OASS will compute the reverberation for multible range offsets between the source (at origin in OAST) and the receiver array origin in OASS. This allows for efficient computation of the range-dependence of the reverberant field. The range offsets are specified as a minimum and maximum value, RMIN, RMAX in km, and the number of offsets considered NR.
Note that the offset does not apply to option a. The covariance matrix is computed for zero offset. For bistatic scenarios the range must therefore be specified directly in the receiver coordinates.
On the other hand the other reverb options C,D,r do not use the horizontal coordinates of the array, i.e they basically compute the reverb for a VLA at different horizontal offsets. In other words, only the receiver depths are used for these options.