Advanced Communications Technology Satellite (ACTS)

Technology

Earth Stations

T1VSAT

T1 very small aperture terminals (T1VSAT) were developed for NASA by the Harris Corporation to work with the on-board processor and prove that small terminals could be used with spot beams in a single-hop, full mesh network. Using a 1.2-meter antenna, these terminals provided a full 1.8 Mbps on-demand service at data rates from 64 Kbps to 1.8 Mbps for voice, video and data.

They operated using time division multiple access (TDMA) in a demand-assigned multiple access (DAMA) scheme. Communications to the spacecraft occurred at a burst rate of 27.5 Mbps (uncoded) and 13.75 Mbps (coded). The spacecraft burst traffic at 110 Mbps (uncoded) and 55 Mbps (coded) to these terminals.

Maximum EIRP: 60/66 dBW. Maximum G/T: 16/22 dB/K. Modulation: 5 MSK for uplink and downlink. Nominal BER: 5x10^-7(10 dB fade margin).