The aim of research is the adaptation of code division multiple access (CDMA) technics for a radio frequency identification systems based on surface acoustic waves technology. The object of this research is a pseudo-random code of CDMA systems. The question of increasing the pseudo-random code vocabulary size, while maintaining good correlation characteristics is under consideration. The criterion for quality of pseudo-random code is the level of multiple access interference (MAI). This criterion is estimated by the maximum level of aperiodic correlation function between each pair of code words. The solution of the problem is achieved by signal processing and does not affect coding issues. A code is generated with necessary vocabulary size and a minimum level of MAI is achieved by using dual correlation processing. The concept of dual correlation processing is to seek a correlation function for two weakly dependent information features of the code. An additional informational sign is the amplitude spectrum of a code word. The correlation characteristics of the code after processing are modeled.