Showing papers on "Telecommunications link published in 1974"

Transmission of 4Ø-Phase-Shift Keyed Time-Division Multiple Access over Satellite Channels

Abstract: The design of 60 Mbit/s/180 Mbit/s time-division multiple-access (TDMA) channels for the European Communication Satellite (ECS) system is analyzed and a possible configuration is suggested [1]. The effects of adjacent-channel interference, nonlinear power amplifiers both on the ground and in space, uplink and downlink noise are investigated and results are shown. Methods for carrier recovery are investigated and comparisons made. The complete channel design includes pulse-shaping filters, satellite filters, limiters before each TWT, and a filter after the earth-station TWT to limit the radiated spectrum.

Optimal Channelization in FDMA Communications

Abstract: For most efficient performance in frequency-division multiple access (FDMA), a hard-limiting repeater should be operated completely channelized (i.e., each uplink carrier should be individually filtered and power-controlled prior to spacecraft limiting and downlink transmission). When there are a large number of uplink carriers involved, however, complete channelization is no longer feasible, and the uplink carriers must be grouped together (assigned frequencies), which allows joint filtering and amplification. In this correspondence, it is shown that an optimal grouping procedure always exists for minimizing required repeater power, no matter how many carriers and groups are to be used.