Microcontroller Unit (MCU)
Decision Logic & Timer

Solenoid Valve Control
(Gas Shut-Off)

Alert & Notification Module
(Buzzer, LED, LCD, IoT)

Microcontroller (Tx)
Sensor Data → Encoding → FSK Modulation

Piezoelectric Transducer
(Acoustic Transmission)

Water Channel
(Transmission Medium)

Hydrophone
(Acoustic Reception)

Pre-Amplifier
(TL082/LM386)

Band-Pass Filter
(3 kHz - 5 kHz)

Microcontroller (Rx)
ADC → FSK Demodulation → Data Output