Reply by Jaime Andres Aranguren Cardona●February 10, 20102010-02-10
Hi Mike, Rammya,
SigmaDSP family from ADI is 28-bit fixed point and uses a 5.23 representation to
store numbers; as Mike correctly pointed out there is a manual available when
you install the tools, however it is important to read it carefully since is not
state-of-the-art documentation, so to say, but surely the guys at ADI are
taking good note of that and working hard to improve it.
Nevertheless, it is important to look at the datasheets of the family
members' theirselves, since they have quite a lot interestign information
on number format and its handling for those small, nice and powerful audio
DSP engines.
________________________________
Von: Mike Rosing
An: r...@ymail.com
CC: a...
Gesendet: Dienstag, den 9. Februar 2010, 15:03:20 Uhr
Betreff: Re: [adsp] Filter coefficient calculation in Sigma studio
Howdy Rammya,
I'm betting you have the same answer - but the representation of the
numbers is different. What is the format of the hex output? I've never
used the ADAU 1701, so I don't know how they mash the bits around to get
what they need. But I would think it's in a manual somewhere.
Patience, persistence, truth,
Dr. mike
On Mon, 8 Feb 2010, rammya_tv@ymail. com wrote:
> hi....
> 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 you people calculate filter coefficient.
>
> - main specification we needed to design a filter
> 1)Type[LPF,HPF, etc]
> 2)frequency
> 3)Q
> 4)Gain
>
> 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.
>
> ->ω0 = 2*pi*f0/Fs
> ->gainLinear = 10^(gain/20)
>
> ->Lowpass
>
> ->Transfer Function
> ->H(s)=1/(s^ 2+(s/Q)+1)
>
> ->Coefficients
> ->alpha = sin(ω0)/(2*Q)
> ->a0 = 1 + alpha
> ->a1 = -2*cos(ω0)
> ->a2 = 1 - alpha
> ->b0 = (1 - cos(ω0)) * gainLinear / 2
> ->b1 = 1 - cos(ω0) * gainLinear
> ->b2 = (1 - cos(ω0)) * gainLinear / 2
> After compiling we'll get coefficients a1,a2,b0,b1, b2 in hex format in
CAPTURE WINDOW of software.
> when i did manual calculation using the expression provided in software
i'm not getting, proper answer.
> Please help me to get detail calculation with the specification i given
above.
> with regards
> rammya
> ------------ --------- --------- ------ __________________________________________________
Reply by Jaime Andres Aranguren Cardona●February 10, 20102010-02-10
Hi,
A couple recent discussion on Analog Devices' EZ (Engineer Zone)
will provide you with the aid you need:
----- Ursprüngliche Mail ----
Von: "r...@ymail.com"
An: a...
Gesendet: Dienstag, den 9. Februar 2010, 5:25:06 Uhr
Betreff: [adsp] Filter coefficient calculation in Sigma studio
hi....
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 you people calculate filter coefficient.
- main specification we needed to design a filter
1)Type[LPF,HPF, etc]
2)frequency
3)Q
4)Gain
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.
->ω0 = 2*pi*f0/Fs
->gainLinear = 10^(gain/20)
->Lowpass
->Transfer Function
->H(s)=1/(s^2+(s/Q)+1)
->Coefficients
->alpha = sin(ω0)/(2*Q)
->a0 = 1 + alpha
->a1 = -2*cos(ω0)
->a2 = 1 - alpha
->b0 = (1 - cos(ω0)) * gainLinear / 2
->b1 = 1 - cos(ω0) * gainLinear
->b2 = (1 - cos(ω0)) * gainLinear / 2
After compiling we'll get coefficients a1,a2,b0,b1,b2 in hex format in
CAPTURE WINDOW of software.
when i did manual calculation using the expression provided in software i'm
not getting, proper answer.
Please help me to get detail calculation with the specification i given
above.
with regards
rammya
Reply by Jaime Andres Aranguren Cardona●February 10, 20102010-02-10
Hi, it's me again.
Do not forget to normalize the filters' coefficients (divide them all
by a0, then ignore a0 itself since it is an 1.0 internally), and invert the sign
for a1 and a2. This is such a common cause of failure!
________________________________
Von: Mike Rosing
An: r...@ymail.com
CC: a...
Gesendet: Dienstag, den 9. Februar 2010, 15:03:20 Uhr
Betreff: Re: [adsp] Filter coefficient calculation in Sigma studio
Howdy Rammya,
I'm betting you have the same answer - but the representation of the
numbers is different. What is the format of the hex output? I've never
used the ADAU 1701, so I don't know how they mash the bits around to get
what they need. But I would think it's in a manual somewhere.
Patience, persistence, truth,
Dr. mike
On Mon, 8 Feb 2010, rammya_tv@ymail. com wrote:
> hi....
> 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 you people calculate filter coefficient.
>
> - main specification we needed to design a filter
> 1)Type[LPF,HPF, etc]
> 2)frequency
> 3)Q
> 4)Gain
>
> 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.
>
> ->ω0 = 2*pi*f0/Fs
> ->gainLinear = 10^(gain/20)
>
> ->Lowpass
>
> ->Transfer Function
> ->H(s)=1/(s^ 2+(s/Q)+1)
>
> ->Coefficients
> ->alpha = sin(ω0)/(2*Q)
> ->a0 = 1 + alpha
> ->a1 = -2*cos(ω0)
> ->a2 = 1 - alpha
> ->b0 = (1 - cos(ω0)) * gainLinear / 2
> ->b1 = 1 - cos(ω0) * gainLinear
> ->b2 = (1 - cos(ω0)) * gainLinear / 2
> After compiling we'll get coefficients a1,a2,b0,b1, b2 in hex format in
CAPTURE WINDOW of software.
> when i did manual calculation using the expression provided in software
i'm not getting, proper answer.
> Please help me to get detail calculation with the specification i given
above.
> with regards
> rammya
> ------------ --------- --------- ------ __________________________________________________
Reply by Mike Rosing●February 9, 20102010-02-09
Howdy Rammya,
I'm betting you have the same answer - but the representation of the
numbers is different. What is the format of the hex output? I've never
used the ADAU 1701, so I don't know how they mash the bits around to get
what they need. But I would think it's in a manual somewhere.
Patience, persistence, truth,
Dr. mike
On Mon, 8 Feb 2010, r...@ymail.com wrote:
> hi....
> 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 you people calculate filter coefficient.
>
> - main specification we needed to design a filter
> 1)Type[LPF,HPF, etc]
> 2)frequency
> 3)Q
> 4)Gain
>
> 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.
>
> ->ω0 = 2*pi*f0/Fs
> ->gainLinear = 10^(gain/20)
>
> ->Lowpass
>
> ->Transfer Function
> ->H(s)=1/(s^2+(s/Q)+1)
>
> ->Coefficients
> ->alpha = sin(ω0)/(2*Q)
> ->a0 = 1 + alpha
> ->a1 = -2*cos(ω0)
> ->a2 = 1 - alpha
> ->b0 = (1 - cos(ω0)) * gainLinear / 2
> ->b1 = 1 - cos(ω0) * gainLinear
> ->b2 = (1 - cos(ω0)) * gainLinear / 2
> After compiling we'll get coefficients a1,a2,b0,b1,b2 in hex format in
CAPTURE WINDOW of software.
> when i did manual calculation using the expression provided in software
i'm not getting, proper answer.
> Please help me to get detail calculation with the specification i given
above.
> with regards
> rammya
>
Reply by ramm...@ymail.com●February 9, 20102010-02-09
hi....
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 you people calculate filter coefficient.
- main specification we needed to design a filter
1)Type[LPF,HPF, etc]
2)frequency
3)Q
4)Gain
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.
After compiling we'll get coefficients a1,a2,b0,b1,b2 in hex format in
CAPTURE WINDOW of software.
when i did manual calculation using the expression provided in software i'm
not getting, proper answer.
Please help me to get detail calculation with the specification i given
above.
with regards
rammya