Research On The Key Technology Of The Baseband Signal Processing In Satellite Receiver

With the continuous development in China’s aerospace industry, developTracking and Data Relay Satellite System(TDRSS) can be described as a generaltrend in China. Since the type of satellite communication system is diversified and theequipment management and maintenance works is very complex and hard，it has agreat practical significance to research the TDRSS with software method.According to the high dynamic characteristic of TDRSS，based on the detailedanalysis of the key problems in traditional system，this thesis have designed a suite ofscheme of the baseband signal processing which consists of signal acquisition, signaltracking, signal dispreading and demodulation three parts, and mainly discussed thekey technology of this method：signal acquisition and signal tracking.Aimed at the disadvantage in acquisition rate of traditional signal acquisitionmethod, this thesis made an improved signal acquisition method base on theDFT-IDFT algorithms, which can obtain the same accuracy with only5%averageacquisition time than the traditional algorithm when SNR is greater than-16dB.Aimed at the disadvantage of narrow effective range in traditional PN codetracking method, this thesis made an improved PN code tracking method base on thetraditional delay locked loop.It owns the same accuracy as conventional method,butcan provide an1times wider effective range. It also has a strong ability in continuoussignal tracking.Aimed at the disadvantage of narrow effective range and low applicationflexibility in traditional carrier tracking method，this thesis put forward a new signalcarrier tracking method based on a high-resolution Fourier transform algorithm,whichcan works at any degree of accuracy in any effective range.Besides，this thesis also put forward a new bit synchronization method combinedwith the specific characteristics in this subject. Compare with the traditional mehod, itis more directly on the synchronization and has less overhead.With the verification by DSP software simulation, the scheme mentioned in thisthesis can do acquisition and tracking works for baseband TDRSS signal with anyfrequency offset, and can also work on well with the signal dispreading anddemodulation. This thesis provide some theoretical and technical basis of satellitesoftware receiver，meanwhile，there are also some detail need to optimize andimprove in its practice.