Reply by Randy Yates June 20, 20152015-06-20
gyansorova@gmail.com writes:

> On Wednesday, June 17, 2015 at 1:07:23 AM UTC+12, randeepk wrote: >> Hi, >> >> I am trying to design an analog transfer function in digital domain. I >> tried using various methods like impulse invariance and bilinear >> transform. But when I used bilinear transform I am getting error of around >> 1db at nyquist frequency. >> Are there any other better methods??? >> >> Thanks >> >> >> --------------------------------------- >> Posted through http://www.DSPRelated.com > > make sure you sample 10 to 20 times the max frequency of interest.
That's not really necessary with FDLS. -- Randy Yates Digital Signal Labs http://www.digitalsignallabs.com
Reply by June 19, 20152015-06-19
On Wednesday, June 17, 2015 at 1:07:23 AM UTC+12, randeepk wrote:
> Hi, > > I am trying to design an analog transfer function in digital domain. I > tried using various methods like impulse invariance and bilinear > transform. But when I used bilinear transform I am getting error of around > 1db at nyquist frequency. > Are there any other better methods??? > > Thanks > > > --------------------------------------- > Posted through http://www.DSPRelated.com
make sure you sample 10 to 20 times the max frequency of interest.
Reply by Steve Pope June 17, 20152015-06-17
Greg Berchin  <gjberchin@chatter.net.invalid> wrote:

>[URL omitted]
>I am obligated to inform that the document referenced there is copyright >material. I am not the copyright holder; I am the author. The rights >belong to IEEE.
Greg -- thanks for pointing this out. The website for this URL states the licensing as "CC Attribution-Share Alike 2.0 Unported except where otherwise noted". (I do not know if this is binding; IANAL etc.) Steve
Reply by Greg Berchin June 17, 20152015-06-17
On Wed, 17 Jun 2015 07:16:58 -0500, "alpha1" <103600@DSPRelated> wrote:

>Right now I am going through Greg's FDLS method
[URL omitted] I am obligated to inform that the document referenced there is copyright material. I am not the copyright holder; I am the author. The rights belong to IEEE.
Reply by alpha1 June 17, 20152015-06-17
>> >>As Eric said -- tell us what you're really trying to do. >> >>-- >> >>Tim Wescott >>Wescott Design Services >>http://www.wescottdesign.com > >I am trying to realise a deemphasis filter on the CDDA output. In CDDA
the
>sampling rate is 44.1Khz. >De emphasis transfer function is (10^6 + 15s)/(10^6 + 50s). > >I have seen discussions regarding this before here. I feel that this has >to be discussed in general scenario where one is trying realise an
analog
>transfer function in digital domain. > > >--------------------------------------- >Posted through http://www.DSPRelated.com
Randeepk, seems that we are on the same side.... Greg berchin's FDLS method would be a good choice. Robert orban has solution for 48Khz. But I found it is difficult to follow his method. https://groups.google.com/forum/#!msg/comp.dsp/9kuirTaABzg/CSg4hgh0saoJ Right now I am going through Greg's FDLS method http://robotics.itee.uq.edu.au/~elec3004/2014/lectures/Precise%20Filter%20Design%20%28chapter%29.pdf --------------------------------------- Posted through http://www.DSPRelated.com
Reply by randeepk June 17, 20152015-06-17
> >As Eric said -- tell us what you're really trying to do. > >-- > >Tim Wescott >Wescott Design Services >http://www.wescottdesign.com
I am trying to realise a deemphasis filter on the CDDA output. In CDDA the sampling rate is 44.1Khz. De emphasis transfer function is (10^6 + 15s)/(10^6 + 50s). I have seen discussions regarding this before here. I feel that this has to be discussed in general scenario where one is trying realise an analog transfer function in digital domain. --------------------------------------- Posted through http://www.DSPRelated.com
Reply by Tim Wescott June 16, 20152015-06-16
On Tue, 16 Jun 2015 08:07:19 -0500, randeepk wrote:

> Hi, > > I am trying to design an analog transfer function in digital domain. I > tried using various methods like impulse invariance and bilinear > transform. But when I used bilinear transform I am getting error of > around 1db at nyquist frequency. > Are there any other better methods???
It sounds like you really mean that you're trying to replicate the effects of an already-specified analog transfer function in the digital domain. Unless the sampling rate is considerably higher than your highest frequency of interest, this is fraught with inaccuracies. You best bet would be to increase your sampling rate so that you have no frequencies of interest at Nyquist -- if you don't have tons of attenuation at Nyquist then there's a good chance that you're not going to care what your filter is doing because aliasing will be driving you up the wall. As Eric said -- tell us what you're really trying to do. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by Eric Jacobsen June 16, 20152015-06-16
On Tue, 16 Jun 2015 08:07:19 -0500, "randeepk" <106589@DSPRelated>
wrote:

>Hi, > >I am trying to design an analog transfer function in digital domain. I >tried using various methods like impulse invariance and bilinear >transform. But when I used bilinear transform I am getting error of around >1db at nyquist frequency. >Are there any other better methods??? > >Thanks
What sort of transfer function are you trying to convert? Eric Jacobsen Anchor Hill Communications http://www.anchorhill.com
Reply by randeepk June 16, 20152015-06-16
Hi,

I am trying to design an analog transfer function in digital domain. I
tried using various methods like impulse invariance and bilinear
transform. But when I used bilinear transform I am getting error of around
1db at nyquist frequency. 
Are there any other better methods??? 

Thanks


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