This paper considers the performance enhancement of a space-time turbo codes processing system employing a combined turbo code and antenna transmission diversity scheme for direct sequence spread spectrum communication system. Turbo codes have been shown to approach the Shannon limit for error correcting capability at low signal-to-noise ratios given large sized frames. Extensive research efforts have been examining ways to enhance the performance of turbo codes for
short frames (e.g., voice transmission). The proposed system is investigated over Rayleigh fading channels only and also in case of narrowband jamming environment in addition to Rayleigh fading channels. This paper focuses on the implementation and performance of a modified turbo decoder for this model. Furthermore, the description of the concatenation of turbo code and direct sequence/spread spectrum with a space-time block codes are presented. Simulation results show that substantial benefits can be obtained by direct sequence spreading with space time coding the coded bits over Rayleigh fading and narrowband jamming environment.