The Influence of the Transducer Bandwidth and Double Pulse Transmission on the Encoded Imaging Ultrasound

An influence effect of fractional bandwidth of ultrasound imaging transducer on the gain of compressed echo signal being the complementary Golay sequences (CGS) with different spectral widths is studied in this paper. Also, a new composing transmission method of CGS is discussed together with compression technique applied in order to increase the signal-to-noise ratio (SNR) and penetration. The CGS with two different bit lengths, one-cycle and two-cycles are investigated. Two transducers with fractional bandwidth of 25% and 80% at centre frequency 6 MHz are used. The experimental results are presented, clearly proofing that increasing of the code length leads to compressed echo amplitude enhancement. The smaller the bandwidth is the larger is this effect; the pulse-echo sensitivity of the echo amplitude increases by 1.88 for 25% fractional bandwidth and 1.47 for 80% while preserving time resolution. The presented results of double transmission of short codes show the penetration and SNR improvement while maintaining dead zone.