Real time High Accuracy Phase Difference Measurement for Parallel Multi-Channel Sensors

Abstract

This paper presents a real time high accuracy phase difference measurement method for parallel multi-channel sensors. The parallel data acquisition from multiple sensors is commonly used in Sonar based systems to increase distance measurement accuracy and reliability. Due to the mismatch in the analog path and PVT variations, the sensor signal experience delay among multiple channels. It causes phase difference which need to be consider for precise distance measurement. A LabVIEW based real time phase difference measurement method is proposed by using NI PXIe-6555 high speed digital I/O (HSDIO). The serial digital data from sensor’s ADC is converted into parallel in FPGA and then multiplexed with channel ID. The NI PXIe-6555 reads parallel multiplexed data from FPGA and calculate phase difference among multiple channels in LabVIEW with six digit fractional precision. A real time phase difference measurement of two parallel channel ADC chip for SONAR application is also performed while considering channel mismatch and PVT variations.