Hi Does anyone have some guidelines on how to implement a 4'th order low-pass Butterworth IIR filter in fixed point. My cut-off frequency is relatively close to the DC frequency so high precision is needed for the coefficients. What about realization structure and so on! I have implemented the bit-flipping algorithm in http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization of coefficients and it indeed works, but does some other techniques allow for further reductions of number of bits used to represent the coefficients. Thomas

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11/5/2003 11:43:23 PM

I've found the normalized lattice-ladder approach yields low distortion even at low frequencies. The cost is more multiplies per filter. Is this a hardware/FPGA implementation? "Heureka" <stoltzo@hotmail.com> wrote in message news:boc1up$l86$1@news.cybercity.dk... > Hi > > Does anyone have some guidelines on how to implement a 4'th order low-pass > Butterworth IIR filter in fixed point. My cut-off frequency is relatively > close to the DC frequency so high precision is needed for the coefficients. > What about realization structure and so on! > > I have implemented the bit-flipping algorithm in > http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization of > coefficients > and it indeed works, but does some other techniques allow for further > reductions of number of bits used to represent the coefficients. > > Thomas > >

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11/6/2003 12:13:00 AM

Might have to go with 32 bit filter states and/or coefficients. Or you can try some of the noise shaping that's been described in here every now and then. I would cascade 2, 2nd order biquads ( if it's being done in software ). Robert www.gldsp.com "Heureka" <stoltzo@hotmail.com> wrote: >Hi > >Does anyone have some guidelines on how to implement a 4'th order low-pass >Butterworth IIR filter in fixed point. My cut-off frequency is relatively >close to the DC frequency so high precision is needed for the coefficients. >What about realization structure and so on! > >I have implemented the bit-flipping algorithm in >http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization of >coefficients >and it indeed works, but does some other techniques allow for further >reductions of number of bits used to represent the coefficients. > >Thomas > ( modify address for return email ) www.numbersusa.com www.americanpatrol.com

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11/6/2003 4:31:00 AM

Heureka wrote: > Hi > > Does anyone have some guidelines on how to implement a 4'th order > low-pass Butterworth IIR filter in fixed point. My cut-off > frequency is relatively close to the DC frequency so high > precision is needed for the coefficients. What about realization > structure and so on! > > I have implemented the bit-flipping algorithm in > http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization > of coefficients > and it indeed works, but does some other techniques allow for > further reductions of number of bits used to represent the > coefficients. > > Thomas Which is your relative cut-off frequency Fc/Fs? How many real bits has your signal? How many bits do you need after the filter stage? Bernhard

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11/6/2003 7:01:21 AM

Hello: Basic Guidelines: Use 2 2nd order Direct Form I (two delay lines, to avoid overflow of internal filter states) cascaded sections. You most likely will need to halve the a1 coeficient in each stage (if it is greater than 1) and do two macs on that part of the calculation. For low fc/fs, you may need 32 bit recursive data paths. Matlab has tools to take general transfer functions B(z)/A(z) and restructure them to cascaded second order sections. Regards -S www.appliedsignalprocessing.com "Heureka" <stoltzo@hotmail.com> wrote in message news:boc1up$l86$1@news.cybercity.dk... > Hi > > Does anyone have some guidelines on how to implement a 4'th order low-pass > Butterworth IIR filter in fixed point. My cut-off frequency is relatively > close to the DC frequency so high precision is needed for the coefficients. > What about realization structure and so on! > > I have implemented the bit-flipping algorithm in > http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization of > coefficients > and it indeed works, but does some other techniques allow for further > reductions of number of bits used to represent the coefficients. > > Thomas > >

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11/6/2003 5:16:51 PM

Sorry for my late reply! The filters are to be implemented on a FPGA. The cutoff frequency is fs/64. When I convert the floating point coefficients linearly I have to use 30 bit in order to have a stop band attenuation at 70 dB. With the bit.flipiing algorithm I can get the bit number down to 20 bit. I need to use as few multiplications as possible, since power consumption is of the essence - but area is too. Can anyone recommend some nice litterature adressing this issue! Thomas "Bernhard Holzmayer" <holzmayer.bernhard@deadspam.com> wrote in message news:1097769.KRe6XMYa8L@holzmayer.ifr.rt... > Heureka wrote: > > > Hi > > > > Does anyone have some guidelines on how to implement a 4'th order > > low-pass Butterworth IIR filter in fixed point. My cut-off > > frequency is relatively close to the DC frequency so high > > precision is needed for the coefficients. What about realization > > structure and so on! > > > > I have implemented the bit-flipping algorithm in > > http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization > > of coefficients > > and it indeed works, but does some other techniques allow for > > further reductions of number of bits used to represent the > > coefficients. > > > > Thomas > > Which is your relative cut-off frequency Fc/Fs? > How many real bits has your signal? > How many bits do you need after the filter stage? > > Bernhard >

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11/6/2003 7:38:37 PM

FPGA with minimal multiplies? In that case, scratch my previous idea of the normalized Lattice-Ladder implementation. "Heureka" <stoltzo@hotmail.com> wrote in message news:3faaa32c$0$69926$edfadb0f@dread12.news.tele.dk... > Sorry for my late reply! > > The filters are to be implemented on a FPGA. The cutoff frequency is fs/64. > When I convert the floating point coefficients > linearly I have to use 30 bit in order to have a stop band attenuation at 70 > dB. With the bit.flipiing algorithm I can get the bit number down to 20 bit. > I need to use as few multiplications as possible, since power consumption is > of the essence - but area is too. > > Can anyone recommend some nice litterature adressing this issue! > > Thomas > > > "Bernhard Holzmayer" <holzmayer.bernhard@deadspam.com> wrote in message > news:1097769.KRe6XMYa8L@holzmayer.ifr.rt... > > Heureka wrote: > > > > > Hi > > > > > > Does anyone have some guidelines on how to implement a 4'th order > > > low-pass Butterworth IIR filter in fixed point. My cut-off > > > frequency is relatively close to the DC frequency so high > > > precision is needed for the coefficients. What about realization > > > structure and so on! > > > > > > I have implemented the bit-flipping algorithm in > > > http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization > > > of coefficients > > > and it indeed works, but does some other techniques allow for > > > further reductions of number of bits used to represent the > > > coefficients. > > > > > > Thomas > > > > Which is your relative cut-off frequency Fc/Fs? > > How many real bits has your signal? > > How many bits do you need after the filter stage? > > > > Bernhard > > > >

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11/7/2003 1:47:17 AM

Hi Thomas! You can also use Lattice Digital Wave filter sections to implement 1-st and 2-nd order allpass sections in cascade. From these allpass sections in cascade one can form a sum or difference dependent on how the filter should act (LP, HP etc.). The resulting filter require minimal number of multipliers and wordlength. Jon Harris wrote: > FPGA with minimal multiplies? In that case, scratch my previous idea of the > normalized Lattice-Ladder implementation. > > "Heureka" <stoltzo@hotmail.com> wrote in message > news:3faaa32c$0$69926$edfadb0f@dread12.news.tele.dk... > >>Sorry for my late reply! >> >>The filters are to be implemented on a FPGA. The cutoff frequency is > > fs/64. > >>When I convert the floating point coefficients >>linearly I have to use 30 bit in order to have a stop band attenuation at > > 70 > >>dB. With the bit.flipiing algorithm I can get the bit number down to 20 > > bit. > >>I need to use as few multiplications as possible, since power consumption > > is > >>of the essence - but area is too. >> >>Can anyone recommend some nice litterature adressing this issue! >> >>Thomas >> >> >>"Bernhard Holzmayer" <holzmayer.bernhard@deadspam.com> wrote in message >>news:1097769.KRe6XMYa8L@holzmayer.ifr.rt... >> >>>Heureka wrote: >>> >>> >>>>Hi >>>> >>>>Does anyone have some guidelines on how to implement a 4'th order >>>>low-pass Butterworth IIR filter in fixed point. My cut-off >>>>frequency is relatively close to the DC frequency so high >>>>precision is needed for the coefficients. What about realization >>>>structure and so on! >>>> >>>>I have implemented the bit-flipping algorithm in >>>>http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization >>>>of coefficients >>>>and it indeed works, but does some other techniques allow for >>>>further reductions of number of bits used to represent the >>>>coefficients. >>>> >>>>Thomas >>> >>>Which is your relative cut-off frequency Fc/Fs? >>>How many real bits has your signal? >>>How many bits do you need after the filter stage? >>> >>>Bernhard >>> >> >> > >

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11/7/2003 8:48:00 AM

Hi all, Can any one help me in finding this solution. I am creating a named pipe in a service with the name same as that is generated by the windows spooler. So that whenever a print is issued in any of the applications the spooler generates the file in system folder. Not that when a file with the same name as namepipe is created that spooler file contents had to come to my pipe. but that is not what happening. your help in this regard will be of great help to me. thank you very much, regards, Mohd Moinuddin Pasha. ...

Hello, I am totally new to Mathematica and trying to program a simple FEM-type problem. I am trying to take the partial derivative (symbolically) of an expression that is a function of four points in 3D. All I can think of to do is F[p1,p2,p3,p4] = stuff then D[F,p1,p2,p3,p4] . But I keep getting a zero expression as a result. (where stuff is a nasty combination of these points) Any thoughts? mroc_1000@hotmail.com (mroc) wrote in message news:<boign7$oj1$1@smc.vnet.net>... > Hello, I am totally new to Mathematica and trying to program a simple > FEM-type problem. I am tr...

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1) Is it been tried that on a same frequency slot (bandwidth) many wireless nodes (devices) communicate with single node (device) using different (orthogonal) spread spectra sequence signals? if yes what is the upper limit on number of multipoint-point? what is the hardware used can it be radio modems offered with FHSS or DSSS capacity? 2) If in a cellular like network designer wants to reduce the hands off protocol to alloting fixed chip sequences to each node (a controlled network) and uses same link all over the geography, in this case base stations or sink nodes are placed at locations wh...

Daniel Barlow noted a point here -> http://ww.telent.net/diary/2002/11/ that "Lisp is unsuitable for Google because implementations don't cope with their scary scaling requirements.". True enough, just to start up SBCL on my machine takes up 26M (python 4M, perl 3M, ruby 2.5M, C++ 1.2M, and C 0.9M ). Which is not good if you want thousands of processes (doing simple things) running simultaneously. So I would like to invite comments from people who know about this, is it possible to create a runtime shared library as a Lisp implementation? Also how well supported is multi-th...

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Can anyone show me what I am doing wrong here? raub@kushana-47>cat moose.sh #!/bin/sh SEARCHUSERS="raub" # For each user in the list for i in $SEARCHUSERS do ls ~"$i" done raub@kushana-48>sh /tmp/moose.sh ~raub: No such file or directory raub@kushana-49> I also tried something like ls `eval echo "~$i"` which produced the same results. I also tried ksh and bash and had removed the double quotes, as in ls ~$i but am still having the same results. What should I try next? -- Mauricio ...

hi, I am looking for a Sr.SAP with good knowledge in Fixed Assets / SME. if suitable kindly mail me your resume and rates. Email your resume to : carmelc@gmail.com. REQUIREMENT: Sr. SAP Resource -- Fixed Assets GURU // SME NOT looking for an AP/AR resource w/some fixed assets Rate: Best Start: ASAP (this week or early next is required) Duration: 9/30/05 w/possibility of extension Location: OH. ...

Hi: I tried to solve a 4 order PDE through pdetool, but I found it seemed could solve only 2 order problem. So is there easy way to solve 4 order PDE? Thanks ...

With the recent "fix" of course it appears. http://www.techweb.com/article/showArticle.jhtml?articleId=175802806&pgno =1 ust days after Microsoft rushed out a patch for a bug in Windows Metafile (WMF) image processing, a security company has warned customers that multiple memory corruption vulnerabilities in the same rendering engine could leave users open to attack. "An attacker may leverage these issues to carry out a denial-of-service attack or execute arbitrary code," Symantec said in a vulnerability alert issued through its DeepSight Management System. The...

I am developing and testing a dedicated LAN composed of just two Windows computers with Ethernet adapters. The application will deal with UDP only. No TCP. For various reasons, I would like to bypass the DNS stuff and use a statically defined IP address in the "server" side of the UDP connection. (The "server" will eventually be replaced with an embedded Ethernet device with limited resources.) The trouble is, I seem unable to use the Windows Sockets API to force a fixed IP address (10.10.6.100) in the "server". Evidence is that after calling bind a...

Sad. Someday in the distant future, they might get it right. Maybe with OSXII - but it's doubtful. ...

mysql_query("START TRANSACTION", $link2); $q2=mysql_query("SELECT pictures.pid AS pid FROM pictures,counter WHERE pictures.pid>counter.pid LIMIT 1", $link2); if ($row2=mysql_fetch_assoc($q2)) { mysql_query("UPDATE counter SET pid=$row2[pid]", $link2); $n=$row2['pid']; } else { //reached end of table. mysql_query("UPDATE counter SET pid=1", $link2); $n=1; } mysql_free_result($q2); mysql_query("COMMIT", $link2); the transaction makes no difference in the outcome. I've even tried locking the tables, but tha...

I am experimenting with matlab the LMS algorithm , there are many m files I can find. the problem is that I want to using simulink to do it, but i don't kown how to construct the model,anybody can give me some idea. thank u ...

Here is the puzzle. You have a string. You have a list of strings and/or regular expressions. You want to find the match, if any, between your string and an element in the list. If the list is also just strings, you can create a hash with the strings as keys then do a hash lookup to do the match. That's fast, even if the list is very long. However, what is most of the list is string literals, but you want to be able to use regexps or some sort of wildcard matching for some of the matches, too. Does anyone have any bright ideas about how to do this as quickly as possible? The...

Is it possible to implement a point-to-point link on FreeBSD without using PPP? I'm trying to create a "tappable" link between a fbsd firewall and router that can be used to monitor multiple networks (connected to the router) using Snort. I realize that I could just as easily use a /30, but I'm just curious if it could be done with a /31 not using PPP. NAT for the internet connection is performed by the firewall Here is a rude drawing of the network (hopefully Google Groups, doesnt distort it too much). Internet -----> Firewall --------------------> Router ...

hii my friends =FD want to a filter for porn picture if you know , please help me :S:S how do =FD separate porn form not porn I don't want my web site porn;) (my english bad I hope understant it. very very thans ) oruccim@gmail.com schrieb: > hii my friends > � want to a filter for porn picture > if you know , please help me :S:S > how do � separate porn form not porn > I don't want my web site porn;) > (my english bad I hope understant it. very very thans ) If anybody know how to do that, he or she would immediatly become incredibly rich, selling this magic fil...

Example: <form action="..." method="post"> <input type=image name="Image1" onclick="beforeSubmit();" src="..."/> </form> When I click on the image the form submitted to the server. As I can see post data contains next additional values: Image1.x=121 and Image1.y=64 These values are coordinates of clicked point relative to image. Can I get these values in onclick event handler (within the beforeSubmit method)? marss a �crit : > Example: > <form action="..." method="post"> > <i...

Dear All, I do not have any background in DSP, so please excuse if this question seems silly. I am working on a bugfix for an IIR filter implementation in C. It takes samples from ADC and filters them. Filtering is done by an First order IIR filter. The transfer function is as follows: /* First order IIR filter z-transform(formula): [ 2^-n/(1-(2^-n)) ] H(z) = --------------------------------- [1 - ( (1/ (1- (2^-n)))*Z^-1 )] and the final equation which is implemented into code is a sfollows: Output = ([1/(2^n -1)]*input) + ([2^n/(2^n -...

Actually, I'm not even sure it's possible to dynamically allocate a fixed size one dimensional array. So here's the problem: I have a type 'board' defined as so: typedef char board[8][8] and I am supposed to write a function with the following prototype: Board *new_board(); which would require me to use malloc for allocation. I've tried many different things that I'd be ashamed to post here but have found no solution. The problem is that it doesn't seem possible to cast a char* or char** to a fixed length array (e.g. char[8] or char[8][8] or board in this cas...

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Hi all, I'm trying to simulate a fixed weght machine. This machine has two entry points with grapes that have two different probabilistic distributions. Then a work center pick from several queues a combination so grape1+grape2=target+-tol. Anyone is familiar with this kind of work? Best Regards, Jaime ...

Just a small little program. Can not figure out what am I doing wrong. #include <stdio.h> #include <limits.h> #include <float.h> int main() { double max = FLT_MAX; double sub = 16703.627681; double result = max - sub; printf("%f - %f = %f\n", max, sub, result); return 0; } Output: 340282346638528859811704183484516925440.000000 - 16703.627681 = 340282346638528859811704183484516925440.000000 Any help would be highly appreciated. Thanks On Oct 25, 7:56 pm, spooler...@gmail.com wrote: > Just a small little program. Can not figure out what am I doing wrong...

hi everyone: Today I came cross a strange problem about function returning point. I have a function for replace chinses character to english character. sub replace_par{ my $str =3D shift; $str =3D~ s/\xA3\xA8/\(/; $str =3D~ s/\xA3\xA9/\)/; return $str; } Then I calling this function in a subroutine. as follows: ..=2E. ... ### first we open a text file, and read line by line: open(F,"<aaa.txt"); while(<F>){ ..=2E. ... #according the context we have read, we named function name. my $progName =3D $conf->{'feedname'} . '_slicecheck...