Long-Range Low-Power Wireless Sensor to Monitor Temperature and Humidity of Dairy Calves

This paper presents a low-power wireless sensor for monitoring the temperature and humidity of dairy calves over extended distances. The wireless sensor consists of a microcontroller with a LoRa^® radio, temperature and humidity sensors, and a power controller. The sensor samples data once every minute and remains in sleep mode most of the time. To save power during sleep, the power controller shuts off power to the sensor. The sensor was prototyped, and its operation was verified in a field test with three calves. The sensor is active for data sensing, processing, and transmission for about 458 ms in each cycle and dissipates an average of 16.13 mW during the active period. It is estimated that the sensor would operate for approximately 33 months using a CR2477 coin cell battery with a sampling rate of one data point per minute.