Estimation of Echo Amplitude and Time Delay for OFDM-Based Ground-Penetrating Radar

The orthogonal frequency division multiplexing (OFDM) based ground-penetrating radar (GPR) has been proven to have many advantages. The estimation of amplitudes and time delays of interface echoes is significant particularly in GPR systems for pavement profiling. For the recently developed OFDM-based GPR systems, this letter proposes an algorithm for precisely estimating the echo amplitudes and time delays. We estimate the propagation channel in frequency domain and transform the resulted channel frequency response to time domain. Considering the reduction of the channel impulse response (CIR) leakage caused by IFFT, a windowing method is applied before the IFFT. The challenge is that the general windowing method leads to resolution decrease and peak value losses for the windowed CIR, which contains the echo amplitude and time delay information. We design a window that causes very little echo amplitude loss and improves the estimation resolution. In this way, the echo amplitudes and time delays can be obtained from the largest few extreme values of the windowed CIR. The algorithm performs a low complexity, and the simulation results show that the estimation errors for both amplitudes and time delays are small with the range resolution improved.