A Two-Step Compressed Sensing Approach for Single-Snapshot DOA Estimation of Closely Spaced Signals

Algorithm 2

The proposed two-step CS-based algorithm.

	Input:
	The observed single-snapshot signal ;
	A new double-structure measurement matrix for preestimation, ;
	A new double-structure measurement matrix for the second step, ;
	Output:
	The DOA estimator, ;
(1)	Divide the initial search space into () parts to construct the overcomplete dictionary matrix .
(2)	Generate the measured signal and the sensing matrix .
(3)	Calculate the DOA rough estimator using the OMP method [40].
(4)	Narrow the search space as based on the rough estimator, where .
(5)	Divide the search space into parts to construct the overcomplete dictionary matrix .
(6)	Generate the measured signal and the sensing matrix .
(7)	Calculate the DOA accurate estimator using the OMP method in [40].
(8)	return.