Demand Control Ventilation Communication System

The purpose of this project is to produce a more energy-efficient method of transmitting data from a carbon dioxide sensor to a receiver. In current configurations, carbon dioxide sensors send data via Wi-Fi to a controller connected to a heating, ventilating, and air conditioning unit, which processes the data and adjusts its output to condition the air. Wi-Fi power consumption decreases the battery life of the carbon dioxide sensor. The proposed design, which uses less power than Wi-Fi, is an optical communication system that transmits sensor data via light-emitting diode to a receiver that interprets the signal. The design borrows technology from existing infrared remote controls and modulates the LED signal, which results in a higher signal-to-noise ratio at a given power output. The electrical output of the sensor is modulated at 57.6 kHz, which is faster than typical infrared applications. The modulated LED then sends pulses at 940 nm toward a specialized receiver that filters this wavelength and driving frequency. The receiver decodes the data and displays the output on a viewing screen.