Indian Journal of Science and Technology

Abstract

Background: Data Handling Unit (DHU) is a one of the most important units of Command and Data Handling System (CDHS) in a satellite. The unit is responsible for Telemetry (TM) acquisition and Tele commands (TC) Execution and onboard communication management through shared and dedicated links. Objectives: This paper presents an effective COTS based implementation of DHU for micro satellites. Methods: Controller Area Network (CAN) is used in the proposed system as shared communication link. It is preferred over I1 C because of higher immunity to losses. Redundancy is very important in a satellite system, since on-site maintenance is not possible after its launch. In order to add redundancy to this system, direct links and dual redundant CAN is added to the system. Findings: Two different designs are presented for Data Handling Unit. In the first design FPGA has been used as central processor and its advantages and disadvantages analyzed. The second design based on PIC microcontroller is proposed. Paper also presents the software design for TM, TC, CAN, and Analog to Digital Converter (ADC) and UART. Results presented in the paper show successful testing of individual modules as well as the complete system. Simulation based testing was done for hardware having simulation models. In other cases, hardware based testing was performed by displaying result on onboard LCD and on PC using UART. Application: The proposed DHU can be used in weather monitoring satellites, aircrafts for communication of flight sensors data and automobiles for effective communication between sub-systems.

Keywords: Micro-Satellite, CAN, DHU