Tags:Chirp-coded excitation, Conventional excitation, Match filter, Signal processing and Ultrasound
Abstract:
Innovative coded excitation techniques have been proposed to increase the signal-to-noise ratio (SNR) of ultrasound signals, which are significantly attenuated by scattering and absorption. Among the methods applied, the linear-frequency modulation signal, commonly defined as chirp signal, has been studied to provide images with greater depth, even in high attenuation media, maintaining the spatial resolution found in conventional excitation systems. This article presents a graphical user interface (GUI) based on Matlab to simulate short-duration conventional excitation (CE) pulses and long-duration chirp-coded excitation (CCE) pulses. The GUI allows the selection of apodization window, center frequency, and pulse duration parameters. In addition, it is possible to configure the bandwidth of the chirp signal. Pulse evaluations were performed with a central frequency of 1.6 MHz, using three cycles for CE and a duration of 5, 10, and 20 µs for CCE with a bandwidth of ±200 kHz, ±400 kHz, and ±1 MHz in a phantom simulated with ten targets. The echo signals for the CCE were processed using a matched filter to evaluate the spatial resolution and attenuation. Simulation results demonstrate the flexibility and performance of the proposed GUI for ultrasound excitation studies. The evaluation of CCE with a frequency of 1.6 MHz ± 1 MHz and matched filter improved spatial resolution by 86%. In contrast, a maximum increase in attenuation of the processed signal of 33% was observed.
A Matlab-Based Graphical User Interface to Assess Conventional and Chirp-Coded Ultrasonic Excitation