How to Apply Matched Filtering in Matlab?

[bumclouds]

Homework Statement

Our job is to recreate the system in the above diagram in Matlab. I've been able to do all the stages effectively except the "matched filtering" part.

Homework Equations

The Attempt at a Solution

I don't really understand matched filtering very well. I don't know if I have a stream of 1000 bits of data, if each bit goes once at a time through the matched filter, or all 1000 bits get filtered at once. Here's what I tried to do:

"Sig" is the variable which contains 1000 bits of binary data mixed with white noise, with a signal to noise ratio of 1dB. "s" is the variable which contained the binary data before noise was added.

Below is my attempt at a matched filter, to try to maximize the signal to noise ratio.

%matched filtering loop 1
for count = 1:1000
    if s(count) == 1
        H = 1;
    else
        H = 0;
    end
Sig(count) = filter(Sig(count),1,H);
end

Am I doing it completely wrong?

Thanks!
-Andrew

 

[KataKoniK]

Dear Andrew,

Thank you for reaching out regarding your difficulty with the matched filtering portion of the system you are recreating in Matlab. I understand that this concept can be confusing, but it is an important tool in signal processing and I am happy to help clarify it for you.

Firstly, let me explain the purpose of matched filtering. Matched filtering is used to enhance the signal-to-noise ratio of a received signal by correlating it with a known signal, called the reference signal. In your system, the reference signal is likely the original binary data without noise.

Now, to answer your question, the matched filter should be applied to all 1000 bits at once, rather than one at a time. The purpose of the filter is to enhance the overall signal, not each individual bit. Therefore, your approach of using a for loop is not necessary.

To implement the matched filter in Matlab, you can use the command "conv(Sig, s)" which will perform a convolution between the received signal (Sig) and the reference signal (s). This will result in a filtered signal with a higher signal-to-noise ratio.

I hope this helps clarify the concept of matched filtering for you. Please let me know if you have any further questions or need any additional assistance.