Abstract
Microscopic LDV is made to explore the flow velocity in an extremely small area. Though it has a good spatial resolution, Doppler signals obtained from it have fewer wavenumbers in one burst signal than normal LDV. Therefore, duration time of one signal is very short. Furthermore measurements on such as lymph flow, not enough S/N ratio is expected because of scattered lights from tissues or vessel walls. So, traditional signal processing method like Burst Spectrum Analyzer (BSA) which is based on an extremely fast hardwared FFT processor is unsuited for these signals under low S/N ratio.
This paper describes a problem in case of processing signals obtained from microscopic LDV using conventional BSA through basic simulation. From this simulation, we made a correction coefficient which correspond to Doppler signals and applied it to spectrum of Doppler signals. Moreover, because of their short duration time, spectrum broadening occurs when such signals are analyzed using FFT. By taking account of this characteristic and improving the conventional BSA in two ways, we propose a new signal processing method to distinguish the spectrum of Doppler signal from that of noise. Furthermore, we carried out a fundamental experiment to examine their effectiveness on such signals.
