Phase-Gradient autofocus (PGA) technique is

robust over a wide range of imagery and phase error

functions but the convergence usually requires 4-6

iterations. In this paper, we propose to speed up the

estimation convergence by selectively increasing the pool of

quality synchronisation sources and not to be limited by the

range pixels of the SAR map. This is highly probable since

each range bin contains more than 1 prominent scatterers

across the integration aperture. It is also highly probable

that the least brightest selected scatterer in a range gate may

turn out to be of higher energy as compared to the

maximum brightest scatterer of another gate. With

appropriate target filtering to final select the quality

scatterers out of the large pool and higher-order phase error

measurement tool, the new algorithm achieves near

convergence quality without iteration. We named this

solution the Quality PGA algorithm (QPGA).