A Low-Cost Multimodal Detector for Emergency Signals and Closed-Loop Search Guidance: A Prototype Study Using Controlled RF, Audio, and Vibration Tests. J. High School Res. [Internet]. 2026 Jul. 2 [cited 2026 Jul. 26];3(1):91326003-1:91326003. Available from: https://jhsr.net/index.php/jhsr/article/view/46