AbstractThis paper proposes the real time implementation of CDMA, a multiple access technique, which brings forth the complete bandwidth usage by spreading the data of same transmitted power, over the whole bandwidth thereby ensuring safe communication and preventing the occurrence of jamming. GNU Radio is a software defined radio which puts experiments into practice using software rather than the normal hardware implementation. Blocks for data spreading, code despreading with and without code tracking are created using Zero Correlation Zone code (ZCZ, a combination of ternary codes that is 1, 0 and -1 which is specified in the program). Thus the real time implementation of CDMA checks the feasibility of an asynchronous multiuser communication among users with good results.