Improving performance of pulse compression in a Doppler ultrasound system using amplitude modulated chirps and Wiener filtering.
The use of coded excitation and pulse compression in transcranial Doppler (TCD) ultrasound systems is in the very early stages; the optimal processing scheme has yet to be determined. This study uses linear frequency-modulated (FM) chirps with 0.8-MHz bandwidth and compares the use of pulses with and without amplitude modulation and also matched filtering vs. Wiener filtering. The results demonstrate that using amplitude-modulated pulses vastly improves the axial resolution and provides a more predictable mainlobe-to-sidelobe distance in the radiofrequency (RF) signal. It is also shown that a Wiener filter can provide better performance than a matched filter, in terms of axial resolution and sidelobe level in the RF signal and signal-to-noise ratio in conventional sonograms. Although this study uses a TCD system, the techniques described are equally as applicable in other Doppler ultrasound devices.
Cowe
Joanne
J
Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, UK. j.cowe@le.ac.uk
Gittins
John
J
Evans
David H
DH
D004581:Electronics; D006801:Humans; D020766:Intracranial Embolism / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted; D017585:Ultrasonography, Doppler, Transcranial / Q000295:instrumentation / Q000379:methods*