| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 97 === In this thesis, we analyzed the acoustic signal from the hemodialysis patient’s arteriovenous graft, and developed an algorithm for stenosis detection. Based on our analysis, we found that their blood flow generates a baseband signal which is between 1 to 1.67Hz over a carrier whose frequency range is highly correlated to the stenosis level in the arteriovenous graft. The carrier signal is much weaker(less than -100dB) than the baseband signal, as a result it is very difficult to observe the carrier directly and come up with a reliable detection result. By analyzing the signal in the time-frequency domain, we design an align-and-average scheme to suppress possible noises, and based on our analysis and observation, an array of cascaded bandpass filters are applied for detection purpose.
Using our new technique, the results have been proved to within 5% of miss fire rate. The false alarm rate is about 23%, unfortunately. This leaves room for future improvement, however.
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