A novel subspace projection anti-jamming algorithm based on spatial blind search is proposed,which uses multiple single-constrained subspace projection parallel filters.If the direction of arrival(DOA)of a satellite s...A novel subspace projection anti-jamming algorithm based on spatial blind search is proposed,which uses multiple single-constrained subspace projection parallel filters.If the direction of arrival(DOA)of a satellite signal is unknown,the traditional subspace projection anti-jamming algorithm cannot form the correct beam pointing.To overcome the problem of the traditional subspace projection algorithm,multiple single-constrained subspace projection parallel filters are used.Every single-constrained anti-jamming subspace projection algorithm obtains the optimal weight vector by searching the DOA of the satellite signal and uses the output of cross correlation as a decision criterion.Test results show that the algorithm can suppress the jamming effectively,and generate high gain toward the desired signal.The research provides a new idea for the engineering implementation of a multi-beam anti-jamming algorithm based on subspace projection.展开更多
The spoofing capability of Global Navigation Satellite System(GNSS)represents an important confrontational capability for navigation security,and the success of planned missions may depend on the effective evaluation ...The spoofing capability of Global Navigation Satellite System(GNSS)represents an important confrontational capability for navigation security,and the success of planned missions may depend on the effective evaluation of spoofing capability.However,current evaluation systems face challenges arising from the irrationality of previous weighting methods,inapplicability of the conventional multi-attribute decision-making method and uncertainty existing in evaluation.To solve these difficulties,considering the validity of the obtained results,an evaluation method based on the game aggregated weight model and a joint approach involving the grey relational analysis and technique for order preference by similarity to an ideal solution(GRA-TOPSIS)are firstly proposed to determine the optimal scheme.Static and dynamic evaluation results under different schemes are then obtained via a fuzzy comprehensive assessment and an improved dynamic game method,to prioritize the deceptive efficacy of the equipment accurately and make pointed improvement for its core performance.The use of judging indicators,including Spearman rank correlation coefficient and so on,combined with obtained evaluation results,demonstrates the superiority of the proposed method and the optimal scheme by the horizontal comparison of different methods and vertical comparison of evaluation results.Finally,the results of field measurements and simulation tests show that the proposed method can better overcome the difficulties of existing methods and realize the effective evaluation.展开更多
A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two mo...A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width （HPBW） is 113° in both the x-z and y-z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.展开更多
The integration of GNSS （Global Navigation Satellite System） and INS （Inertial Navigation System） using IMU （Inertial Measurement Unit） is now widely used for MMS （Mobile Mapping System） and navigation applica...The integration of GNSS （Global Navigation Satellite System） and INS （Inertial Navigation System） using IMU （Inertial Measurement Unit） is now widely used for MMS （Mobile Mapping System） and navigation applications to seamlessly determine position, velocity and attitude of the mobile platform. With low cost, small size, ligh weight and low power consumtion, the MEMS （Micro-Electro-Mechanical System） IMU and low cost GPS （Global Positioning System） receivers are now the trend in research and using for many applications. However, researchs in the literature indicated that the the performance of the low cost INS/GPS systems is still poor, particularly, in case of GNSS-noise environment. To overcome this problem, this research applies analytic contrains including non-holonomic constraint and zero velocity update in the data fusion engine such as Extended Kalman Filter to improve the performance of the system. The benefit of the proposed method will be demonstrated through experiments and data analysis.展开更多
A good design of LNA for S band satellite navigation receivers and 4G LTE wireless communication system has been implemented in this paper.Due to increased congestion in the present L band,the S Band frequency from 24...A good design of LNA for S band satellite navigation receivers and 4G LTE wireless communication system has been implemented in this paper.Due to increased congestion in the present L band,the S Band frequency from 2483.5-2500 MHz has been allocated for the future satellite navigation systems.For this purpose ATF-34143 amplifier(pHEMT)having high electron mobility and fast switching response has been chosen due to its very low Noise Figure(NF).The amplifier has been designed having bandwidth of 0.8 GHz from 1.8-2.6 GHz.Because of the large bandwidth,the amplifier could serve many wireless communication applications including 4G LTE mobile communication at 2.1 GHz.The design was implemented using the micro strip technology offering extremely low noise figure of 0.312 dB and 0.377 dB for 2.1 GHz and 2.49 GHz respectively.The gain of the amplifier was low and found to be 10.281 dB and 9.175 dB.For the purpose of increasing the gain of an amplifier,the proposed LNA design was then optimized by using Wilkinson Power Divider(WPD).The Balanced LNA design using WPD offered very low noise figure of 0.422 dB and 0.532 dB respectively and the gain was considerably increased and was found to be 20.087 dB and 17.832 dB respectively against 2.1 GHz and 2.49 GHz.Simulations and measurements were taken in Agilent Advanced Design System(ADS)software.The suggested LNA can be used for a variety of wireless communications applications including the future S band satellite navigation systems.展开更多
In this paper,we study scene image recognition with knowledge transfer for drone navigation.We divide navigation scenes into three macro-classes,namely outdoor special scenes(OSSs),the space from indoors to outdoors o...In this paper,we study scene image recognition with knowledge transfer for drone navigation.We divide navigation scenes into three macro-classes,namely outdoor special scenes(OSSs),the space from indoors to outdoors or from outdoors to indoors transitional scenes(TSs),and others.However,there are difficulties in how to recognize the TSs,to this end,we employ deep convolutional neural network(CNN)based on knowledge transfer,techniques for image augmentation,and fine tuning to solve the issue.Moreover,there is still a novelty detection prob-lem in the classifier,and we use global navigation satellite sys-tems(GNSS)to solve it in the prediction stage.Experiment results show our method,with a pre-trained model and fine tun-ing,can achieve 91.3196%top-1 accuracy on Scenes21 dataset,paving the way for drones to learn to understand the scenes around them autonomously.展开更多
Raw observations(carrier-phase and code observations)from the Global Navigation Satellite System(GNSS)can now be accessed from Android mobile phones(Version 7.0 onwards).This paves the way for GNSS data to be utilized...Raw observations(carrier-phase and code observations)from the Global Navigation Satellite System(GNSS)can now be accessed from Android mobile phones(Version 7.0 onwards).This paves the way for GNSS data to be utilized for low-cost precise positioning or in ionospheric or tropospheric applications.This paper presents results from data collection campaigns using the CAMALIOT mobile app.In the frst campaign,116.3 billion measurements from 11,828 mobile devices were collected from all continents.Although participation decreased during the second campaign,data are still being collected globally.In this contribution,we demonstrate the potential of volunteered geographic information(VGl)from mobile phones to fill data gaps in geodetic station networks that collect GNSS data,e.g.in Brazil,but also how the data can provide a denser set of observations than current networks in countries across Europe.We also show that mobile phones capable of dual-frequency reception,which is an emerging technology that can provide a richer source of GNSS data,are contributing in a substantial way.Finally,we present the results from a survey of participants to indicate that participation is diverse in terms of backgrounds and geography,where the dominant motivation for participation is to contribute to scientific research.展开更多
In view of the failure of GNSS signals,this paper proposes an INS/GNSS integrated navigation method based on the recurrent neural network(RNN).This proposed method utilizes the calculation principle of INS and the mem...In view of the failure of GNSS signals,this paper proposes an INS/GNSS integrated navigation method based on the recurrent neural network(RNN).This proposed method utilizes the calculation principle of INS and the memory function of the RNN to estimate the errors of the INS,thereby obtaining a continuous,reliable and high-precision navigation solution.The performance of the proposed method is firstly demonstrated using an INS/GNSS simulation environment.Subsequently,an experimental test on boat is also conducted to validate the performance of the method.The results show a promising application prospect for RNN in the field of positioning for INS/GNSS integrated navigation in the absence of GNSS signal,as it outperforms extreme learning machine(ELM)and EKF by approximately 30%and 60%,respectively.展开更多
Satellite signal simulator for global navigation satellite system(GNSS)can evaluate the accuracy of capturing,tracing and positioning of GNSS receiver.It has significant use-value in the military and civil fields.The ...Satellite signal simulator for global navigation satellite system(GNSS)can evaluate the accuracy of capturing,tracing and positioning of GNSS receiver.It has significant use-value in the military and civil fields.The system adopts the overall design scheme of digital signal processor(DSP)and field-programmable gate array(FPGA).It consists of four modules:industrial control computer simulation software,mid-frequency signal generator,digital-to-analog(D/A)module and radio frequency(RF)module.In this paper,we test the dynamic performance of simulator using the dynamic scenes testing method,and the signal generated by the designed simulator is primarily validated.展开更多
The theoretical aspects of the precise velocity determination of Low Earth Orbit (LEO) satellites'on board Global Navigation Satellite Systems (GNSS) receivers are derived. It shows that the receiver's Phase L...The theoretical aspects of the precise velocity determination of Low Earth Orbit (LEO) satellites'on board Global Navigation Satellite Systems (GNSS) receivers are derived. It shows that the receiver's Phase Lock Loop (PLL) is required to feature extremely small group delay within its low frequency band, which is in contrast to existing work that proposed wide band linear phase filters. Following this theory, a Finite Impulse Response (FIR) filter is proposed. To corroborate, the proposed FIR filter and an Infinite Impulse Response (IIR) filter lately proposed in literals are implemented in a LEO satellite onboard GNSS receiver. Tests are conducted using a third party commercial GPS signal generator. The results show that the GNSS receiver with the proposed FIR achieves 11 mm/s R.M.S precision, while the GNSS receiver with the IIR filter has a filter-caused velocity error that can not be ignored for space borne GNSS receivers.展开更多
For global navigation satellite system(GNSS)in the application of high earth orbit(HEO)determination,there are problems such as small number of visible satellites and weak signal magnitude.The transmitting and receivi...For global navigation satellite system(GNSS)in the application of high earth orbit(HEO)determination,there are problems such as small number of visible satellites and weak signal magnitude.The transmitting and receiving errors of GNSS signal in the environment of HEO space are analyzed,and related compensating scheme is also proposed.Acquisition of GNSS signal is implemented by using weak signal acquisition technology based on Duffing.Precise tracking of weak GNSS signal is also realized by adopting dynamic detection and compensation technology based on Duffing chaotic oscillator.Simulation results show that,certain acquisition sensitivity and navigation precision can be reached,and the acquisition and tracking of weak GNSS signal can be realized by using the proposed technology,which provides good technology support for autonomous navigation of HEO and large elliptical spacecrafts.展开更多
Satellite positioning technology has been widely used in all kinds of military and civil land, marine, space and aeronautical target positioning tasks, naviga tion activities and accurate surveying measurements since ...Satellite positioning technology has been widely used in all kinds of military and civil land, marine, space and aeronautical target positioning tasks, naviga tion activities and accurate surveying measurements since 90 s in the last cen tury due to its advantage in providing all-weather, real-time, three dimensional and high precision positioning information, as well as speed and accurate timing information. By now, it has already formed a new hi-tech industry basically.This paper briefly reviews the development of the global satellite positioning and navigation technologies including the basic information of China's "Plough navigation system", introduces the history of satellite positioning technology and its major application fields as well as the status quo of this being industri alized trade in China, gives an account of the writers' vision for the application and prospect of the satellite positioning technologies in China, and approaches the tactics and stresses of the satellite positioning technology's application and its industrialization future in China.展开更多
Selecting the optimal reference satellite is an important component of high-precision relat/ve positioning because the reference satellite directly influences the strength of the normal equation. The reference satelli...Selecting the optimal reference satellite is an important component of high-precision relat/ve positioning because the reference satellite directly influences the strength of the normal equation. The reference satellite selection methods based on elevation and positional dilution of precision （PDOP） value were compared. Results show that all the above methods cannot select the optimal reference satellite. We introduce condition number of the design matrix in the reference satellite selection method to improve structure of the normal equation, because condition number can indicate the ill condition of the normal equation. The experimental results show that the new method can improve positioning accuracy and reliability in precise relative positioning.展开更多
基金Supported by the Natural Science Foundation of Hebei Province(F2011205023)the National Natural Science Foundation of China(61175059)。
文摘A novel subspace projection anti-jamming algorithm based on spatial blind search is proposed,which uses multiple single-constrained subspace projection parallel filters.If the direction of arrival(DOA)of a satellite signal is unknown,the traditional subspace projection anti-jamming algorithm cannot form the correct beam pointing.To overcome the problem of the traditional subspace projection algorithm,multiple single-constrained subspace projection parallel filters are used.Every single-constrained anti-jamming subspace projection algorithm obtains the optimal weight vector by searching the DOA of the satellite signal and uses the output of cross correlation as a decision criterion.Test results show that the algorithm can suppress the jamming effectively,and generate high gain toward the desired signal.The research provides a new idea for the engineering implementation of a multi-beam anti-jamming algorithm based on subspace projection.
基金supported by the National Natural Science Foundation of China(41804035,41374027)。
文摘The spoofing capability of Global Navigation Satellite System(GNSS)represents an important confrontational capability for navigation security,and the success of planned missions may depend on the effective evaluation of spoofing capability.However,current evaluation systems face challenges arising from the irrationality of previous weighting methods,inapplicability of the conventional multi-attribute decision-making method and uncertainty existing in evaluation.To solve these difficulties,considering the validity of the obtained results,an evaluation method based on the game aggregated weight model and a joint approach involving the grey relational analysis and technique for order preference by similarity to an ideal solution(GRA-TOPSIS)are firstly proposed to determine the optimal scheme.Static and dynamic evaluation results under different schemes are then obtained via a fuzzy comprehensive assessment and an improved dynamic game method,to prioritize the deceptive efficacy of the equipment accurately and make pointed improvement for its core performance.The use of judging indicators,including Spearman rank correlation coefficient and so on,combined with obtained evaluation results,demonstrates the superiority of the proposed method and the optimal scheme by the horizontal comparison of different methods and vertical comparison of evaluation results.Finally,the results of field measurements and simulation tests show that the proposed method can better overcome the difficulties of existing methods and realize the effective evaluation.
基金supported by the NSFC-Guangdong (Grant No.U1035002) and NSFC-NSAF (Grant No.10976010)National Key Project of Science and Technology of China (Grant No. 2009ZX03006-003)the Technology Key Projects of Guangdong Province of China (Grant Nos.2009A080207006 and 2009A080207002)
文摘A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width （HPBW） is 113° in both the x-z and y-z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.
文摘The integration of GNSS （Global Navigation Satellite System） and INS （Inertial Navigation System） using IMU （Inertial Measurement Unit） is now widely used for MMS （Mobile Mapping System） and navigation applications to seamlessly determine position, velocity and attitude of the mobile platform. With low cost, small size, ligh weight and low power consumtion, the MEMS （Micro-Electro-Mechanical System） IMU and low cost GPS （Global Positioning System） receivers are now the trend in research and using for many applications. However, researchs in the literature indicated that the the performance of the low cost INS/GPS systems is still poor, particularly, in case of GNSS-noise environment. To overcome this problem, this research applies analytic contrains including non-holonomic constraint and zero velocity update in the data fusion engine such as Extended Kalman Filter to improve the performance of the system. The benefit of the proposed method will be demonstrated through experiments and data analysis.
文摘A good design of LNA for S band satellite navigation receivers and 4G LTE wireless communication system has been implemented in this paper.Due to increased congestion in the present L band,the S Band frequency from 2483.5-2500 MHz has been allocated for the future satellite navigation systems.For this purpose ATF-34143 amplifier(pHEMT)having high electron mobility and fast switching response has been chosen due to its very low Noise Figure(NF).The amplifier has been designed having bandwidth of 0.8 GHz from 1.8-2.6 GHz.Because of the large bandwidth,the amplifier could serve many wireless communication applications including 4G LTE mobile communication at 2.1 GHz.The design was implemented using the micro strip technology offering extremely low noise figure of 0.312 dB and 0.377 dB for 2.1 GHz and 2.49 GHz respectively.The gain of the amplifier was low and found to be 10.281 dB and 9.175 dB.For the purpose of increasing the gain of an amplifier,the proposed LNA design was then optimized by using Wilkinson Power Divider(WPD).The Balanced LNA design using WPD offered very low noise figure of 0.422 dB and 0.532 dB respectively and the gain was considerably increased and was found to be 20.087 dB and 17.832 dB respectively against 2.1 GHz and 2.49 GHz.Simulations and measurements were taken in Agilent Advanced Design System(ADS)software.The suggested LNA can be used for a variety of wireless communications applications including the future S band satellite navigation systems.
基金supported by the National Natural Science Foundation of China(62103104)the Natural Science Foundation of Jiangsu Province(BK20210215)the China Postdoctoral Science Foundation(2021M690615).
文摘In this paper,we study scene image recognition with knowledge transfer for drone navigation.We divide navigation scenes into three macro-classes,namely outdoor special scenes(OSSs),the space from indoors to outdoors or from outdoors to indoors transitional scenes(TSs),and others.However,there are difficulties in how to recognize the TSs,to this end,we employ deep convolutional neural network(CNN)based on knowledge transfer,techniques for image augmentation,and fine tuning to solve the issue.Moreover,there is still a novelty detection prob-lem in the classifier,and we use global navigation satellite sys-tems(GNSS)to solve it in the prediction stage.Experiment results show our method,with a pre-trained model and fine tun-ing,can achieve 91.3196%top-1 accuracy on Scenes21 dataset,paving the way for drones to learn to understand the scenes around them autonomously.
基金supported by the European Space Agency’s Navigation Science Office through the NAVISP Element 1 Program in the CAMALIOT(Application of Machine Learning Technology for GNSS IoT Data Fusion)project(NAVISP-EL1-038.2).
文摘Raw observations(carrier-phase and code observations)from the Global Navigation Satellite System(GNSS)can now be accessed from Android mobile phones(Version 7.0 onwards).This paves the way for GNSS data to be utilized for low-cost precise positioning or in ionospheric or tropospheric applications.This paper presents results from data collection campaigns using the CAMALIOT mobile app.In the frst campaign,116.3 billion measurements from 11,828 mobile devices were collected from all continents.Although participation decreased during the second campaign,data are still being collected globally.In this contribution,we demonstrate the potential of volunteered geographic information(VGl)from mobile phones to fill data gaps in geodetic station networks that collect GNSS data,e.g.in Brazil,but also how the data can provide a denser set of observations than current networks in countries across Europe.We also show that mobile phones capable of dual-frequency reception,which is an emerging technology that can provide a richer source of GNSS data,are contributing in a substantial way.Finally,we present the results from a survey of participants to indicate that participation is diverse in terms of backgrounds and geography,where the dominant motivation for participation is to contribute to scientific research.
基金supported in part by the National Natural Science Foundation of China(No.41876222)。
文摘In view of the failure of GNSS signals,this paper proposes an INS/GNSS integrated navigation method based on the recurrent neural network(RNN).This proposed method utilizes the calculation principle of INS and the memory function of the RNN to estimate the errors of the INS,thereby obtaining a continuous,reliable and high-precision navigation solution.The performance of the proposed method is firstly demonstrated using an INS/GNSS simulation environment.Subsequently,an experimental test on boat is also conducted to validate the performance of the method.The results show a promising application prospect for RNN in the field of positioning for INS/GNSS integrated navigation in the absence of GNSS signal,as it outperforms extreme learning machine(ELM)and EKF by approximately 30%and 60%,respectively.
基金Shanxi Provincial Science and Technology Research Fund(No.2012021013-6)
文摘Satellite signal simulator for global navigation satellite system(GNSS)can evaluate the accuracy of capturing,tracing and positioning of GNSS receiver.It has significant use-value in the military and civil fields.The system adopts the overall design scheme of digital signal processor(DSP)and field-programmable gate array(FPGA).It consists of four modules:industrial control computer simulation software,mid-frequency signal generator,digital-to-analog(D/A)module and radio frequency(RF)module.In this paper,we test the dynamic performance of simulator using the dynamic scenes testing method,and the signal generated by the designed simulator is primarily validated.
基金Supported by the National Natural Science Foundation of China(No.61132002,61231011)
文摘The theoretical aspects of the precise velocity determination of Low Earth Orbit (LEO) satellites'on board Global Navigation Satellite Systems (GNSS) receivers are derived. It shows that the receiver's Phase Lock Loop (PLL) is required to feature extremely small group delay within its low frequency band, which is in contrast to existing work that proposed wide band linear phase filters. Following this theory, a Finite Impulse Response (FIR) filter is proposed. To corroborate, the proposed FIR filter and an Infinite Impulse Response (IIR) filter lately proposed in literals are implemented in a LEO satellite onboard GNSS receiver. Tests are conducted using a third party commercial GPS signal generator. The results show that the GNSS receiver with the proposed FIR achieves 11 mm/s R.M.S precision, while the GNSS receiver with the IIR filter has a filter-caused velocity error that can not be ignored for space borne GNSS receivers.
基金the National Key Research and Development Program of China(No.2016YFB0501000)the Major Program of National Natural Science Foundation of China(No.61690214)the Project of D020214.
文摘For global navigation satellite system(GNSS)in the application of high earth orbit(HEO)determination,there are problems such as small number of visible satellites and weak signal magnitude.The transmitting and receiving errors of GNSS signal in the environment of HEO space are analyzed,and related compensating scheme is also proposed.Acquisition of GNSS signal is implemented by using weak signal acquisition technology based on Duffing.Precise tracking of weak GNSS signal is also realized by adopting dynamic detection and compensation technology based on Duffing chaotic oscillator.Simulation results show that,certain acquisition sensitivity and navigation precision can be reached,and the acquisition and tracking of weak GNSS signal can be realized by using the proposed technology,which provides good technology support for autonomous navigation of HEO and large elliptical spacecrafts.
文摘Satellite positioning technology has been widely used in all kinds of military and civil land, marine, space and aeronautical target positioning tasks, naviga tion activities and accurate surveying measurements since 90 s in the last cen tury due to its advantage in providing all-weather, real-time, three dimensional and high precision positioning information, as well as speed and accurate timing information. By now, it has already formed a new hi-tech industry basically.This paper briefly reviews the development of the global satellite positioning and navigation technologies including the basic information of China's "Plough navigation system", introduces the history of satellite positioning technology and its major application fields as well as the status quo of this being industri alized trade in China, gives an account of the writers' vision for the application and prospect of the satellite positioning technologies in China, and approaches the tactics and stresses of the satellite positioning technology's application and its industrialization future in China.
基金partially sponsored by the National 973 Project of China(2013CB733303)partially supported by the postgraduate independent exploration project of Central South University(2014zzts249)
文摘Selecting the optimal reference satellite is an important component of high-precision relat/ve positioning because the reference satellite directly influences the strength of the normal equation. The reference satellite selection methods based on elevation and positional dilution of precision （PDOP） value were compared. Results show that all the above methods cannot select the optimal reference satellite. We introduce condition number of the design matrix in the reference satellite selection method to improve structure of the normal equation, because condition number can indicate the ill condition of the normal equation. The experimental results show that the new method can improve positioning accuracy and reliability in precise relative positioning.
