Effective normal binary ordering in QAM compared with Gray coded scheme for enhanced voice quality in software defined radios

Quality means uniformity around a target value. The quality of transmitted voice is an important means of gauging performance of equipment and services related to voice communication. This paper shows how normal binary ordering in quadrature amplitude modulation (QAM) can be used in an effective manner for voice transmission purposes in a soft radio to give better quality results. This would be compared to the M-ary Gray Coded Mapping Scheme which has proved so far a vital tool in error correction. These comparisons apply under some shortcomings like the use of same number of quantization levels i.e. M number of quantization levels for a signal being fed to an M-ary modulator, e.g. using 16 level quantization along with 16-QAM. The paper will review the comparison of the two coding schemes used in modulation techniques for voice signals. The relative and accuracy of the two techniques would also be discussed. It will be shown that for the above mentioned scenario (M quantization levels and M-ary QAM), the normal binary coded QAM performs better than Gray-coded QAM. This being done, a second scheme is proposed which performs much better than the previous.