1. A method to generate radar cross section (RCS) signatures, comprising: determining a spectrum of a first object using a computer; and using the spectrum of the first object to generate RCS signatures of a plurality of objects, using the computer, by applying the spectrum of the first object to each of the plurality of objects, using the spectrum of the first object comprising: interpolating time; selecting frequencies to match a center frequency and bandwidth of a radar pulse; resampling to frequency sampling of radar to match a range bin size; and shifting and applying trajectory phase and scaling.