Wiener filter - MATLAB implementation

In summary, the conversation discusses the implementation of an 11-tap linear equalizer (Wiener filter) to remove noise from a QPSK signal over a multipath channel. The implementation involves using an input sequence, a vector p, and the autocorrelation function of the noisy received sequence to calculate filter coefficients. However, the speaker is having difficulty getting it to work in MATLAB and is seeking guidance. They are also advised to repost or move the conversation to a more appropriate section.
  • #1
hugheyst
5
0
Hello,

I'm currently working on a project in which I am required to implement an optimum 11-tap linear equalizer (Wiener filter) to remove additive noise from a QPSK signal over a multipath channel. The channel impulse response h{k} is known.

My understanding of the implementation:

Input sequence A

vector p = [gh,d gh,d-1 ... gh,0 0 0 0 ... 0] is length 11, where d is a delay in samples.

From this vector, p, and the autocorrelation function of the noisy received sequence, R, we can calculate the filter coefficients c like so:

c = σ2A(R-1p)*

We then convolve this vector c with the noisy received sequence to obtain a 'less dirty' version of the transmitted sequence A.

This is the explanation I've been given; however, I still cannot get it to work in MATLAB. My bit error rate is 50% over a wide range of signal-noise ratios for AWGN. Perhaps someone could point me in the right direction?
 
Physics news on Phys.org
  • #2
I think you should repost this or ask the moderator to move it to the "Electrical Engineering" section...
 

1. What is a Wiener filter and how does it work?

A Wiener filter is a signal processing algorithm used to remove noise from a signal. It works by taking a noisy signal and estimating the original signal using a mathematical model. The filter then calculates the difference between the noisy signal and the estimated signal, and uses this difference to filter out the noise.

2. Why is it important to implement a Wiener filter in MATLAB?

MATLAB is a powerful tool for signal processing and has built-in functions for implementing Wiener filters. By using MATLAB, the implementation of the filter becomes more efficient and accurate, saving time and effort for the scientist. Additionally, MATLAB allows for easy visualization of the filtered signal, making it easier to analyze and interpret the results.

3. What are the necessary steps for implementing a Wiener filter in MATLAB?

The first step is to define the noisy signal and the mathematical model for the original signal. Then, the filter coefficients are calculated using the Wiener-Hopf equation. Next, the filter is applied to the noisy signal using the filter coefficients. Finally, the filtered signal is visualized and compared to the original signal to assess the effectiveness of the filter.

4. Can a Wiener filter be used for any type of signal?

Yes, a Wiener filter can be applied to any type of signal as long as the mathematical model for the original signal is accurately defined. However, the effectiveness of the filter may vary depending on the complexity of the signal and the amount of noise present.

5. Are there any limitations to using a Wiener filter in MATLAB?

One limitation of using a Wiener filter in MATLAB is that it assumes the noise in the signal is Gaussian and uncorrelated with the original signal. If these assumptions are not met, the filter may not be as effective. Additionally, the accuracy of the filter depends on the accuracy of the mathematical model used for the original signal.

Similar threads

  • MATLAB, Maple, Mathematica, LaTeX
Replies
9
Views
4K
  • Set Theory, Logic, Probability, Statistics
Replies
15
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
1
Views
13K
  • Electrical Engineering
Replies
1
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
4
Views
5K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
  • Calculus and Beyond Homework Help
Replies
3
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
8
Views
67K
Replies
4
Views
6K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
3K
Back
Top