Ultrasound harmonic golay-coded excitation with differential pulsing

摘要

Harmonic imaging using harmonic Golay-coded excitation that encodes the fundamental and second harmonic signals utilizes the transmit sequences encoded using QPSK implemented as quarter-cycle circular rotations or shifts of the base pulse. This is implemented by time shifting the chips of the transmit sequence encoded with a j or j code symbol by fractional cycle at center frequency relative to the chips encoded with a 1 or 1 code symbol. A different QPSK transmit code is used for each of four transmits A, B, C and D. The transmit codes are selected such that (AB) and (CD) are encoded by Y and X, respectively, while (A²B²) and (C²D²) are encoded by X and Y, respectively, where X and Y form a Golay code pair. The coding and decoding technique achieves fundamental suppression and second harmonic compression for a given Golay code pair X and Y.