Broadcasting is a fundamental operation in any wireless network, more so in wireless sensor networks, where each sensor node has limited transmission range as well as battery power. Broadcasting protocols for wireless sensor networks are required to simultaneously minimize resource usage and optimize performance metrics such as latency and reliability. Broadcasting becomes even more challenging, when nodes in the networks are duty cycled and sleep scheduling is asynchronous. In this paper, we propose a Coverage-based Adaptive Preamble Broadcasting (CAPB) Protocol, which utilizes the MAC layer preamble sending property before the data packet, counter-based approach with the area-based schemes in order to exploit the maximum advantage of these approaches. Our algorithm is compared against a fix probabilistic technique. CAPB maximizes the reach ability and rebroadcast saving while consuming the minimum possible power of the sensor nodes. CAPB also achieves higher throughput as compared to probability-based broadcasting scheme.