doi:10.3850/978-981-08-7615-9_RE11

ABSTRACT

This paper describes a multi-peak detection technique for the wireless sensing of human respiratory rate and amplitude using low-power ultra wideband impulse radio (UWB-IR) signal. The accurate detection of respiratory rate and amplitude are crucial for the assessment of obstructive sleep apnea syndrome (OSAS) and respiration training/therapy of spinal cord injury (SCI) patients. Since the propagation time of the backscattered radio signal reflected by human chest is linearly related to the displacement of human chest, both the chest respiration rate and amplitude can be measured using UWB radio. However, similar to any other wireless system, the accuracy of UWB-IR measurement is limited by the received signal-to-noise ratio at the receiver. The proposed multipeak detection technique is able to improve the received signal-to-noise ratio (SNR) in a way that is similar to the matched filtering effect. The primary idea of multi-peak detection is to shift-and-add the sub-peaks of the received UWB-IR signal to the main peak. This is possible because the time locations of the sub-peaks of the UWB signal relative to the main peak time location are known a-priori, since these peak locations are expected to remain unchanged after propagating through the channel. Based on the experiment results, the SNR obtained using multi-peak detection is found to be higher than the SNR obtained using single-peak detection by approximately 7dB.

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