Improved resolution and dynamic range in medical ultrasonic imaging using depth-dependent mismatched filtering

The authors present a depth-dependent mismatched-filter pulse compression technique which improves range resolution and dynamic range of coded excitation ultrasonic imaging compared to a matched-filter pulse compression. After choosing a suitable magnitude spectrum, frequency weighting is used to design the appropriate mismatched filter depth-dependently, which allows to control mainlobe width and sidelobe characteristics. Both simulations and measurements are used to demonstrate the efficacy of the technique. A VLSI implementation of a depth-dependent mismatched filter is shown to be feasible.