Droidtracer: traçador de curvas de resposta em frequência

Abstract

The frequency response of a system is one of the most important tools to analyse and describe circuits and systems, whether they are known or not. The acquisition of the frequency response of electrical circuits can be a costy process, since readings are made at several different frequencies with the operation of an oscilloscope and a wave generator. This problem becomes even worst when the system or circuit is unknown, since the operator does not know the critical frequency points, where the variation of the frequency response is more abrupt. Therefore, the goal of this project is to develop a device that is capable of acquiring the frequency response automatically. To do so, the Droidscope acquisition system was used as the device basis, Droidscope is an undergraduate thesis developed at UTFPR in 2017. Droidscope is capable of acquiring signals at the audio frequency range and display these signals on any Android device. The capability to integrate with mobile devices is of great value, as it significantly increases the usability of the system. This paper covers the development of a signal generator circuit and the modifications made on the original Droidscope system, in order to improve its performance and adapt its operation to fit the frequency response drawer needs. In order to provide the ability to change the characteristics of the generated signal quickly and flexibly the signal generation technology used was the direct digital synthesis. The result of this project is a device capable of obtaining the frequency response of unknown circuits and present this response graphically on any Android device.