What is a military satellite communication system and european communications satellite system?

What is a military satellite communication system and european communications satellite system?

1. Military satellite communication system
Military satellite communication systems provide military users with covert, reliable, interconnected services covering a wide area. Military communication satellite System satellites meet high data transfer rates, including beyond line-of-sight (LOS) mobility services for military aircraft, helicopters, ships, and personnel pods. Both DSCSIV and MILSAT-COM provide reliable and covert communications capabilities, serving both strategic and tactical communications requirements. The system provides high interference immunity, nuclear scintillation protection and physical survivability in harsh space environments. Its battery pack power requirements are greater than 3.75kW, while the solar panels must be designed to provide more than 12.5kW of output power for a seven-year satellite life and more than 15kW for a 10-year satellite life.

What is a military satellite communication system and european communications satellite system?
Military satellite communication system

2. Eutelsat communications satellite system
The European Telecommunications Satellite System (EUROPSAT) provides communications and telecommunications services for European countries and North Atlantic Treaty Organization (NATO) forces. The system provides covert communication services, especially for NATO forces. The system was launched in 1994 and provides telecommunications and data transmission services across the European continent. The TWTAs, rated at 580W and 620W of output, constantly charge the onboard batteries via large solar panels. The working life of the satellite is about 7 years. Interstellar relays at mmWave frequencies (36 ~ 38 GHz) can be accommodated with minimal cost and complexity. In every communications satellite, once the satellite is at a designated station, its attitude must remain fixed to keep the antenna beam oriented. As mentioned earlier, attitude control and stabilization of each satellite or spacecraft is very important, despite the adverse effects of uncompensated motion from gravitational gradients, Earth’s magnetic field, solar radiation, and interfering forces acting on the satellite. . To eliminate the effects of uncompensated motion, some kind of stabilization mechanism is necessary, which is accomplished by rotating the satellite in orbit at a rate of 30 to 100 r/min. A spin-stabilized device means that a given solar panel is effectively illuminated by the sun only 1/π or 32.8% of the time if the solar cell is not spinning. The battery capacity will be only 1/π of the value it could have achieved, and this particular issue must be considered in battery design choices. Larger solar panels may require a dual-spin configuration. Even higher solar panel output may require three-axis stabilization technology to achieve higher output power from solar panel to onboard battery charging. The satellite communication system uses nickel-cadmium batteries to meet the 2.5kW DC power requirement, which will require a solar panel rated at over 20kW.

What is a military satellite communication system and european communications satellite system?
Eutelsat communications satellite system