可調式多頻可攜式無線裝置於遠距呼吸與心跳的偵測

Abstract

本論文研究以都卜勒原理為架構，建立2.4G與4~6GHz兩套非接觸式雷達收發機，用以偵測人體的呼吸與心跳，由於呼吸與心跳會產生不同程度的動態起伏，造成反射訊號的相位調變，透過接收機以同步解調的方式，直接把微波訊號降到基頻，再以Labview數位濾波來分離，呼吸高通濾波截止頻率0.15Hz；心跳帶通濾波0.9~1.5Hz，累積20秒數據來做快速傅立葉轉換(FFT)。在頻域上，擷取所要頻率範圍內的最大值來顯示每分鐘的心跳數與呼吸數。操作頻率包含免認證的ISM頻段(2.4G、5.8G)，由於頻率越低，波長越長，衰減量越低且因元件特性擁有較大的輸出功率，能應用於遠距遮蔽情況下的室內外監測，對於心跳微小振幅的量測，需較短波長來提高接收的靈敏度，針對此問題，本研究設計一個可調式4~6GHz多頻系統，根據不同環境，可以選擇適合的頻率，有效偵測人體呼吸與心跳的訊號。除了雷達系統外，本研究也加入2.4G與寬頻的八木天線製作，利用平面八木架構可提供高度整合、面積小及較佳的指向性，另外在2.4G系統上還加入了環行器，使得接收與發送只需共用一根天線即可。準確率以市售的血氧濃度機來做比較，針對不同的受測者，做不同頻段、距離、遮蔽物及單分雙分雷達架構的量測，接著測試雷達輻射範圍與呼吸諧波對心跳頻率的影響，來驗證應用於臨床心肺檢測及遠距量測的實用性。

The main research is the Doppler principle. To establish 2.4G and 4 ~ 6GHz non-contact radar transceiver, used to detect human respiration and heartbeat. Due to respiration and heartbeat will produce dynamic changes,resulting in phase modulation on reflected signal. In the receiver use synchronize demodulation, the microwave signal transfer to baseband directly and then to separate the respiration and heartbeat in Labview digital filter. Respiration uses high-pass filter( 0.15Hz ); Heartbeat uses band-pass filter (0.9~1.5Hz).That accumulate 20 seconds of data to do the fast Fourier transform.In the frequency domain, to capture the frequency in maximum peak to display per minute number of heartbeats and respiration. The operational frequency have no certification ISM band (2.4G, 5.8G), due to the lower frequency have longer wavelength and the lower attenuation that have greater output power with component characteristics in lower frequency. It can be applied to indoor and outdoor monitoring for long rang covered condition. In order to measure the small amplitude of heartbeat that need short- wavelength to increase receive sensitivity. For this question, the paper design switchable multi- frequency system, to select the appropriate frequency on the different environment. In addition to radar systems, the 2.4GHz and broadband yagi antenna are maked, the plane Yagi architecture provides a complete integration, small size and better directivity. While the 2.4G system also connects the circulator that make receiver and transmitter just share an antenna. The compare of accuracy used commercially Oxygen machine for different subject, distance and shelter in different frequency and monostatic, bistatic radar architecture. Finally test radar range and the effects of respiration harmonics that verify the usefulness of clinical cardiopulmonary testing and remote detection.