LMS theory,there are 3 signal as follows. 1. the signal to be filterd; 2. the expectation signal,which is used to compare with filtered signal to get error signal; 3. the error signal,which (can be get from 2 and ) is used to update the filter coefficients; But always some articles about LMS adaptive filters say of reference signal. In the 3 signals above,which does reference signal refer to ? Cheers Hyee
Which does reference signal refer to in LMS theory?
Started by ●November 23, 2009
Reply by ●November 23, 20092009-11-23
>LMS theory,there are 3 signal as follows. > >1. the signal to be filterd; >2. the expectation signal,which is used to compare with filtered >signal to get error signal; >3. the error signal,which (can be get from 2 and ) is used to update >the filter coefficients; > >But always some articles about LMS adaptive filters say of reference >signal. > >In the 3 signals above,which does reference signal refer to ? >Not 1,2,3. I think you speek about 4 - desired response at time n, to which LMS is adapted.
Reply by ●November 23, 20092009-11-23
>>LMS theory,there are 3 signal as follows. >> >>1. the signal to be filterd; >>2. the expectation signal,which is used to compare with filtered >>signal to get error signal; >>3. the error signal,which (can be get from 2 and ) is used to update >>the filter coefficients; >> >>But always some articles about LMS adaptive filters say of reference >>signal. >> >>In the 3 signals above,which does reference signal refer to ? >> > >Not 1,2,3. I think you speek about 4 - desired response at time n, >to which LMS is adapted. >Sorry. After reread Widrow: desired response - 2; reference - 1;
Reply by ●November 23, 20092009-11-23
On Nov 23, 9:32�pm, "vashkevich" <ovashkev...@gmail.com> wrote:> >>LMS theory,there are 3 signal as follows. > > >>1. the signal to be filterd; > >>2. the expectation signal,which is used to compare with filtered > >>signal to get error signal; > >>3. the error signal,which (can be get from 2 and ) �is used to update > >>the filter coefficients; > > >>But always some articles about LMS adaptive filters say of reference > >>signal. > > >>In the 3 signals above,which does reference signal refer to ? > > >Not 1,2,3. I think you speek about 4 - desired response at time n, > >to which LMS is adapted. > > Sorry. After reread Widrow: > desired response - 2; > reference - 1;- Hide quoted text - > > - Show quoted text -Thank you! But I would rather refer to 2. Could you show me the details you read?
Reply by ●November 23, 20092009-11-23
On Nov 23, 1:45�am, HyeeWang <hyeew...@gmail.com> wrote:> LMS theory,there are 3 signal as follows. > > 1. the signal to be filterd; > 2. the expectation signal,which is used to compare with filtered > signal to get error signal; > 3. the error signal,which (can be get from 2 and ) �is used to update > the filter coefficients; > > But always some articles about LMS adaptive filters say of reference > signal. > > In the 3 signals above,which does reference signal refer to ? > > Cheers > HyeeHyee, What you are refering to as the expectation signal is the reference. I've never seen it referred to as the expectation signal, so let me explain a bit further. The "filterd signal" is really an estimation. It is a prediction of the reference or desired signal. The "filtered" signal is subtracted from the reference to obtain the error. The desired and the reference are the same. Maurice Givens
Reply by ●November 24, 20092009-11-24
On Nov 23, 8:45�pm, HyeeWang <hyeew...@gmail.com> wrote:> LMS theory,there are 3 signal as follows. > > 1. the signal to be filterd; > 2. the expectation signal,which is used to compare with filtered > signal to get error signal; > 3. the error signal,which (can be get from 2 and ) �is used to update > the filter coefficients; > > But always some articles about LMS adaptive filters say of reference > signal. > > In the 3 signals above,which does reference signal refer to ? > > Cheers > HyeeThere are only two inputs to an LMS algorithm - primary and reference. If you get them the wrong way round try swapping them! Hardy
Reply by ●November 24, 20092009-11-24
HyeeWang wrote:> LMS theory,there are 3 signal as follows. > > 1. the signal to be filterd; > 2. the expectation signal,which is used to compare with filtered > signal to get error signal; > 3. the error signal,which (can be get from 2 and ) is used to update > the filter coefficients; > > But always some articles about LMS adaptive filters say of reference > signal. > > In the 3 signals above,which does reference signal refer to ? > > Cheers > HyeeThe answer is: "it depends". In an automatic line canceller, the reference signal is often taken from a better source of the interference. So, it's not on your list. It's a version of the signal to be filtered but not the signal to be filtered itself. Presumably the signal to be filtered includes a version of the reference summed with a version of the signal desired in the filtered output. In an automatic line enhancer, the reference signal is a delayed version of the signal to be filtered or vice versa. I don't think it matters which. Fred
Reply by ●November 24, 20092009-11-24
>HyeeWang wrote: >> LMS theory,there are 3 signal as follows. >> >> 1. the signal to be filterd; >> 2. the expectation signal,which is used to compare with filtered >> signal to get error signal; >> 3. the error signal,which (can be get from 2 and ) is used to update >> the filter coefficients; >> >> But always some articles about LMS adaptive filters say of reference >> signal. >> >> In the 3 signals above,which does reference signal refer to ? >> >> Cheers >> Hyee > >The answer is: "it depends". > >In an automatic line canceller, the reference signal is often taken from>a better source of the interference. So, it's not on your list. It's a>version of the signal to be filtered but not the signal to be filtered >itself. Presumably the signal to be filtered includes a version of the >reference summed with a version of the signal desired in the filtered >output. > >In an automatic line enhancer, the reference signal is a delayed version>of the signal to be filtered or vice versa. I don't think it matterswhich.> >Fred >Hmm...I'm agree and got mixed up itself Let's return to source from inventors of LMS In early publication of Widrow&Hoff I did not find term "reference" at all. You can see the book (next links), where reference to refernce :) exist, but authors are writing only about "reference filter" from which "desired signal" is obtained. http://www3.interscience.wiley.com/cgi-bin/bookhome/109855400?CRETRY=1&SRETRY=0 or free resource http://books.google.ru/books?id=U8X3mJtawUkC&pg=PA143&lpg=PA143&dq=S.+Haykin+and+B.+Widrow&source=bl&ots=Bwm60_llNb&sig=OYAsD2VjFBy298E_hIXOcRMonNQ&hl=ru&ei=Nn4LS5TMCY2-mQOOrPiABA&sa=X&oi=book_result&ct=result&resnum=4&ved=0CB0Q6AEwAw#v= Oleg.
Reply by ●November 24, 20092009-11-24
On Nov 24, 1:44�pm, HardySpicer <gyansor...@gmail.com> wrote:> On Nov 23, 8:45�pm, HyeeWang <hyeew...@gmail.com> wrote: > > > LMS theory,there are 3 signal as follows. > > > 1. the signal to be filterd; > > 2. the expectation signal,which is used to compare with filtered > > signal to get error signal; > > 3. the error signal,which (can be get from 2 and ) �is used to update > > the filter coefficients; > > > But always some articles about LMS adaptive filters say of reference > > signal. > > > In the 3 signals above,which does reference signal refer to ? > > > Cheers > > Hyee > > There are only two inputs to an LMS algorithm - primary and reference. > If you get them the wrong way round try swapping them! > > HardyThank you. Could you explain the roles of " only two inputs to an LMS algorithm "--- primary and reference? That is same as the topic.
Reply by ●November 24, 20092009-11-24
On Nov 24, 2:04�pm, Fred Marshall <fmarshallx@remove_the_xacm.org> wrote:> HyeeWang wrote: > > LMS theory,there are 3 signal as follows. > > > 1. the signal to be filterd; > > 2. the expectation signal,which is used to compare with filtered > > signal to get error signal; > > 3. the error signal,which (can be get from 2 and ) �is used to update > > the filter coefficients; > > > But always some articles about LMS adaptive filters say of reference > > signal. > > > In the 3 signals above,which does reference signal refer to ? > > > Cheers > > Hyee > > The answer is: "it depends". > > In an automatic line canceller, the reference signal is often taken from > a better source of the interference. �So, it's not on your list. �It's a > version of the signal to be filtered but not the signal to be filtered > itself. �Presumably the signal to be filtered includes a version of the > reference summed with a version of the signal desired in the filtered > output. > > In an automatic line enhancer, the reference signal is a delayed version > of the signal to be filtered or vice versa. �I don't think it matters which. > > Fred- Hide quoted text - > > - Show quoted text -Than you . But I am sorry to say you did not get the essence of topic. I am not puzzling about how to feed the LMS algo but how the term "refenerce signal " act as ?
