From: rammya.tv on 9 Feb 2010 04:04 hi.... in my previous posy i found w0 is not clear so resending my queries again. i'm currently working on Analog Devices Dsp processor ADAU 1701.. Sigma studio is the software we are now on,in that i have some queries in the way they calculate filter coefficient. - main specification i needed to design a filter 1)Type[LPF,HPF, etc] 2)frequency 3)Q 4)Gain eg: I want a 2nd order LPF with Frequency= 1000 Q=0.5 Gain=1 The given below derivation is the one which i got from sigma studio help window. ->w0 = 2*pi*f0/Fs ->gainLinear = 10^(gain/20) ->Lowpass ->Transfer Function ->H(s)=1/(s^2+(s/Q)+1) ->Coefficients ->alpha = sin(w0)/(2*Q) ->a0 = 1 + alpha ->a1 = -2*cos(w0) ->a2 = 1 - alpha ->b0 = (1 - cos(w0)) * gainLinear / 2 ->b1 = 1 - cos(w0) * gainLinear ->b2 = (1 - cos(w0)) * gainLinear / 2 After compiling we'll get coefficients a1,a2,b0,b1,b2 in hex format in CAPTURE WINDOW of software. i did manual calculation using the expression provided above and compare with that of coeffients of software, but it differs. Please help me to get detail calculation with the specification i given above. We know w0 = 2*pi*f0/Fs -what is the value of pi(180 0r 3.14) -w0 is the angular representation of requency i think it will be 180 -then in above value of alpha will be zero always. -it means Q doesnt have any importantce in filter design -please suggest a good book which describe in detail about filter design with regards rammya  |  Pages: 1 Prev: Filter coefficient calculation In Sigma studioNext: Simulating Sample Jitter