(1185) AN IMPROVED EDUCATIONAL SOFTWARE FOR LEARNING SPREAD-SPECTRUM COMMUNICATIONS OVER A REAL ACOUSTIC CHANNEL USING AUDIO HARDWARE

摘要

Focusing on the subject “Signal processing for communications” taught in the Master ofTelecommunication Engineering at University of Jaen (Spain), it is difficult to learn advanced digitalcommunications because the student must have a deep mathematical background and master thefundamentals of digital communications explained in previous subjects of TelecommunicationEngineering Degree. This paper is an improved and extended version of a previous work titled“Enhancing the transference of knowledge of topics about advanced digital communicationstechniques using a multimedia interactive simulator” published in the 6th International Technology,Education and Development Conference (INTED) in 2012. Specifically, we propose educationalsoftware for learning direct sequence spread-spectrum communications over a real acoustic channel(it ranges until 20Khz) using audio hardware such as multichannel audio interface, loudspeakers and amicrophone. The proposed software evaluates a multiuser transmission scenario in which a realtransmission has been considered, in other words, each received signal from a user is notsynchronized with the rest of the users. Each loudspeaker is used to generate the transmission ofeach user while the unique receiver of the system is implemented using only one microphone. Allstages of a direct sequence spread-spectrum (DSSS) communication system have been implementedand adapted to use the acoustic channel, such as spreading codes, modulation using an audiblecarrier, synchronization… In order to achieve a powerful and reliable tool of self-learning, each studentcan modify a set of parameters related to the spread-spectrum communication system evaluatingdifferent transmission scenarios. The advantage of the software proposed is that each student canobserve all temporal-spectral transformations suffered by the input signal at each stage of thecommunication system from the transmitter to the receiver. Due to the use of an acoustic channel,each student can heard how each signal sounds before and after the spreading transformation. Allthese complementary information increases the efficiency of the transference of knowledge betweenlecturer-students. New material associated to direct sequence spread-spectrum communications hasbeen created. The student must study the content of the material and interacts with the proposededucational software in order to complement the theoretical concepts explained in classroom. Thematerial and the educational software will be available in the web-based platform Integriertes Lern-,Informations- und Arbeitskooperations-System (ILIAS) of the University of Jaen. In this way, theautonomous study of the student is reinforced using the web-based platform resources.