be non-causal, and exhibit symmetry about the origin. Requiring a non-zero constant phase will just multiply the non-causal, symmetric signal by a complex constant --- making that signal complex-valued. – Peter K. Oct 21 '13 at 16:49
• Are you looking for a filter that does not affect the phase? – Hasan Oct 21 '13 at 16:56