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Matched filter

Asked by vsee on 1 Apr 2011

How can I write a mtached filter in Matlab? I have the filter design and signal processing tool boxes.

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vsee

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4 Answers

Answer by Honglei Chen on 1 Apr 2011

If you have a signal, x, then the matched filter's coefficients is given by time reverse of x, i.e., x(end:-1:1). If your signal is complex, you also need to to use complex conjugate. You can then use it just as an FIR filter. For example,

>> x = ones(10,1);
>> b = x(end:-1:1);
>> y = filter(b,1,x);

3 Comments

vsee on 1 Apr 2011

Thanks. I entered the same code that you provided. x is a column vector of 10 one's. b seems to be the same. Is b really the mirror image of x? In other words can you explain what x(end:-1:1) is doing? Thanks

Honglei Chen on 4 Apr 2011

I was just giving an example. x and b are the same because x happens to be the same as its time inverse. You can replace x with a vector representing your particular signal. The key here is "end:-1:1" which flips the signal. You can also use flipud or fliplr depending on your vector's orientation.

Nuzat Alam on 3 Apr 2013

Hii i was wondering what is the impulse response of matched filter here?I think it is related to b. Do you think if i want to select a specific sample number for b, i also need to change the length of input signal x?

Honglei Chen
Answer by Andrew Newell on 1 Apr 2011

Check out MATLAB Simulations for Radar Systems Design from the File Exchange.

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Andrew Newell
Answer by Bhaskar on 15 Apr 2011

To elaborate on Honglei's answer. If the signal you are trying to design a matched filter for, is x, then --

>> b = x(end-1:1);
>> y = filter(b,1,x);

You should already have x.

1 Comment

mmm ssss on 9 Jan 2012

how can implement the same filter on image ?

how i should represent x.

Bhaskar
Answer by Mathuranathan Viswanathan on 13 Apr 2013

Hi You can try the model given here

Square Root raised Cosine - Matched filter implementation http://www.gaussianwaves.com/2011/04/square-root-raised-cosine-filter-matchedsplit-filter-implementation-2/

Regards Mathuranathan

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Mathuranathan Viswanathan

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