The main aim with any modern digital communication systems is to provide error free data transmission. To achieve this aim, error control coding techniques are applied with these systems. In this paper, digital communication system was implemented based on convolutional code, aided by soft-bit decoding for error free transmission. Fixed length source encoder was represented with this work, and statistically described the output of the source encoder and save this description at the receiver as a priori knowledge about the source encode. These a priori knowledge were exploited at the receiver to improve the performance of the proposed system in term of BER by conceal the errors occurred through the transmission of information over AWGN channel, aided the convolutional encoder. Significant improvements were obtained with this proposed system.