The attitude of synthetic aperture radar (SAR) antenna cannot be fully controlled or precisely measured, which causes the ambiguity of Doppler centroid and thus degrades the image quality. A few Doppler ambiguity resolvers (DARs) have been developed by evaluating image quality, which focus on the data with all possible ambiguity numbers until the maximum image contrast or the minimum image entropy is found. Despite of their robustness on various cases, these approaches rely on repeatedly focusing the data, resulting in a heavy computational load. A new DAR that successfully employs the property of range profiles is proposed, and this approach greatly improves the efficiency while keeping robustness.