Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Software » comp.soft-sys.matlab

Topic: odd behavior in decimate
Replies: 0  

Advanced Search

Back to Topic List Back to Topic List  
Aaron

Posts: 1
Registered: 9/10/13
odd behavior in decimate
Posted: Sep 10, 2013 1:46 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

If I run this command:
plot(decimate(ones(100000,1),10,n)-1)
(n is the IIR filter order for anti-aliasing)
I get reasonable results for n=3,5,7,9,11,13 (random-looking hash, on the order of 1e-7 or smaller)
However, if I use n=2,4,6,8 there is a significant DC error in the signal (values around -0.0114). n=10,12 gives a similar result to the odd orders.
It looks like there may be some odd DC behavior with the Chebyshev type I filters at even orders <= 8. If so, this makes the TMW default of n=8 a little scary.



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.