How It Works
Our project consists of three parts: the antenna, the FPGA board and an Android phone with the SDRoid application. The antenna receives a wide range of frequencies which can include Bluetooth, WiFi, 3G or 4G network signals. The signal is sampled by the FPGA board which is controlled by the SDRoid app. The SDRoid app allows the user to choose the modulation type and frequency, the FPGA then downconverts the signal accordingly. After the downconversion is done, the signal is transmitted to the phone through the audio jack and demodulated in software.
The antenna is sensitive to frequencies from 100kHz to 1MHz. It amplifies the signal, adds a 2.5V offset and lowpass filters before being sampled by the ADC.
The purpose of the FPGA Digital Down Conversion (DDC) board is to directly sample the antenna signal, shift a signal down to baseband, and convert the signal back to an analog signal before being sent to the smartphone.
The software for this project was written as an application for the Android operating system, and it was written in Java, which is the default language for the platform. The software has four main components: user interface (U.I.), audio recording, signal processing and audio output. Each of these components are run in separate threads for optimal performance.
The SDRoid app that we have developed has two demodulation types: AM and voice. Because signal processing is all done in software, other wireless protocols can be added with simple software updates.
- Allow police and rescue services to use one device for radio communications and information display
- Military able to use adaptive frequency bands and varying encryption through software updates
- Implemented within future smartphones to allow connectivity to future 5G networks with software update
- Aftermarket attachment for current smartphones to upgrade network connection
- Enable any network provider the use of any type of phone
- Reduce electronic landfill