| The power-and-bandwidth-efficient modulations were developing in the deep space communication system for the long communicate distance and the increase telemetry. Continuous phase modulation (CPM) is a method for modulation of data commonly used in wireless modems. It is used primarily because continuous phase modulation has good spectral efficiency for a noncoherent modulation technique. Furthermore, CPM is typically implemented as a constant-envelope waveform. Therefore, CPM is attractive because the phase continuity yields high spectral efficiency, and the constant-envelope yields excellent power efficiency, those excellent character are applicable to the deep space communications.The primary drawback of the CPM signals is the high implementation complexity required for an optimal receiver, in this thesis, two kinds of demodulation schemes for the CPM signals are analyzed, the purpose is to reduced the complexity of the receiver and simplified the modulation. The signal model of continuous phase modulation is provided firstly, then the linearization representation (Laurent's decomposition) of CPM signals is investigated, it can be expressed as a sum of a finite number of time limited amplitude modulated pulses, this scheme can reduced the complexity of the receiver by detect the"main pulse". The algebraic receiver is based in a new estimation/identification theory that has also already been used for channel identification and signal deconvolution.Feher-patented quadriphase-shift-keying (FQPSK) is a kind of modulations that make up for the attendant small loss in power efficiency by offering a more significant improvement in bandwidth efficiency; its root is in cross-correlated PSK (XPSK). Based on the concept of CPM and XPSK, a novel modulation scheme named shaped quadrature phase-shift-keying (SQPSK) is presented for the deep space communications. We concentrated research on the Laurent's representation of the SQPSK signals and the detail spectrum analysis to SQPSK was carried out. |
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