Reduction to monostatic focusing of bistatic or motion compensated SAR surveys

The authors study the response caused by a point scatterer in the general case of bistatic surveys. The relative time–space function, called the flat top hyperbola, is derived. The complexity of this curve stimulates the reduction of a general bistatic survey to a monostatic one, following the techniques used in seismic data processing. The scatterers corresponding to a single received pulse in a bistatic configuration are located on the intersection of the ground plane with an isochronal ellipsoid that has source and receiver as foci. These scatterers are then considered as targets of amonostatic configuration. Thus, a bistatic configuration is reduced to a monostatic one by identifying an approximate space-varying transfer function between the two configurations. This paper, a sequel to a recently published paper, also addresses the problem of motion compensation, in that the first survey could also be monostatic, and the location of the second monostatic survey is at choice. The use of a digital elevation model is shown to be essential for the correct determination of the transfer function in the general case. It is not necessary if the source and receivers have a constant distance and follow the same trajectory