For the distributed target in spherically invariant random vector clutter
a dual-threshold GLRT detector with constant false alarm rate (CFAR) property is derived.The distributed target
which is modeled as a subspace random signal
may be distributed both in range and in Doppler frequency axes.The cell whose signal-to-clutter ratio is higher is selected by the first threshold.Then the accumulation of energy is implemented in these selected cells
and it makes a final decision according to the second threshold.Assuming that the normalized clutter covariance matrix is known
the dual-threshold GLRT is devised.The probability of false alarm of dual-threshold GLRT is derived and it ensures CFAR property.And then according to a secondary data set to estimate the clutter normalized clutter covariance matrix
the adaptive detector is obtained.The performance assessment conducted by Monte Carlo simulation confirms the effectiveness and robustness of the proposed detector.