Title :
Spectral Doppler technique with extended unambiguous velocity range
Author :
Mo, LarryY L. ; Ji, Ting-Lan ; McLaughlin, Glen W.
Author_Institution :
Novasonics Inc., Mountain View, CA, USA
Abstract :
A hybrid pulsed wave Doppler technique is proposed which combines high pulse repetition frequency (HPRF) operation with inter-pulse encoding and 2D-FFT processing. A windowed, linear FM-chirp of ascending pitch, and its time-reversed copy, are used to encode alternate transmit firings at doubled the maximum PRF based on the round-trip distance between the Doppler sample gate and the transducer. Three key properties of the chirp pair are described which enable 1) HPRF operation with significant suppression of the ghost sample gate sensitivity profile; and 2) 2D-FFT spectral analysis which strongly reduces speckle variance. Selected simulation results are presented based on synthesized RF signals for 3 MHz Doppler, 20-cycle chirps and typical pulsatile flow parameters.
Keywords :
Doppler measurement; biomedical ultrasonics; blood flow measurement; fast Fourier transforms; medical signal processing; pulsatile flow; speckle; spectral analysis; 2D-FFT spectral analysis; 3 MHz; alternate transmit firings encoding; chirp pair key properties; established clinical tool; extended unambiguous velocity range; noninvasive blood flow measurement; simulation results; speckle variance reduction; spectral Doppler technique; synthesized RF signals; typical pulsatile flow parameters; Chirp; Decoding; Encoding; Fluid flow measurement; Frequency; Multiaccess communication; Spectral analysis; Transducers; Ultrasonic imaging; Ultrasonic variables measurement;
Conference_Titel :
Ultrasonics Symposium, 2002. Proceedings. 2002 IEEE
Print_ISBN :
0-7803-7582-3
DOI :
10.1109/ULTSYM.2002.1192580
