Abstract:

In the University Center of Defense (CUD) of the Spanish Naval Academy (ENM) a degree in Mechanical Engineering is taught. The compulsory subjects of naval intensification, placed in the 4th and 5th year, allow students to supplement their knowledge in the naval world which is where they will play its professional activity.

The subject of "Radiocommunications Systems" (SRCOM) is one intensification subject and is essential for the future of a Navy Officer. The aim of SRCOM subject is to provide students with a basic training, both theoretical and practical, on the principles of radio communications. The practice part of the course is composed of several experiments related to analog and digital modulation, antennas and radiowave propagation, that allow students to put theory into practice.

Traditionally, various kits of training equipment solutions have been used. However, these predefined experiments do not perfectly suit to the subject’s program. The experiments are focused on students with deeper knowledge in telecommunications topics and are too specific, leading to a difficulty on the adjustment of practices to the theoretical contents of the subject. Those kits are very closed and do not allow to experiment with new radio technologies. Furthermore, they work with simulated signals, so sometimes students lose the perception of the reality of what they are doing.
To achieve the "learning to learn" task involved in the Bologna process, students must build their knowledge from their own learning and experience. In many cases, students do not have enough time to acquire this knowledge through experimentation or they do not have access to facilities when they want. In addition, radio receivers are generally expensive for the university and unaffordable for students, so their experience outside the laboratory becomes impossible.

The recent outbreak of Software Defined Radios (SDR), where traditionally hardware components are substituted by software, have revolutionized the way we understand and manage radiocommunications. Radio equipment based on SDR devices are a fact as they are present in many communications equipment. However, the educational use of the SDR equipment is virtually no-existent.

The current state of technology allows low cost portable SDR receivers to tune emissions in a simple way with almost no experience and little effort. The great flexibility of this equipment allows a perfectly adaptation of the practice part of the subject to the theory objectives and makes possible to learn outside the classroom, something unthinkable until now. To achieve this, the student only needs a low-cost SDR receiver, a computer and some free software.
This paper presents a new teaching methodology for practicing radiocommunications where subject learning outcomes and skills are acquired and strengthened through experimentation with an SDR device that can receive, display and analyze radio transmissions in different bands and of different nature.

Therefore, a very flexible tool adaptable to the radiocommunication subject in any related university degree has been discovered; furthermore this contribution represents a cost reduction compared to the expensive and closed "training kits" which are avoided making a significant saving for the Centre. Finally, experimentation with radio transmissions of the "real world" allows the students to assimilate concepts better and definitely motivates the alumni achieving surprising results.