Alternate architectures and technologies for Intelsat type DSI design

The architectural choices in the unit design have to do with the amount of storage and the type of storage in the unit, the type of high-speed interface, the type of echo-protection features, the FEC encoding, and the degree of human interface for testing and maintenance. Since the interpolation process takes time, the unit is by necessity memory-oriented, and an efficient choice of memory architecture is cardinal. The two principal design choices are referred to as 'oorder and storage' and 'storage and order.' Store-and-order implies storage of data on all received channels (regardless of whether they are to be processed), followed by data routing for selected channels. Order-and-store implies immediate selection of the traffic to be processed. The architecture is also affected by the choice of interface between the DSI (digital speech interpolation) and the 'satellite' side equipment. Although the principal choice is between word- and bit-oriented data transmission, tradeoffs exist involving handshaking for control signals as well.