f



CIC Group Delay

I would like to know if I can predict what the group delay of a CIC
filter is.

I have an agressive FIR BPF where the sample rate is 2000 x the filter
bandwidth. The group delay is longer than I would like it to be. Could
a CIC filter offer a lower group delay?

I'll need to interpolate back to the original sample rate, so I need to
take that into consideration as part of the answer.

Thanks, in advance.

Jim

0
10/12/2005 4:52:41 AM
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jim_nospam_beasley@yahoo.com wrote:
> I would like to know if I can predict what the group delay of a CIC
> filter is.

What is a CIC filter?


Bob
-- 

"Things should be described as simply as possible, but no 
simpler."

                                              A. Einstein
0
arcane (515)
10/12/2005 5:00:37 AM
"Bob Cain" <arcane@arcanemethods.com> wrote in message 
news:dii59h19o4@enews4.newsguy.com...
>
> jim_nospam_beasley@yahoo.com wrote:
>> I would like to know if I can predict what the group delay of a CIC
>> filter is.
http://www.google.com/search?hl=en&q=%22cic+filter%22+%22group+delay%22
>
> What is a CIC filter?
>
http://www.google.com/search?hl=en&q=cic+filter
>
> Bob
> -- 
>
> "Things should be described as simply as possible, but no simpler."
>
>                                              A. Einstein
Simple enough, Bob? ;-)
Cheers, Syms. 


0
symon_brewer (114)
10/12/2005 11:47:21 AM
<jim_nospam_beasley@yahoo.com> wrote in message 
news:1129092761.120373.45800@z14g2000cwz.googlegroups.com...
>I would like to know if I can predict what the group delay of a CIC
> filter is.
>
> I have an agressive FIR BPF where the sample rate is 2000 x the filter
> bandwidth. The group delay is longer than I would like it to be. Could
> a CIC filter offer a lower group delay?

I assume your current filter is linear phase.  The delay through a linear 
phase FIR filter is half the filter length.  Since a CIC filter is also a 
linear phase, the delay through the CIC will be half the length of its 
impulse response, which is the sum of the lengths of each stage.

For a given delay, a CIC will not filter as well as a low-pass FIR designed 
without restrictions.  Similarly, for a given set of performance criteria, a 
well designed low-pass will require less delay than a CIC to meet them.

If you need to minimize group delay in the passband, you want a minimum 
phase IIR.  Keep in mind, though, that a filter as narrow as you indicate is 
going to have a lot of passband delay no matter what you do.

--
Matt



0
mt0000 (280)
10/13/2005 12:44:39 AM
Jim,

A CIC filter is only good for the start of the decimation or end of the
interpolation, you can't reasonably replace your filter with only a CIC
filter or filters; a CIC filter is only a good filter if you are
GROSSLY oversampled.  For a multirate implementation (which your 1000x
oversampling screams for) you might start with some CIC filters
followed by some halfband filters and a final FIR filter, take the rate
back up using the halfband and CIC filters in reverse order.

I am curios how long is the FIR you have designed?  What are the
required design specs (normalize to Fs if you like)? Is linear phase a
requirement?

Dirk


jim_nospam_beasley@yahoo.com wrote:
> I would like to know if I can predict what the group delay of a CIC
> filter is.
>
> I have an agressive FIR BPF where the sample rate is 2000 x the filter
> bandwidth. The group delay is longer than I would like it to be. Could
> a CIC filter offer a lower group delay?
>
> I'll need to interpolate back to the original sample rate, so I need to
> take that into consideration as part of the answer.
> 
> Thanks, in advance.
> 
> Jim

0
dbell (153)
10/13/2005 7:49:25 AM
Thanks, all, for your replies.  Yes, it's pretty clear I can't get
something for nothing. While addressing some system level concerns, to
test some basic principals, the order of the FIR was about 5700. A
multi-rate filter is preferable, and will reduce the resource
requirements tremendously. I was most concerned with what to do about
the group delay.  A quick check with cascaded multirate filters didn't
give much improvement in delay.

I'll probably explore some compromises, such as with filter bandwidth,
and delay is going to be on the order of 1/BW.

0
10/14/2005 2:39:29 AM
If you can ease up on whatever transition bandwidth requirements you
have, or the stop band requirements, that will help too.

Dirk

0
dbell (153)
10/14/2005 2:51:44 AM
It's a damn good article - one of the best I've ever read within the
class of engineering magazine articles. 

--Randy

0
yates (3949)
10/14/2005 2:13:54 PM
On Tue, 11 Oct 2005 22:00:37 -0700, Bob Cain
<arcane@arcanemethods.com> wrote:

>
>
>jim_nospam_beasley@yahoo.com wrote:
>> I would like to know if I can predict what the group delay of a CIC
>> filter is.
>
>What is a CIC filter?
>
>
>Bob

Hi,
  ya' have a look at:

http://www.embedded.com/shared/printableArticle.jhtml?articleID=160400592

[-Rick-]

0
R
10/14/2005 2:33:32 PM
On 11 Oct 2005 21:52:41 -0700, jim_nospam_beasley@yahoo.com wrote:

>I would like to know if I can predict what the group delay of a CIC
>filter is.
>
>I have an agressive FIR BPF where the sample rate is 2000 x the filter
>bandwidth. The group delay is longer than I would like it to be. Could
>a CIC filter offer a lower group delay?
>
>I'll need to interpolate back to the original sample rate, so I need to
>take that into consideration as part of the answer.
>
>Thanks, in advance.
>
>Jim

Hi,

  as far as I recall, the delay through a 
single-stage CIC filter having D delay elements 
in its comb filter will be

  Delay = (D - 1)/2   samples.

[-Rick-]


0
R
10/14/2005 2:41:33 PM
Randy Yates wrote:
> It's a damn good article - one of the best I've ever read within the
> class of engineering magazine articles. 

Hear, hear! I found a typesetting error, though. Somewhere near the 
bottom, F_s turned into >_s. I figures it out, though! :-)

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
0
jya (12871)
10/14/2005 3:10:01 PM

Rick Lyons wrote:
> On Tue, 11 Oct 2005 22:00:37 -0700, Bob Cain
>>What is a CIC filter?
>>
>>Bob
>
> Hi,
>   ya' have a look at:
> 
> http://www.embedded.com/shared/printableArticle.jhtml?articleID=160400592

Thanks, Rick.  Excellent article.


Bob
-- 

"Things should be described as simply as possible, but no 
simpler."

                                              A. Einstein
0
arcane (515)
10/14/2005 6:10:26 PM
Thanks, Rick. That is a very helpful article. (Jerry, you didn't catch
the missing minus sign in the Euler's identity preceding equation 9?).
I have also been refering to Harris's  Multirate Signal Processing.

My simulation results suggest I will need more supression around the
zeros of the filter before I decimate. Otherwise, the residual around
that zero will fold into my band of interest at a level I can't
tolerate.

I am considering cascading (I think this is called "sharpening"?)...

                      Hk(Z)=[(1-Z^-M)/(1-Z^-1)]^K

But I don't see how to take advantage of the Noble Identity that is
obtained in the Hogenauer method. The advantage I am refering to is the
reduction of memory requirements by decimating immediately after the
integrator. It's not a big deal, since the cost of a few registers
isn't too high, but I would like to understand what optimizations I can
obtain while cascading.

Jim

0
10/16/2005 5:04:10 PM
On 14 Oct 2005 07:13:54 -0700, "Randy Yates" <yates@ieee.org> wrote:

>It's a damn good article - one of the best I've ever read within the
>class of engineering magazine articles. 
>
>--Randy

Hi Randy,
  Thanks.  

Actually, Ray Andraka help me an 
awful lot with the text of that article.
He's a true "CIC expert".

Wonder what's "happening" with Ray.
[-Rick-]

0
R
10/19/2005 4:37:57 PM
On Fri, 14 Oct 2005 11:10:01 -0400, Jerry Avins <jya@ieee.org> wrote:

>Randy Yates wrote:
>> It's a damn good article - one of the best I've ever read within the
>> class of engineering magazine articles. 
>
>Hear, hear! I found a typesetting error, though. Somewhere near the 
>bottom, F_s turned into >_s. I figures it out, though! :-)
>
>Jerry

Hi Jerry,

  yea, I see that typo now.  That ">_s" is supposed 
to be "Fs,in" where the "s,in" characters are 
subscripted.  My original manuscript didn't have 
that error.  (It makes me think that all italicized 
characters in a manuscript must be "re-typed" 
by some magazine production person.)

See Ya',
[-Rick-]

0
R
10/19/2005 4:40:56 PM
On Fri, 14 Oct 2005 11:10:26 -0700, Bob Cain
<arcane@arcanemethods.com> wrote:

>
>
>Rick Lyons wrote:
>> On Tue, 11 Oct 2005 22:00:37 -0700, Bob Cain
>>>What is a CIC filter?
>>>
>>>Bob
>>
>> Hi,
>>   ya' have a look at:
>> 
>> http://www.embedded.com/shared/printableArticle.jhtml?articleID=160400592
>
>Thanks, Rick.  Excellent article.
>
>
>Bob

Hi Bob,

  Thanks for sayin' "Thanks".

[-Rick-]

0
R
10/19/2005 4:41:36 PM
On 16 Oct 2005 10:04:10 -0700, jim_nospam_beasley@yahoo.com wrote:

>Thanks, Rick. 

Hi Jim,
  you're most welcome.

>That is a very helpful article. (Jerry, you didn't catch
>the missing minus sign in the Euler's identity preceding equation 9?).

I also see that typo now that you point it out.
My original manuscript didn't have 
that error.    Again, it makes me think that all 
italicized characters in a manuscript must be 
"re-typed" by some magazine production person.

>I have also been refering to Harris's  Multirate Signal Processing.

Good idea.  Harris a "Master of Sample Rate Change".

>My simulation results suggest I will need more supression around the
>zeros of the filter before I decimate. Otherwise, the residual around
>that zero will fold into my band of interest at a level I can't
>tolerate.
>
>I am considering cascading (I think this is called "sharpening"?)...
>
>                      Hk(Z)=[(1-Z^-M)/(1-Z^-1)]^K

Yep, cascaded CIC filters give increased attenuation 
around the zeros.  Commercial chips that use CIC filters 
often have the capability to cascade 3-5 CIC filters.
(However, such simple cascading isn't called "sharpening", at 
least not that I know of.   There a filtering technique called 
"filter sharpening", but it's not just simple cascading of 
some single filter.  Matt Donadio wrote an article about 
this for my "DSP Tips & Tricks" column in the Sept., 2003, 
issue of the IEEE Sig. Proc. magazine.)

>But I don't see how to take advantage of the Noble Identity that is
>obtained in the Hogenauer method. The advantage I am refering to is the
>reduction of memory requirements by decimating immediately after the
>integrator. It's not a big deal, since the cost of a few registers
>isn't too high, but I would like to understand what optimizations I can
>obtain while cascading.

Humm, I'm guessing that you're talking about the 
N = D/R shown in Figure 9 of my article
(although, I'm not sure).
Remember, in most applications that I've seen 
D = R, so N = 1.  So instead of needing D 
storage locations for the comb filter, you 
only need one location.

Good Luck Jim.

See Ya',
[-Rick-]



0
R
10/19/2005 5:00:21 PM
jim_nospam_beasley@yahoo.com wrote:

> But I don't see how to take advantage of the Noble Identity that
> is obtained in the Hogenauer method. The advantage I am refering
> to is the reduction of memory requirements by decimating
> immediately after the integrator. 

If your word width allows for multiple integration, you could push 
the comb filters in at least the last few CIC blocks to the end of 
the chain and run them all at the output sample rate.


Martin

-- 
Quidquid latine dictum sit, altum viditur.
0
10/19/2005 8:24:54 PM
On 19 Oct 2005 20:24:54 GMT, Martin Eisenberg
<martin.eisenberg@udo.edu> wrote:

>jim_nospam_beasley@yahoo.com wrote:
>
>> But I don't see how to take advantage of the Noble Identity that
>> is obtained in the Hogenauer method. The advantage I am refering
>> to is the reduction of memory requirements by decimating
>> immediately after the integrator. 
>
>If your word width allows for multiple integration, you could push 
>the comb filters in at least the last few CIC blocks to the end of 
>the chain and run them all at the output sample rate.
>
>
>Martin
>
>-- 
>Quidquid latine dictum sit, altum viditur.

Hi Martin,
  just out of curiosity, what does

   "Quidquid latine dictum sit, altum viditur."

mean in English?

Thanks,
[-Rick-]

0
R
10/20/2005 1:54:22 AM
Rick Lyons wrote:
> On 19 Oct 2005 20:24:54 GMT, Martin Eisenberg
> <martin.eisenberg@udo.edu> wrote:
> 
> 
>>jim_nospam_beasley@yahoo.com wrote:
>>
>>
>>>But I don't see how to take advantage of the Noble Identity that
>>>is obtained in the Hogenauer method. The advantage I am refering
>>>to is the reduction of memory requirements by decimating
>>>immediately after the integrator. 
>>
>>If your word width allows for multiple integration, you could push 
>>the comb filters in at least the last few CIC blocks to the end of 
>>the chain and run them all at the output sample rate.
>>
>>
>>Martin
>>
>>-- 
>>Quidquid latine dictum sit, altum viditur.
> 
> 
> Hi Martin,
>   just out of curiosity, what does
> 
>    "Quidquid latine dictum sit, altum viditur."
> 
> mean in English?

"Whatever is said in Latin, seems profound."

But I prefer "Quidquid latine dictum sit, altum sonatur" which means
"Whatever is said in Latin, sounds profound."

-- 
Jim Thomas            Principal Applications Engineer  Bittware, Inc
jthomas@bittware.com  http://www.bittware.com    (603) 226-0404 x536
Never ascribe to malice that which is adequately explained by 
incompetence. -
Napoleon Bonaparte
0
jthomas2 (337)
10/20/2005 12:00:05 PM
Jim Thomas wrote:
> Rick Lyons wrote:

>> Hi Martin,
>>   just out of curiosity, what does
>> 
>>    "Quidquid latine dictum sit, altum viditur."
>> 
>> mean in English?
> 
> "Whatever is said in Latin, seems profound."
> 
> But I prefer "Quidquid latine dictum sit, altum sonatur" which
> means "Whatever is said in Latin, sounds profound."

I've occasionally considered changing to "Quidquid latine scriptum 
sit, altum viditur" but never have, for some reason. What do you 
think?


Martin

-- 
Teach a man to make fire, and he will be
warm for a day. Set a man on fire, and he
will be warm for the rest of his life.
--John A. Hrastar
0
10/20/2005 12:45:02 PM
Martin Eisenberg wrote:
> I've occasionally considered changing to "Quidquid latine scriptum 
> sit, altum viditur" but never have, for some reason. What do you 
> think?

I like it!  I wish I knew enough Latin to be dangerous rather than only 
slighty un-ignorant (or to use bad Latin, a non-ignoramus).

A friend of mine has a t-shirt that says "It's all fun and games until 
someone loses an eye" except of course, that it's written in Latin.  I 
don't remember the Latin, and I could not even BEGIN to translate it.

-- 
Jim Thomas            Principal Applications Engineer  Bittware, Inc
jthomas@bittware.com  http://www.bittware.com    (603) 226-0404 x536
Never ascribe to malice that which is adequately explained by 
incompetence. -
Napoleon Bonaparte
0
jthomas2 (337)
10/20/2005 4:59:06 PM
Jim,

Looks like this topic has received many replies.  Here is my view: The
CIC architecture is just a computationally efficient implementation of
a boxcar FIR filter.  If you have a 5 stage CIC then you have 5
convolved boxcar filters.  The amount of interpolation or decimation is
the length of the boxcar.  Here is a simple octave/matlab example:


K=10;    % amount of interpolation/decimation
N=5;      % number of stages
taps = ones(1,K);
for t=1:N
 taps = conv(taps,ones(1,K));
end
plot(taps);

Michael

0
10/20/2005 6:44:18 PM
Rick Lyons wrote:
> On Fri, 14 Oct 2005 11:10:01 -0400, Jerry Avins <jya@ieee.org> wrote:
> 
> 
>>Randy Yates wrote:
>>
>>>It's a damn good article - one of the best I've ever read within the
>>>class of engineering magazine articles. 
>>
>>Hear, hear! I found a typesetting error, though. Somewhere near the 
>>bottom, F_s turned into >_s. I figures it out, though! :-)
>>
>>Jerry
> 
> 
> Hi Jerry,
> 
>   yea, I see that typo now.  That ">_s" is supposed 
> to be "Fs,in" where the "s,in" characters are 
> subscripted.  My original manuscript didn't have 
> that error.  (It makes me think that all italicized 
> characters in a manuscript must be "re-typed" 
> by some magazine production person.)
> 
> See Ya',
> [-Rick-]
> 

Quick note on the hardware implementation of cic's.  In interpolation,
you do not need the center differentiator/integrator, it can be replaced 
with a ZOH and have identical functionality.  I know that's true for 
D=1, have not looked at D >1.

Also, in decimation the center stage can be replaced with a resettable 
integrator and get rid of the diff. stage for hardware savings.

Tim
0
emale80919 (16)
10/21/2005 3:31:12 PM
On Fri, 21 Oct 2005 11:31:12 -0400, ETS <emale80919@yahoo.com> wrote:

  (snipped)
 
>
>Quick note on the hardware implementation of cic's.  In interpolation,
>you do not need the center differentiator/integrator, it can be replaced 
>with a ZOH and have identical functionality.  I know that's true for 
>D=1, have not looked at D >1.
>
>Also, in decimation the center stage can be replaced with a resettable 
>integrator and get rid of the diff. stage for hardware savings.
>
>Tim

Hi Tim,

   darn, I'm afraid I don't follow you here.
Is there some website where I can go to 
learn more about this "zero-order hold
method to reduce CIC filter hardware "idea?

Thanks,
[-Rick-]

0
R
10/27/2005 7:22:16 PM
Rick Lyons wrote:
> On Fri, 21 Oct 2005 11:31:12 -0400, ETS <emale80919@yahoo.com> wrote:
> 
>   (snipped)
>  
> 
>>Quick note on the hardware implementation of cic's.  In interpolation,
>>you do not need the center differentiator/integrator, it can be replaced 
>>with a ZOH and have identical functionality.  I know that's true for 
>>D=1, have not looked at D >1.
>>
>>Also, in decimation the center stage can be replaced with a resettable 
>>integrator and get rid of the diff. stage for hardware savings.
>>
>>Tim
> 
> 
> Hi Tim,
> 
>    darn, I'm afraid I don't follow you here.
> Is there some website where I can go to 
> learn more about this "zero-order hold
> method to reduce CIC filter hardware "idea?
> 
> Thanks,
> [-Rick-]
> 
Hmmm..  not sure about a web page, but look at it like this for a
second order Cic interpolator:


  -> C -> C -> Zero stuff -> I -> I
Is equivalent to
  -> C -> ZOH -> I

The reason is the comb, zero stuff, integrate makes a zero order hold.
Since the integrators are running at R times the comb rate, you just
hold the data going into the integrator and you get your ZOH for free.

ex: put an impulse into the center C -> zero stuff -> I
that upsamples by 3

Input:       [0 0 0 0 1 0 0 0 0]
Comb output: [0 0 0 0 1 -1 0 0 0]
zero stuff:  [0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 -1 0 0 0 0 0 0 0 0]
Integrate:   [0 0 0 0 0 0 0 0 0 0 0 0 1 1 1  0 0 0 0 0 0 0 0 0]

You can see the response is a ZOH, which is exactly the same thing
you get by samping the input sequence wrt the high side clock.
So, the whole center section basically is removed with no functionality
loss.  One of those rare instances where you get something for nothing.

Take a look at this and I'll post for the decimator, it's a little 
different and the savings isn't as good, but it still save some hardware.


Tim
0
emale80919 (16)
10/28/2005 5:22:46 PM
On Fri, 28 Oct 2005 13:22:46 -0400, ETS <emale80919@yahoo.com> wrote:

>Rick Lyons wrote:
>> On Fri, 21 Oct 2005 11:31:12 -0400, ETS <emale80919@yahoo.com> wrote:
>> 
>>   (snipped)
>>  
>> 
>>>Quick note on the hardware implementation of cic's.  In interpolation,
>>>you do not need the center differentiator/integrator, it can be replaced 
>>>with a ZOH and have identical functionality.  I know that's true for 
>>>D=1, have not looked at D >1.
>>>
>>>Also, in decimation the center stage can be replaced with a resettable 
>>>integrator and get rid of the diff. stage for hardware savings.
>>>
>>>Tim
>> 
>> 
>> Hi Tim,
>> 
>>    darn, I'm afraid I don't follow you here.
>> Is there some website where I can go to 
>> learn more about this "zero-order hold
>> method to reduce CIC filter hardware "idea?
>> 
>> Thanks,
>> [-Rick-]
>> 
>Hmmm..  not sure about a web page, but look at it like this for a
>second order Cic interpolator:
>
>
>  -> C -> C -> Zero stuff -> I -> I
>Is equivalent to
>  -> C -> ZOH -> I
>
>The reason is the comb, zero stuff, integrate makes a zero order hold.
>Since the integrators are running at R times the comb rate, you just
>hold the data going into the integrator and you get your ZOH for free.
>
>ex: put an impulse into the center C -> zero stuff -> I
>that upsamples by 3
>
>Input:       [0 0 0 0 1 0 0 0 0]
>Comb output: [0 0 0 0 1 -1 0 0 0]
>zero stuff:  [0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 -1 0 0 0 0 0 0 0 0]
>Integrate:   [0 0 0 0 0 0 0 0 0 0 0 0 1 1 1  0 0 0 0 0 0 0 0 0]
>
>You can see the response is a ZOH, which is exactly the same thing
>you get by samping the input sequence wrt the high side clock.
>So, the whole center section basically is removed with no functionality
>loss.  One of those rare instances where you get something for nothing.
>
>Take a look at this and I'll post for the decimator, it's a little 
>different and the savings isn't as good, but it still save some hardware.
>
>
>Tim

Hi Tim,
  Thanks for the reply.  I'll print out your 
post here and have a careful look at it in the next few days.

Thanks again,
[-Rick-]

0
R
10/28/2005 11:58:28 PM
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It is known, that non-uniformity of the frequency response of the channel influences level of ISI. And what kind of distortions is characteristic for non-uniform group delay time? On Feb 5, 3:08=A0am, "alex65111" <alex65...@list.ru> wrote: > It is known, that non-uniformity of the frequency response of the channel > influences level of ISI. And what kind of distortions is characteristic f= or > non-uniform group delay time? A non-constant group delay vs frequency (non-linear phase vs frequency) distorts the pulse shape. This causes ISI. John >On Feb 5, 3:08=A0a...

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Dear all I not very familiar with filter design in Matlab and I am probably missin something when it comes to "group delay". My problem comes as follows. From what I have understood, if I have a filter such that its group dela response (plotted with grpdelay[b,a] in matlab with a,b the filte coefficients) provides 17 as the group delay (in samples) at f=0.1 (normalized frequency so f=0.14*fs/2=0.14*500=70Hz, sampling frequenc being 1000 Hz) then passing a sinusoid whose frequency is 70Hz through th filter I should get at the output the same sinusoid (assuming gain is one delayed by...

Filter Group Delay
The Matlab command 'grpdelay' is restricted to digital filters only. Does there exist some counterpart to 'grpdelay' that operates in the analog domain? Some Matlab commands have separate versions for the analog and digital domains, and I wonder why 'grpdelay' does not. For example, the 'butter' command to generate Butterworth filter coefficients has digital and analog versions. The analog version is useful for understanding the stand-alone characteristics of a proposed filter, i.e., the characteristics that are independent of a particular sampled data record. ...

Linux Fails in Munich, Delays, Delays, Delays
The pipedream of Linux being used by Government is quickly fading. The first big deployment has been full of "snags" and "delays"... just like using Linux! We told everyone this, now the truth is known. - Munich announces delay in Linux migration into 2006 9/7/2005 4:55:02 PM, by Jeremy Reimer The municipal government of Munich, Germany released a statement yesterday that the migration of its office PCs to Linux and OpenOffice.org, which was scheduled to be completed in 2005, has slipped to at least next year. The original plan, which involved switching all 14,00...

delays: inertial delays vs. transport delays
Hello, I have some issues with delays which I would appreciate very much if someone could please clarify for me, as they are not clear to me right now. I would like to know what the difference between an inertial delay and a transport delay is and why VHDL would need to have these two distinct types of delay. Also, it seems to me that specifying delays in VHDL designs can only serve the purose of simulation since the delays inherent in the physical hardware cannot, as far as I know, be controlled with software: they certainly cannot be made smaller than what they are, but I'm not sur...

group delay of FIR filter
Hi all, Consider a FIR filter with coefficients [1 2 3 2 1] I know the group delay is 2, (5-1)/2. Can anyone tell how to deduce the group delay of 2 without going through the d(theta)/d(omega) mathematics? Is there an easy way to find the group delay? cfy30 cfy30 wrote: > Hi all, > > Consider a FIR filter with coefficients [1 2 3 2 1] > > I know the group delay is 2, (5-1)/2. Can anyone tell how to deduce the > group delay of 2 without going through the d(theta)/d(omega) mathematics? > Is there an easy way to find the group delay? You just found it. What more do yo...

Definition of Group (Envelope) Delay
I've been racking my brain on this one the last couple of days. So, group delay is defined as the derivative of phase with respect to frequency. My simple question is: why? We would all agree that the time delay of a sinusoid induced by a change in phase (phase delay) is equal to the ratio of the change in phase to the frequency. Also, for a linear phase response, the derivative would be equal to the ratio. Both phase delay and group delay would be constant. I have been searching for a while now and haven't found anything beyond 'it can be shown that...' In Richard Lyons' book, he simply uses 'is defined as...' Could someone provide, or refer me to, a derivation showing the relationship between an amplitude modulated sinusoid and group delay? Cheers, -Dan "dszabo" <62466@dsprelated> writes: > I've been racking my brain on this one the last couple of days. So, group > delay is defined as the derivative of phase with respect to frequency. > > My simple question is: why? > > We would all agree that the time delay of a sinusoid induced by a change in > phase (phase delay) is equal to the ratio of the change in phase to the > frequency. > > Also, for a linear phase response, the derivative would be equal to the > ratio. Both phase delay and group delay would be constant. > > I have been searching for a while now and haven't found anything b...

group delay DC filter
Dear all, My task is to implement a very narrow high pass filter to remove a DC offset of a signal. So the cut off frequency of the filter is very low. The filter must be linear phase. A first implementation was made using a double cascaded moving average filter. The filter seems to do its job very well. Unfortunately the group delay of the filter is too large. I have read some articles on multi rate filtering. Although I the feeling I could use this to find a filter with a shorter group delay most articles point out that multi rate filtering is not used to lessen the group delay. Let...

Negative Group Delay Circuit
http://www.kuee.kyoto-u.ac.jp/~kitano/paper/slp2/slp2.pdf They appear to get an output before there is an input! Surely some mistake... Hardy HardySpicer wrote: > http://www.kuee.kyoto-u.ac.jp/~kitano/paper/slp2/slp2.pdf > > They appear to get an output before there is an input! Surely some > mistake... Unfortunately they found it had already been reported in last month's journal. ;) I once wasted an entire day trying to do that (back when I was 21 or so). These guys don't seem to have got the memo about causality. Love to see them build one that works. Cheers ...

Linear Phase and group delay
Hi , I have a trivial question .Could anyone explain the concept of linear phase and group delay . I went throught the books but I cant visualize the concept . Symmetric impulse response => Linear Phase and Constant group delay . but Linear Phase does not imply constant group delay . ?? Thanks in Advance Regards Vijay pcvijay30@gmail.com writes: > Hi , > > I have a trivial question .Could anyone explain the concept of linear > phase and group delay . I went throught the books but I cant visualize > the concept . > > Symmetric impulse response => Linear Pha...

[News] Windows Vista: Delays, Delays, More Delays and Doubt
Microsoft's Vista faces delays as public tests continue ,----[ Quote ] | David Bradshaw, principal analyst for Ovum, the technology research | group, said that delays to the full release of Vista remained a danger, | noting that such testing programmes are becoming increasingly normal. He | said that public testing programmes were useful in highlighting problems | of compatibility, where the software fails to work properly with certain | printers, software programs or hardware. | | Although the discovery of a problem could force a rewrite, Mr Bradshaw | said, "it would have to be a...

JMeter Thread Group Delay
Hi I have a JMeter script with 1 Thread Group that contains about 10 requests. I want the script to run indefinitely every 5 minutes with no delays between each individual requests and currently i cannot seem to find a way to do that. There are various Timers i can add to a Thread Group, all they do is delay individual requests as opposed to delaying the execution of the whole Thread Group. Does anyone know if there is a way to implement this? ...

Group By, Limit only group?
Greetings. I'm looking to select data from a table and group by some values.. but I'm looking to limit the number of rows returned for each group, but not the entire query. Here's my table set up (Not from MySQL, just typed up.. but it'll give you the idea): CREATE TABLE bank_ident_all_t( ident_id INT(9) UNSIGNED ZEROFILL NOT NULL, ident_type ENUM('ach','cc') NOT NULL, bank_id INT UNSIGNED NOT NULL, ref_count INT UNSIGNED NOT NULL DEFAULT 1, last_updated INT UNSIGNED NOT NULL, PRIMARY KEY(ident_id, ident_type, bank_id), INDEX(ident_id, ident_type) )...

Is this group only a Google group?
Hello, I'm discovering APL and I posted a question yesterday on the comp.lang.apl = nntp group. While searching for more information about APL, I stumbled upon= this Google group. I see that it has the same posts than the nntp group, b= ut the last nntp post is from October 1st, 2014. I'm thus wondering if there is are synchronization issues between nntp and = the Google group, or if the problem is with my nntp provider. Thanks, Alan Hi, comp.lang.apl is definitely a usenet group. Many providers aren't retaining many newsgroups long enough and also seem to ...

Re: Google groups delay
Indeed ... maybe 97000 is a magic number for them (96999 is the number of topics currently listed)? -Joe On Mon, Oct 27, 2008 at 6:41 PM, Richard <richard.hockey@gmail.com> wrote: > Anyone noticed that google groups is not updating SAS-L ? > Today the newest item is dated 2 days ago. > R > ...

Channel-Group Groups
When configuring a T1 and setting up the timeslots you have an option to set the channel group group number. What exactly does the "channel-group" group number do? Normally, I plug in 1, but you can set it from 0-23. channel-group ?? timeslots 1-24 speed 64 (?? is where the group number would go.) Thanks Amy. On 16 Dec 2004 10:53:42 -0800, amyl@paxemail.com wrote: ~ When configuring a T1 and setting up the timeslots you have an option ~ to set the channel group group number. What exactly does the ~ "channel-group" group number do? Normally, I plug in 1, but you can ~ set it from 0-23. ~ ~ channel-group ?? timeslots 1-24 speed 64 ~ (?? is where the group number would go.) ~ ~ Thanks ~ Amy. The channel-group number becomes part of the name of the serial interface you create. For example, if you do this: controller T1 2 channel-group 3 timeslots 1-24 speed 64 then this creates an interface called "Serial 2:3" You can configure multiple channel-groups (and/or ds0-groups if your platform supports it), so pick a unique channel-group/ ds0-group ID for each such group ... e.g. controller t1 2 channel-group 0 timeslots 1-4 speed 64 channel-group 1 timestots 5-12 speed 64 ds0-group 2 timeslots 13-24 type e&m-fgb Aaron ...

Delay when sending to queue grouped
Dear group, I am currently setting up queue groups by using the following macros in my sendmail.mc file: define(`QUEUE_DIR', `/var/spool/mqueue')dnl QUEUE_GROUP(`autohandled', `P=/var/spool/mqueue/autohandled, I=5m, R=5')dnl define(`LOCAL_PROG_QGRP', `autohandled')dnl However, when sending through the 'prog' mailer, the message is not delivered instantly, but rather queued FIRST, and then delievered after the first queue run (within 5 minutes). Note that this behaviour only occurs when sending through the Mail Submission Program (MSP), and not directly to sendmail using the "-Am" switch. Why isn't my message being sent to the mailer first, and then queued later, if necessary? Am I missing something? I know that this doesn't happen if I don't specify queue groups, but is this a result of a misconfiguration, or is this how queue groups act by default? Thanks in advance, - Anthony ...

group delay in decimate command
i'm simulating a baseband ofdm system digital front end and cannot understand how groupdelay of the filter before downsampling is a problem. following is my code tot_data = ofdm_data; % Upsampling up_conv = interp(tot_data, 30); % Downsampling dec_fir = fir1(30, 1/30); up_conv = filter(dec_fir, 1, up_conv); decim = downsample(up_conv(1:end), 30); I observe that the constellation diagram is scattered a little bit (there is no noise in the system) you can say 3 dB degradation is observable. Now when i compensate the group delay of the filter up_conv in downsample command, the scatter pl...

http://groups-beta.google.com/group/Configuration-Management join this group on google beta group site
Please join the new group on google beta group site http://groups-beta.google.com/group/Configuration-Management Thanks for your interest pompy Belkar wrote: > Please join the new group on google beta group site > http://groups-beta.google.com/group/Configuration-Management > Thanks for your interest If everybody here created a new group there, we all would have to follow hundreds of groups to keep up with discussion. Why not use the Usenet, with its standard protocols to access the information? Heiner -- ___ _ / __| |_ _____ _____ _ _ Heiner STEVEN <hei...

Filter design with a desired group delay?
Hi, The fdatool in matlab usually designs a real equiripple filter with a group delay (N-1)/2 or N/2, where N is filter length. Given desired magnitude response, to design a linear phase filter with a prescribed group delay, will the optimum filter be real coefficient and symmetric? Thanks. ZedToe "ZedToe" <acoustictech_zhangtao@yahoo.com.sg> wrote in message news:7c4bf533.0401070850.53b25746@posting.google.com... > Hi, > > The fdatool in matlab usually designs a real equiripple filter with a > group delay (N-1)/2 or N/2, where N is filter length. > > Gi...

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