In a synthesis array, modulation of each antenna's signal is often used for separating desired from undesired signals, or for separating two desired signals. This requires the use of modulating functions that are orthogonal among the antennas. Among two-valued functions, only the Walsh functions and the Rademacher functions are known to form mutually orthogonal sets. An earlier memo (#287) claimed that the square waves whose frequencies are proportional to the positive integers are mutually orthogonal, but this is incorrect.
View a pdf version of ALMA Memo 385.
Download a ps version of ALMA Memo 385.
Last modified: 2001 August 10
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