Subscriber terminals using Amplitude Companded Single Sideband (ACSSB)

With the introduction of amplitude companded single sideband (ACSSB) modulation, and other innovations, small subscriber satellite terminals providing voice and up to 2400 bit per second (bps) data capability have been produced. These terminals address a class of applications that requires: access to the public switched telephone network (PSTN); reliable voice and data communication; modest capital and operating costs; ease of installation and operation; and in some cases, portability. This paper discusses applications, design goals and characteristics of subscriber terminals, concluding with two representative network scenarios. Applications of these terminals differ from those best served by very small aperture terminals (VSATs) by offering low startup costs and by servicing primarily voice traffic. Fold-up antennas and compact reliable radio frequency (RF) electronics have made highly portable terminals a reality also. Private networks are possible using simple circuit sharing techniques while larger networks can utilize circuit switching to achieve significant economies in operating costs. Recent regulatory changes have paved the way for increased activity and development in these markets.