SAMSON JOHN ARNOLD L.
T41 – SIGPROL
Machine Problem
1. Using the cov_m function, determine the autocorrelation sequence rxx(l) and the
crosscorrelation sequence rxy(l) for the following sequences.
x(n) = 0.9n , 0 ≤ n ≤ 20 ;
y(n) = 0.8-n , -20 ≤ n ≤ 0
Describe your observation of these results
OUTPUT:
The Auto correlation of the signal as displayed is symmetrical. This is further proven with the
symmetrical property of correlation. The coding principle and steps were almost the same
when compared to that of the convolution except that the second signal is flipped.
The plot for Cross correlation is not symmetrical. This type of correlation is used to
determine the degree of difference and similarities between two or more signals.
2. In a certain concert hall, echoes of the original audio signal x(n) are generated due to the
reflections at the walls and ceiling. The audio signal experienced by the listener y(n) is a
combination of x(n) and its echoes. Let
y(n) = x(n) + αx(n-k)
where k is the amount of delay in samples and α is its relative strength. We want to estimate the
delay using correlation analysis.
1. Determine analytically the crosscorrelation ryx(l) in terms of the autocorrelation rxx(l).
2. Let x(n) = cos(0.2πn) + 0.5cos(0.6 πn), α = 0.1, and k = 50. Generate 200
samples of y(n) and determine its correlation. Can you obtain α and k by observing ryx(l)?
CONCLUSION:
As a whole generalization, correlation is the process of
comparing the differences and similarities present
between two or more signals. Convolution is the process
of manipulating signals. It may be altered or improved
mathematically. Dissimilar in computing for the signal’s
convolution, the correlation does not need to be
flipped. It may be worked upon directly. The signal is
no longer shifted. The degree of similarity between
signals is the primary purpose for correlating signals.
Modifying, altering and performing signal manipulation
falls under convolution. Cross correlation does not
evidently yield a symmetric output signal. Only when
performing Auto correlation does it results in a
symmetric signal response.