On Jul 9, 12:11 am, Oli Charlesworth <ca...@olifilth.co.uk> wrote:
..> dbd wrote:
..>
..> > The zero-stuffed H2 does not have the correct response for the
single
..> > stage filter design scheme given.
..>
..> Yes, but when convolved with H1, it does.

No. The H1 from an efficiently designed two stage version does not
have a narrow enough transition band to work with your H2' to form a
single stage decimator with the same pass and stop bands.

..> ...
..> The problem I face is why the example I've given would appear to
..> demonstrate otherwise!

You have compared the operations in a two stage filter that works (by
definition) for the desampling task and single stage filter that
doesn't meet specs.

..> Oli

If you have the information to, try actually specifying the filters
for an example before you compare. Or try it with one of the examples
in the references.

Dale B. Dalrymple