Implementation of Message Queuing Telemetry Transport Protocol in Model Rocket

Abstract

Microcontroller devices are incorporated in the flight computer that convey data to the ground station in the design and implementation of model rocketry. In the field of rocketry, data transfer speed and precision are critical. Due to its small code footprints and low network bandwidth requirements, the Message Queuing Telemetry Transport (MQTT) messaging protocol tackles both of these issues. MQTT uses Transmission Control Protocol (TCP) which ensures packet delivery, as opposed to User Datagram Protocol (UDP), which is faster but does not guarantee packet delivery or even the sequence in which packets are delivered. MQTT also uses a single connection to send messages, making it faster than Hypertext Transfer Protocol (HTTP), which requires a three-way TCP handshake every time a message is transmitted. This paper describes how to incorporate MQTT messaging protocol to the flight software to facilitate communication between the onboard computer and the ground station. Publish and subscribe architecture in MQTT was utilized where the onboard computer published sensor values to particular topics and the ground station subscribed to these topics so as to receive the data. This communication was facilitated by MQTT broker that acted as an intermediary between the two clients. From field tests carried out, data transmission was found to be fast and reliable as all the data packets transmitted were received from a distance of 300 m, the onboard computer and the ground station were able to interact through Wi-Fi, and the sensor data from the onboard computer was plotted and displayed on the ground station dashboard. Keywords— HTTP, Microcontrollers, model rocketry, MQTT,MQTT broker, TCP, UDP