The INMARSAT-3 payload remote terminal unit

The INMARSAT-3 payload remote terminal unit (PRTU) provides the major telemetry and telecommand interface between the payload and the spacecraft TT&C subsystem. Its primary functions are: generation of high level pulse commands; and acquisition of analogue and status telemetry. The quantity of command and telemetry channels dealt with is substantial. Consequently the PRTU serves to simplify the spacecraft to payload interface and enhances the capability of the TT&C subsystem