Relatively Moving Target Return Emulation for high Coherently Processed Time-Bandwidth Products

The accurate modelling of relative target motion is essential for coherent radar processing and suitable emulation approaches for radar testing. Special consideration will be required if an instantaneously wide signal spectrum is processed over a long timespan and a non-stationary target return migrates in relative range. Thereby, a fast moving isotropic point scatterer will span concurrently a set of distinct Doppler frequencies and range cells. The often used, processing inherent, short-term narrowband motion approximation becomes then too inaccurate. This publication describes the Doppler effect modelling for relative fast target motion with a conceptual modelling principle, which is independent of the spectral content in the processed radar bandwidth. It is founded on the intentional sampling clock difference between two clock domains. Based on this principle, conceptual approaches have been tested to verify its real-time capability for moving target response emulation and modelling. In addition, the sampling rate transfer requirement in DSP based bistatic radar architectures is highlighted. Further, experimental moving and effectively accelerated target returns are related to emulated and simulated return shapes by the use of a coherently received multi-carrier OFDM waveform with digital reference.