A novel electronic lock using ultrasound Morse code based on FIR filter

This study was based on the Internet of Things (IoT) architecture to propose an ultrasonic Morse code electronic lock for a home access control and safety system. Audio components of a smartphone were employed for ultrasonic Morse coding. Once the password of the receiver is confirmed to be correct through a microphone and micro-controller decoding, the details about the unlocking personnel and unlocking actions are uploaded to cloud server via Wi-Fi. In addition, because noise frequency of an environment influences ultrasonic Morse code determination, this study proposed the use of Moving Average of Median Filter to process microphone sound signals so that the unlocking device is free from environmental noise influences. This study consists of four sections: 1. Ultrasonic Morse code generator; 2. Ultrasonic Morse code decoder; 3. Digital filter; and 4. MediaTek Cloud Sandbox integrated cloud monitoring system. The experimental results indicated that the proposed electronic lock can remain fully functional in a noisy environment, including coding, transmitting, receiving, filtering, decoding, uploading, and remote monitoring processes. Moreover, the operating interface is simple and user friendly, making it applicable to users of varying ages.