Store-and-forward message switching using polar-orbiting microsatellites

The University of Surrey have demonstrated that microsatellites can implement store and forward message switching networks involving hundreds of small ground terminals. These satellites, called PACSATS (packet satellite), use packet radio techniques and advanced onboard computers. The new UoSAT onboard computer uses a real-time, multitasking operation developed by Quadron Services Inc. Programmers write the satellite software in the `C´ language, and use standard development, simulation and debugging tools running on MS-DOC PCs. Programs are tested using a spacecraft emulator based on a standard IBM 80186 coprocessor card installed in the developer´s PC. This environment has permitted the relatively rapid development of sophisticated store-and-forward communications protocols for the satellite onboard computer