ORIGINAL ARTICLE European Journal of Applied Physics www.ej-physics.org DOI: http://dx.doi.org/10.24018/ejphysics.2021.3.1.42 Vol 3 | Issue 1 | January 2021 13 I. INTRODUCTION The evolution of technology has always accompanied armed conflicts in the world. Many inventions emerged as a direct consequence of the two world wars. Radar, tanks, and even the discovery of the nuclear bomb and its impact were major inventions that gave its users an advantage over enemies. We can affirm in these situations that they allowed the countries that had them to have clear advantage over all their opponents. The concept of information-seeking dates to the period of ancient China when Sun Tzu, a brilliant General and Chinese strategist, argued that information was crucial to gaining an advantage over an opposing force in a given strategic situation [1]. In this way, we can infer that telecommunication plays a fundamental role in the defense of each country. In addition, the technological means are constantly evolving, and the latest inventions allow information to be obtained in an increasingly rapid and credible way. Thus, by using technologies, it is possible to detect, eliminate or cause casualties in the enemy, increasingly, with the minimum commitment of our forces. The concept of time becomes very important in a conflict. Thus, the faster the information is disseminated, the faster the decisions can be taken by the command, which will make the actions/missions that the militarized forces perform in the different theaters of operation more likely to succeed [2]. This means that the military needs media that allow the upward flow of information to the commander and descendant flow towards the subordinates to facilitate the necessary coordination on the battlefield of the different missions during the battle. In addition, it is necessary that there be different programs that integrate and concentrate information in a central body (high military ranks) to enable the two essential functions in the Army, Command and Control (C2). Thus, the objective of this dissertation is the development of an optical communication system for implementation in the military vehicles, and to accomplish this objective it is necessary: to carry out a previous study of the optical communication systems in the world; explain the framework of the theme in the current panorama in the Portuguese Army; to carry out the determination of the system parameters taking into account all the limitations of the project and to validate all the work done through system block simulations as well as system-wide simulations. II. THE STATE OF ART A. Optical Communication System An optical communication system presents in its constitution numerous functional blocks, with the fundamental objective of exchanging information between two terminals, usually referred to as transmitter and receiver. The amount of information that can be transmitted in any communication system is directly related to the bandwidth of the signal sent, which in turn directly relates to its working frequency. Thus, when optical signals are used in the communication, it is possible to guarantee very high Tactical Communications between Military Vehicles André Filipe da Silva Ferreira, Maria João Martins, João Paulo N. Torres, and António Baptista ABSTRACT The increasing evolution and development of telecommunications as well as the need for wider bandwidths to comply with the users’ needs, has led to the development of the so-called free space optical communications. The advantages of optical communications in comparison to radio frequency communications draw interest for certain military applications. This paper describes the simulation, development and implementation of an optical communication system which integrates the various functional blocks of the optical emitter and the optical receiver and presents some theoretical considerations about the specific characteristics of the propagation of the optical signals in free space. The implementation of this system in military vehicles to allow wider bandwidth in military communications, as well as to function as an alternative system to the used systems, is one of the objectives of this dissertation. For this purpose, two circuits (emitter and receiver) were projected and designed including the design of printed circuit boards (PCB) and performed some simulations of the optical part of the complete system and the electronic simulation of some parts of the electronic circuits. Keywords: Military, Communication, Vehicles. Published Online: January 10, 2021 ISSN: 2684-4451 DOI :10.24018/ejphysics.2021.3.1.42 André Ferreira Academia Militar, Lisboa, Portugal. João Torres* Instituto Superior Técnico and Academia Militar, Lisboa, Portugal. (e-mail: joaoptorres hotmail.com) Maria Martins Academia Militar, Lisboa, Portugal. António Baptista Instituto Superior Técnico, Lisboa, Portugal. *Corresponding Author @