Study On High-precision Measuring And Data Processing For GNSS Anti-jamming Receiver

When Global Navigation Satellite System(GNSS)is applied in military fields,such as aircraft landing and drone cluster flight,the problem of high-precision positioning in interference environment must be resolved.High-precision measuring and data processing are two challenges for the GNSS anti-jamming receiver.For the high-precision measuring,traditional space-time adaptive processors(STAP)based on power inversion(PI)criterion and minimum variance distortionless response(MVDR)criterion introduce pseudo-code and carrier phase tracking biases.When the vector of the GNSS signal is known,some researches propose the modified MVDR algorithms which constrain the linearity phase characteristic of the equivalent channel.However,extra inertial device is needed to get the vector of the GNSS signal.For the high-precision data processing,ambiguity resolution(AR)and cycle slip detection and repair are two important issues.Multi-frequency observations are now available and how to use the multi-frequency observaitions to improve the performance of the ambiguity resolution and cycle slip detection and repair needs to be studied.In this paper,high-precision measuring and high-precision data processing for GNSS anti-jamming receiver are studied.The main works are as follows.1,Space-time adaptive processor(STAP)based on the PI criterion can effectively suppress interference for GNSS receiver when steering vector of the GNSS signal is unknown.However,existing space-time PI processing methods will introduce meter-level pseudo-code tracking biases into the GNSS receiver measurements which cause several-meter-level position errors.A distortion less pseudo-code tracking space-time PI algorithm is proposed.The major novelty of the proposed method is ensuring the symmetry of output signal’s cross-correlation function by constraining coefficients at the expense of about half of temporal freedom degrees.Several experiments are implemented to test the performance of the proposed algorithm.For comparison,the results of the PI algorithm and the MVDR algorithm are also shown.Results show that for the PI algorithm and the MVDR algorithm,pseudo-code tracking biases are introduced in different experiments;however,for the proposed algorithm,there are no pseudo-code tracking biases in those experiments.As a result,the effectiveness of the proposed method is verified.The proposed algorithm is majorly for PI criterion,but it is also applicable to MVDR criterion.2,STAP algorithm based on the PI criterion can cause carrier phase biases.A distortion less carrier phase tracking space-time PI algorithm is proposed.The proposed algorithm maintains the real value properties of the temporal tap coefficients by constraining the weights at the expense of about half of spatial freedom degrees.Several experiments are implemented to test the performance of the proposed algorithm.The results of the PI algorithm,the MVDR algorithm and the proposed algorithm are shown for comparison.Results show that when the number of interferences is less than half of the number of antenna elements,the proposed algorithm can mitigate the interference by implementing null at the directions of the interfernces and there is no carrier phase bias;when interferences vary,different degrees of carrier phase biases are introduced into the PI algorithm and the MVDR algorithm,however,there is no bias introduced into the proposed algorithm.As a result,the effectiveness of the proposed method is verified.The proposed algorithm is majorly for PI criterion,but it is also applicable to MVDR criterion.3,Because of different parameters of code tracking,the measure noise of code on each frequency is different.An unequal-weighted triple frequency ambiguity resolution(TCAR)algorithm for long-baseline static triple-frequency ambiguity resolution is proposed.The algorithm is conducted in cascaded steps.When calculating the coefficients of the extra-wide-lane(EWL),wide-lane(WL)and narrow-lane(NL)combinations,the difference of pseudo range noise is considered.Real triple-frequency BDS observations are analyzed to evaluate the performance of the proposed algorithm.Results show that compared to the classical equal-weighted algorithm,the proposed algorithm shows a comparable performance for the EWL and WL ambiguity resolution and much better performance for the NL ambiguity resolution.4,Due to the development of GNSS,quadruple-frequency signals are now available in China’s Bei Dou Navigation Satellite System(BDS)and the European Galileo system,which can contribute to positioning precision.A method using four linear combinations to detect and repair quadruple-frequency cycle slips is proposed in the paper.Ionospheric residual is modeled as bias and combined noise is modeled as variance of the normal distribution and the fixing probility of the cycle slip fixing can be calculated.The choices of the four linear combinations are conducted in cascaded steps in accordance to the cycle slip fixing probability.When the four detection combinations are determined,cycle slips on original carrier phase observations can be uniquely determined.The proposed algorithm has been tested on real 30-second quadruple-frequency static observations of BDS and Galileo and on real 0.05-second quadruple-frequency kinematic observations of BDS and Galileo.Simulated and real cycle slips are tested.The results show that the proposed algorithm can detect and repair cycle slips even for one cycle effectively.Finally,we summary the main work and present the future work.