This paper presents a real-time positioning system for indoor use, which utilizes ultrasonic waves. Many existing systems were prevented from real-time applications by long detection time and calculation time. The proposed system utilizes multiple frequencies of ultrasonic waves, which lead to the reduction of positioning interval and system complexity. We developed our prototype system with Arduino Uno, and achieved 30 ms of the positioning interval.
Metastability of RS latches can be a source of entropy for true random number generators (TRNGs). This study presents a new composition of an RS latch using the latch functionality of storage elements of Xilinx FPGAs. Our TRNG is implemented as a soft macro, or RTL description with directives, which is easily integrated into other logic components. According to our evaluation with an Artix-7 FPGA (XC7A35T), our TRNG with 320 latches (716 LUTs and 974 registers) passed the NIST SP 800-22 test suite without post-processing. Also, our new TRNG presented a 2.3x better areadelay product than the existing design to pass the diehard test.
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