Dodds, David2024-07-122024-07-121997-12December 1https://hdl.handle.net/10388/15796This thesis evaluates the suitability of various baseband line coding techniques for data transmission in a simultaneous voice and data environment. A method of using the existing telephone wires to provide Internet access as well as regular voice communication is being developed at Telecommunications Research Laboratories in Saskatoon. This method currently utilizes Apple Computer's LocalTalkTM transmission protocol at 230.4 kb/s. An alternative coding method is desired that will increase the data transmission rate while retaining the desirable transmission characteristics of the LocalTalkscheme. The data signal bandwidth is limited by high frequency attenuation of the telephone line and by low frequency filters used to separate the data and voice signals. Through computer simulation, a number of potential line coding methods were characterized by their power spectral density and eye diagram performance. These characterizations were used to evaluate data transmission capacity, error performance and potential interference with voice communication. Alternative coding methods were compared to the biphase method used for LocalTalkTM transmission. Bipolar-return to zero (BP-RZ) and bipolar-non return to zero (BP-NRZ) ternary coding provide the greatest potential improvement in data transmission rate while sacrificing the least in transmission performance. Other ternary codes are poor alternatives, due mainly to their dependence on low frequency transmission. Quaternary and pentary methods are also poor, due mainly to decreased separation between possible signal levels and resulting errors due to intersymbol interference. Integrated circuits are widely available for handling 2B1Q quaternary coding, and some related codes, such as balanced 3B2Q or 5B4Q, may be practical if intersymbol interference can be reduced through wave shaping or improved equalization techniques. Further, a new technique for spectral shaping of data sequences through insertion of extra symbols has been identified as a topic for further study.Thesis