Constellation Overview
The atContact network will use a constellation of seven spacecraft to provide a broad range of wideband telecommunications services, including two-way, wide-band data transport, multimedia services and private network services. The data rates are in a range from 75 Mbps to 750 Mbps for the downlink (space-to Earth) direction and 0.5 Mbps to 700 Mbps for the uplink (Earth-to-space) direction. The actual data rate will depend on the desired link availability, earth terminal antenna size, type of service, etc.
The system’s earth terminal users will be able to communicate with any of the satellites in view, whether GSO or non-GSO. The user terminals will be equipped with tracking antennas so that they can maintain continuous transmission with the satellites in view – a feature that is particularly useful for the three non-GSO satellites that will operate in highly-elliptical orbits (HEO). User earth terminal antenna sizes will range from 0.7 m to 2.7 m in diameter, depending on the applications and the desired link availability.
The system will use fixed-satellite service (FSS) spectrum in the Ka-band frequency ranges for its communications links. In the Ka-band, between the non-GSO and the GSO satellites, the bands 18.3-19.3 GHz, 19.7-20.2 GHz, 28.35-29.1 GHz and 29.5-30 GHz will be utilized.
The system will use fixed-satellite service (FSS) spectrum in the Ka-band frequency ranges for its communications links. In the Ka-band, between the non-GSO and the GSO satellites, the bands 18.3-19.3 GHz, 19.7-20.2 GHz, 28.35-29.1 GHz and 29.5-30 GHz will be utilized.
Each satellite will use two megahertz of spectrum in each direction of the extended C-band frequencies, 3650-3700 MHz for downlink and 6425-6525 MHz for uplink, for transfer orbit and on-orbit emergency telemetry and command (TT&C) operations. For regular on-orbit operations, the satellites’ TT&C subsystem will uses two megahertz of spectrum in each the 19 and 29 GHz bands for telemetry and for telecommands.
The HEO satellites will operate in the 19.7-20.2 GHz and 29.5-30 GHz on a secondary, non-unacceptable interference basis. The geosynchronous, circular-orbit satellites in the non-GSO component will not operate in the 19.7-20.2 GHz and 29.5-30 GHz bands. In the Ka-band, the system plans to use small earth terminal antennas, in a range from 0.7 m to 1.2 m.