Efficient Digital Fiilters

By Matthew Donadio

Abstract:

What would you do in the following situation? Let ’ s say you are diagnosing a DSP system problem in the field. You have your trusty laptop with your development system and an emulator. You figure out that there was a problem with the system specifications and a symmetric FIR filter in the software won ’ t do the job; it needs reduced passband ripple, or maybe more stopband attenuation. You then realize you don ’ t have any filter design software on the laptop, and the customer is getting angry. The answer is easy: You can take the existing filter and sharpen it. Simply stated, filter sharpening is a technique for creating a new filter from an old one [1] – [3] . While the technique is almost 30 years old, it is not generally known by DSP engineers nor is it mentioned in most DSP textbooks.

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Matthew,

You are right. Not many textbooks cover this technique, but some of them do mention the topic in their references.

What can do for IIR filter .

Hi,
This PDF file is Chapter 1 of the book: "Streamlining Digital Signal Processing, a Tricks of the Trade Guidebook" (published by Wiley & Sons and the IEEE).
By the way, in the first sentence of the last paragraph on page 6 of the PDF file, the phrase "half-power" should be changed to "half-amplitude".
To answer the question: "What can do for IIR filter." (sic), as pointed out in Section 13.13 of the 2nd edition of the book: "Understanding Digital Signal Processing" (Prentice Hall Publishing), filter sharpening can only be used on filters that have constant group delay. So filter sharpening can't be used for IIR filters.

Hi Rick,
Is there any good reference to design an efficient IIR filter?
BC

how to implement fir using poly phase in C which works for all L, M in L/M ratio?
Let us assume all pi/max(L,M) filters are already designed and their to access.
Please guide me, I messed up with some issues like getting images, hormonics of input sine tone in output.

hi any good book which guides only on FIR filter,,

thanks