scholarly journals High Precision Pseudo-Range Measurement in GNSS Anti-Jamming Antenna Array Processing

Electronics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 412
Author(s):  
Zukun Lu ◽  
Feiqiang Chen ◽  
Yuchen Xie ◽  
Yifan Sun ◽  
Hongliang Cai
Keyword(s):  
Antenna Array ◽  
Interference Cancellation ◽  
Array Processing ◽  
Satellite System ◽  
Delay Constraint ◽  
Problem Space ◽  
Range Measurements ◽  
Adaptive Array Processing ◽  
Channel Mismatch ◽  
Global Navigation Satellite

Radio frequency interference has become a rising problem to the signal of the Global Navigation Satellite System (GNSS). An effective way to achieve anti-jamming is by using an antenna array in GNSS signal processing. However, antenna array processing will cause a decline in the accuracy of pseudo-range measurements because of the channel mismatch and some other non-ideal factors. To solve this problem, space–time or space–frequency adaptive array processing is widely used for interference cancellation while constraining the delay of each antenna at the same time. In this paper, an anti-jamming algorithm with a time-delay constraint is proposed, where one antenna is chosen as the reference and data from other antennas is corrected based on the signal received from it. The deduction and simulation results show that the proposed algorithm can effectively improve the accuracy of pseudo-range measurements without degradation of anti-jamming performance.

scholarly journals The Unbiased Characteristic of Doppler Frequency in GNSS Antenna Array Processing

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Yuchen Xie ◽  
Zhengrong Li ◽  
Feiqiang Chen ◽  
Huaming Chen ◽  
Feixue Wang
Keyword(s):  
Antenna Array ◽  
Carrier Phase ◽  
Array Processing ◽  
Doppler Frequency ◽  
Low Complexity ◽  
Satellite System ◽  
Accurate Estimation ◽  
Array Technology ◽  
Gnss Receivers ◽  
Global Navigation Satellite

The antenna array technology, especially the spaced-time array processing (STAP), is one of the effective methods used in Global Navigation Satellite System (GNSS) receivers to refrain the power of jamming and enhance the performance of receivers in the circumstance of interference. However, biases induced to the receiver because of many reasons, including characteristic of antennas, front-end channel electronics, and space-time filtering, are extremely harmful to the high precise positioning of receivers. Although plenty of works have been done to calibrate the antenna and to mitigate these biases, achieving a good performance of antijamming, high accuracy, and low complexity at the same time still remains challenging. Different from existing works, this paper leverages the characteristic of GNSS signal’s Doppler frequency in STAP, which is proven to remain unbiased to solve the problem, even when the nonideal antennas are used and the interference circumstance changes. Since the integration of frequency is carrier phase, the unbiased Doppler frequency leads to an accurate estimation of carrier phase which can be used to calibrate the antenna array without extra apparatus or complicating algorithms. Therefore, a simple Doppler-aid strategy may be developed in the future to solve the difficulty of STAP bias mitigation.

scholarly journals Impact on Antijamming Performance of Channel Mismatch in GNSS Antenna Arrays Receivers

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Zukun Lu ◽  
Junwei Nie ◽  
Feiqiang Chen ◽  
Gang Ou
Keyword(s):  
Transfer Function ◽  
Global Navigation Satellite System ◽  
Antenna Arrays ◽  
Group Delay ◽  
Satellite System ◽  
Navigation Satellite ◽  
Amplitude Wave ◽  
Channel Mismatch ◽  
Global Navigation Satellite ◽  
The Impact

The performance of antijamming is limited by channel mismatch in global navigation satellite system (GNSS) antenna arrays receivers. Only when the amplitude and phase characteristics of each array channels are the same is the interference likely to be completely suppressed. This paper analyzes the impact on antijamming performance of channel mismatch. We built the model of channel mismatch and derived the impact on transfer function with space-time adaptive processor (STAP) of channel mismatch in theory. The impact factor of channel mismatch is proposed by the fuzzy transfer function, which could directly reflect the antijamming performance under channel mismatch. In addition, every characteristic in the channel mismatch model is analyzed. The analysis results show that the greatest impacts on antijamming performance are the range of amplitude wave and the group delay bias, while the influence of the number of amplitudes is next. As for the effect of group delay fluctuation is the smallest.

scholarly journals Cascaded Multitype Interferences Suppression Method Using Sparse Representation and Array Processing for GNSS Receiver

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Qiang Guo ◽  
Liangang Qi
Keyword(s):  
Sparse Representation ◽  
Array Processing ◽  
Matching Pursuit ◽  
Interference Suppression ◽  
Satellite System ◽  
Signal Interference ◽  
Wideband Interference ◽  
Interference Signals ◽  
Suppression Method ◽  
Global Navigation Satellite

Interference suppression techniques have been intensively studied in nearly two decades due to their importance for maintaining the integrity and functionality of global navigation satellite system (GNSS). However, the interference suppression method applicable for the complex receiving environment in which there are multitype interfering signals has not been considered in most of the researches. To deal with this problem better, a cascaded multitype interferences suppression method using sparse representation and array processing is proposed. In the first stage, according to the sparsity of the narrowband and modulated wideband interference signals, a novel parallel multichannel signal interference suppression method based on matching pursuit (MP) algorithm and a design strategy for the overcomplete dictionary are proposed to mitigate the interferences with sparse features. Then, the minimum power distortionless response (MPDR) beamformer is employed in the second stage to suppress the residuary interferences (such as Gaussian noise interferences). Compared with existing algorithms, the proposed method can not only effectively suppress the interference arriving from the same direction with the desired signal and increase the Degree of Freedom (DoF) of the array antenna, but also introduce no distortion into the navigation signal. The effectiveness of the proposed method is illustrated by theoretical analysis and several simulation results.

Compact antenna array receiver for robust satellite navigation systems

2014 ◽  
Vol 7 (6) ◽  
pp. 735-745 ◽  
Author(s):  
S. Irteza ◽  
E. Schäfer ◽  
R. Stephan ◽  
A. Hornbostel ◽  
M. A. Hein
Keyword(s):  
Antenna Array ◽  
Degrees Of Freedom ◽  
Satellite System ◽  
Navigation Systems ◽  
Matching Network ◽  
Compact Antenna ◽  
Interference Signals ◽  
Satellite Navigation Systems ◽  
Global Navigation Satellite ◽  
The Impact

A compact navigation receiver comprising a decoupled and matched four-element L1-band antenna array with an inter-element separation of a quarter of the free-space wavelength is presented in this paper. We investigate the impact of the decoupling and matching network on the robustness of the navigation receiver. It is observed that in order to achieve high robustness with a compact antenna array, it is necessary to employ a decoupling and matching network, particularly in case of three spatially separated interferers. Furthermore, we study the influence of the polarization impurity of the compact planar antenna array on the equivalent carrier-to-interference-plus-noise ratio (CINR) of the receiver when impinged with different numbers of diametrically polarized interference signals. It is shown that the higher-order modes possess strong polarization impurity, which may halve the available degrees-of-freedom for nulling in the presence of linear-polarized interferers, using a conventional null-steering algorithm. We verify the robustness of the designed compact receiver by means of a complete global-navigation-satellite-system demonstrator. It is shown that the maximum jammer power that is allowed us to maintain the CINR above 38 dBHz with three interferers can be improved by more than 10 dB if a decoupling and matching network is employed.

scholarly journals Complexity and Limitations of GNSS Signal Reception in Highly Obstructed Enviroments

2021 ◽  
Vol 11 (2) ◽  
pp. 6864-6868
Author(s):  
A. Hussain ◽  
F. Akhtar ◽  
Z. H. Khand ◽  
A. Rajput ◽  
Z. Shaukat
Keyword(s):  
Signal Strength ◽  
Satellite System ◽  
Statistical Characteristics ◽  
Navigation Systems ◽  
Path Delay ◽  
Range Measurements ◽  
Signal Characteristics ◽  
Satellite Visibility ◽  
Nlos Reception ◽  
Global Navigation Satellite

Multipath (MP) and/or Non Line-Of-Sight (NLOS) reception remains a potential vulnerability to satellite-based positioning and navigation systems in high multipath environments, such as an urban canyon. In such an environment, satellite signals are reflected, scattered or faded, and sometimes completely blocked by roofs and walls of high-rise buildings, fly-over bridges, complex road structures, etc. making positioning and navigation information inaccurate, unreliable, and largely unavailable. The magnitude of the positioning error depends on the satellite visibility, geometric distribution of satellites in the sky, and received signal quality and characteristics. The quality of the received signal (i.e. its statistical characteristics) can significantly vary in different environments and these variations can reflect in signal strength or power, range measurements (i.e. path delay and phase difference), and frequency, all of which distort the correlation curve between the received signal and receiver-generated replicas, resulting in range errors of tens of meters. Therefore, in order to meet stringent requirements defined for the Standard Positioning Service (SPS), the characterization of distortions that could significantly affect a Global Navigation Satellite System (GNSS) signal is essentially important. The scope of this paper is to detect possible imperfections/deviations in the GNSS signal characteristics that can occur due to MP or NLOS reception and analyze its effects. For this purpose, analysis of fading patterns in received signal strength (i.e. Carrier-to-Noise Ratio and strength fluctuations) is carried out in both clear LOS and high MP environment and then its impact on satellite lock state (i.e. tracking) is assessed. Furthermore, phase fluctuations and range residuals are computed to analyze the effects of path delays. The results show that significant variations can occur in GNSS signal characteristics in the MP environment that may result in loss of lock event and inaccurate/faulty range measurements.

scholarly journals A Spatial-Temporal Approach Based on Antenna Array for GNSS Anti-Spoofing

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 929
Author(s):  
Yuqing Zhao ◽  
Feng Shen ◽  
Guanghui Xu ◽  
Guochen Wang
Keyword(s):  
Antenna Array ◽  
Doa Estimation ◽  
Satellite System ◽  
Oblique Projection ◽  
Power Comparison ◽  
Signal Model ◽  
Baseband Signal ◽  
Gnss Receivers ◽  
Navigation Signals ◽  
Global Navigation Satellite

The presence of spoofing signals poses a significant threat to global navigation satellite system (GNSS)-based positioning applications, as it could cause a malfunction of the positioning service. Therefore, the main objective of this paper is to present a spatial-temporal technique that enables GNSS receivers to reliably detect and suppress spoofing. The technique, which is based on antenna array, can be divided into two consecutive stages. In the first stage, an improved eigen space spectrum is constructed for direction of arrival (DOA) estimation. To this end, a signal preprocessing scheme is provided to solve the signal model mismatch in the DOA estimation for navigation signals. In the second stage, we design an optimization problem for power estimation with the estimated DOA as support information. After that, the spoofing detection is achieved by combining power comparison and cross-correlation monitoring. Finally, we enhance the genuine signals by beamforming while the subspace oblique projection is used to suppress spoofing. The proposed technique does not depend on external hardware and can be readily implemented on raw digital baseband signal before the despreading of GNSS receivers. Crucially, the low-power spoofing attack and multipath can be distinguished and mitigated by this technique. The estimated DOA and power are both beneficial for subsequent spoofing localization. The simulation results demonstrate the effectiveness of our method.

The characteristics of transforming coordinates from the geocentric system WGS-84 for the Mercator projection under low latitudes conditions

2018 ◽  
Vol 940 (10) ◽  
pp. 2-6
Author(s):  
J.A. Younes ◽  
M.G. Mustafin
Keyword(s):  
Coordinate System ◽  
Satellite System ◽  
Programming Algorithm ◽  
Low Latitude ◽  
Model Calculations ◽  
Mercator Projection ◽  
Low Latitudes ◽  
Rectangular Coordinates ◽  
Global Navigation Satellite ◽  
Coordination Methods

The issue of calculating the plane rectangular coordinates using the data obtained by the satellite observations during the creation of the geodetic networks is discussed in the article. The peculiarity of these works is in conversion of the coordinates into the Mercator projection, while the plane coordinate system on the base of Gauss-Kruger projection is used in Russia. When using the technology of global navigation satellite system, this task is relevant for any point (area) of the Earth due to a fundamentally different approach in determining the coordinates. The fact is that satellite determinations are much more precise than the ground coordination methods (triangulation and others). In addition, the conversion to the zonal coordinate system is associated with errors; the value at present can prove to be completely critical. The expediency of using the Mercator projection in the topographic and geodetic works production at low latitudes is shown numerically on the basis of model calculations. To convert the coordinates from the geocentric system with the Mercator projection, a programming algorithm which is widely used in Russia was chosen. For its application under low-latitude conditions, the modification of known formulas to be used in Saudi Arabia is implemented.

Adaptive antenna array processing with kernels

2007 ◽  
Author(s):  
M. Martinez-Ramon ◽  
A. Navia-Vazquez ◽  
C.G. Christodoulou ◽  
A.R. Figueiras-Vidal
Keyword(s):  
Antenna Array ◽  
Array Processing ◽  
Adaptive Antenna ◽  
Adaptive Antenna Array
Sign in / Sign up

Export Citation Format

Share Document