Integrated Turbo Decoder for Validation of Baseband Data handling System

The function of baseband data handling systems in the satellite is to encode and format the payload data suitable for the transmission on a noisy channel. For deep space missions the encoding technique to be used as per the guidelines of CCSDS is Turbo Coding for Eb/No of 0.7dB. Coding gain achieved at the ground stations using Turbo Codes is approximately 8 dB with BER of 10-6. This is better than 3dB compared to other codes. Thus turbo codes are preferred in deep space missions where power consumption at the satellite is critical (signal power is not being increased beyond a value due to implementation reasons). To test the data handling systems, payload simulator, acquisition and processing system is used. The processing system does the data decoding and de-formatting of the data to extract the actual space packets. This can be implemented either in hardware or software. The processing systems for data decoding used have multiple functionalities and are also expensive. The cost effective and user friendly solution is the software implementation of the turbo decoder. This paper presents the test system and its modules used for validating the data handling system. The paper emphasizes on Turbo decoder rate ${\textstyle\frac{1}{2}}$ implementation in C- code using SOVA algorithm.