Hi Angilberto, On Thu, 2019-12-19 at 15:13 +0000, Angilberto Muniz Sb wrote: > In the docs it says the xlating fir filter is a symmetric one,
certainly not in general. The FIR filter can whatever filter you put in there. You're thinking of an example somewhere! So, what docs *specifically* say that? > has linear phase shift and causes no phase distortion. I'd agree with "if it's symmetric, it's got a linear phase shift". I wouldn't fully agree with "no phase distortion", because it's still a frequency-dependent shift. > Lets say I have the following setup: > > x(t) = cos(wt), > s1(t) = x(t) upshiffted to w1, s2(t) = x(t) upshiffted to w2 > > s(t) = s1(t) + s2(t). > > Now, I apply two xlating filters to s(t): > > r1(t) = s(t) filtered and downconverted to w > r2(t) = s(t) filtered and downconverted to w > > I see a phase shift (or time delay) between x(t) and r1(t) or r2(t). Yes, that's *group delay*. Best regards, Marcus
smime.p7s
Description: S/MIME cryptographic signature
