How to play Maximum length sequence twice?

Hello,

       I need some help with maximum length sequence. My tutor gaves us a code with a transfer function measurement made with noise using the cross spectra  equation Sxy/(Sxx*Sxy) where x and y are the input and output respectively.  But I'm suppose to find out how to the  measurement more accurate. I know I'm suppose to use maximum length sequence and from what I understand (correct me if i'm wrong) I should play the mls signal twice (2 periods) and use the second period to compute the calculation. Although I can't figure it out how do do the code to play the sequence twice.  Signal, mls sequence and filter are underneath:

 N = 1023;
 [x fs bits] = wavread('mls1023');  %read in mls signal, input signal in x

[b,a] = cheby1(9,0.5,0.7,'High');      %generate a LTI system (a simple filter)

y = filter(b,a,x);            %pass signal through LTI system 

     Thanks for any help in advance...

    Catarina

Answer 1

[Geoff]

If you just want to repeat your signal you can append a copy like this (assuming single-row vector):

x = [x x];

[catarina]

Hi Geoff,

Thanks for this. How do I write the code to play the second part of the signal, being the first period to excite the filter and the second do compute the calculations?

Cheers

Catarina