Navigation Receiver Research Articles

Analyzing the Indirect Effects of Lightning on Unmanned Aerial Vehicle Navigation Receivers

To investigate the interference effects of lightning on unmanned aerial vehicle (UAV) navigation receivers, an analytical approach for the evaluation of indirect lightning effects is suggested. The blocking mechanism of lightning pulses on the receiver is analyzed using the vector method. A behavioral-level simulation model of the receiver’s radio frequency (RF) front-end is constructed, and a lightning pulse injection simulation is performed based on the advanced design system (ADS). The simulation results indicate that lightning pulses induce blocking interference on the RF front-end of the navigation receiver, reducing its sensitivity and dynamic range. This interference is attributed to gain compression and degradation of the noise figure in the low-noise amplifier (LNA). To further validate the simulation results, a pin injection test is carried out to examine the influence of lightning pulses with different peak voltages on receiver sensitivity. The test results indicate a notable reduction in the receiver sensitivity when the lightning pulse peak reaches 250 V. The sensitivity trends across various test panels are consistent, and the damage thresholds are similar. These findings confirm the accuracy of the simulation results.

Principles of construction of nanosatellite radar systems based on global navigation satellite system reflectometry

Objectives. The development of radar remote sensing systems based on the reception of signals of navigation satellite systems reflected from the surface enables a constellation of nanosatellites to be deployed, in order to perform radar surveying of the Earth’s surface. The aim of this work is to develop the principles of construction of onboard bistatic remote sensing systems on nanosatellites, in order to assess the energy potential and possibilities for its increase.Methods. The optimal processing method in onboard bistatic radar systems is a development of known analytical methods of optimal processing in monostatic systems. The calculation of the energy potential is based on the experimental data obtained by other authors.Results. The utilization of signals from navigation satellite systems for surface sensing is a promising and developing area. The USA and China have deployed satellite constellations to perform remote sensing using reflected signals of navigation satellites. An algorithm for optimal processing in such systems, which realizes the principle of aperture synthesis, was developed, and the energy potential of bistatic synthetic aperture radar was calculated. In order to achieve this processing, the proposed scheme uses a standard navigation receiver to form reference signals.Conclusions. The application of optimal processing methods in bistatic radar enables a synthetic aperture based on scattered satellite navigation system signals. In order to improve the accuracy of estimates, the signal-to-noise ratio needs to be increased by combining coherent accumulation (aperture synthesis) and incoherent accumulation (aggregating measurements from different spacecraft). The signal processing methods and receiver structure proposed in this work onboard nanosatellites allow aperture synthesis to be achieved with realizable hardware requirements.

Cascaded multiplier-free implementation of adaptive anti-jamming filter based on GNSS receiver

Evaluating the computational complexity is critical for assessing the time-domain anti-jamming performance of GNSS receivers. The multiplier is the core component that contributes to the computational complexity in time-domain anti-jamming. However, current algorithms aimed at reducing the complexity of time-domain anti-jamming typically concentrate on shortening the filter length, which fails to address the high computational complexity introduced by the use of multipliers. This paper introduces a cascaded multiplier-free approach for implementing time-domain anti-jamming in navigation receivers. We propose a numerical power decomposition technique based on optimal Canonical Signed Digit coding and coefficient decomposition. By substituting the multiplier with minimal adder and shift operations, the computational complexity of the anti-jamming filter with a high quantization bit-width can be considerably decreased. An optimization strategy is presented, and the low-complexity multiplier-free technique is applied to the time-domain anti-jamming filter. Compared to the traditional Canonical Signed Digit multiplier-free technique, our method can reduce the components required for a 12-bit quantization anti-interference filter by one adder, 20 shift operations, and five coded word lengths, while maintaining a pseudo-range measurement deviation below 0.27 ns.

ВЛИЯНИЕ ПОГРЕШНОСТЕЙ ИЗМЕРЕНИЯ КООРДИНАТ СУДНА НА КАЧЕСТВО ПРОЦЕССА УПРАВЛЕНИЯ

Autopilots are an integral part of modern ships. However, at present, many tasks are emerging, including the ones in the unmanned navigation field, requiring the use of new control algorithms and new means of monitoring navigation parameters. In particular, to solve such problems as keeping a vessel on a given trajectory, automating the ships’ divergence and similar tasks, it is necessary to have means of continuous monitoring of the ship’s location. For this purpose, receivers of global navigation satellite systems can be applied. To model control processes, it is necessary to know the distribution of positioning errors of modern devices. Some works show that over long time intervals (a day or more), positioning errors can be considered a random process with a Gaussian distribution. This paper presents the experimental study results of the distribution of positioning errors of a ship navigation receiver operating in the GPS and GLONASS systems, in a combined GPS/GLONASS mode, as well as in the indicated modes with differential corrections. The paper shows that at time intervals of seconds – minutes (characteristic of ship’s control systems), positioning errors of the navigation receiver cannot be represented by a random process with a Gaussian distribution law. The paper presents the results of a mathematical modelling of the process of holding a ship on a given trajectory using experimental values of positioning sensor errors. For the research, a mathematical model of an innovative ship with a wheel-propulsion steering complex is used. An algorithm is created that makes it possible to keep a vessel on a given trajectory with an accuracy acceptable for a practical use, commensurate with deviations determined by the design features of the ship’s hull and its propulsors.

Analysis of the approaches to protection against interference of UAV satellite navigation receivers.

The main approaches to the construction of signal receivers of global satellite navigation systems of unmanned aerial vehicles, protected from the influence of artificially created interference, are considered. Such systems are equipped with multi-element phased antenna arrays and devices of controlled reception pattern antenna. In the process of processing the received information signal by the Controlled Reception Pattern Antenna device. the selection of interference and their suppression (compensation) is ensured, which is equivalent to the formation of dips in the spatial pattern of the antenna array at the corners that correspond to the directions of the interference sources. The basic principles of the implementation of the adaptive algorithm for processing the received information signal are given. The design and composition of the navigation receiver of the «Orlan-10» unmanned aerial vehicle equipped with a Controlled Reception Pattern Antenna device is considered. A conclusion was made regarding the fundamental possibility of creating a domestic navigation receiver with a Controlled Reception Pattern Antenna device. In the future, it is envisaged to deploy works on the creation of Controlled Reception Pattern Antenna devices with a greater number of antenna elements and the use of optimization principles of the quantitative composition of adaptation operations, in order to ensure the performance of these devices with a greater number of simultaneously enabled sources of interference and higher levels of their signal power.

Global Navigation Satellite System Receiver Positioning in Harsh Environments via Clock Bias Prediction by Empirical Mode Decomposition and Back Propagation Neural Network Method.

This paper proposes a novel method to improve the clock bias short-term prediction accuracy of navigation receivers then solve the problem of low positioning accuracy when the satellite signal quality deteriorates. Considering that the clock bias of a navigation receiver is equivalent to a virtual satellite, the predicted value of clock bias is used to assist navigation receivers in positioning. Consequently, a combined prediction method for navigation receiver clock bias based on Empirical Mode Decomposition (EMD) and Back Propagation Neural Network (BPNN) analysis theory is demonstrated. In view of systematic errors and random errors in the clock bias data from navigation receivers, the EMD method is used to decompose the clock bias data; then, the BPNN prediction method is used to establish a high-precision clock bias prediction model; finally, based on the clock bias prediction value, the three-dimensional positioning of the navigation receiver is realized by expanding the observation equation. The experimental results show that the proposed model is suitable for clock bias time series prediction and providing three-dimensional positioning information meets the requirements of navigation application in the harsh environment of only three satellites.

The field experiments results on remote determination of soil moisture portraits

The introduction of precision farming technologies into the practice of agricultural production is an urgent task, the solution of which would ensure the sustainable development of crop production, cost reduction and saving of water and other resources. The purpose of the work is to obtain and demonstrate the results of field experiments on remote determination of soil moisture portraits, temperature maps of the soil surface and relief maps conducted in the fields of the vegetable complex of CJSC «Gorodishche» in the Stupinsky district of the Moscow region using a complex of a new bipolarization microwave radiometer and a precision navigation receiver placed on a tractor. Field experiments on remote determination of portraits of soil moisture and surface temperature were carried out, as well as the microrelief parameter was determined and the features of the mutual correlation characteristics of various thematic maps were studied. Maps of portraits of humidity and temperature and surface topography of the soil were obtained. The electromagnetic compatibility of the microwave radiometer with «John Deere» tractor systems has been verified. Data have been prepared for entering into the database of radiometric measurements of soils. The work carried out will make it possible to clarify some parameters of the microwave radiometric system and its compatibility with the navigation receiver, radio modem and carrier systems. The analysis of the data obtained will make it possible to develop recommendations for optimizing technological processes and reclamation measures. The accumulation of a database of radiometric measurements will allow the further use of artificial intelligence technologies to refine the brightness-humidity conversion algorithms and the introduction of the developed equipment and algorithms into the technological processes of growing crops ensures the sustainable development of crop production technologies, increasing yields and obtaining additional profit by the agro-industrial complex.

Synergy in Future Avionics: An Overview of Multiple Technologies for Small Air Traffic Segment in the COAST project

The paper describes research and development activities under Clean Sky 2 Cost optimized Avionic System (COAST) program. The main goal of this development was to deliver technology enablers at TRL 5 for affordable cockpit and avionics. The target segment for the technology enablers is aircraft with 1 to 19 passengers and small cargo aircraft belonging to CS-23 category. The main aim is to provide overall summer during the whole COAST program development per individual technology. Sections are divided per each technology with their results and overall contribution to the program. The Clean Sky 2 COAST program covered the development of following technologies: Cockpit Architecture SAT avionic system architecture, Flight Management Tactical Separation System (TSS), Advanced Weather Awareness System (AWAS), Flight Reconfiguration System (FRS), Navigation and Surveillance Dual Frequency Multi-Constellation GNSS Receiver (GNSS), Low-cost Integrated Navigation System (NAV), Affordable Integrated Surveillance System (SURV), Platform technologies Compact Computing Platform (CCP), High Integrity Electronics for health monitoring (HIE), Integrated Mission Management System Integrated Mission Management System (IMMS). These technologies were part of several flight test campaigns which took place in the Czech Republic with Evektor company using EV-55 aircraft.

Verification of drone formation relative positioning technology based on Beidou

High precision drone formation flight requires real-time knowledge of the three-dimensional position and velocity information of the carrier. The Beidou navigation system, due to its all-weather and high-precision characteristics, can provide good relative position results for drones. However, when drones move at high speeds and in complex environments, The Beidou navigation receiver may experience various errors, leading to poor positioning results or even inability to locate. This paper provides targeted technical design for the reliability of Beidou relative positioning in complex environments during drone flight, monitors navigation data in real time to improve the fixed reliability of overall ambiguity, and uses BeiDou signal simulator to simulate and generate observation data for analysis and processing. The test results show that this method improves the continuity and reliability of the fixed ambiguity of Beidou, and can meet the requirements of real-time formation flight of drone.

Integration of carbon dioxide sensor with GNSS receiver for dynamic air quality monitoring applications

Air pollution is a significant problem in big cities due to the rapid increase of anthropogenic activities and severe traffic congestion. Therefore, real-time and micro tools for air monitoring are urgently necessary for fast and better policy decision-making. The current city air monitoring tool is typically static and serves a macro area. This study introduces technology development to integrate the air quality sensor with the satellite-based navigation receiver. This study used a carbon dioxide (CO2) MH-Z19C sensor and real-time kinematic global navigation satellite system (RTK GNSS) U-Blox F9P with GNSS Trimble NetR9 receiver. The field air quality monitoring (CO2 observed in ppm) and the movement velocity (vehicle speed observed in km/h) were recorded on two main roads of Jakarta by using a survey vehicle. The study compares the observation results of the non-integrated system (NIS) and integrated technology system (IS). The two systems generated the CSV database (CO2 and vehicle speed); however, IS generated the automatic synchronized and error-free data output. The statistical regression analysis of CSV data (CO2 and vehicle speed) between the NIS and IS reported significant results, which means both are reliable. Still, the NIS did not require manual synchronization, with some possibility of error. The R square values show a significant gap (speed 0.99 over CO2 0.144), indicating that IS needs further development as the CO2 data varies due to technicality. The finding presents that integrating the CO2 sensor and GNSS receiver generates a more effective time synchronization process and a reliable error removal technique in developing the CSV data. This finding is a significant reference in developing the integrated satellite-based receiver system with external environmental sensors.

An Unassisted Super-Resolution Satellite Navigation Receiver Using GPS L5 Signals

An Unassisted Super-Resolution Satellite Navigation Receiver Using GPS L5 Signals

Design of Light, Small, and High-precision Digital Servo Clock for LEO Constellation

Modern low earth orbit (LEO) satellite systems have placed increasingly stringent requirements on spaceborne time-frequency systems in the fields of constellation autonomous management, distributed synthetic aperture radar (SAR) imaging, and navigation time service. Admittedly, the original high-stability constant-temperature crystal oscillator and high-stability temperature-compensated crystal oscillator can no longer comply with the indicator requirements of clock source frequency characteristics and clock synchronization accuracy. Likewise, traditional satellites use atomic clocks (rubidium atomic clocks and cesium atomic clocks). On account of their inherent characteristics, the ground receiving system needs to observe and count the clock parameter characteristics for a long time after the satellite enters orbit and frequently modify the future working state parameters. The features of being expensive and bulky increase the operation and maintenance costs of the ground system and the complexity of engineering implementation. In this paper, a kind of light and small high-precision digital servo clock based on the deep coupling of the global navigation satellite system (GNSS) is designed for the LEO satellite constellation. The tame clock is deeply coupled with the GNSS navigation receiver, and the high precision time-frequency difference between the local clock frequency source and GNSS is obtained by using the carrier and pseudo-range measurement information of visible satellite and carrier phase measurement information of the receiver. It not only utilizes the short-term high stability of OCXO but also employs the long-term time-frequency maintenance ability of GNSS so that the tamed OCXO is locked in GNSS for a long time, which can achieve frequency calibration of local clock sources and long-term output to various space-borne systems. The system is small in size and low in power consumption, with output frequency stability better than 3E-13 (10000 s), accuracy better than ±2E-13, and timing accuracy better than ±10 ns, which is comparable to the key technical indexes of spaceborne miniaturized rubidium clocks, in line with the current demand of miniaturization, low power consumption, and low cost of LEO constellations.

Adaptive Satellite Navigation Anti-Interference Algorithm Based on Inverse Cosine Function

Contrasting the dilemma that the traditional time-domain least mean square (LMS) algorithm in the existing satellite navigation receiver anti-interference system cannot satisfy the convergence time is short and maintain a low level of steady-state error at the same time, an inverse cosine variable step size LMS algorithm (ICVS-LMS) is proposed. To begin with, the LMS algorithm, with a fixed step size focuses on its effectiveness in attenuating and suppressing interference signals, is analyzed, and then the proposed ICVS-LMS algorithm is analyzed. In conclusion, both the ICVS-LMS algorithm and the traditional algorithm are simulated and compared in terms of their effectiveness in suppressing interference in satellite navigation signals. The experimental results demonstrate that the improved algorithm significantly reduces convergence time while maintaining a small steady-state error. The improved algorithm demonstrates high robustness and an obvious suppression effect on interference signals. The anti-interference performance is 8.41–12.22% higher than that of the proposed algorithm.

Improved path following for autonomous marine vehicles with low-cost heading/course sensors: comparative experiments

By overcoming constraints of low-cost sensors equipped on the autonomous marine vehicle (AMV), the classic path following approaches based on heading autopilot and course autopilot are improved to enhance the following accuracy of AMV, respectively. For the heading autopilot, adaptive line-of-sight (ALOS) is proposed to compensate for the generalized sideslip including the actual sideslip angle and the magnetic compass bias. For the course autopilot, extended Kalman filter (EKF) is employed to fusion the position and yaw angular rate to obtain the more precise and stable course, so as to substitute the unreliable course feedback from the satellite navigation receiver in cases of low speed and non ideal positioning. The performance and characteristics of both improved schemes are summarized through comparative experiments conducted on a low-cost AMV. Compared with the classic path following method, the straight line path following accuracy of the heading autopilot with generalized sideslip compensation and the course autopilot with EKF feedback are improved by 78.3% and 85.8% respectively. The circular path following accuracy are improved by 61.8% and 66.7% respectively. Engineers can choose the path following methods flexibly based on the hardware configuration, working environment and path type of the AMV to improve the following accuracy.

Research on Electromagnetic Damage Effects in Navigation Receiver by PCI Testing

The EMP couples with electronic devices via cables, inducing electromagnetic damage effects. This paper elucidates the operational principles of a navigation receiver and simplifies the study by focusing on the radio frequency front-end module. Many PCI tests were conducted on its signal input port, yielding the damage threshold of the navigation receiver. An analysis of the output waveforms of the modules that incurred damage was also performed. Through infrared research, it was discovered that the damaged LNA experiences a rapid temperature rise to around 73°C during operation with applied power. The electromagnetic damage effect in the LNA primarily stems from internal MOS transistor short circuits. The BPF protects the subsequent circuit stages but is also susceptible to damage.

Assisted-GNSS positioning algorithm based on one-way fuzzy time information

In order to solve the problem that the accuracy of approximate position and approximate time information is limited by the traditional auxiliary positioning algorithm, this paper analyzes the problem that the calculation amount may increase and fail when these auxiliary information exceeds the precision requirement range and puts forward a positioning algorithm based on one-way fuzzy time assistance that is suitable for the positioning solution of GNSS satellite navigation receivers under the condition of fuzzy time information, such as the rotation condition. Methods using the reference information in the ephemeris information, the relatively accurate approximate time information can be reasonably searched and verified so as to achieve the effect of obtaining the positioning result with less calculation. The experimental results show that this method can accurately calculate the exact position even if there is an error in the approximate position information under the condition of one-way time assistance, which not only solves the problem that it cannot be positioned under the conditions of rotation but also does not increase the additional calculation amount and has practical engineering value.

Ionospheric Effect on Global Navigation Satellite System Performance - A Review

Satellite-based Communication, Navigation, Surveillance and Air Traffic Management (CNS/ATM) systems have been adopted by the international aviation community to meet the challenges of continuously rising global air traffic. Global Navigation Satellite System (GNSS) has been prescribed for the provision of navigation services to the air traffic. Performance of GNSS depends upon many factors including refraction and scintillation effects of ionosphere on the satellite signals. Severity of this effect depends largely upon the geographical location of the navigation receiver, the time of the day, the month of the year and the year on the 11-year solar cycle. This paper studies ionosphere mechanism and discusses its effect on the performance of GNSS. The paper also predicts the performance during solar cycle maximum expected in 2013-2014 [Jensen, Anna B.O., Mitchell, Cathryn 2011]. It touches upon the preparations going on to face the adverse effects of increased solar activity during the cycle maximum and recommends coordination/cooperation between various relevant organizations/institutions in the processes of data collection and development of a model.

Preliminary processing of data from a satellite navigation receiver in the problem of three-dimensional upper ionosphere tomography

Preliminary processing of data from a satellite navigation receiver in the problem of three-dimensional upper ionosphere tomography

Cold-Start Satellite Signal Acquisition Aided by an Antenna Array in the Presence of Outliers

In the cold-start mode, this work addresses the issue of signal acquisition for a satellite navigation receiver aided by an antenna array in the presence of outliers. First, the satellite signals acquisition is formulated as a problem of sparse matrix recovery in terms of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell _{2,1}$</tex-math></inline-formula> -norms minimization which encourages row sparsity of signal matrix and effectively suppresses outliers simultaneously. Then, an iterative reweighted framework and the Lagrange multipliers method with complex-valued conjugate gradient descent are employed to find a suitable solution. After that, to accelerate the convergence rate of the mean square error (MSE), an improved <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell _{2,1}$</tex-math></inline-formula> -norms cost function with composite regularizers is devised, where several conjugate gradients of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell _{2,1}$</tex-math></inline-formula> -norms are derived in detail and convex optimization theory is employed to find the global minimum. At last, actual satellite almanac is downloaded to provide the information of the visible satellites and then numerical results are presented to demonstrate the effectiveness of the proposed methods.

Global Ionospheric Response to Intense Variations of Solar and Geomagnetic Activity According to the Data of the GNSS Global Networks of Navigation Receivers

Global Ionospheric Response to Intense Variations of Solar and Geomagnetic Activity According to the Data of the GNSS Global Networks of Navigation Receivers