The Research Of Low-complexity Demodulation For Multi-h CPM

With the fastly development of aeronautical telemetry, in order to improve theapplicability of military aeronautical transfer capacity, American military hammered atsearching new aeronautical telemetry to replace the PCM/FM telemetry which has beenused for ten years. Multi-h CPM has been elected as aeronautical novel telemetry Tier IIby Advanced Range Telemetry(ARTM) due to its constant envelope, continuous phaseand three times the spectral efficiency of PCM/FM. At the same time, Multi-h CPM isadopted as part of the IRIG-106standard. Although Multi-h CPM technology has manyadvantages, it has high demodulation computation complexity so that restrict theapplication of Multi-h CPM.Firstly, the paper introduces the common expression and phase state of Multi-h andinvestigates the performance of Multi-h CPM from bandeidth efficiency point of viewWe draw a conclusion that the bandeidth efficiency of Multi-h CPM is higher thancommon CPM at the expense of high computation and complexity.Secondly, from the point of view noncoherent scheme, via computer simulations,we analyse the performance of Limiter-Discriminator, Phase Differential, NoncoherentSequence Detector and One-symbol Differential Trellis Detector proposed in the paper.Considering the performance and complexity, the result shows that the One-symbolDifferential Trellis Detector proposed in the paper can regard as optimal noncoherentdemodulation scheme.To improve the performance of Multi-h CPM, we research the methods of Multi-hCPM coherent demodulation: Maximum Likelihood Sequence Detector, OptimalDemodulation based on PAM decomposition and Suboptimal Demodulation based onPAM decomposition. The analysis result shows that the suboptimal demodulation basedon PAM decomposition scheme can reduce complexity efficiently, and the loss can beignored. Therefore, the suboptimal demodulation based on PAM decomposition schemeis regarded as optimal coherent demodulation scheme.Finally, we research the modulation index estimation approach based on periodicity,high-order statistics and CPM cyclic property. And then, we research how to distinguishthe Multi-h CPM modultaion index by the three estimation methods. At last, we drawthe conclusion that the approach based on periodicity and high-order statistics can beused full-response Multi-h CPM. And, the novel Data-Aided recognization approachpresented in the paper is applied to each Multi-h CPM signals.