Automatic VSAT antenna pointing system featured with non-horizontal alignment autocorrect

Abstract

This paper presents the development of an automatic pointing system for very small aperture terminal (VSAT) antenna. The system which uses AVR microcontroller as a main controller unit (MCU) is featured with non-horizontal alignment autocorrect. User interface is implemented using android smartphone connected wirelessly to the MCU using bluetooth module. The android smartphone also reads the latitude and longitude position of the VSAT antenna location using global positioning system (GPS) module for calculating the required azimuth and elevation pointing angle to the satellite. In case of non-horizontal aligned VSAT antenna, the calculation of azimuth and elevation angles for alignment autocorrect is provided through additional compass and accelerometer modules. The mechanical system uses elevation-over-azimuth configuration with offset-fed for VSAT antenna parabolic reflector with the diameter of 0.74m. The system has been tested to point towards the Palapa-D satellite located at 113°E. The pointing time takes less than 3 minutes, while the average speed of azimuth and elevation rotations is 6.3° per second with the load of 30kg. The differences of pointing angle obtained from the calculation are 2.7” and 17.3” for azimuth and elevation angles, respectively.