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[Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pa
From: |
Renato |
Subject: |
[Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has strange pass band |
Date: |
Tue, 8 May 2018 11:18:23 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36 |
Follow-up Comment #2, bug #53855 (project octave):
Same problem in MatLab...
File attached.
IF you increase the high frequency cut-off, the result is much better. But I
didn't undestand why...
In the example below, I changed the high-frequency cut-off from 100Hz to
200Hz.
++
n = 5;
hpf = 200;
lpf = 10*hpf;
[b, a] = butter (n, [hpf/22050, lpf/22050]);
freqz (b, a, 4096, 44100)
ax = findall (gcf, 'type', 'axes');
set (ax, 'xlim', [hpf/4 lpf*4]);
set (ax, 'xscale', 'log');
subplot (2, 1, 1);
set (gca, 'ylim', [-35 3]);
--
(file #44120)
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Additional Item Attachment:
File name: test_RYamane.png Size:54 KB
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- [Octave-bug-tracker] [bug #53855] [signal] butter filter with strange results, Renato, 2018/05/07
- [Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has strange pass band, Mike Miller, 2018/05/07
- [Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has strange pass band,
Renato <=
- [Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has strange pass band, Dmitri A. Sergatskov, 2018/05/08
- [Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has round-off errors, Mike Miller, 2018/05/08
- [Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has round-off errors, Renato, 2018/05/08
- [Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has round-off errors, Mike Miller, 2018/05/08
- [Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has round-off errors, Renato, 2018/05/08
- [Octave-bug-tracker] [bug #53855] [octave forge] (signal) butter band pass filter with higher order has round-off errors, Mike Miller, 2018/05/08