Barker coded excitation using LFM carrier for improving axial resolution in ultrasound imaging
Improving the axial resolution of ultrasound imaging system can have broad clinical impact. In this paper, a novel Barker coded excitation uses LFM carrier (LFM-Barker coded excitation) instead of sinusoid carrier (Sinusoid-Barker coded excitation). Pulse compression scheme of LFM-Barker coded excitation is developed that consists of LFM mismatched filter, Barker matched filter and sidelobe suppression filter. In simulation, the axial resolution is almost doubled with a slight decrease of SNR gain of less than 1 dB using LFM-Barker coded excitation compared to Sinusoid-Barker coded excitation. The -6 dB mainlobe width is 0.6 μs and 1.5 μs, respectively. Maximum range sidelobe level is observed at -35 dB. Additionally LFM-Barker coded excitation is robust for frequency dependant attenuation of tissue. Simulation of B-mode images is carried out to demonstrate the advantage of LFM-Barker coded excitation system of good axial resolution.