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1) What are the major components of a satellite?
All communication satellites have two major sub-systems, the communications payload and the "bus". The communications payload is the system that relays customer signals from an on-board transmitting station back to the earth to either single (point to point) or multiple receiving stations, the downlink (point to multi-point).
2) What is a payload?
The payload consists of the high gain antennas, receivers, multiplexers (MUX's), and power amplifiers (transmitters - SSPA, TWTA, HPA, etc.). We call the signal path inside the spacecraft a "transponder". Customer signals are received on an antenna at a specific frequency and polarization. The signal then passes through an input MUX (chanellizer), is amplified, and passes through an output demultiplexer (another type of MUX, also known as a combiner). To efficiently utilize the available broadcast spectrum, the signal is converted to a different frequency and polarization. The signal is then re-transmitted back to the ground to a downlink on earth.
3) How robust is the system carrying my signal?
Many different levels of redundancy are available to the customer. From backup components, to moving the signal from one transponder to another, or even possibly moving the signal to another satellite, many levels of protection are available, depending upon the needs of the customer.
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