Abstract: Bridge Function is a three valued function, and is made by the initial sequence according to copy and shift ways. It includes Walsh Function and Block Function. Generalized Bridge Function, which is an extension of Bridge Function, is a multi valued function, and is made by the initial sequence according to generalized copy and shift ways. It includes Bridge Function, Chrestenson Function and Watari Function. This paper briefly introduces some research progress of Beijing University of Aeronautics and Astronautics on the orthogonal function of non sine within last twenty years, emphasizing to introduce the copy theory, Bridge Function, Generalized Bridge Function and Easily Generated Function analysis.

Key words: copy theory, Walsh function, bridge function, generalized bridge function, easily-generated function