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M-Sequence Sensor and Continuous Basis Estimator for Wall Parameter Estimation Utilizing Through the Wall Sensing

Non-destructive estimation of the physical parameters of a medium is an important topic in sensing systems to characterize materials. It is also used in through-the-wall sensing to localize objects behind a medium. Achieving high accuracy and resolution using simple and cost-effective sensors are eminent points in this aim, which needs to note system design and signal processing categories. From the system viewpoint, using wideband signals can bring higher resolution, however, at the cost of more complexity of hardware. Although signal processing can be used to improve the resolution, since the estimation algorithms work on discrete grids, there will be a limited resolution defined by the sampling frequency. This paper provides an efficient approach from the viewpoints of system design and signal processing for low cost, accurate, and super resolution through the wall sensing. We have used maximum length binary sequence (M-sequence) as stimulus. After designing the sensor, a complementary algorithm based on continuous basis compressive time delay estimation is established to mitigate the imposed limitation by the data capturing unit. Our simulation and measurement results show that the proposed algorithm with the presented hardware can bring the unknown parameters of a sample of wall with an accuracy of more than 95% and with 50% improvement in the resolution of system. Furthermore, the distance of a metallic sheet placed behind the sample is also measured with an excellent accuracy of 95%.