The Ground Station basically consists of (1) Antenna & Receive System (2) Archival & Quick Look Browse System (3) Test Facility and (4) Support systems (Communication Networks; UPS and Standby DG power systems etc.)

•  Antenna Receive System: Antenna Receive System can be broadly represented by the following block schematic diagram.

Antenna & Tracking Pedestal: The Antenna is a dual shaped parabolic solid reflector of 7.5 m. dia meter with a shaped hyperbolic sub-reflector of 0.736-m. dia meter. The main reflector is made out of 16 Nos of radially stretch formed panels having 1.6mm thick aluminium sheeting and duly stiffened by aluminium ‘Z' sections. The front end feed system is a composite multi element monopulse type in a cassegrain configuration capable for S and X band reception. The Tracking pedestal is an Elevation over Azimuth mount type steel structure. Each axis is driven by a pair of Brushless DC/AC servomotors coupled in an anti backlash mode through reduction gearboxes and slewring bearings. The electro mechanical brakes, tachometers, torque couplings, shaft encoders, limit switch assembly, manual crank drive and stow-lock arrangements are housed at appropriate locations in the pedestal housing.

Servo Drive System: A closed loop higher order Servo control system of type I/II having high gain and narrow and wide band features with high acceleration and precision tracking accuracy. The system can be operated in different modes selectable from a PC in remote mode and also from a front panel of the servo Electronics unit in local mode. The system operates in Manual rate and in Auto Track in local mode and in a Programme Track mode from a PC in remote selection. Low maintenance, high speed, Brushless Servomotors with associated IGBT based servo controllers drives the antenna with precision control. Antenna position information is derived using optical encoders.

Receive System: The front end feed sub-system receives the R.F. Signals transmitted by the satellite through the Antenna. These R.F signals after due amplification and division flows through Synthesized Down Converter units where in it under goes down conversion to Intermediate Frequencies at 720 MHz (for X-Band) and 70MHz (for S-band). The 720MHz IF data signal flows through two sets of Multi Function Data Demodulator & Bit synchronizer (Demod / BSSC) units. The Demod / BSSC units extracts data & clock after necessary Demodulation, Bit Synchronization and Signal Conditioning outputs them to the Data Archival & Quick Look Browse system (DAQLB) for further processing.

Salient Features of the antenna & Servo System

Direct Archival and Quick Look Browsing System (DAQLB)

The DAQLB System is configured around a high end PC/Server system having internal RAID, Advance Front End Hardware (AFEH) Units, Digital Linear Tape (DLT) drive units, Precision Timing System and High speed Interfaces. The real time data and clock output of the BSSC units along with time code is fed to AFEH units through Data path Controller. The AFEH after performing the Frame synchronization and word synchronization of the payload data transfers it to RAID of DAQLB system. Several Custom built Software modules contributes in generating the mission specific level zero products for each satellite in a defined time line. After necessary processing in near real time the system generates Sensor wise Payload data, quick Browse data and Ancillary data. The sensor data recorded on Super DLTs will be sent to Balangar for necessary further processing. Where as, the quick Browse data and the ADIF data will be transferred to Balanagar through the dedicated Networks.

The Ground Station is equipped with several DAQLB systems to take care of the Direct Archival and Quick Look operational requirements of different satellites. All systems are inter connected through a Network Back Bone consisting of Switches, Routers, Hub etc, to have flexibility in scheduling of systems & also to serve for redundancy and backup needs.

•  A general block schematic depiction of DAQLB System

Timing System

Ground Station is maintaining its own Universal timing system to an accuracy of a few microseconds using Global Position System (GPS) and distributing to all DAQLB systems. The Timing System consists of precision Time Code Generators, Time Code Translators, Time Distribution unit, GPS Receivers.

Test Facility

Routine testing Antenna Receive and data archival chain of each Terminal is conducted using stand Test set up. Qualitative and Quantitative validation of the complete chain will be evaluated. It has mainly Local Loop Testing and Boresight Radiation Testing. The test set up includes a Custom built Data Simulator and Boresight Antenna system with mission specific suit cease model.

•  Support Systems

Communication Networks

Shadnagar Ground Station is having dedicated communication links with Space Craft Control Centre (SCC), Bangalore and Data Processing Centre, Balanagar. Space Net communication using INSAT Satellite is providing voice and limited data transfer network. A dedicated 2 Mbps Fiber optic leased link between Ground Station and Balanagar is providing data transfer in a limited way.

UPS &D.G. Power System

Ground Station is having Uninterrupted Power Supply (UPS) system providing quality power to all critical Equipments. The Station self-reliament in its captive power Generations having multiple D.G. sets with high redundancy supporting the daily operations.