HB filters Опции

[pirri]

I've simulated in Matlab 3-steps decimation (3--3--2), using FIRs before every step. For the first 2 stages i used HB lowpass filters and for the last FIR lowpass. It seems to be ok and i see the peak.
But in some books it's written that HB FIR is useful just in case of factor two decimation. Will it work with *3 decimation at all? If no, what is the problem?
I'll be happy to get explanation or a useful link.
I can also understand Russian. Thanks in advance!

Сообщение отредактировал pirri - Jul 21 2009, 09:46

[alex_os]

I've simulated in Matlab 3-steps decimation (3--3--2), using FIRs before every step. For the first 2 stages i used HB lowpass filters and for the last FIR lowpass. It seems to be ok and i see the peak.
But in some books it's written that HB FIR is useful just in case of factor two decimation. Will it work with *3 decimation at all? If no, what is the problem?
I'll be happy to get explanation or a useful link.
I can also understand Russian. Thanks in advance!

Если наложения спектра, которые возникают при децимации в 3 раза , не затрагивают интересующую Вас область спектра почему бы так и не делать?
Видимо участки спектра пораженные наложениями отфильтровываются последующими ступенями дециматора.