## Bidirectional equalization

Started by in comp.dsp12 years ago 3 replies

Hello, I'm simulating a Decision Feedback Equalizer for MSK signal, using the well know LMS algorithm. In order to get better performance I...

Hello, I'm simulating a Decision Feedback Equalizer for MSK signal, using the well know LMS algorithm. In order to get better performance I tried to equalize each packet in two stages. The structure of the packet is as follows: [Payload1 TrainingSeq Payload2] Since the training sequence is placed in the middle (GSM like), I'd like to equalize the second part in forward direction and the firs...

## first tap of equalizer

Started by in comp.dsp15 years ago 1 reply

dear all, I was trying to implement constant modulus algorithm for blind channel equalization. I found that the filter taps of the equalizer...

dear all, I was trying to implement constant modulus algorithm for blind channel equalization. I found that the filter taps of the equalizer are modified according to W(k+1)=W(k)+ mu * conj(x(k)) * e(k) where mu= adaptation size W the filter taps. x(k)= transmitted symbol e(k)= error given by e(k)= y(k) * (b^2 - abs(y(k))^2) where b^2= 13.2 and y(k)= equalized output. my question i...

## expectations from a DFE ?

Started by in comp.dsp16 years ago 3 replies

Hi, I've been experimenting with adaptive filters for channel equalization and I have a problem with decision feedback case. Initially I...

Hi, I've been experimenting with adaptive filters for channel equalization and I have a problem with decision feedback case. Initially I started with a T/2 fractional linear equalizer adapted with LMS and then converted this to delayed LMS with two delays. I am currently not adding any noise just trying to compensate for the ISI generated by the channel although there is quantization error a...

## Single carrier with frequency domain equalization (SCFDE)

Started by in comp.dsp15 years ago 6 replies

I have seen some paper demonstrating the benefit of SCFDE over OFDM, basically low PAPR performance, comparable complexity, improved performance...

I have seen some paper demonstrating the benefit of SCFDE over OFDM, basically low PAPR performance, comparable complexity, improved performance especially when convolutional code rate is high. But why we see many standards still using OFDM, but not SCFDE?

## Equalization for FH-4FSK system

Started by in comp.dsp14 years ago 4 replies

Hi, I would like to design use an equalizer for improving the performance of 4fsk-frequency hopping system in rayleigh fading, I ve seen...

Hi, I would like to design use an equalizer for improving the performance of 4fsk-frequency hopping system in rayleigh fading, I ve seen matlab functions but they all are for linear modulations or is there any function for non linear modulations??. Can any one please guide me on this issue? Is there any particular technique that is useful for this case?? thanks

## estimation of autocorrelation matrix or eigenvalue spread.

Started by in comp.dsp16 years ago 12 replies

Hi everyone, I am experimenting with some equalization schemes and to judge the performance, I need to estimate the eigenvalue spread of the...

Hi everyone, I am experimenting with some equalization schemes and to judge the performance, I need to estimate the eigenvalue spread of the input to the equalizer. Currently I am working with a single input stream of many thousands of samples, and I am assuming that my data is more or less uniformly distributed. To get the eigenvalues, I generate R = Sum( x[k]*x[k]T) where x[k] is a vector...

## Loudspeaker Equalization using FIR (newbie)

Started by in comp.dsp16 years ago 5 replies

Hi! I am a newbie on DSP working on a project which involves using a few different kinds of loudspekers so I have to be able to equlize them....

Hi! I am a newbie on DSP working on a project which involves using a few different kinds of loudspekers so I have to be able to equlize them. The plan is to do that using a FIR filter. All implementation is done in MATLAB. I have not been able to find any good matlab examples on this matter. I have got this far: 1. Got a nice 128 samples impulse response. 2. I use the rceps function to get...

## MMSE & LMS Equalization Question

Started by in comp.dsp12 years ago 5 replies

Ok so, i'm confusing myself somewhere and its driving myself crazy. I have written matlab implementations of MMSE (wiener) and LMS...

Ok so, i'm confusing myself somewhere and its driving myself crazy. I have written matlab implementations of MMSE (wiener) and LMS (gradient method .. h = h(n-1) + mu*dE/dh) to minimize the following equation: ( s[n] - yhat[n] )^2 where s[n] is the original 'sent' message and yhat[n]=conv(Hhat,y[n]) where y[n] is the signal received at the transmitter (with noise/channel effects). That i...

## classification under optimal and sub-optimal

Started by in comp.dsp14 years ago 2 replies

well all dsp members, i want to clarify under what circumstances does the optimal and sub-optimal classifcations...

well all dsp members, i want to clarify under what circumstances does the optimal and sub-optimal classifcations of a particular algorithm is done. we say EQUALIZATION with error control coding can be done in two ways 1. optimal receiver has to tackle out both ISI and error correcting code be decoded jointly(i mean joint decoding mechanism) 2. suboptimal rec...

## Blind System Identification

Started by in comp.dsp15 years ago 6 replies

Okay, so I'm trying to work my way through "Blind System Identification and Channel Equalization of IIR Systems without...

Okay, so I'm trying to work my way through "Blind System Identification and Channel Equalization of IIR Systems without Statistical Information", by Bai and Fu; specifically "Algorithm 4.1". Though the nomenclature seems to be standard for multirate systems, it is cumbersome. But I think I've got a good handle on the technique, up to the point just beyond equation (4.6), where it says: ....

## Equalization: FDE or TDE? SC-FDE/OFDM?

Started by in comp.dsp19 years ago 5 replies

I have some questions.... Given the elegance of FDE, why has FDE lagged behind in use compared to TDE? Also, why is OFDM so popular when SC-FDE...

I have some questions.... Given the elegance of FDE, why has FDE lagged behind in use compared to TDE? Also, why is OFDM so popular when SC-FDE is so much better? (No ICI, no peak to average issues)

## Help on MMSE and Least Squares

Started by in comp.dsp16 years ago

Hi, I'm a rookie in Adaptive DSP and equalization and I have questions bugging me and I need some help from you all.Now wherever I have read,they...

Hi, I'm a rookie in Adaptive DSP and equalization and I have questions bugging me and I need some help from you all.Now wherever I have read,they talk of MMSE criterion and a LS(Least Square)Solution/Fit.From how I see, MMSE is point on error surface in terms of expectation of error and a LS is best solution with limited degrees of freedom.Can anyone throw a little more light on how these are rel...

## Zero forcing EQ question

Started by in comp.dsp17 years ago 2 replies

Hello All! I obtained a matlab code which do the zero forcing equalization on an awgn channel, and plots the BER vs. SNR Please look at this...

Hello All! I obtained a matlab code which do the zero forcing equalization on an awgn channel, and plots the BER vs. SNR Please look at this small code if it is correct, my question is: where are the filter coefficients here or how can I obtain this, as I don't see them ??? Thanks for you effort, Reno N: number of symbols we transmit h: impulse response snrDB: SNR in dB, actually: ...

## MAP vs MLSE

Started by in comp.dsp15 years ago 3 replies

Hi guys, I'm currently doing my literature review on both types of equalization. Based on what I understand, both have comparable performance...

Hi guys, I'm currently doing my literature review on both types of equalization. Based on what I understand, both have comparable performance but use different approach; MLSE: sequence detection while MAP symbol by symbol detection. Since both relatively similar, how can we choose which type of equalizer is suitable to combat ISI? Responds pointing to publications and articles are very much ...

## different channel types, impulse response

Started by in comp.dsp17 years ago 1 reply

Hello! My task is to implement several channel equalization methods in matlab. (AWGN,BPSK). I have to do the BER/SNR simulations using...

Hello! My task is to implement several channel equalization methods in matlab. (AWGN,BPSK). I have to do the BER/SNR simulations using different channel types like rural, hilly, urban..etc I'm looking for the corresponding impulse response values for them, but I didn't find any. Please help me, how to solve this problem, thank you, regards, Balage

## VSB as QAM

Started by in comp.dsp15 years ago

Hi, I'm currently try to develop an 8-VSB demodulator (for ATSC terestrial digital TV). I saw that there is a simple way to covert to 8-VSB...

Hi, I'm currently try to develop an 8-VSB demodulator (for ATSC terestrial digital TV). I saw that there is a simple way to covert to 8-VSB signal to 64-QAM (offset QAM, to be more precise). My question is: is demodulating QAM is more cost-efficient than woking directly on VSB signal? (by means of equalization, synchronization etc') Thanks!

## impulse response calculation

Started by in comp.dsp17 years ago 1 reply

Hello All! For channel equalization I need to simulate several environments (rural, urban..etc). I read the IEEE 802.16 recommendation on...

Hello All! For channel equalization I need to simulate several environments (rural, urban..etc). I read the IEEE 802.16 recommendation on Time Varying Radio Propagation Channel models paper, as this describes several channel models but I don't find that formula from which I can calculate the impuse response values in order to do the simulation in matlab. Thanks for your help in advanc...

## Peaking equalization - low phase delay

Started by in comp.dsp11 years ago 17 replies

Hi all, I'm trying to implement a graphic equalizer tool (in c++) for a non-audio system with bandwidth 0 - 40 Hz, and hoped someone in the...

Hi all, I'm trying to implement a graphic equalizer tool (in c++) for a non-audio system with bandwidth 0 - 40 Hz, and hoped someone in the Comp.DSP community would be kind enough to offer helpful advice? We have a quasi-realtime system in which minimal phase delay is of critical importance, but minimal signal distortion is also a requirement (obviously). We want to keep delays below about 7...

## LDPC code

Started by in comp.dsp12 years ago 10 replies

Hello Everybody Recently I simulated a regular rate 1/2 LDPC code over AGWN and I got the expected BER plot. Then I thought to simulate...

Hello Everybody Recently I simulated a regular rate 1/2 LDPC code over AGWN and I got the expected BER plot. Then I thought to simulate the same code over frequency selective channel. I am using linear MMSE equalizer and then LDPC decoding. So basically it is one time equalization and decoding. However, I am not getting any coding gain over uncoded system even after 100 LDPC iterations....

## TI DSP uP vs FPGA

Started by in comp.dsp18 years ago 7 replies

I am trying to determine the best solution for real time image/video processing in hardware... Does anyone have any thoughts as to which...

I am trying to determine the best solution for real time image/video processing in hardware... Does anyone have any thoughts as to which solution (FPGA or DSP uP) is better. I would like to run several (roughly 10) convolution filters as well as perform image histogram equalization operations on each frame of a gray 640x480 frame at a rate of about 15 fps. Any comments would be most appr...