Technology Study Of The Carrier Synchronization For Burst-Mode DSSS Signal Digital Receiver

Spread spectrum communication technology is widely used in the military communicationfield which requires high confidentiality and is coupled with a bad electromagnetic environment,due to its excellent capacity of anti-artificial interference, multi-path interference and intercept.Burst-mode communication means that the transmitter sends the information in the form of shortdata frames on the random time points in the communication process, because of the uncertain andshort transmitting time, the anti-intercept capacity of the signal is enhanced. By combining theSpread spectrum communication technology with burst-mode communication technology, we canimprove the communication system’s confidentiality and anti-interference capacity efficiently.Carrier synchronization is a key technology in the digital receiver, which is the premise andfoundation for receiver to correctly demodulate the received data, and decide the whole system canwork normally or not.This paper mainly researches how to fulfill carrier synchronization in the limited pilotsequence for burst-mode DSSS signal in the digital receiver under the situation of low SNR andlarge carrier frequency offset, then to correctly demodulate the follow-on information data, andestablish a reliable communications link. The research is done under the background of aburst-mode DSSS communication system research project.Firstly the paper introduces the development status and trend at home and abroad of spreadspectrum technology and carrier synchronization technology. The basic theories of spread spectrumtechnology and the technology of direct spread spectrum also have also been introduced.Secondly the frame structure of the burst-mode signal used in this paper is provided, theresearches which we did are around this signal structure from beginning to end. The general blockdiagram of the transmitter and receiver in the burst-mode DSSS communication system which weresearched is also provided, and we give some simple explanations to the important components ofthe block diagram.Then the capture method based on DMF of the burst-mode DSSS signal is discussed. Aquantitative analysis is done to the Doppler frequency shift which will produce a huge effect duringthe acquisition process. And the two dimension search strategy which combines the PN code’sphase with Doppler frequency is put forward and the basic theories of DLL are also introduced.After that, we develop this paper’s key further: carrier synchronization technology, and designtwo hybrid carrier synchronization schemes based on the frame structure of burst-mode signal: FFT+SongWeiLoop and FLL+SongWeiLoop, thereafter, the algorithm is simulated on Matlab. Thesimulation result shows that all two schemes can fulfill the carrier synchronization in the requiredpilot sequence of the burst-mode signal, under the system’s technical indicators, correctlydemodulate the follow-on information data, so the schemes which we designed is effective, and ofpractical value.Finally, the paper makes a summary about the finished work and indicates the following work.