Digital Satellite Phone Terminal System (DSPT system or DSPS) project involves setting up a VSAT (Very Small Aperture Terminal) Based network for BSNL. The system consists of HUB Station and Remote Digital Satellite Phone Terminals working in Ku-Band (Transmit Frequency is 13.75-14.5 GHz and Receive is 10.7-12.75 GHz). DSPT Network provides PSTN connectivity to rural, remote, inaccessible and hilly areas via INSAT (Indian National Satellite) or leased transponder for DTS network. The VSAT system works in a star topology using DAMA (Demand Assigned Multiple Access) technology. For BSNL VSAT network the Hub shall be located at Sikanderabad (A.P.), adjoining Delhi, in Uttar-Pradesh and there shall be 15000 DSPT remotes located over several states in India with higher proportions being in North, North East and East provinces.
The Hub of DSPT system will be composed of Indoor and Outdoor facilities. The outdoor facility is a complete Antenna and RF path while the indoor comprises the Hub Base-band and the other equipments:
The Hub of DSPT system comprises of Indoor facilities and Outdoor facilities.
Indoor facilities: Indoor facilities has following components,
a. Hub Base-band
b. Transit switch.
In the Indoor facility consists of redundant Hub-base band unit, a Transit switch to provide connectivity to PSTN network, associated Data-Base servers, Billing system consisting of Billing system Hardware and software, the data networking equipment consisting Firewall, web-server, Authentication server and router to provide backend connectivity to the Internet. The base-band and remotes have a NMS and its database to configure and manage the entire VSAT-based network.
a. Antenna (8.1 Meter antenna assembly): In the Outdoor facility has an Extended motion antenna assembly, which is controlled by 3-phase Elevation and Azimuth motors. The Antenna consists of a Cass-grain Feed Horn with Hyperbolic dish at focus of antenna.
b. RF path: RF path consists of Transmit chain and Receive chain.
Transmit chain consists of
-ULPC (Up Link Power Control),
- Up Converter and
- SSPA (Solid State Power Amplifier) and
Receive chain consists of
- Trance reject filter,
- Radar reject filter,
- LNA (Low Noise Amplifier),
- Power divider and Down converter.