lab05 - Correlation is the same as convolution with a time...

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Electronic Navigation Systems – Lab 5 Part 1 Write a Matlab program to implement the C/A code generator shown below: 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 + + + + all 1’s C/A code Demonstrate for at least three diFerent codes that the ±rst ten chips are the same as shown in Table 3-I on page 8 of ICD-GPS-200. 1

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Part 2 For at least one C/A code, convert the (0,1) code to (1,-1), then calculate and plot the autocorrelation function. Your plot should be similar to the one shown below. -600 -400 -200 0 200 400 600 -0.5 0 0.5 1 Part 3 For at least one pair of C/A codes, plot the cross correlation function. Your plot should be similar to the one shown below. -600 -400 -200 0 200 400 600 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 2
Hint What is required for this lab is the correlation of a periodic sequence with a F- nite length sequence, or, equivalently, the circular correlation of two sequences.
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Unformatted text preview: Correlation is the same as convolution with a time reversal of one of the se-quences: R xy [ n ] = x [ n ] * y [-n ] This type of convolution can be easily accomplished with the aid of the discrete ±ourier transform (D±T), also known as the fft function in Matlab. If X [ k ] is the D±T of x [ n ], Y [ k ] is the D±T of y [ n ], and S xy [ k ] is the D±T of R xy [ n ], then S xy [ k ] = X [ k ] Y * [ k ]. The complete algorithm is 1. Calculate the D±T’s of x [ n ] and y [ n ]. 2. Conjugate one of the sequences. 3. Multiply the two sequences point wise. 4. Calculate the inverse D±T of the product. 3...
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lab05 - Correlation is the same as convolution with a time...

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