Abstract:

The conceptual idea of the authors of this article is to develop software for the implementation of an APRS-based tracker designed to train students studying Masters courses at higher technical schools in Computer and Communication Systems as well as Hardware and Software Systems.

The article presents software modules of the APRS ™ (Automatic Packet Reporting System) based tracker, which is a type of digital amateur radio packets used to determine real-time location of a subject. It has been developed and approbated in the educational process at the Faculty of Physics of the University of Paisii Hilendarski.

APRS is an individual national channel that provides a mobile radio amateur link around the world, which can be used to track real-time events in the surrounding area from 10 to 30 minutes. The information that is transmitted on the network may include short messages, SOS alerts and meteorological conditions reports. The APRS network is well-developed in all countries around the world as the main carrier frequency in each continent varyies from the country’s standardization.

The APRS based tracker is an engineering solution that is a product of the successful operation of the APRS network with the reliability of the GPS system. Students acquire lasting knowledge and skills to work with APRS trackers linked between GPS and radio that modulate data on AX25 and APRS protocol and radios that transmit data to the global APRS network., The device with a host of up-to-date applications is available thank to the combination of modern microcontrollers with appropriate software and APRS technology.

The engineering tasks undertaken by students in the implementation of the device are limited to: appropriate choice of microcontroller, development of I/O board, selection and development of suitable software for correct operation and testing the reliability of the device.

The article demonstrated the functional tests of the developed software modules and presents the results of the conducted outdoor test - the GPS module connects with satellites for 6 seconds; repeated indoor test- in order to get a more accurate result (for which the GPS (Global Positioning System) module connects from 14 to 90 seconds). Also, the article shows the results from a conducted test in a moving vehicle at an average speed of 50 km/h. In this case, the GPS module connects to satellites for about 2 to 5 minutes.

The choice of network communication focuses on the fact that the APRS network is developed globally and there are the so-called orbital APRS repeaters. It is flexible even in cases when one or more of its units fail and can produce real-time communication and collaboration with advanced technologies.

The developed APRS tracker can be applied to the following spheres: mountain tourism and mountaineering, expedition missions in hard-to-reach areas, forest fires, organizing and managing long-term rescue operations after a natural cataclysm, organizing and maintaining the operation of rescue posts, searching and transporting people in hard-to-reach mountainous terrain at the request of competent authorities.

Keywords:

SOS, Automatic Packet Reporting System, Global Positioning System.