A two-pulse technique for extracting 3rd harmonic from ulasound contrast agent echo signal

Multi-pulse techniques like CPS (contrast pulse sequence) and TPS (triplet pulse sequence) are the most popular methods for separating the 3^rd harmonic signals from received signal. Those two methods, however, transmit a pulse at least three times along each scanline with different phase and amplitude, which results in the frame rate reduction. In this paper, we propose a technique using two pulses whose phase difference is 90° and a simple digital filter. The second harmonic signal is eliminated by summing two received signals as their phase difference becomes 180° and then the fundamental signals are eliminated by using a digital filter. Computer simulations are performed for different values of signal bandwidths and filter specifications. The results show the maximum error is −35.5dB compared to TPS.