ISRO Telemetry, Tracking and Command Network (ISTRAC), Bengaluru is entrusted with the major responsibility to provide tracking support for all the satellite and launch vehicle missions of ISRO. ISTRAC has also been mandated to provide space operations support for Deep Space Missions of ISRO. For supporting Deep Space Missions, a large number of ground stations are required to provide Telemetry Tracking and Command (TTC) support during the launch and initial phase. Based on the launch vehicle trajectory and visibility requirement, many a time, the TTC stations are to be located in mid sea, wherein, conventional Ground Station Antenna will not be suitable. In order to cater to these specific requirements, ISTRAC has designed and developed a 4.6 meter Ship Borne Transportable (SBT) Antenna Terminal that meets the launch vehicle TTC requirements.
The SBT Antenna system consists of 3-axis Antenna Mount, a Motion Simulator, Reflector & Feed, Servo Control Systems and RF Electronics. Mechanical Systems Area (MSA) of ISTRAC made a detailed study of the technical requirements, availability of similar systems internationally and derived state-of-the-art specifications. The major design challenges in this system are: Development of a 3-axis antenna mount to compensate for the pitch, roll and yaw disturbances of the ship during tracking of the launch vehicle; Design and develop a motion simulator to simulate the base disturbances experienced by the ship during sea state condition; Flexibility for change over from S-Band TTC station to X-Band TTC station with minimum hardware changes; Packaging the entire system within in the standard ISO container is a very important requirement towards shipping to other countries; and Redundancy in drive systems.
The final system performance and validation was carried out by a sea trial, wherein, the Antenna system was integrated on SAGAR MANJUSHA Ship hired from National Institute of Ocean Technology (NIOT). The ship was stationed at a specified observation point in Bay of Bengal and has successfully tracked PSLV-C38 launch vehicle from predicted Acquisition Of Signal (AOS) time (T+60sec) to Loss Of Signal (LOS) time (T+596sec) in auto track mode. The quality of the data acquired was as per the prediction.
The Antenna system was realised with the participation of Indian Industries and has been tested and validated on a motion simulator. ISRO has built this 4.6 meter Ship Borne Antenna System indigenously, fulfilling all the specifications and has established in-house capability for meeting future requirements. It also improved the operational reliability due to in-house know-how of the system engineering, besides reducing the cost considerably.
By: ISRO Gov
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