Design and implementation of a APRS Target Tracking System

Abstract

The aim of this project is to develop a target tracking system using APRS packets for the GranaSAT group. This group will use as a Stratospheric balloon that will send the APRS packets in a modulated signal using the Bell 202 standard (AFSK1200). During the development, an incremental approach will be used to obtain functional versions of the software in a reduced time, increasing its capabilities in each iteration. As for the main programming language, Python will be used in its version 3.X. To process the signals, a demodulator will be built applying different DSP techniques. Then, the necessary parameters to align the antenna to the target will be calculated using an ellipsoidal model of the Earth. These parameters determine the position of the rotor, which will be controlled by Hamlib, and finally, all information collected will be stored in a SQLite database. The result is a system that is mainly composed of a VHF antenna, a rotor that allows the antenna to be aligned, an RTL-SDR device to receive the signal from the target and an industrial computer with the software to manage all of the above. As for the software, it can be run autonomously without user intervention and is capable of automatically restarting in the event of unexpected errors, so as not to loss the tracking of the target. Finally, different tests will be carried out on the system to verify the compliance with the proposed objectives.