Adaptive filters, MATLAB Programming

Adaptive filters can also be used in other applications. Speech recognition, for example, is performed in a non-stationary environment, and therefore may require adaptive filtering. Consider first the structure shown in Figure which consists of two separate parts. The first synthesizes a signal from white noise, using an autoregressive model, and the second adapts its coefficients so as to recreate the initial signal.

Figure: Synthesis and Analysis Structure for an AR Model

2009_Adaptive ?lters.png

- Write a program to implement the above network and use an AR model with a=[1 0.9 0.2]; if the adaptation algorithm works well 1 and 2 should converge to -0.9 and -0.2 respectively; explain this result.

- Test your program and observe the evolution of 1 and 2. Be careful to choose the right adaptation gain (an adaptation gain of 0.01 would be appropriate).

In speech recognition only the right part of the structure is used. A characteristic sound is used as an input and the filter finds the coeffcients 1 2 n, so that the average output error squared is minimised; hence, the structure is trained in such a way, so that when its input is a delayed version of the sound, it will output the sound itself (and hence the term predictor); the predictor presented on the figure above would be a second order predictor. An th order predictor would be one that uses samples delayed by 1,2,...,n samples, to create its output.

In speech recognition only the right part of the structure is used. A characteristic sound is used as an input and the filter finds the coeffcients 1 2 n so that the average output error squared is minimised; hence, the structure is trained in such a way, so that when its input is a delayed version of the sound, it will output the sound itself (and hence the term predictor); the predictor presented on the figure above would be a second order predictor. An nth order predictor would be one that uses samples delayed by 1,2,...n samples, to create its output.

- Use the sound files that you have recorded to test the performance of such a predictor. You should have five files, each containing 1000 samples, corresponding to the sounds "e", "a", "s", "t" and "x". Use each file as an input vector to the predictor. Investigate the selection of the adaptation gain and the order of the predictor. You might also consider gear shifting.

The quality of the predictor is indicated by the prediction gain which is defined as 1134_Adaptive ?lters2.png

- Access the performance of the predictor for each file by finding its prediction gain (typical values of prediction gains are on the order of 1-25).

- Optional: A much simplified version of the LMS algorithm is called the sign LMS algorithm and is based upon

2026_Adaptive ?lters1.png

Write a MATLAB routine to simulate this algorithm and compare its performance with that of the basic LMS algorithm. Alter the adapta-
tion gain as above and compare performances.

- Comment upon its convergence properties.

Posted Date: 2/27/2013 6:48:00 AM | Location : United States







Related Discussions:- Adaptive filters, Assignment Help, Ask Question on Adaptive filters, Get Answer, Expert's Help, Adaptive filters Discussions

Write discussion on Adaptive filters
Your posts are moderated
Related Questions
Linspace function: Likewise, the linspace function generates a linearly spaced vector; linspace(x,y,n) generates a vector with n values in the inclusive range from x to y. For

how to find matrix inverse using matlab command

Strings: The MATLAB also handles strings that are a sequence of characters in single quotes. For illustration, using the double function on a string will represent the equival

how to find absolute value of a number

1. Assume that there exists a surface that can be modeled with the equation:  z = e-(x 2 + y 2 ).  a) Calculate ∇z at the point (x = 0, y = 0). b) In addition, use MATLAB to

Size function - Dimensions of matrix: For the matrix mat shown next, it has three rows and two columns, therefore the size is 3 × 2. The length is the larger dimension that is

In the manufacturing of ball bearings, the components, such as the ball, are hardened through a process of heating and then rapid cooling or "quenching" by submersion in an oil or

Temperature readings were done every hour (starting at 1 P.M., but the end time could vary) and stored in a vector called readings. Write a function called halffit that receives th


Illustration of switch statement: Here are the two illustrations of calling this function: >> quiz = 22; >> lg = switchletgrade(quiz) lg = X >> quiz = 9; >>