How accrues the delay in mfilt.firsrc ?

Hello,

can anybody explain me the delay from the filter mfilt.firsrc? In http://www.mathworks.de/help/toolbox/dsp/ref/mfilt.firsrc.html you can find an example in the upper part. After interpolation and decimation the filtered data have a transient oscillation of 13 Samples.

For correct representation you have to delay the signal in the line

stem(n(1:45)/(fs*l/m),y(13:57),'r','filled') with

y(13:57). Why is this 13?

I can not explain it to me.

Thank you for your help.

Stef

Answer 1

[Wayne King]

Hi Stef, you can find that by

hm = mfilt.firsrc(l,m);
mean(grpdelay(hm))/m
% now start the output signal at 12+1
y = y(13:end);

[Stef]

Hello Wayne,

thank you for your answer.

Stef