Date of this Version
The University of Nebraska has developed an ultra-wideband (UWB) random noise radar system which transmits an ultra-wideband random noise (Gaussian) waveform with a uniform power spectral density (PSD) in the 1-2 GHz frequency range. The ability of the system to characterize the Doppler shift of moving targets exhibiting varying linear and rotational velocities was clearly demonstrated [l, 2]. In this paper, we look at the range and range rate resolution issues by analyzing the Woodward’s ambiguity function . In general, the radar signal ambiguity function is defined as the normalized response of a filter matched to a return signal with range rate V0 to a return signal with range rate V1. It describes the resolution properties of a given signal in range and range rate. However, for a random noise radar a correlator matched to transmit process is required. Therefore, an analogous ambiguity function may be defined as the expected value of the response of the correlator matched to a target moving with range rate V0, to the return signal from the target with range rate V1. Moreover, for a UWB transmit random process, the compression or stretch due to the range rate on the envelope of the return process cannot be ignored.