Interleaved sampling and concurrent filter of optic-fiber distributed temperature sensors

This paper presents an embedded solution of concurrent low-pass filter and sample interleaving system which process back-scattered signal of optic-fiber distributed temperature sensors at 250 MSPS. The logic design is implemented on a data acquisition platform with four ADC channels and FPGA-ARM processors; samples from two ADCs are merged and reconstructed to double the equivalent sampling rate. A low-cost FPGA processes Stokes and anti-Stokes signals from up to 20000 measurement locations along the fiber. In the experiments the comparison between interleaved data and original data shows that quantization noises around input signal frequency were evidently reduced but small distortions of high frequency were introduced. The concurrent filter guaranteed a SNR of 42.3 for the distributed temperature sensors.