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Satélite de Coleta de Dados - SCD-3

The SCD3 system is a Brazilian effort toward a communication system using a small Low Earth Orbit satellite, and the Gateway Station design proposed for the system. A pilot voice communication system employing Code Division Multiple Access (CDMA) is considered in the SCD3 mission to validate such communication concepts. Message communication services and propagation characteristics measurements over the Equatorial region are also included in the system. The SCD3 system is composed by the SCD3 satellite with its onboard communication payload, by a set of voice and message user terminals and by a Gateway Station. The Gateway Station has the capability to transmit and receive four simultaneous beams with independent Doppler correction and channel power control.

The SCD3 space segment is composed by a three axis stabilized satellite, with 180 Kg weight and 185 W generated power, flying in an equatorial orbit of 1100 km altitude with a 2 hours period. Due to the SCD3 satellite design constraints, four beams are provided by phased array antennas in the L and S bands. Each beam can deliver up to 2 W in the S Band and 2.5 W in the C band.

The SCD3 Ground Segment comprises: a) the Satellite Control Center, located in São José dos Campos; b) three TT&C Stations, one of which portable, the fixed ones located at Cuiabá and Alcântara; c) the RECDAS Data Communication Network, which provides the data communication links between the Ground Stations, the Mission and Satellite Control centers and the Gateway Station; d) a Gateway Station with RF subsystem, voice baseband channel processing, message communication and propagation characteristics measurements; e) a set of voice and message terminals; f) a Data Collection Mission Center, located in Cachoeira Paulista, which receives, processes, stores and distributes the Data Collection Platform (DCP) messages; g) a number of small UHF Receiving Stations, which acquire DCP messages directly from the satellite, for storage and further processing according to the user application requirements.