Abstract: A down range returns simulator for generating simulated radar reflected returns for testing advanced radar waveforms and associated signal processing. The simulator generates return signals based from real mission data, data transforms, arbitrary reference waveform convolutions, and radio and intermediate frequencies. The simulator includes a source of field data, synthetic target, an analog to digital converter for generating digital waveform returns, and RF/IF waveform generator, and a source of clutter waveform characteristics (OPINE, weather, and electronic counter-measures effects). The RF/IF waveform generator uses FFTs and IFFTs in order to develop realistic digital samples for evaluation software and Doppler images. The simulator apparatus provides a target return simulation as if received by radar in a down range mission flight test without the costly expense of conducting a mission flight test for collecting the appropriate data signatures for evaluation.