Transformed Auto-correlation
  A transformed auto-correlation method is presented here, where a received signal is transformed based on a priori reflecting model, and then the transformed signal is cross-correlated to its original one. If the model is correct, after transformation, the reflected signal will be coherent to the transmitted signal, with zero delay. A map of transformed auto-correlation function with zero delay can be generated in a given parametric space. The significant peaks in the map may indicate the possible reflectors nearby the central transmitter. The true values of the parameters of reflectors can be estimated at the same time. 
Jianfeng Zhou (1 and 2), Yang Gao (1 and 2) ((1) Key Laboratory of   Particle & Radiation Imaging, Tsinghua University, (2) ...
astro-ph.IM