A REVIEW OF THIRTY YEAR’S DEVELOPMENTS AND RESEARCHES ON UNCODED QPPM SYSTEMS

Abstract

In recent years the researches and applications of QPPM systems in telemetry have drawn much attention, but there are still some problems to be clearified and solved. In this paper we reviewed the classical literatures on un-coded QPPM systems which were published in the past thirty years. After analysing the conclusions and related derivation presented in these publications, we got: 1) M.J.F, Golay and JRA Jacobs stated that the QPPM’s efficiency ß may indefinetely approach Shannon theoretical limit with as small error probability as desired as soon as one can appropriately choose the parameters of the system. In our opinion, this conclusion cannot hold true. In fact, the efficiency curve ß = F(α) of QPPM is only similar in form to the Shannon theoretical limit and there is still a large difference. 2) In past 30 years Golay and the others analysed merely the relation between the word error probability PWE and the efficiency ß , They didn’t study the relation between the bit error probability PBE and ß . Some authors regarded QPPM’s PWE as being equal to other digital system’s PBE, and concluded that QPPM is better than the other systems. We consider that this is not appropriate. 3) In order to remedy the untouched problem, we derived the relation PBE =F(α) of QPPM system. As it is seen from these relation curves that the required α of QPPM is 4.CdB~4.4dB more than the ß of coherent detection PSK system when PBE=10^-4 and α varries from 2 to 100. (ie. the efficiency of QPPM is worse than PSK.)