relation of equalizer and channel coding

Started by buaawh in comp.dsp13 years ago 3 replies

Hello, Well known that decision-feedback equalizer is generally superior than linear equalizer, I was surprised to read the statement in a...

Hello, Well known that decision-feedback equalizer is generally superior than linear equalizer, I was surprised to read the statement in a paper: "Finally it is to mention that a combination of channel coding (Viterbi Decoding) and DFE did not lead to a performance gain compared to channel coding and linear equalization. It is well known that this combination represents a critical one..." ...


Need help on LMS based equalizer for GSM

Started by richard_zhang in comp.dsp13 years ago 4 replies

Hi all, I am doing GSM software defined radio and trying to use normalized LMS algorithm to implement an equalizer, since LMS has low...

Hi all, I am doing GSM software defined radio and trying to use normalized LMS algorithm to implement an equalizer, since LMS has low complexity. But now I find that the BER is not improved at all after adding the equalizer block. I just simply take the normalized LMS algorithm and use it, and don't have deep investigation on it. My questions are: 1) typically, how much the BER performanc...


a question about map equalizer

Started by zqchen in comp.dsp14 years ago 4 replies

A question puzzled me for days, have to look for help here: > From the derivation of MLSE, a matched filter is obviously needed before the...

A question puzzled me for days, have to look for help here: > From the derivation of MLSE, a matched filter is obviously needed before the equalizer. Starting from continuous signal, the operation of matched filter and sampling is so natural. But so far as I read about MAP equalizer, I doubt the matched filter is needed no more. Or maybe I've missed something, at least it's not so clearly


Graphic Equalizer

Started by Stacy in comp.dsp14 years ago 3 replies

I want to implement a graphic equalizer in S/W. I assume it is a bunch of bandpass filters with boost/cut at their respective frequencies. Has...

I want to implement a graphic equalizer in S/W. I assume it is a bunch of bandpass filters with boost/cut at their respective frequencies. Has anyone else done this or know of any links?


Audio equalizer!

Started by tasi in comp.dsp17 years ago 2 replies

Hi, Greeting, I am interesting with a fully digital audio equalizer. For I am a fresh in this field, I don't how to start. Does somebody can...

Hi, Greeting, I am interesting with a fully digital audio equalizer. For I am a fresh in this field, I don't how to start. Does somebody can tell me how to get/find a useful information? Thx


non-integer fractionally spaced equalizer?

Started by Muzaffer Kal in comp.dsp13 years ago 3 replies

Hi everyone, I'm considering implementing a fractionally spaced equalizer and one question which has bugged me in the past is whether a...

Hi everyone, I'm considering implementing a fractionally spaced equalizer and one question which has bugged me in the past is whether a non-integer, smaller than 2 fractional spacing would have any benefits (ie better equalization). Suppose the signal rate is 100 M bauds and the signal bandwidth is around 70 Mhz. A T/2 fractional equalizer would need a 200 MHz ADC but would 140 MHz sampling ...


Wiener Hopf Equalizer delay

Started by porterboy in comp.dsp17 years ago 2 replies

CONTEXT:********************** Transmit x(n) receive y(n). Wiener-Hopf (MMSE) FIR Equalizer is... w = inv(Ryy)rxy where Ryy is the received...

CONTEXT:********************** Transmit x(n) receive y(n). Wiener-Hopf (MMSE) FIR Equalizer is... w = inv(Ryy)rxy where Ryy is the received signal autocorrelation and rxy is the channel input-output crosscorrelation: rxy(k) = E(x(n-D)y(n+k)). The D is a delay parameter chosen to make sure the equalizer is causal. It specifies the location of the impulse of the equalized channel. QUESTIO...


LMMSE equalizer

Started by Andrew2006 in comp.dsp14 years ago 3 replies

From some technical papers, I found out that non-adaptive MMSE block equalizer has been used to equalize for time-varying channels. Since adaptive...

From some technical papers, I found out that non-adaptive MMSE block equalizer has been used to equalize for time-varying channels. Since adaptive algorithm (LMS, RLS,....) is not applied here, then how the researchers simulate for the BER performance? Can anyone please help? Thanks.


timing recovery & equalizer latency

Started by kal in comp.dsp17 years ago 3 replies

Hi, I have a fully digital receiver where timing recovery and equalizer are adding significant latency and I would like to try and reduce it as...

Hi, I have a fully digital receiver where timing recovery and equalizer are adding significant latency and I would like to try and reduce it as much as possible. The timing recovery is done with a fractional delay filter (a farrow type FIR filter) where only one fractional value which gets multiplied by the outputs of the multi-branch fixed FIR filters is adapted. The equalizer is a fully ...


equalizer with different location of the main tap

Started by zohreh in comp.dsp14 years ago 2 replies

Hi there, I simulate a system with upsampling 4 at the transmitter. Then, I use the equalizer and change the main tap. when I use different...

Hi there, I simulate a system with upsampling 4 at the transmitter. Then, I use the equalizer and change the main tap. when I use different location for main tap, the amount of timing error the receiver can beer is different and depends on the location of the main tap. Now, I realize that the timing error can change the group delay and equalizer can compensate for that. Is there anyone know...


Digital Equalizer Design for a Radio Receiver

Started by Anonymous in comp.dsp15 years ago 16 replies

Hi all, I am currently on a design of an equalizer for Medium/Short wave AM receiver. Problem statement: Medium /Short waver AM receiver...

Hi all, I am currently on a design of an equalizer for Medium/Short wave AM receiver. Problem statement: Medium /Short waver AM receiver suffers from sudden volume reduction irrespective of the Automatic gain control in receiver. How does this can be addressed. I am trying to control this audio reduction by an equalizer. But how does the actual reduction of audio in the radio program ...


cma equalizer

Started by Anonymous in comp.dsp15 years ago 9 replies

hello,erevyone.Recently I have been designing a blind channel equalizer based on the Constant Modulus Alogrithm.But I have a question that...

hello,erevyone.Recently I have been designing a blind channel equalizer based on the Constant Modulus Alogrithm.But I have a question that I can't think over.The question is as follows: The alogrithm I use is below: y(k)=3D =A1=C6f(k)x(N-k); % f(k+1)=3Df(k)-mu*e(k)*x(k); % e(k)=3D4*conj(y(k))*(abs(y(k))^2-R2); the transmitted signal is modulated by the QPS...


A que on LMS vs NLSM

Started by cpshah99 in comp.dsp11 years ago 2 replies

Hi All It is known from the books that NLMS is better than LMS when the dynamic range of the input signal to the equalizer is large. But...

Hi All It is known from the books that NLMS is better than LMS when the dynamic range of the input signal to the equalizer is large. But if we use an AGC before the equalizer and then use LMS to adapt the taps, what would be the performance compared to NLMS? Best Regards Chintan


Specifications of an Equalizer

Started by rkthebad in comp.dsp15 years ago

Hello everyone, I owe my thanks to many of you for helping me implement my fixed-point graphic equalizer. I was trying to get its...

Hello everyone, I owe my thanks to many of you for helping me implement my fixed-point graphic equalizer. I was trying to get its characteristics/specifications in terms of its Frequency response, Signal-to-noise ratio and Total harmonic distortion. I came across this article http://www.rane.com/note145.html . Is this the best source? Or do you have any other suggestions? For SNR,...


Equalizer

Started by Tom in comp.dsp14 years ago 13 replies

I have two complex signals (Input and output) of a channel I need to equalize. I can have 2 linear equalizers one for the real part and one for...

I have two complex signals (Input and output) of a channel I need to equalize. I can have 2 linear equalizers one for the real part and one for the imaginary and train them independently or I can use one complex equalizer and train it using the complex signal. My questions are which one is better? Is there any advantage of one on the other or they are equivalent ? Regards Tom ...


equalizer error bias

Started by mk in comp.dsp14 years ago 2 replies

Hi, I have a channel with significant ISI with a 3 level (1,0,-1) transmission. The transmitted data and the receiver data after quantization...

Hi, I have a channel with significant ISI with a 3 level (1,0,-1) transmission. The transmitted data and the receiver data after quantization have zero mean. The problem is that the error output of the equalizer after convergence is not zero mean even (it's slightly positive) though its variance is very low (around 22dB below signal power). It's been pointed to me that it should be zero mean...


first tap of equalizer

Started by aamer in comp.dsp14 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...


Parametric equalizer

Started by Kuba in comp.dsp16 years ago 1 reply

Hi everybody, I am new in this group and I have a problem. I have a project that requires a parametric equalizer on TI C6713. Can anyone help...

Hi everybody, I am new in this group and I have a problem. I have a project that requires a parametric equalizer on TI C6713. Can anyone help me with this? I have a little experience with programming TI ( I have made my past projects with Motorola 56300). Do You have some links that can help me? Maybe someone has links to good sites describing " How to start programming TI with CCS " ...


Matched filter and LMS equalizer

Started by Richard_K in comp.dsp14 years ago 2 replies

Hi, Is it possible for a LMS equalizer in multipath environment to achieve better BER performance as compared to matched filter in AWGN...

Hi, Is it possible for a LMS equalizer in multipath environment to achieve better BER performance as compared to matched filter in AWGN channel?


equalizer output issue - eqout.jpg (0/1)

Started by Muzaffer Kal in comp.dsp13 years ago 5 replies

Hi everyone, I'm working on an LMS adaptive filter which is behaving in somewhat of an unexpected way. The attached image shows the histogram of...

Hi everyone, I'm working on an LMS adaptive filter which is behaving in somewhat of an unexpected way. The attached image shows the histogram of the equalizer output after convergence; my slicer thresholds are at 0.5 and -0.5 (ie anything above 0.5 is sliced to 1, anything below -0.5 is sliced to -1 and anything in between is sliced to 0; this is a 3 level code.) Then I use an error generate...