使用華氏碼並建構於可程式邏輯板之人體通道傳輸收發器;An FPGA-based Transceiver for Human Body Channel Communication using Walsh Codes

[[abstract]]在人口老化及現代科技的發展之下，可攜式醫療電子設備及可隨身佩戴、隨時測量的電子裝置越來越多。這類型的裝置大多是使用無線的方式進行傳輸，像是常見的藍芽傳輸、ZigBee。但是這些技術有很高的耗電量以及因為很多裝置也使用相同頻帶造成嚴重的干擾的問題。因此，以人體通道作為傳輸媒介的技術被提出。人體通道傳輸可以避免干擾的問題、能提供較穩定的傳輸，同時其功率消耗比較低。因為以上的優點，我們提出一個以人體通道傳輸的傳收器。 Virtex-7 VC707 evaluation board (EVB) 板是一張具有穩定且高速工作頻率的 EVB板，我們把人體通道傳收器建構於其上並且以華氏碼作為調變碼。華氏碼具有正交特性，所以可以容忍低於一半華氏碼長度的錯誤位元資料能被正確解調。除此之外，我們選取長度為2的continuous identical digits (CID)華氏碼避免過長的CID出現造成接收端難以回復訊號。在bit error rate (BER)量測中，以140公分傳輸距離傳送108個位元資料時，在488 Kbps (3.12 Mcps), 976 Kbps (6.25 Mcps), 以及1.95 Mbps (12.5 Mcps) 上並沒有任何錯誤資料發生。在3.9 Mbps (12.5 Mcps) 的傳輸率下，BER達到10-5。 在本研究提出的人體通道傳輸收發器，基於傳輸穩定度的提高，我們也提供直接傳輸多媒體資料的模式，在電腦上把圖片分解經由universal asynchronous receiver/transmitter (UART) 介面送到傳送器，經由最長為140公分、1.95 Mbps的速度傳到人體通道後，能正確地把它接收回，最後可以重建回原來完整的圖片。 In recent years, the portable healthcare devices are more and more popular. The wireless transmissions are widely used in these devices, such as Bluetooth and ZigBee. However, these techniques have drawbacks of high power consumption and have interferences in the shared frequency band, Therefore, body channel communication (BCC) is proposed because it has relatively low power consumption and has less interferences. The proposed BCC transceiver which using Walsh codes as modulated codes is implemented on the Vurtex-7 VC707 evaluation board (EVB). The Walsh codes are orthogonal codes and the maximum number of error bits that can be tolerated can be up to half of the code’s length. Moreover, the CID of the Walsh codes are limited to 2 to avoid the no data transition situation which makes the receiver difficulty to recover the clock and data. There are no error bits occurred when transmitting 108 bits at 140 cm distance and at data rate of 488 Kbps (3.12 Mcps), 976 Kbps (6.25 Mcps), and 1.95 Mbps (12.5 Mcps). Moreover, the BER is 10-5 at 3.9 Mbps (12.5 Mcps). In the proposed BCC transceiver, because of high data reliability, the multi-media transmission is supported. The image can be completely transmitted and received through 140 cm distance and the maximum data rate is 1.95 Mbps