Hi Tramp,
Re: #3, When you say, “the imaginary part of the sparam,” do you mean the
negative frequencies?
If so, did you remember to exclude your d.c. point, when forming your negative
frequency values?
If not, your indices might be off by one everywhere in your negative frequency
space.
Have you tried windowing the frequency domain data before transforming?
-db
On Jun 11, 2020, at 4:43 AM, Tramp <farhilltramper@xxxxxxxxx> wrote:
Hi experts,
When obtaining the impulse response using ifft, often the generated ir
(impulse response) shows a bit of ripple&noise before t=0. I did some
experiments and here is the observation:
1. Increasing fmax, which is the max freq for the IL extrapolation, doesnt
help reduce the ripple.
2. Changing delta-f shows no avail as well.
3. Although the causality of the sparam is already good enough, still I
tried composing a 'causal' sparam by replacing the imag part of the sparam
w/ the Hilbert transform of the real part. Unfortunately, the thereafter
produced ir is a complete mess. What went wrong here?
I read from some literatures where the authors said they simply zero-out
all the ripples before t=0. Is this a recommended approach? Are there
better solutions to obtain a genuine ir?
Best Regards,
Tramp
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu