P2D-9 A Frequency-Compensated Coded-Excitation Pulse to Improve Axial Resolution of Ultrasonic System

This work presents a method for coded excitation of ultrasound system using a compensated frequency modulation based on the spectral response of the echo from a flat reflector. The method provides an improvement of the overall range resolution of the ultrasound system comprising the pulse generator, impedance matching networks, receive amplifier and transmit/receive transducer. The method was tested in terms of the range resolution for the echo from a flat reflector and with the transducer of the ultrasound system excited with a linear frequency modulated coded excitation and with the proposed compensated frequency modulation coded excitation. The received echo was compressed using the cross-correlation technique and the width of the compressed echo-pulse envelope was around 1.02 and 0.85 mus for linear frequency modulation and compensated frequency modulation coded excitations, respectively