# Low-Power, High Data-Rate Digital Capsule Endoscopy Using Human Body Communication
## 4 CEHBC System Measurement and Performance
### Performance of the CEHBC System
The proposed CEHBC-TXD can support a relatively high data rate while using its clock a few tens of MHz slower. The energy consumption figure associated with the power and transmission data rate also has the small value of 0.616 nJ/bit. In addition, the results show the benefits from a high-resolution image of 480 \(\times\) 480 bytes. Because the proposed method does not use an image compressor, if the data rates after image compression are compared in the structure of the papers written in the table, it can be confirmed that the data rate is the highest reported, with respect to the operating carrier frequency. The total power consumption of the CEHBC capsule endoscope is 57.5 mW. The FPGA consisting of CEHBC-TXIF and CEHBC-TXD consumed 6.34 mW to transmit the image data. The remaining blocks such as CMOS image sensor and LED etc. used 51.16 mW. Compared with the capsule endoscope proposed in [10], it can be seen that the total consumed power of the capsule of [10] is 90 mW, since \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Distance between Electrodes**} & \multicolumn{6}{c}{**The Direction of the Capsule Endoscope towards the Electrode**} \\ \cline{2-9}  & **E1** & **E2** & **E3** & **E4** & **E5** & **E6** & **E7** & **E8** \\ \hline
6 cm & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
11 cm & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: BER performance of the CEHBC system. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **CEHBC Tx field Programmable Gate Array (FPGA) Block** & **CEHBC Rx FPGA Block** \\  & **(CEHBC-Tx Interface (TXIF) \& CEHBC-Tx Digital (TXD))** & **(CEHBC-RXD \& CEHBC-RXIF)** \\ \hline field programmable & Actel ICLOO & Xilinx Artix 7 \\ gate array (FPGA) & AGLN125V5-C581 & XC7A50T-C5324 \\ \hline synthesis and & Libero v11.8 & Vivado 2015.3 \\ \hline logic size & CEHBC-TXIF Core: 1084 of 3072 (35.29\%) & Resource Utilization (LUT) \\  & CEHBC-TXD Core: 521 of 3072 (16.96\%) & 5231 of 32,600 (16.05\%) \\ \hline input/output voltage & LVCMOS 3.3V & LVCMOS 3.3V \\ level & CEHBC-TXIF-2.63 mW & 114 mW \\ \hline main clock frequency & 32 MHz & 32 MHz \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Synthesis results of CEHBC digital blocks. three 1.5 V coin batteries are used in series and the total consumed current is 20 mA. The FPGA consumed power in the capsule endoscope of [10] is 12.42 mW. This comparison confirms that the CEHBC capsule endoscope is not only capable of high resolution image transmission, but also low power operation. Table 6 shows the performance comparison of the capsule endoscope using HBC. Both the MiroCam capsule and the CEHBC capsule have commonalities in using the HBC to transmit baseband signals without the RF transmitter. However, the following differences exist. The main difference between the MiroCam capsule and the CEHBC capsule is that image resolution is increased. The CEHBC capsule uses a transmission method capable of image data transmission with 480 \(\times\) 480 pixel, which is more than twice as much as the 320 \(\times\) 320 pixel image data. This enhancement is made possible by the use of modulation methods such as the dual mode FSDT, rather than simply increasing the sampling frequency or hardware complexity. Therefore we think that the CEHBC capsule using the FSDT structure proposed in this paper is more efficient in terms of power consumption and price. The CEHBC capsules are larger and heavier than the MiroCam capsule. This is because a commercial image sensor PIXELPLUS PO8030D (digital image sensor, 2010, PIXELPLUS, Suwon-si, South Korea) is used for transmitting the 480 \(\times\) 480 image data. Since it is a general-purpose image sensor product, it consumes a large amount of power and uses a large-capacity battery. Therefore, the total power of the implemented CEHBC capsule is large because of using the PO8030D image sensor. However, there is a possibility that the consumption power of the capsules will also decrease if the image sensor for capsules is used later.