Research On Code-aided Carrier Phase Synchronization Algorithm At Low SNRS And Strong Phase Noise

Humans have been exploring the universe environment beyond the earth, anddeep space exploration is an important way and method to understand the universe.Deep space exploration aims at objects as far as tens of thousands of meters away,the energy of electromagnetic wave degrades as in proportion to the square oftransmission distance in space. Meanwhile, the mobility of the space explorer,making carrier parameters of the weak signal more variable and further reducingthe SNR of the received signal, results in the information of the receiver can not bedecoded. Therefore, unique transmission features of deep space communicationspresent new challenges to the estimation and detection technology of weak signalreception. The main work of this paper is divided into two parts, the first is to buildan information-reduced carrier synchronization system, and then propose a rotationmetric function and give complete phase ambiguity resolutions.Through a detailed analysis of the coding and decoding processes, weoptimizes the construction of the parity check matrix and a applicable constructionproposed for deep space communications effectively and improved the receivergain of the baseband signal. Code-aided carrier phase synchronization has beenintroduced. However, the input of the loop includes modulated data in classicalschemes, it will suffer from squaring loss. For example, the squaring loss of theCostas loop is1.76dB when the SNR is equal to0dB. This thesis describes anexcellent IRCS system, the decision information is transferred between the LDPCdecoder and the synchronization module. The soft information of the decoder canassists in removing modulation data, suppressing the cross product of the signaland the noise, thereby eliminating the squaring loss. Simulation results show that inthe range of0.4dB to1.7dB, the loss of the bit error rate (BER) curves of theproposed system are in less than0.2dB relatively ideal system, proving that a goodsolution to the problem squared loss.Phase ambiguity problem in carrier synchronization systems is rarelyconcerned, but it is one of the major difficulties of practical applications. This workanalyzes the the disadvantage of the prefix sequence method, then we employ theinformation of the decoder output, and establish a rotating metric function RMF toidentify the ambiguous phase shift. Finally, simulation results show that, theaverage estimates of the system can be captured within±180ophase shift, the offsetof the root mean square phase error remain in1orelative to the MCRLB and theBER of the proposed system approximate to the performance of the idealsynchronized system.