Adaptive Filtering in Real Time

Started by Zachary Rimkunas in comp.dsp16 years ago 3 replies

Hi, I am a newbie trying to do real time adaptive filtering on an Analog Devices blackfin 21535. I'm not trying to do anything too complex,...

Hi, I am a newbie trying to do real time adaptive filtering on an Analog Devices blackfin 21535. I'm not trying to do anything too complex, just a simple LMS algorithm (1 mic, 2 loudspeakers and a reference). Does anyone know of any good online reference sites w/ some example code or just information on this? Any help is appreciated. Zach


Back to the LMS again

Started by Zach R. in comp.dsp16 years ago 2 replies

Hi all, I am currently trying to implement a simple LMS algorithm in C and on an analog deviced blackfin ez-kit. The only real problem is...

Hi all, I am currently trying to implement a simple LMS algorithm in C and on an analog deviced blackfin ez-kit. The only real problem is that I am trying to implement it in a streaming manner and as close to real time as possible. I have an implementation but it isn't working. I am wondering how many samples should I be looking at when estimating the gradient? The books I have been ...


LMS limitations?

Started by Zach R. in comp.dsp16 years ago 14 replies
LMS

Hi, I have implemented a simple LMS algorithm w/ a 10th order filter. My goal is to completely cancel my reference signal. I can get it to...

Hi, I have implemented a simple LMS algorithm w/ a 10th order filter. My goal is to completely cancel my reference signal. I can get it to work with a sine wave at about 75 Hz. When I try to cancel a 150 Hz signal all I get is an unstable response. Ultimately I would like to be able to do a decent job of cancelling a voice signal. My main question is: Is it even possible for a LM...


How to decide the filter length in ADNC using LMS Algo ?

Started by Sandeep Chikkerur in comp.dsp15 years ago 6 replies

Hi, How to decide the FIR - filter length (no. of taps) required to design the ADAPTIVE NOISE CANCELLER ? I am using the LMS...

Hi, How to decide the FIR - filter length (no. of taps) required to design the ADAPTIVE NOISE CANCELLER ? I am using the LMS Algorithm.. Thanks in advance...


DC shift of the h(impulse response of the room) when using NLMS adaptive filtering

Started by Andrew Xiang in comp.dsp16 years ago 6 replies

Anyone encountered this problem when using NLMS? The h shifts up after running for sometime, I noticed this for both white noise and color voice...

Anyone encountered this problem when using NLMS? The h shifts up after running for sometime, I noticed this for both white noise and color voice signals. What caused the shift and how to avoid it? thanks Andrew


complex lms

Started by Leeshauyao in comp.dsp16 years ago 1 reply
LMS

when doing subband, you get the signal in complex value, and you do lms in complex value, when you reconstruct the complex e back to full-band...

when doing subband, you get the signal in complex value, and you do lms in complex value, when you reconstruct the complex e back to full-band e, how will you get real value back? or just take magnitude? Lee


1.15 LMS problem ...please help

Started by rahul in comp.dsp16 years ago 1 reply

Hi friends, I am running an 1 tap complex tracker with an adaptive weight using a LMS algorithm. u-input d-ideal points y-filtered...

Hi friends, I am running an 1 tap complex tracker with an adaptive weight using a LMS algorithm. u-input d-ideal points y-filtered points w- coefficient y(i)=w*(i).u(i) e(i)=d(i)-y(i) w(i+1)=w(i)+mu.e(i).u(i) mu=0.01 The floating point algorithm works well with this value of mu. I have done a matlab fixed point 1.15 and 1.31 implementation of the above , and find that it ...


LMS identifying Non-Min Phase systems

Started by Tom in comp.dsp16 years ago 8 replies

Suppose we have two signals - a Primary and Reference as in classical noise cancelling except that the mics are about one foot apart (for...

Suppose we have two signals - a Primary and Reference as in classical noise cancelling except that the mics are about one foot apart (for an acoustic problem). Let us suppose that the top path (for simplicity) has a transfer function (1-0.5z^-1) and the bottom path has a TF of unity. This of course is not realistic but I want to keep the sums easy. Now if we use LMS the LMS algorithm will c...


LMS fixed point implementation

Started by fran in comp.dsp16 years ago 1 reply

Hi everyone! I need a fixed point implementation for the LMS algorithm;I have to implement it on a TI dsp board (c6711 or a c5000); can anyone...

Hi everyone! I need a fixed point implementation for the LMS algorithm;I have to implement it on a TI dsp board (c6711 or a c5000); can anyone suggest me where I can find this code? thank you guys! f


LMS

Started by Rob Judd in comp.dsp16 years ago 1 reply
LMS

Greetz, Can someone point me to an actual coded implementation of an RLS filter? I've dug all over the net and all I keep turning up is...

Greetz, Can someone point me to an actual coded implementation of an RLS filter? I've dug all over the net and all I keep turning up is professorial papers full of maths, or ads for student DSP toolboxes. TIA, Rob VK3XVK SDR-1000 project http://www.flex-radio.com


Which noise?

Started by Manuel Tramontana in comp.dsp16 years ago 2 replies

Dear chaps, I have a problem. I have a signal recorded from a ultrasonic transducer of a chemical reaction. It is rich of noise, expecially...

Dear chaps, I have a problem. I have a signal recorded from a ultrasonic transducer of a chemical reaction. It is rich of noise, expecially the white one. I tried to filter with normal filter (butterworth band pass), but I did not obtained a lot of success. So, I thought was better delete the White gaussian noise with an adaptive filter. I used the demo of Simuling of LMS but I have probl...


noise..how to regulate it?

Started by Manuel Tramontana in comp.dsp16 years ago 1 reply

Dear chaps, I have a problem. I have a signal recorded from a ultrasonic transducer of a chemical reaction. It is rich of noise, expecially...

Dear chaps, I have a problem. I have a signal recorded from a ultrasonic transducer of a chemical reaction. It is rich of noise, expecially the white one. I tried to filter with normal filter (butterworth band pass), but I did not obtained a lot of success. So, I thought was better delete the White gaussian noise with an adaptive filter. I used the demo of Simuling of LMS but I have probl...


Channel equalization for MSK

Started by Vikram Chandrasekhar in comp.dsp16 years ago 4 replies

Hello, I am trying to set up an adaptive LMS adaptive equalizer to apply the equalizer on a phase modulated signal eg: MSK. For modulation...

Hello, I am trying to set up an adaptive LMS adaptive equalizer to apply the equalizer on a phase modulated signal eg: MSK. For modulation schemes such as PSK/QAM, the effect of a channel filter leads to severe ISI and hence channel equalizers are very important. Further, they have been extensively documented and well-studied. How severe is the effect of a channel filter on a MSK type si...


Adaptive arrays

Started by John in comp.dsp16 years ago 2 replies

Hey, I need to design an adaptive array for automatic interference rejection using the LMS algorithm in MATLAB. There is a target...

Hey, I need to design an adaptive array for automatic interference rejection using the LMS algorithm in MATLAB. There is a target signal cos(2*pi*f0*t) and three interference signals cos(2*pi*f0*t) coming in at angles of 45, -30 and -60 degrees. The adaptive array will consist of eight elements. The input signals are sampled at Ts=2*10^-10 s where t=0,Ts,2Ts,3Ts,4Ts...f0=3*10^8 Hz,lambda=1 ...


TMS320C6416 CPU USAGE PROBLEM (Help needed ASAP!!)

Started by Jay in comp.dsp15 years ago 11 replies

We are fourth year electrical engineering students involved in a Final Design Project course. (Approaching deadline date) We are using a...

We are fourth year electrical engineering students involved in a Final Design Project course. (Approaching deadline date) We are using a TMS320C6416 DSK DSP by Texas Instruments to perform some adaptive noise cancellation. Unfortunately we have run into some serious unexpected CPU Usage problems. We think that our C code is relatively simple. Our code consists of a simple LMS algorithm...


Echo Canceller: Measuring Performance

Started by Rob Hutchinson in comp.dsp15 years ago 5 replies

I'm simulating an echo canceller in Matlab, using a FIR adaptive LMS filter. I'm using the standard noise cancelling approach: -adaptive filter...

I'm simulating an echo canceller in Matlab, using a FIR adaptive LMS filter. I'm using the standard noise cancelling approach: -adaptive filter input u(n) = far end speech -adaptive filter output is y(n) -impulse response of echo path is h(n) -near end speech is ne(n) -d(n) = ne(n) + u(n) (*) h(n) ----> where (*) denotes convolution -adaptive filter error single e(n) = d(n) - y(n) -In


Are there any LMS IC's?

Started by Tom in comp.dsp15 years ago 8 replies
LMS

I saw almost 15 years ago tha there was to be an LMS IC available but it never materialised. I was wondering if there are any readily...

I saw almost 15 years ago tha there was to be an LMS IC available but it never materialised. I was wondering if there are any readily available Least-mean Squares ICs on the market. There must be many custom ones of course and many papers on the subject. Tom


Filtered-X LMS - what's the purpose?

Started by Jack L. in comp.dsp15 years ago 3 replies

Hi group, I have read a bit upon the Filteret-X LMS algorithm that seems to be particularly useful in ANCs. However, I can't really get the...

Hi group, I have read a bit upon the Filteret-X LMS algorithm that seems to be particularly useful in ANCs. However, I can't really get the purpose of this algorithm; exactly, what problem is it trying to solve, or why was it "invented"? The weight update equation is somewhat different to the ordinary LMS in the sense that the new weight is the result of the present weight minus my*error s...


Which dsp for LMS?

Started by Country Loon in comp.dsp15 years ago 5 replies

If I want to do real-time LMS on an audio application,what DSP is best if I need say 400 weights? Thanks Tom

If I want to do real-time LMS on an audio application,what DSP is best if I need say 400 weights? Thanks Tom


c6711 dsk & adaptive filter problem

Started by yoga in comp.dsp15 years ago 1 reply

Hi everyone, I'm a student working on modified Griffith-Jim beamforming for my masters project. I'm implementing this algorithm in TI's c6711...

Hi everyone, I'm a student working on modified Griffith-Jim beamforming for my masters project. I'm implementing this algorithm in TI's c6711 dsk, and also using PCM3003 codec to get two input's from the microphones. I'm trying to reduce the background noise using an adaptive filter (its based on NLMS). I have done the implementation in c-code in CCS, but I have a bit of problem with t...