Anurag- > 3). In which applications.. do we use an IIR filter??? There are some applications where the usage of FIR filters is simply not practical. Put another way, some applications where only reasonable amount of processing power is available but a very high degree of filtering is required can be solved only by using IIR filters. They are more *realizable* than FIR filters in some situations. Assume this situation and see if you can design a (practical!) FIR filter for the same: Problem Defintion: -------------------------- To do filtering on a certain signal- a sine wave consisting of three different frequency ranges. ie, in real-time the signal could consist of any 3 frequencies of the folllowing nature- 1]any one particular frequency in the range 9.5-16.5hz 2]any one particular frequency in the range 19-31hz 3]any one particular frequency in the range 38-62hz The signal that *passes* through your filter should be a combination of three frequencies out of these three *boxes* only! Assume also that the required frequency resolution is .5hz. I.e i need to do know the difference between 9.5hz and 10.0 hz. Exactly. Assume, available processing power: 50 MIPS! Design the filter as both IIR and FIR and see which is more practical.As a simple thumb rule, if the order of the filter is greater than 5 or 10...forget it! Points to Poinder: ------------------------ 1] So,the maximum frequency is not more than 100hz 2] My signal of interest could be 25hz,40hz and 12hz the first time and 30hz,50hz and 10hz the next time and so on...if so, they should be passed...otherwise they should be rejected Caution: ----------- Your filter should pass 10.5 hz but should *not* pass 17.5hz, your filter should pass 20 hz but *should not pass* 32 hz etc... Not a valid solution: -------------------------- A pass-band filter of range,say, 8hz-80hz(which covers all the 3 ranges i mentioned above...) Why? -------- Figure out. Hints: ------ 1] The desired filter passbands are centered at 2:1 frequency multiples 2] Are they octaves apart? 3] Paramteric Eq's? Finally, Is the solution elliptical in nature? --Bhooshan.N.Iyer _________________________________________________________________ Dont just search. Find. Check out the new MSN Search! http://search.msn.click-url.com/go/onm00200636ave/direct/01/ |