  A moving target may enter a radar coverage area unannounced and leave after
an unspecified period, which implies that the target's entry time and departure
time are unknown. In the absence of these time information, target detection
and parameter estimation (DAPE) will be severely impacted. In this paper, we
consider the coherent detection and parameters estimation problem for a radar
moving target with unknown entry time and departure time (that is, the time
when the target appears-in/leaves the radar detection field is unknown),
involving across range cell (ARC) and Doppler spread (DS) effects within the
observation period. A new algorithm, known as window Radon Fractional Fourier
transform (WRFRFT) is proposed to detect and estimate the target's time
parameters (i.e., entry time and departure time) and motion parameters (i.e.,
range, velocity and acceleration). The observation values of a maneuvering
target are first intercepted and extracted by the window function and searching
along the motion trajectory. Then these values are fractional Fourier
transformed and well accumulated in the WRFRFT domain, where the DAPE of target
could be accomplished thereafter. Experiments with simulated and real radar
data sets prove its effectiveness.
