Error Rate Control in Humidity and Temperature Sensors Using IoT and ThingSpeak

Abstract

Internet of things (IoT) in recent years became widely spread over several applications, and use different types of sensors, actuators and software tools. This paper focuses on DHT11 humidity and temperature sensor accuracy; many experiments were conducted to measure readings in different environments and on different sensors.

Readings were uploaded over online server (thingSpeak), from NodeMCU ESP2566 board. Uploaded data were analyzed for different cases. Results showed that in normal conditions, the temperature variance between three sensors was below 0.3 Celsius degrees, and below 2% for humidity. But when added external source of heat and humidity for 10 minutes, the temperature variance increased to 1.4 Celsius degrees and 11% for humidity. To verify the measurements of temperature, an LM35 sensor was added to compare with DHT11 temperature readings, it was found that the readings were almost the same and difference is less than 0.8 Celsius degrees.

It found that accuracy in DHT sensors is fair, especially with applications where readings change in a normal pattern. To alleviate error rate in fluctuating environments, averaging for multiple readings is required to get more accurate values.