Zadoff-Chu sequence concept
60 views (last 30 days)
Show older comments
Zaddoff-Chu sequence has two main propoerties: 1- constant modulus 2- good correlation characteristics. Most of the papers claim that the autocorrelation of sequence has zero values for all shifted version of sequence except the lag=0. However, if you try to use the matlab code zadoffChuSeq(u,N) to varify this propoerties, you will find the small peaks at time axis. This means it is not perfrectely sequqnce as they calimed. Did I miss somthing?
4 Comments
Manikanta Aditya
on 18 Apr 2024
As, you’re observing very large peaks around the zero-lag peak with zadoffChuSeq(3,67), it might be worth double-checking the implementation of the function for any potential errors or deviations from the theoretical formula. Additionally, ensure that the parameters used (such as u and N) satisfy the necessary conditions for a Zadoff-Chu sequence.
If after verification everything seems correct, then these large peaks might be an artifact of how MATLAB handles computations and displays plots rather than an issue with the sequence itself.
The image you attached indeed shows a prominent peak near x=60 and several smaller peaks throughout the plot. These peaks could be due to the reasons mentioned above.
Answers (1)
AH
on 18 Apr 2024
The Zadoff-Chu sequences have the useful property of having zero cyclic autocorrelation at all nonzero lags. One fast way to check this property is shown below
N = 67;
x = zadoffChuSeq(3,N);
X = fft(x);
cR = fftshift(ifft(X.*conj(X))); % circular correlation
figure
plot((-(N-1)/2:(N-1)/2),abs(cR))
xlabel("Lag")
ylabel("Autocorreleation")
5 Comments
See Also
Categories
Find more on Spectral Measurements in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!