Techniques Of Constant Envelope Transmitting And Robust Receiving For Modern GNSS Signals

New signal design features are adopted in modern Global Navigatin Satellite System,and thus significantly improved the signal service performance.But meanwhile,they also introduce new challenges for both the satellite transmitters and user receivers that process modern signals,especially the constant envelope signal generating and robust signal receiving.The thesis concentrates on technologies of signal generating and receiving,mainly the key technologies of constant envelope signal generating and robust receiving,and the following six aspects are studied:(1)We present the asymmetric dual quadrature phase shift keying modulation,and extend its basic form to two generalized forms,including unequal power and dual-frequency forms.The new modulations could realize the constant envelope transmitting one QPSK signal and two binary coded signals.The asymmetric dual quadrature phase shift keying modulation can combine regional open service signal and global open service signal on BDS B1 band with power efficiency of 82.4%,better than power efficiency of Majority Voting technology,which is just 72.6%.The dual-frequency asymmetric dual quadrature phase shift keying modulation can combine regional open and authorized service signals and global civil service signal on BDS B1 bnad with power efficiency of 76.05%.(2)We present a generalized dual-frequency constant envelope modulation named generalized constant envelope binary offset carrier modulation.The new modulation realizes constant envelope transmitting arbitrary numbers of dual-frequency signals with unequal power allocation,which breaks the constrainst of the traditional dual-frequency modualtions.The backward compatibility problem of transmiting the regional QPSK signal and the global dual-frequency signals on B2 band can be solved by adopting the new modualtion.Meanwhile,the asymmetric AltBOC modulation with arbitrary power allocatin on two sidebands is proposed.It can also solve the backward compatibility problem of BDS B2 band t with the power efficiency of higher than 74.13%.(3)We present the cosine-phased general removing ambiguity via side peak suppression acquisition method,which can solve the problem of unambiguous acquisition the cosine-phased BOC signal and break the constraint of traditional general removing ambiguity via sidepeak suppression acquisition method.For low-order BOC signal,such as cosine-phased BOC(10,5)signal,the new acquisition method has similar performance as the double sideband acquisition method,and outperforms the the single sideband acquisition method.Meanwhile,In order to solve the problem of serious detection performance loss applying the side peak suppression method to high-order BOC signal,we present a new ambiguity removing technique for high-order BOC signal.The new technique significantly outperforms the side peak suppression acquisition method in acquisition performance.(4)We present an unambiguous BOC signal acquisition technique under dynamic conditions,which is based on the idea of dynamic delay compensation.By proposing a variable fractional delay filter design method based on iterative least square with the minimum detection loss,we can solve the problem of serious acquisition performance loss of normal acquisition methods.Assume the search step of carrier Doppler is 500 Hz,the correlation losses of sine-phased and cosine-phased BOC signals are 1.8dB and 2.2dB respectively when one-order variable fractional delay filter is adopted.Meawhile,the correlation losses of two types of BOC signals are 1dB and 1.2dB respectively when three-order variable fractional delay filter is adopted.(5)We present the cosine-phased pseudo-correlation function based unambiguous delay lock loop,which solves the problem of unambiguous tracking cosine-phased BOC signal and extends the application range of traditional pseudo-correlation function based unambiguous delay lock loops.By adopting the idea of side peak suppression and considering the characteristic of cosine-phased BOC signal,a new group of local code can be generated,which is used to construct the new unambiguous discriminator.The new delay lock loop outperforms the traditional dual side band method both in tracking performance and multipath mitigation performance,and the multipath error envelope area increases only 30% compared with that of match receiving.(6)We present the pseudo-correlation function based unambiguous multiplex delay lock loop for high-order BOC signal.By adopting several groups of local codes,the new unambiguous discriminator is constructed and solves the problem of serious tracking performance loss using traditional pseudo-correlation function based delay lock loop for high-order BOC signal.The new delay lock loop outperforms the traditional delay lock loop in tracking performance.Meanwhile,a new loop structure with two combined loops is proposed,which extend the dynamic pull-in range to a whole code chip,and posses the advantages of wide pull-in range and high ranging precision.Finally,the research work of this thesis are summarized and reviewed,the future work is also presented.The main researches can be used in related projects of BDS and othr global satellite navigation systems.