Orthogonal Golay code based ultrasonic imaging without reducing frame rate

Orthogonal Golay codes feature perfect sidelobe cancellation properties, and are simple to implement because they have elements of +1 and -1 only. However, the frame rate is reduced by one half due to the requirement of two consecutive transmissions per scanline. This paper presents an ultrasonic B-mode imaging method using orthogonal complementary Golay codes without reducing the frame rate while achieving good SNR. In the method, the member codes applied to transducer elements are alternated from one transmission to another, with the focal points switched as well. The sidelobe and grating lobe levels from combining four consecutive transmit events are found to be as much as about 10 dB less than those from combining two transmit events.