Forums

BPSK decode with Goertzel Algorithm

Started by Thomas Magma July 12, 2004
Try asking the authors Rick Lyons and Eric Jacobsen if either of them have it
available on a web page or will send it to you.  You should be able to find
their e-mail addresses by Googling comp.dsp for past posts by them.

"Thomas Magma" <somewhere@overtherainbow.com> wrote in message
news:sbBLc.73668$od7.19366@pd7tw3no...
> I just went and read the abstract to "The Sliding DFT" It looks like a good > article, one that I would enjoy reading, but they want you to pay to become > a member. > > The opening line of the abstract to that article implies the article is > referring to spectrum analysis and perhaps not to phase demodulation. This > would probably use an optimized Goertzel (magnitude) sliding window and > would be a different kind of beast than one used for phase demodulation. > > Don't think I want to shell out $147 dollars to read that article. Unless > someone else knows of an cheaper way of doing so. > > Thomas > > "Jon Harris" <goldentully@hotmail.com> wrote in message > news:2m7plrFjeloaU1@uni-berlin.de... > > Rick Lyons and Eric Jacobsen, who both posts here, have written an article > on > > the sliding DFT which includes a section on the sliding Goertzel: "The > Sliding > > DFT", IEEE Signal Processing Magazine, Volume 20, No. 2, March 2003.
> I didn't say it couldn't be done -- the Goertzel algorithm behaves > exactly like an integrate and dump if you look at it just right. I was > only saying that by the time you wrapped it with the necessary support > code to make it work you may not see much savings, and _nobody_ but you > would be able to understand the code. > > -- > > Tim Wescott > Wescott Design Services > http://www.wescottdesign.com
Isn't any 'savings' a step forward. I will compare my Goertzel PSK demodulator algorithm speed to a standard conversation (using a lookup table and I and Q channels). Just looking at both algorithms side by side it looks like the Goertzel has a major advantage because it does multiplication only once per sample, where the standard method needs to do it twice for the I and Q. Multiplication being processor hungry. As far as nobody understanding my code, well...when was the last time you understood your FFT code line for line. Most people treat DSP algorithms nothing more than a bunch on 'drag and drop' bag of tricks anyways. Thomas
For what it's worth, I was able to find Eric and Rick's article
on-line. Thanks for the tip, it's a very good article indeed. In my
case I went to our local University's web site (www.unm.edu) and
worked my way through the library search links (Libros) and finally
was directed to IEEE Explora site where I was able to read, save, and
print the article.

Dave Comer

"Thomas Magma" <somewhere@overtherainbow.com> wrote in message news:<sbBLc.73668$od7.19366@pd7tw3no>...
> I just went and read the abstract to "The Sliding DFT" It looks like a good > article, one that I would enjoy reading, but they want you to pay to become > a member. >
Hi Dave,

Thanks for finding that article. I can get on the Libros search links but am
having troubles finding my way into IEEE Explora site like you suggested.
Could you please give me another hint as to the way in.

Thanks,
Thomas

"Dave Comer" <dmcomer@swcp.com> wrote in message
news:f206eebf.0407260808.6b482279@posting.google.com...
> For what it's worth, I was able to find Eric and Rick's article > on-line. Thanks for the tip, it's a very good article indeed. In my > case I went to our local University's web site (www.unm.edu) and > worked my way through the library search links (Libros) and finally > was directed to IEEE Explora site where I was able to read, save, and > print the article. > > Dave Comer > > "Thomas Magma" <somewhere@overtherainbow.com> wrote in message
news:<sbBLc.73668$od7.19366@pd7tw3no>...
> > I just went and read the abstract to "The Sliding DFT" It looks like a
good
> > article, one that I would enjoy reading, but they want you to pay to
become
> > a member. > >
> > Thanks for finding that article. I can get on the Libros search links but am > having troubles finding my way into IEEE Explora site like you suggested. > Could you please give me another hint as to the way in. >
Thomas, The following url strings are the ones I used in order of last to first (The first in this list will get you to the PDF download page). Probably an overkill :) Dave http://ieeexplore.ieee.org/xpl/tocresult.jsp?isNumber=26586&puNumber=79 http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79&year=2003 http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79&year=2003 http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79 http://library.unm.edu/search/tIEEE+Signal+Processing+Magazine/tieee+signal+processing+magazine/1,1,2,E/frameset&FF=tieee+signal+processing+magazine&1,,2 http://library.unm.edu/search/t?SEARCH=IEEE+Signal+Processing+Magazine http://library.unm.edu/search/t http://library.unm.edu/
Thomas Magma wrote:
 > Just looking at
> both algorithms side by side it looks like the Goertzel has a major > advantage because it does multiplication only once per sample, where the > standard method needs to do it twice for the I and Q. Multiplication being > processor hungry.
Multiplication on most DSP's is only one cycle. If the DSP is pipelined, a branch usually costs more than a multiply, so skipping multiplies with branches is a false economy. I dunno what hardware you're using though, so this may not apply to your situation. -- Jim Thomas Principal Applications Engineer Bittware, Inc jthomas@bittware.com http://www.bittware.com (703) 779-7770 Hope springs occasionally.
Hi Jim,

No I'm not using a DSP core. That is why I am so concerned with the speed of
decoding BPSK. I'm doing it on a PDA using the Intel Xscale processor. This
is obviously not optimized for DSP and you also have to deal with delays
from WindowsCE events and system interrupts firing.

Thomas

"Jim Thomas" <jthomas@bittware.com> wrote in message
news:10gd1f66sbt98fc@corp.supernews.com...
> Thomas Magma wrote: > > Just looking at > > both algorithms side by side it looks like the Goertzel has a major > > advantage because it does multiplication only once per sample, where the > > standard method needs to do it twice for the I and Q. Multiplication
being
> > processor hungry. > > Multiplication on most DSP's is only one cycle. If the DSP is > pipelined, a branch usually costs more than a multiply, so skipping > multiplies with branches is a false economy. > > I dunno what hardware you're using though, so this may not apply to your > situation. > > -- > Jim Thomas Principal Applications Engineer Bittware, Inc > jthomas@bittware.com http://www.bittware.com (703) 779-7770 > Hope springs occasionally.
Hi Dave,

Thanks for your help. I followed the links that you posted, but it is still
asking me to log on in order to download the PDF. It doesn't recognise that
I have just come from a subscribing institution (UNM). Is it possible that
your URL is somehow associated with the University or that the University
has placed a cookie onto your machine during a login or an install of some
kind?

Thomas


"Dave Comer" <dmcomer@swcp.com> wrote in message
news:f206eebf.0407270502.2e067786@posting.google.com...
> > > > Thanks for finding that article. I can get on the Libros search links
but am
> > having troubles finding my way into IEEE Explora site like you
suggested.
> > Could you please give me another hint as to the way in. > > > Thomas, > > The following url strings are the ones I used in order of last to > first (The first in this list will get you to the PDF download page). > Probably an overkill :) > > Dave > > http://ieeexplore.ieee.org/xpl/tocresult.jsp?isNumber=26586&puNumber=79 > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79&year=2003 > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79&year=2003 > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79 >
http://library.unm.edu/search/tIEEE+Signal+Processing+Magazine/tieee+signal+processing+magazine/1,1,2,E/frameset&FF=tieee+signal+processing+magazine&1,,2
> http://library.unm.edu/search/t?SEARCH=IEEE+Signal+Processing+Magazine > http://library.unm.edu/search/t > http://library.unm.edu/
Thomas,

I'm not sure, but I may have been able to download the article simply
due to my IEEE membership. That is, I probably have a cookie on my
system that the IEEE system is picking up. I'm not sure how I managed
to get it (I'm not a student at UNM and I don't have a subscription to
the IEEE digital library). Hence, they may make some material
available to members.

Dave


"Thomas Magma" <somewhere@overtherainbow.com> wrote in message news:<dLxNc.122079$Mr4.108656@pd7tw1no>...
> Hi Dave, > > Thanks for your help. I followed the links that you posted, but it is still > asking me to log on in order to download the PDF. It doesn't recognise that > I have just come from a subscribing institution (UNM). Is it possible that > your URL is somehow associated with the University or that the University > has placed a cookie onto your machine during a login or an install of some > kind? > > Thomas > > > "Dave Comer" <dmcomer@swcp.com> wrote in message > news:f206eebf.0407270502.2e067786@posting.google.com... > > > > > > Thanks for finding that article. I can get on the Libros search links > but am > > > having troubles finding my way into IEEE Explora site like you > suggested. > > > Could you please give me another hint as to the way in. > > > > > Thomas, > > > > The following url strings are the ones I used in order of last to > > first (The first in this list will get you to the PDF download page). > > Probably an overkill :) > > > > Dave > > > > http://ieeexplore.ieee.org/xpl/tocresult.jsp?isNumber=26586&puNumber=79 > > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79&year=2003 > > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79&year=2003 > > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79 > > > http://library.unm.edu/search/tIEEE+Signal+Processing+Magazine/tieee+signal+processing+magazine/1,1,2,E/frameset&FF=tieee+signal+processing+magazine&1,,2 > > http://library.unm.edu/search/t?SEARCH=IEEE+Signal+Processing+Magazine > > http://library.unm.edu/search/t > > http://library.unm.edu/
When I access the IEEE site from a subscribing institution, I have to use the 
library's computers.  Have you asked the reference librarian about how you go 
about getting where you want to go?

In article <f206eebf.0407280707.467e05d2@posting.google.com>, dmcomer@swcp.com 
(Dave Comer) wrote:
>Thomas, > >I'm not sure, but I may have been able to download the article simply >due to my IEEE membership. That is, I probably have a cookie on my >system that the IEEE system is picking up. I'm not sure how I managed >to get it (I'm not a student at UNM and I don't have a subscription to >the IEEE digital library). Hence, they may make some material >available to members. > >Dave > > >"Thomas Magma" <somewhere@overtherainbow.com> wrote in message > news:<dLxNc.122079$Mr4.108656@pd7tw1no>... >> Hi Dave, >> >> Thanks for your help. I followed the links that you posted, but it is still >> asking me to log on in order to download the PDF. It doesn't recognise that >> I have just come from a subscribing institution (UNM). Is it possible that >> your URL is somehow associated with the University or that the University >> has placed a cookie onto your machine during a login or an install of some >> kind? >> >> Thomas >> >> >> "Dave Comer" <dmcomer@swcp.com> wrote in message >> news:f206eebf.0407270502.2e067786@posting.google.com... >> > > >> > > Thanks for finding that article. I can get on the Libros search links >> but am >> > > having troubles finding my way into IEEE Explora site like you >> suggested. >> > > Could you please give me another hint as to the way in. >> > > >> > Thomas, >> > >> > The following url strings are the ones I used in order of last to >> > first (The first in this list will get you to the PDF download page). >> > Probably an overkill :) >> > >> > Dave >> > >> > http://ieeexplore.ieee.org/xpl/tocresult.jsp?isNumber=26586&puNumber=79 >> > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79&year=2003 >> > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79&year=2003 >> > http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79 >> > >> > http://library.unm.edu/search/tIEEE+Signal+Processing+Magazine/tieee+signal+pr >ocessing+magazine/1,1,2,E/frameset&FF=tieee+signal+processing+magazine&1,,2 >> > http://library.unm.edu/search/t?SEARCH=IEEE+Signal+Processing+Magazine >> > http://library.unm.edu/search/t >> > http://library.unm.edu/