Software radio modulated transmission interception: SOF-TI

• Main Authors: Echavez, Christian D., Espina, Nicola V., Gironella, Jan Angelo A., Macalintal, Katrina Cyril M.
• Format: text
• Language: English
• Published: Animo Repository 2008
• Subjects: Software radio; Radio > Receivers and reception > Design and construction; Signal processing > Digital techniques
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/14622
• Institution: De La Salle University

Telecommunications has advanced with the abundance and introduction of new protocols, standards and encryption year after year. The results of these advancements can be seen from the 3G cellular phones that make video streaming possible to the VOIP (Voice over Internet Protocol) that allows people to call over the internet. However, these advancements which were meant to make life easier for people have also resulted in certain difficulties. These difficulties arise when it comes to compatibility between different devices and the hardware used to communicate between them. As a result there has been a shift on the paradigm of communication technology. Instead of combining different types of hardware receivers in order to address the variety of existing protocols and standards, a single receiver system interfaced to a computer would be used. The software on the computer would not only control the hardware receiver but also demodulate/decode the signal. By doing so, this would allow the user to modify, refine, and add features to the system by altering codes of the software. The goal of software radio is to create a device that would be able to receive and transmit data. This device should be able to adapt, adjust, and integrate with existing and future protocols and standards with ease, in other words a future proof device. A receiver front-end, which has functions that can be controlled using a software interface, was implemented. Varactor diodes, which have capacitance that is determined by the voltage across it, and voltage controlled oscillator were essential in implementing the receiver front-end. The implementation of software demodulation for AM and FM, and the underlying issues such as decimation are discussed in this paper. The system was not implemented in totality due to the problems of interfacing the ADC and the DSK. The tests done on hardware and software modules show acceptable results with regards to control, bandwidth, effectiveness of subsampling, and analysis of demodulated signals.