The complete set of square waves with frequencies that are integral multiples of a unit frequency cannot be used for phase switching since such a set are not mutually orthogonal,as discussed in ALMA Memos 287 and 385. However,by recognizing that absolute mathematical orthogonality is not required,and by selecting a sub-set of square-waves of certain frequencies, it is possible to design a practical phase switching scheme. Compared to the use of Walsh functions,this scheme has the advantage that the values of cross correlation between pairs of square waves remain very small in the presence of arbitrary relative time shifts.
View a pdf version of ALMA Memo 391.
Download a ps version of ALMA Memo 391.
Last modified: 2001 August 31
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