Mathematical process of transforming RF signal to position information for tracking ingestible capsules

A detailed analysis of scientific work done in transforming radio frequency (RF) signals for tracking an embedded object with special reference to telemetry capsules in the gastro-intestinal (GI) tract is presented in this paper. We fully discuss the mathematics of the necessary stages for transformation from signal to hexadecimal, decimal, to distance up to the stage where the path trajectory is computed. Experimental validation is accomplished by using RF signals at 433MHz, Analog Devices 8052 based microcontroller with ADC capability and a means of transferring the received signal strength intensity voltage converted to digital, from the microcontroller to the personal computer. The primary focus of this paper is a proven practical way of achieving the above tasks by using basic mathematical and computing principles. Consequently, our algorithm-based tracking results for experiments in a liquid medium yielded an average error of less than 21%. These results were validated with the Bland-Altman plots using semi-automated manual measurements as gold standard.