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Maximum Length Sequence (MLS)

Maximum Length Sequence (MLS)

Maximum Length Sequence (MLS)

(OP)
Can anybody explain the concept of MLS to me? Why this signal has the flat frequency spectrum? Also, How can I calculate the power from this signal?

RE: Maximum Length Sequence (MLS)

A maximal sequence has a flat spectrum like white noise.  The output of such a sequence (typically +/1 values that look random) is sometimes called pseudonoise because it looks like it was generated by a pure random process.  The spectrum is flat if you take the fourier transfrom of the autocorrelation of the sequence with itself.  

a memoryless random process will correlate with itself only when the sequence is time aligned with itself--any shift of one sample or more will result in a zero correlation if the sample is large.  Max. Len. linear. shift registers will produce a sequence that appears random statistically but in fact is not.

RE: Maximum Length Sequence (MLS)

(OP)
I see... Thank you for BDJ's website and Johnwiss.. Actually I have tried to find the info. from the website before but I couldn't get the information that I want.. (or maybe I'm not clever enough to understand their 'mathematical explanation')

What I want to find out is that, normally the MLS will use the correlation to get the linear transfer function of the system.. but I use MLS to feed the loudspeaker and use FFT to get its frequency response without using the correlation because I think that if MLS has the flat frequency spectrum then I should be able to use it as white noise. Isn't it right?

The results I got from this method (FFT) can be comparable to the result from the white noise...(I mean the FFT shape)  but what I stuck is how can I get the MLS's power from the signal I generate as I want to get the sensitivity of the loudspeaker in the same time.. (i.e. the dB/1 meter/1 Watt)

Umm... as I read from some papers... so far I haven't seen anybody mentioned about this issure.

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