01-0001-11439f68db-e036-4c08-be17-b1abf4bb0acd.png)
01-0012-075f870d4d-1fcb-4c5b-9b55-12aa8ce0d355.png)
01-0051-052ecadc80-2a2a-49c1-aeb1-dd6c4abff1e3.png)
05-0001-095363216a-abbd-400c-bb15-62b84834d935.png)
02-0001-12bad211c0-cc16-4248-a8f3-6cdb6580f5d2.jpg)
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Display Method:
Display Method:
2021, 46(4): 1-7.
doi: 10.12265/j.gnss.2021011502
Abstract:
Since the concept of Global Navigation Satellite Reflected Signal (GNSS-R) was proposed, GNSS-R has been widely used in remote sensing, and has been used in sea surface height measurement, sea surface wind field inversion, sea ice detection and other aspects. This article mainly introduces the application and research progress of GNSS-R remote sensing technology in sea surface height measurement. Highlights the research progress based on signal-to-noise (SNR) ratio data measurement methods, and briefly describes the theory and signal processing methods involved in SNR ratio data measurement methods and according to the current research progress. The future development direction of sea surface altimetry is prospected.
Since the concept of Global Navigation Satellite Reflected Signal (GNSS-R) was proposed, GNSS-R has been widely used in remote sensing, and has been used in sea surface height measurement, sea surface wind field inversion, sea ice detection and other aspects. This article mainly introduces the application and research progress of GNSS-R remote sensing technology in sea surface height measurement. Highlights the research progress based on signal-to-noise (SNR) ratio data measurement methods, and briefly describes the theory and signal processing methods involved in SNR ratio data measurement methods and according to the current research progress. The future development direction of sea surface altimetry is prospected.
2021, 46(4): 8-15.
doi: 10.12265/j.gnss.2021012703
Abstract:
We systematically evaluated and analyzed the performance of predicted, rapid and final global ionospheric map (GIM) products, provided by 5 IGS ionospheric analysis centers and the international GNSS Monitoring and Assessment System (iGMAS) comprehensive center, over China. The ionospheric total electron content (TEC) values measured by Global Navigation Satellite System (GNSS) and Jason altimeter satellites are selected as references and performances of GIM in standard single-point positioning are also used as indices in the validation. The results showed that the order of performance from high to low of different types of GIM over China is the final GIM, the rapid GIM and the predicted GIM products. Different GIM products are found to have comparable performances over China during low solar activity. The rapid and final GIM products provided by the Universitat Politècnica de Catalunya (UPC) and iGMAS outperform other GIM products during high solar activity.
We systematically evaluated and analyzed the performance of predicted, rapid and final global ionospheric map (GIM) products, provided by 5 IGS ionospheric analysis centers and the international GNSS Monitoring and Assessment System (iGMAS) comprehensive center, over China. The ionospheric total electron content (TEC) values measured by Global Navigation Satellite System (GNSS) and Jason altimeter satellites are selected as references and performances of GIM in standard single-point positioning are also used as indices in the validation. The results showed that the order of performance from high to low of different types of GIM over China is the final GIM, the rapid GIM and the predicted GIM products. Different GIM products are found to have comparable performances over China during low solar activity. The rapid and final GIM products provided by the Universitat Politècnica de Catalunya (UPC) and iGMAS outperform other GIM products during high solar activity.
2021, 46(4): 16-21.
doi: 10.12265/j.gnss.2020111901
Abstract:
BPM HF timing service is a kind of economical and convenient timing service method, which uses short wave radio station to transmit and broadcast the standard time and frequency in China. In order to solve the developing and testing problem of BPM applications, we analyze the characteristics of the BPM HF signal and use the direct digital synthesizer (DDS) technology. In addition, field-programmable gate array (FPGA) and digital to analog converter (DAC) are used as the core hardware platform to complete this design. The theoretical calculation and simulation results prove that the design worked well and it can surely promote the development of BPM HF timing technologies.
BPM HF timing service is a kind of economical and convenient timing service method, which uses short wave radio station to transmit and broadcast the standard time and frequency in China. In order to solve the developing and testing problem of BPM applications, we analyze the characteristics of the BPM HF signal and use the direct digital synthesizer (DDS) technology. In addition, field-programmable gate array (FPGA) and digital to analog converter (DAC) are used as the core hardware platform to complete this design. The theoretical calculation and simulation results prove that the design worked well and it can surely promote the development of BPM HF timing technologies.
2021, 46(4): 22-26.
doi: 10.12265/j.gnss.2020121001
Abstract:
Aiming at the problem of low localization accuracy of classical DV-Hop algorithm, caused by calculation of hop count and hop distance, number of hops-corrected and hop distance optimization-based DV-Hop localization (NHDL) algorithm is proposed in this paper. In NHDL algorithm, the received signal strength values among nodes are used to correct the number of hops. Then, the average distance of each hop of anchor nodes is modified by weighting factor. And the anchor nodes are selected through the concept of collinearity to reduce the localization error. The min-max method is adopted to calculate the position of node. The simulation results show that compared with the traditional DV-Hop algorithm, the average error of localization is reduced.
Aiming at the problem of low localization accuracy of classical DV-Hop algorithm, caused by calculation of hop count and hop distance, number of hops-corrected and hop distance optimization-based DV-Hop localization (NHDL) algorithm is proposed in this paper. In NHDL algorithm, the received signal strength values among nodes are used to correct the number of hops. Then, the average distance of each hop of anchor nodes is modified by weighting factor. And the anchor nodes are selected through the concept of collinearity to reduce the localization error. The min-max method is adopted to calculate the position of node. The simulation results show that compared with the traditional DV-Hop algorithm, the average error of localization is reduced.
2021, 46(4): 27-32.
doi: 10.12265/j.gnss.2021012501
Abstract:
The additional secondary phase factor (ASPF) plays an important role in propagation delay of the low-frequency ground-wave. A method of calculating attenuation for ground-wave propagating over irregular terrain called integral function has been developed recently. It is derived by means of a stationary-phase integration that reduces the dimensionality of the general version, but such an approximation is not valid for all terrain types. The terrain of the actual propagation path changes greatly, and the actual propagation path is corrected by the mathematical morphology method to keep the basic geometric contour and smoothness of the path. The calculation results of the integral equation method show that the actual propagation path can be effectively optimized through the mathematical morphology method.
The additional secondary phase factor (ASPF) plays an important role in propagation delay of the low-frequency ground-wave. A method of calculating attenuation for ground-wave propagating over irregular terrain called integral function has been developed recently. It is derived by means of a stationary-phase integration that reduces the dimensionality of the general version, but such an approximation is not valid for all terrain types. The terrain of the actual propagation path changes greatly, and the actual propagation path is corrected by the mathematical morphology method to keep the basic geometric contour and smoothness of the path. The calculation results of the integral equation method show that the actual propagation path can be effectively optimized through the mathematical morphology method.
2021, 46(4): 33-39.
doi: 10.12265/j.gnss.2021020601
Abstract:
In view of the problem that traditional principal component analysis (PCA) ignores the correlation between coordinate components of stations, a method combining wavelet denoising and multi-directional principal component analysis (WD-MPCA) is proposed, which makes up for the shortcomings of traditional PCA. Compared with empirical mode decomposition and principal component analysis (EMD-PCA) and wavelet denoising and principal component analysis (WD-PCA). The WD-MPCA combination method has the highest accuracy. After denoising by WD-MPCA combination method, the mean median error is 0.83 mm, 0.85 mm and 8.30 mm respectively, which is 81.14%, 81.91% and 40.37% lower than that of the original coordinate residual time series. The WD-MPCA combination method fully considers the correlation between different components of each station. It can effectively remove high-frequency random white noise (WN) and low-frequency colored noise (CN), which is of great significance to the practical application and theoretical development of high-frequency Global Navigation Satellite System (GNSS) technology.
In view of the problem that traditional principal component analysis (PCA) ignores the correlation between coordinate components of stations, a method combining wavelet denoising and multi-directional principal component analysis (WD-MPCA) is proposed, which makes up for the shortcomings of traditional PCA. Compared with empirical mode decomposition and principal component analysis (EMD-PCA) and wavelet denoising and principal component analysis (WD-PCA). The WD-MPCA combination method has the highest accuracy. After denoising by WD-MPCA combination method, the mean median error is 0.83 mm, 0.85 mm and 8.30 mm respectively, which is 81.14%, 81.91% and 40.37% lower than that of the original coordinate residual time series. The WD-MPCA combination method fully considers the correlation between different components of each station. It can effectively remove high-frequency random white noise (WN) and low-frequency colored noise (CN), which is of great significance to the practical application and theoretical development of high-frequency Global Navigation Satellite System (GNSS) technology.
2021, 46(4): 40-44.
doi: 10.12265/j.gnss.2021040701
Abstract:
The black box of wrecked aircraft, as the witness of air disaster, need to be salvaged quickly. In the ocean environment of twenty meters deepth, we search to locate the aircraft black box based on SCOUT+ ultra-short baseline positioning system (USBL). The black box simulator is located in 20 m water depth ocean environment. The positioning accuracy reaches 6.35 m, and the angle positioning accuracy reaches 2.78°. After eliminating the fixed error of installation, the angle positioning accuracy reaches 0.40°. In general, the SCOUT+ detecting accuracy of the black box reaches the expected requirement and meet real needs.
The black box of wrecked aircraft, as the witness of air disaster, need to be salvaged quickly. In the ocean environment of twenty meters deepth, we search to locate the aircraft black box based on SCOUT+ ultra-short baseline positioning system (USBL). The black box simulator is located in 20 m water depth ocean environment. The positioning accuracy reaches 6.35 m, and the angle positioning accuracy reaches 2.78°. After eliminating the fixed error of installation, the angle positioning accuracy reaches 0.40°. In general, the SCOUT+ detecting accuracy of the black box reaches the expected requirement and meet real needs.
2021, 46(4): 45-51.
doi: 10.12265/j.gnss.2021053101
Abstract:
In response to the difficulty in management and control of entry-exit personnel from high-risk epidemic areas during the isolation period, the article designs an "Isolation Housekeeper" management system based on the fusion positioning of Global Navigation Satellite System (GNSS) and network communication. The system relies on GNSS positioning, Cell-ID positioning, WLAN positioning, cloud computing platform, geographic information system and other technologies, to realize the functions of isolated people positioning, motion trail reporting, electronic fence setting, body temperature reporting, body temperature monitoring, out of circle warning, motion trail tracking, etc. This system can provide the enterprises and institutions with safe and effective hierarchical management of each isolated person, so as to achieve registration, real-time control, and trajectory traceability.
In response to the difficulty in management and control of entry-exit personnel from high-risk epidemic areas during the isolation period, the article designs an "Isolation Housekeeper" management system based on the fusion positioning of Global Navigation Satellite System (GNSS) and network communication. The system relies on GNSS positioning, Cell-ID positioning, WLAN positioning, cloud computing platform, geographic information system and other technologies, to realize the functions of isolated people positioning, motion trail reporting, electronic fence setting, body temperature reporting, body temperature monitoring, out of circle warning, motion trail tracking, etc. This system can provide the enterprises and institutions with safe and effective hierarchical management of each isolated person, so as to achieve registration, real-time control, and trajectory traceability.
2021, 46(4): 52-58.
doi: 10.12265/j.gnss.2021032901
Abstract:
In complex indoor environment, ultra wide band (UWB) ranging error can not be effectively compensated by conventional methods, which seriously restricts its positioning accuracy. Based on the analysis of the distribution characteristics of UWB ranging error in indoor environment, two different BP network error correction models with different structures are designed. Model BP1 inputs the ranging values of a single label and four base stations, and outputs four corresponding ranging errors; Model BP2 inputs the three-dimensional coordinates of a pair of labels and a base station, and outputs one corresponding ranging error. The network is trained with high precision total station measurement result as reference value, and the ranging and positioning accuracy before and after model correction are compared and analyzed. The results show that both models can effectively correct ranging errors and improve positioning accuracy. BP1 ranging and positioning accuracy are improved by 83.0%, 75.9%, and BP2 ranging and positioning accuracy is improved by 91.7%, 93.8% on average. BP2 can improve the ranging and positioning accuracy more effectively than BP1, and the positioning accuracy can be improved from decimeter level to centimeter level.
In complex indoor environment, ultra wide band (UWB) ranging error can not be effectively compensated by conventional methods, which seriously restricts its positioning accuracy. Based on the analysis of the distribution characteristics of UWB ranging error in indoor environment, two different BP network error correction models with different structures are designed. Model BP1 inputs the ranging values of a single label and four base stations, and outputs four corresponding ranging errors; Model BP2 inputs the three-dimensional coordinates of a pair of labels and a base station, and outputs one corresponding ranging error. The network is trained with high precision total station measurement result as reference value, and the ranging and positioning accuracy before and after model correction are compared and analyzed. The results show that both models can effectively correct ranging errors and improve positioning accuracy. BP1 ranging and positioning accuracy are improved by 83.0%, 75.9%, and BP2 ranging and positioning accuracy is improved by 91.7%, 93.8% on average. BP2 can improve the ranging and positioning accuracy more effectively than BP1, and the positioning accuracy can be improved from decimeter level to centimeter level.
2021, 46(4): 59-65.
doi: 10.12265/j.gnss.2021052701
Abstract:
In allusion to two commonly used models in single frequency precise point positioning (SF-PPP): SF-PPP with raw and uncombined observations(SF-UC-PPP) and SF-UC-PPP with the constraint of ionospheric delay, considering simultaneously the three different ionospheric delay constraint strategies including constant, step wise relaxed and spatial-temporal strategy, these models are compared and analyzed in positioning accuracy and convergence time using GPS and GPS+BDS data. The experiment result shows that by using the GPS system observations these three models with ionospheric delay constraint can significantly improve the convergence speed of PPP, the step wise relaxed model is the fastest. Its average convergence time is 32.36 min. Accuracy of these four models after convergence is roughly equivalent. By adding the BDS data, the convergence time of these models increases differently. The spatial-temporal model has the most significant improvement, which convergence time is shorted to 59.22% of single system. Aafter the using of BDS data, the accuracy of horizontal direction is improved by 0.5 cm to 1.3 cm, the vertical accuracy has slight decrease.
In allusion to two commonly used models in single frequency precise point positioning (SF-PPP): SF-PPP with raw and uncombined observations(SF-UC-PPP) and SF-UC-PPP with the constraint of ionospheric delay, considering simultaneously the three different ionospheric delay constraint strategies including constant, step wise relaxed and spatial-temporal strategy, these models are compared and analyzed in positioning accuracy and convergence time using GPS and GPS+BDS data. The experiment result shows that by using the GPS system observations these three models with ionospheric delay constraint can significantly improve the convergence speed of PPP, the step wise relaxed model is the fastest. Its average convergence time is 32.36 min. Accuracy of these four models after convergence is roughly equivalent. By adding the BDS data, the convergence time of these models increases differently. The spatial-temporal model has the most significant improvement, which convergence time is shorted to 59.22% of single system. Aafter the using of BDS data, the accuracy of horizontal direction is improved by 0.5 cm to 1.3 cm, the vertical accuracy has slight decrease.
2021, 46(4): 66-69.
doi: 10.12265/j.gnss.2021051801
Abstract:
Real time dynamics of Global Satellite Navigation System (GNSS-RTK) technology has been widely used in various engineering fields. This article describes the principle and advantages of GNSS-RTK technology in railway reconstruction projects. Regional control network is used to collect leveling points, and the results are added to the point correction concentration for post-correction. By comparing the results of existing railway reconstruction projects with those of leveling survey, it is concluded that RTK elevation can reach the accuracy of the fifth grade leveling elevation by adding a certain number of elevation points to participate in point correction, the similar project application has the certain reference significance in the plain or the mountainous area.
Real time dynamics of Global Satellite Navigation System (GNSS-RTK) technology has been widely used in various engineering fields. This article describes the principle and advantages of GNSS-RTK technology in railway reconstruction projects. Regional control network is used to collect leveling points, and the results are added to the point correction concentration for post-correction. By comparing the results of existing railway reconstruction projects with those of leveling survey, it is concluded that RTK elevation can reach the accuracy of the fifth grade leveling elevation by adding a certain number of elevation points to participate in point correction, the similar project application has the certain reference significance in the plain or the mountainous area.
2021, 46(4): 70-75.
doi: 10.12265/j.gnss.2021020702
Abstract:
In this paper, 298 tide gauge stations are used as the research object, and three models of generalized gauss markov (GGM) noise model, autoregressive moving average (ARMA) noise model and Autoregressive fractionally integrated moving average (ARFIMA) noise model are used to estimate the noise model characteristics of the coordinate time series of tide gauge stations and the trend of sea level changes. The influence of time span on the velocity estimation of tide gauge stations analyzed and discussed. The experimental results show that the noise characteristics of coordinate time series of tide gauge stations are mainly ARFIMA(1,0), ARFIMA(2,2), ARMA (1,0); the velocity estimation results of tide gauge stations show that 64.77% of the station velocity values are in the interval of 0 mm/a to 4 mm/a, and the average sea level velocity is 1.25 mm/a, which is on an upward trend. As the time span increases, the velocity uncertainty of the coordinate sequence, of the tide gauge stations, gradually tends to converge from divergence, and a time span more than 110 a helps to obtain a robust estimate of the tide gauge station velocity.
In this paper, 298 tide gauge stations are used as the research object, and three models of generalized gauss markov (GGM) noise model, autoregressive moving average (ARMA) noise model and Autoregressive fractionally integrated moving average (ARFIMA) noise model are used to estimate the noise model characteristics of the coordinate time series of tide gauge stations and the trend of sea level changes. The influence of time span on the velocity estimation of tide gauge stations analyzed and discussed. The experimental results show that the noise characteristics of coordinate time series of tide gauge stations are mainly ARFIMA(1,0), ARFIMA(2,2), ARMA (1,0); the velocity estimation results of tide gauge stations show that 64.77% of the station velocity values are in the interval of 0 mm/a to 4 mm/a, and the average sea level velocity is 1.25 mm/a, which is on an upward trend. As the time span increases, the velocity uncertainty of the coordinate sequence, of the tide gauge stations, gradually tends to converge from divergence, and a time span more than 110 a helps to obtain a robust estimate of the tide gauge station velocity.
2021, 46(4): 76-84.
doi: 10.12265/j.gnss.2020091401
Abstract:
Aiming at the problem of non-linear and non-stationary electrons in the ionospheric total electron content (TEC), and high noise caused by multiple factors, a CEEMD-GRNN ionospheric TEC prediction model combining the complementing ensemble empirical mode decomposition (CEEMD) and generalized regression neural network (GRNN) to solve the problem of poor fitting and low prediction accuracy caused by direct use of raw data for prediction. The ionospheric data of 2019 from IGS center for high, middle and low latitude are used. Different day of year data with magnetic storms and without magnetic storms are tested. Results show that the RMSE of low latitude is 0.97 and the relative accuracy is 91.28, which verifies that the accuracy of the CEEMD-GRNN forecast model is higher than that of the EMD-GRNN and the single GRNN model.
Aiming at the problem of non-linear and non-stationary electrons in the ionospheric total electron content (TEC), and high noise caused by multiple factors, a CEEMD-GRNN ionospheric TEC prediction model combining the complementing ensemble empirical mode decomposition (CEEMD) and generalized regression neural network (GRNN) to solve the problem of poor fitting and low prediction accuracy caused by direct use of raw data for prediction. The ionospheric data of 2019 from IGS center for high, middle and low latitude are used. Different day of year data with magnetic storms and without magnetic storms are tested. Results show that the RMSE of low latitude is 0.97 and the relative accuracy is 91.28, which verifies that the accuracy of the CEEMD-GRNN forecast model is higher than that of the EMD-GRNN and the single GRNN model.
2021, 46(4): 85-92.
doi: 10.12265/j.gnss.2021042501
Abstract:
With the continuous construction of Global Navigation Satellite System (GNSS), the location-based service (LBS) of smart phones has rapidly developed. In this paper, several commonly used smartphone are selected as research objects, such as Samsung S9+(Exynos), Huawei Mate30, Huawei P40 Pro. the measurement receiver UR4B0-D from BDStar Navigation is used for synchronous static observation experiment. the GNSS raw data quality of Android smartphone is analyzed from the aspects of satellite visibility, carrier-to-noise ratio (CNR), satellite altitude angle, multipath error and so on. The results show that there are obvious differences in observation capabilities and data quality among different smartphones. Android smartphones have poor data quality and low CNR. The CNR of Android smartphones has no obvious relationships with the satellite altitude angle. In addition, multipath error is one of the main errors that affect the high-precision positioning of Android smartphones.
With the continuous construction of Global Navigation Satellite System (GNSS), the location-based service (LBS) of smart phones has rapidly developed. In this paper, several commonly used smartphone are selected as research objects, such as Samsung S9+(Exynos), Huawei Mate30, Huawei P40 Pro. the measurement receiver UR4B0-D from BDStar Navigation is used for synchronous static observation experiment. the GNSS raw data quality of Android smartphone is analyzed from the aspects of satellite visibility, carrier-to-noise ratio (CNR), satellite altitude angle, multipath error and so on. The results show that there are obvious differences in observation capabilities and data quality among different smartphones. Android smartphones have poor data quality and low CNR. The CNR of Android smartphones has no obvious relationships with the satellite altitude angle. In addition, multipath error is one of the main errors that affect the high-precision positioning of Android smartphones.
2021, 46(4): 93-100.
doi: 10.12265/j.gnss.2021020101
Abstract:
Ideally, the loop parameters of an digital phase-locked loop (DPLL) is determined by the intersection of the phase noise of the input signal and the voltage-controlled oscillator (VCO). However, the basic module of the phase-locked loop (PLL) will introduce noise into the PLL system, thereby affecting the PLL performance. The method of directly calculating the intersection point of the two cannot take into account the influence of module noise. With the theory of the power-law spectrum model, this paper uses the PLL transfer model to superimpose the noise of the basic module of the PLL on the signal model of the atomic clock and the VCO. After establishing new signal models, it can conveniently and quickly determine the optimal loop parameters of the PLL. The simulation shows that the loop parameters selected by this method can make the output signal have good frequency stability, which can provide theoretical guidance for the selection of the loop parameters of the digital phase-locked device used to purify the atomic clock signal.
Ideally, the loop parameters of an digital phase-locked loop (DPLL) is determined by the intersection of the phase noise of the input signal and the voltage-controlled oscillator (VCO). However, the basic module of the phase-locked loop (PLL) will introduce noise into the PLL system, thereby affecting the PLL performance. The method of directly calculating the intersection point of the two cannot take into account the influence of module noise. With the theory of the power-law spectrum model, this paper uses the PLL transfer model to superimpose the noise of the basic module of the PLL on the signal model of the atomic clock and the VCO. After establishing new signal models, it can conveniently and quickly determine the optimal loop parameters of the PLL. The simulation shows that the loop parameters selected by this method can make the output signal have good frequency stability, which can provide theoretical guidance for the selection of the loop parameters of the digital phase-locked device used to purify the atomic clock signal.
2021, 46(4): 101-105.
doi: 10.12265/j.gnss.2021020102
Abstract:
This paper studied the key technology of high-precision navigation and positioning based on CORS for smart phones, and formed a high-precision navigation and positioning solution for mobile terminals based on JS-CORS. At the same time, the software system was developed, including a set of mobile APP and a location management platform. The construction of high-precision positioning platform for smart phones based on CORS is of great significance to extend the multi applications of smart phones in geographic mapping, intelligent transportation, emergency rescue, public security and other aspects, and expands the application field of CORS as well.
This paper studied the key technology of high-precision navigation and positioning based on CORS for smart phones, and formed a high-precision navigation and positioning solution for mobile terminals based on JS-CORS. At the same time, the software system was developed, including a set of mobile APP and a location management platform. The construction of high-precision positioning platform for smart phones based on CORS is of great significance to extend the multi applications of smart phones in geographic mapping, intelligent transportation, emergency rescue, public security and other aspects, and expands the application field of CORS as well.
2021, 46(4): 106-112.
doi: 10.12265/j.gnss.2021011701
Abstract:
Carrier numerically controlled oscillator (NCO) is a key part of the navigation receiver to strip the carrier of the received signal. In the digital signal processing module, the numerically controlled oscillator quantizes the amplitude and frequency of the local carrier signal through the quantization width and addressing word. The local carrier is designed by the bit width and depth of the memory data. Under the dynamic range of given input signal/interference, this paper optimizes the design of the quantization width and addressing length of the read-only memory (ROM) in the NCO according to the characteristics of the local carrier, adapting it to the actual engineering requirement, which avoids the redundancy of local carrier storage while ensuring the performance of signal-to-noise ratio (SNR) and frequency accuracy. The experimental results show that designing the optimal quantization width and addressing word of the navigation receiver local carrier based on the requirements can ensure the digital down-conversion SNR ratio loss less than 0.1 dB, the relative error of the actual output frequency of the local carrier less than 0.1%, and the optimal quantization width and addressing word less than the value before optimization. The storage resource occupancy rate was reduced, and the adaptability of the local carrier signal under dynamic signals and interference was effectively improved.
Carrier numerically controlled oscillator (NCO) is a key part of the navigation receiver to strip the carrier of the received signal. In the digital signal processing module, the numerically controlled oscillator quantizes the amplitude and frequency of the local carrier signal through the quantization width and addressing word. The local carrier is designed by the bit width and depth of the memory data. Under the dynamic range of given input signal/interference, this paper optimizes the design of the quantization width and addressing length of the read-only memory (ROM) in the NCO according to the characteristics of the local carrier, adapting it to the actual engineering requirement, which avoids the redundancy of local carrier storage while ensuring the performance of signal-to-noise ratio (SNR) and frequency accuracy. The experimental results show that designing the optimal quantization width and addressing word of the navigation receiver local carrier based on the requirements can ensure the digital down-conversion SNR ratio loss less than 0.1 dB, the relative error of the actual output frequency of the local carrier less than 0.1%, and the optimal quantization width and addressing word less than the value before optimization. The storage resource occupancy rate was reduced, and the adaptability of the local carrier signal under dynamic signals and interference was effectively improved.
2021, 46(4): 113-116.
doi: 10.12265/j.gnss.2021031801
Abstract:
The weighted mean temperature is an important parameter in Global Navigation Satellite System (GNSS) meteorology. A new statistical grid model is established by using the reanalysis meteorological data of 2017 in Ningxia. The comparison shows that the new model is more consistent with the actual value than the results of general model. The analysis shows that in order to meet the requirement of high accuracy. It is necessary to establish a suitable model by using the historical meteorological data of the local area.
The weighted mean temperature is an important parameter in Global Navigation Satellite System (GNSS) meteorology. A new statistical grid model is established by using the reanalysis meteorological data of 2017 in Ningxia. The comparison shows that the new model is more consistent with the actual value than the results of general model. The analysis shows that in order to meet the requirement of high accuracy. It is necessary to establish a suitable model by using the historical meteorological data of the local area.
2021, 46(4): 117-126.
doi: 10.12265/j.gnss.2021030102
Abstract:
Aiming at the problems of heary work during establishment of traditional fingerprint database and the large matching error of the traditional random forest, an improved random forest localization method was proposed based on automatic fingerprint database expansion (FDE-IRF) to enhance the efficiency of fingerprint database construction and the accuracy of fingerprint matching. This method improved the traditional all sampling method to construct fingerprint database and the traditional random forest regression positioning method. The combination of sparse sampling fingerprint data of multiple time periods and Kriging interpolation method to complete unsampled fingerprint points improves the efficiency of database construction and gets a strong representative fingerprint database. At the same time, the decision tree weighting strategy is used to improve the average voting method in the traditional random forest, and the data out of bag is used to evaluate the prediction error of the decision tree and assign the corresponding weight, which improves the regression accuracy of the algorithm. The experimental results shows that the average positioning error of the proposed method is 1.26 m, which is at least 14.3% lower than that of similar methods, and verifies the accuracy and effectiveness of the proposed method.
Aiming at the problems of heary work during establishment of traditional fingerprint database and the large matching error of the traditional random forest, an improved random forest localization method was proposed based on automatic fingerprint database expansion (FDE-IRF) to enhance the efficiency of fingerprint database construction and the accuracy of fingerprint matching. This method improved the traditional all sampling method to construct fingerprint database and the traditional random forest regression positioning method. The combination of sparse sampling fingerprint data of multiple time periods and Kriging interpolation method to complete unsampled fingerprint points improves the efficiency of database construction and gets a strong representative fingerprint database. At the same time, the decision tree weighting strategy is used to improve the average voting method in the traditional random forest, and the data out of bag is used to evaluate the prediction error of the decision tree and assign the corresponding weight, which improves the regression accuracy of the algorithm. The experimental results shows that the average positioning error of the proposed method is 1.26 m, which is at least 14.3% lower than that of similar methods, and verifies the accuracy and effectiveness of the proposed method.
2019, 44(2): 1-12.
doi: DOI:10.13442/j.gnss.1008-9268.2019.02.001
摘要：
2018, 43(1): 43-48.
doi: 0.13442/j.gnss.1008-9268.2018.01.008
摘要：
2020, 45(1): 19-25.
doi: DOI:10.13442/j.gnss.1008-9268.2020.01.003
摘要：
2018, 43(6): 1-7.
doi: doi:10.13442/j.gnss.1008-9268.2018.06.001
摘要：
2017, 42(1): 70-73.
doi: 10.13442/j.gnss.1008-9268.2017.01.014
摘要：
2017, 42(6): 16-23.
doi: 10.13442/j.gnss.1008-9268.2017.06.003
摘要：
2017, 42(1): 95-99.
doi: 10.13442/j.gnss.1008-9268.2017.01.019
摘要：
2017, 42(2): 25-31.
doi: doi:10.13442/j.gnss.1008-9268.2017.02.006
摘要：
2017, 42(3): 32-37.
doi: 10.13442/j.gnss.1008-9268.2017.03.007
摘要：
2017, 42(1): 100-103.
doi: 10.13442/j.gnss.1008-9268.2017.01.020
摘要：
2017, 42(5): 53-58.
doi: 10.13442/j.gnss.1008-9268.2017.05.011
Abstract:
2019, 44(1): 1-9.
doi: DOI:10.13442/j.gnss.1008-9268.2019.01.001
Abstract:
2019, 44(2): 1-12.
doi: DOI:10.13442/j.gnss.1008-9268.2019.02.001
Abstract:
2018, 43(6): 8-13.
doi: doi:10.13442/j.gnss.1008-9268.2018.06.002
Abstract:
2019, 44(5): 1-9.
doi: DOI:10.13442/j.gnss.1008-9268.2019.05.001
Abstract:
Bimonthly, Established 1976
Sponsored by：China Institute of Radio Transmission
Competent Authorities：China Electronics Technology Group Corporation
ISSN 1008-9268
CN 41-1317/TN
Article Recommend
MORE>
Development of factor graph and its application technology in positioning and navigation
SIC-based anti near-far effect acquisition method for pseudolites systems
GNSS interference localization technology based on position information of GNSS receivers
Fog positioning and its applications
Construction and development of satellite navigation augmentation systems
Research on GNSS time offset monitoring based on GLONASS IFBs
Download
1 Construction and development of satellite navigation augmentation systems
2 Development of factor graph and its application technology in positioning and navigation
3 Dynamic Positioning Accuracy Test and Analysis of BeiDou Satellite Navigation System
4 Research on the Model of BDS-3 Triple-Frequency Carrier-Phase Combination Observations
Links
MORE>
Total visits
Today's visit
