Introduction to Bridge Functions

In this paper, a bridge function system is introduced, where bridge functions make up a three-valued function system, only taking the values +1, -1, and 0, and they are orthogonal. It is constructed with the concepts of sequence shift and sequence copying. The notation, waveforms, and recursive relation of the bridge functions are given. Walsh functions are a special case of the bridge functions. Block pulses are another special case. The bridge functions connect the Walsh functions and the block pulse functions. The bridge functions have the property of modulo 2 sum.