Demonstration of 3D ISAR Security Imaging at 24GHz with a Sparse MIMO Array

TL;DR

This paper demonstrates a 3D ISAR security imaging system at 24GHz using a sparse MIMO array, combining advanced calibration, motion tracking, and GPU-based processing for real-time human and object imaging.

Contribution

It introduces a novel 3D ISAR imaging setup with a sparse MIMO array, calibration procedures, and an integrated motion tracking and neural network recognition system.

Findings

Successful 3D imaging of humans with concealed objects

Effective calibration of MIMO channel imbalance

Real-time imaging achieved with GPU acceleration

Abstract

A 3D ISAR security imaging experiment at 24GHz is demonstrated with a sparse MIMO array. The MIMO array is an 8Tx/16Rx linear array to achieve real-aperture imaging along the vertical dimension. It is time-switching multiplexed with a low-cost FMCW transceiver working at 22GHz-26GHz. A calibration procedure is proposed to calibrate the channel imbalance across the MIMO array. The experiment is conducted on human moving on a cart, where we take advantage of the linear motion of human to form inverse synthetic aperture along the horizontal dimension. To track the motion of human, a 3D depth camera is used as an auxiliary sensor to capture the rough position of target to aid ISAR imaging. The back projection imaging algorithm is implemented on GPU for quasi-real-time operation. Finally, experiments are conducted with real human with concealed objects and a preliminary automatic object recognition algorithm based on convolutional neural networks are developed and evaluated on real data.