scholarly journals Robustness against Chirp Signal Interference of On-Board Vehicle Geodetic and Low-Cost GNSS Receivers

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5257
Author(s):  
Franc Dimc ◽  
Polona Pavlovčič-Prešeren ◽  
Matej Bažec
Keyword(s):  
Interference Mitigation ◽  
Low Cost ◽  
Density Ratio ◽  
Autonomous Driving ◽  
Signal Interference ◽  
Noise Power ◽  
Reference Base ◽  
Noise Power Spectral Density ◽  
Processing Abilities ◽  
Gnss Receivers

Robust autonomous driving, as long as it relies on satellite-based positioning, requires carrier-phase-based algorithms, among other types of data sources, to obtain precise and true positions, which is also primarily true for the use of GNSS geodetic receivers, but also increasingly true for mass-market devices. The experiment was conducted under line-of-sight conditions on a straight road during a period of no traffic. The receivers were positioned on the roof of a car travelling at low speed in the presence of a static jammer, while kinematic relative positioning was performed with the static reference base receiver. Interference mitigation techniques in the GNSS receivers used, which were unknown to the authors, were compared using (a) the observed carrier-to-noise power spectral density ratio as an indication of the receivers’ ability to improve signal quality, and (b) the post-processed position solutions based on RINEX-formatted data. The observed carrier-to-noise density generally exerts the expected dependencies and leaves space for comparisons of applied processing abilities in the receivers, while conclusions on the output data results comparison are limited due to the non-synchronized clocks of the receivers. According to our current and previous results, none of the GNSS receivers used in the experiments employs an effective type of complete mitigation technique adapted to the chirp jammer.

scholarly journals A Novel Signal Design and Performance Analysis in NavCom Based on LEO Constellation

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8235
Author(s):  
Jing Ji ◽  
Yuting Liu ◽  
Wei Chen ◽  
Di Wu ◽  
Hongyang Lu ◽  
...  
Keyword(s):  
Mutual Influence ◽  
Density Ratio ◽  
Side Lobe ◽  
Low Earth Orbit ◽  
Noise Power ◽  
Signal Design ◽  
Tracking Accuracy ◽  
Alternative Scheme ◽  
Simulation Performance ◽  
Noise Power Spectral Density

The mega-launch of low Earth orbit satellites (LEOs) represents a critical opportunity to integrate navigation and communication (NavCom), but first, challenges related to signal design must be overcome. This article proposes a novel signal scheme named CE-OFDM-PM. Via research on the in-band or adjacent band, it was found that the proposed signal scheme was suitable for S-band and had a wide normalized power spectrum density (PSD), high peak-to-side lobe ratio (PSR), and multiple peaks in autocorrelation. In an analysis of the simulation performance evaluation in navigation and communication, it is found that the proposed signal scheme has the potential for high accuracy, a code tracking accuracy of up to 0.85 m, a small mutual influence between the proposed signal scheme and other schemes, excellent anti-interference properties, and a better performance at both short and long distances in terms of its anti-multipath capability. Furthermore, the proposed signal scheme shows the ability to communicate between satellites and the ground and is outstanding in terms of its bit error rate (BER), CNR, and energy per bit to noise power spectral density ratio (Eb/N0). From the technical, theoretical, and application perspectives, our proposed signal scheme has potential as an alternative scheme in future BDS, PNTs, and even 5G/B5G.

scholarly journals Analisis Unjuk Kerja Convolutional Code pada Sistem MIMO MC-DSSS Melalui Kanal Rayleigh Fading

2017 ◽  
Vol 16 (2) ◽  
pp. 66 ◽  
Author(s):  
Kadek Agus Mahabojana Dwi Prayoga ◽  
Ni Made Ary Esta Dewi Wirastuti ◽  
I Gst A. Komang Diafari Djuni Hartawan
Keyword(s):  
Spread Spectrum ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Convolutional Code ◽  
Multiple Input Multiple Output ◽  
Density Ratio ◽  
Direct Sequence Spread Spectrum ◽  
Noise Power ◽  
Noise Power Spectral Density ◽  
Input Multiple Output

Kombinasi antara sistem MIMO (multiple input multiple output), OFDM (orthogonal frequency division multiplexing), dan spread spectrum serta adanya teknik pengkodean kanal mampu mengurangi efek fading dan error yang terjadi. Penelitian ini bertujuan untuk mengetahui perbandingan performansi dari sistem MIMO MC-DSSS (multi carrier-direct sequence spread spectrum) Uncoded atau tanpa pengkodean kanal dan MIMO MC-DSSS Convolutional Code atau dengan pengkodean kanal Convolutional yang melalui kanal Rayleigh Fading, ditinjau dari nilai dan grafik BER (bit error rate) berbanding Eb/No (energy per bit to noise power spectral density ratio). Penelitian ini menggunakan metode simulasi dengan menggunakan program Matlab R2015a. Hasil dari simulasi didapat unjuk kerja sistem MIMO MC-DSSS dengan Convolutional Code memiliki hasil yang lebih baik dari MIMO MC-DSSS. Pada kanal transmisi Rayleigh Fading untuk mencapi nilai BER sebesar 10-3 pada sistem MIMO MC-DSSS dengan Convolutional Code dibutuhkan Eb/No sebesar -7 dB. Sedangkan pada sistem MIMO MC-DSSS dibutuhkan Eb/No sebesar -3 dB.[turnitin 20%, 7-11-2016]

scholarly journals Analysis of the Ordinary and Extraordinary Ionospheric Modes for NVIS Digital Communications Channels

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2210
Author(s):  
Jordi Male ◽  
Joaquim Porte ◽  
Tomas Gonzalez ◽  
Josep M. Maso ◽  
Joan L. Pijoan ◽  
...  
Keyword(s):  
Low Cost ◽  
Satellite Communications ◽  
Frequency Instability ◽  
Mean Value ◽  
Single Frequency ◽  
Delay Spread ◽  
Noise Power ◽  
Ordinary Wave ◽  
Polarization Diversity ◽  
Noise Power Spectral Density

Sensor networks have become more popular in recent years, now featuring plenty of options and capabilities. Notwithstanding this, remote locations present many difficulties for their study and monitoring. High-frequency (HF) communications are presented as an alternative to satellite communications, being a low-cost and easy-to-deploy solution. Near vertical incidence skywave (NVIS) technology provides a coverage of approximately 250 km (depending on the frequency being used and the ionospheric conditions) without a line of sight using the ionosphere as a communication channel. This paper centers on the study of the ionosphere and its characteristic waves as two independent channels in order to improve any NVIS link, increasing its robustness or decreasing the size of the node antennas through the appliance of specific techniques. We studied the channel sounding of both the ordinary and extraordinary waves and their respective channels, analyzing parameters such as the delay spread and the channel’s availability for each wave. The frequency instability of the hardware used was also measured. Furthermore, the correlation coefficient of the impulse response between both signals was studied. Finally, we applied polarization diversity and two different combining techniques. These measurements were performed on a single frequency link, tuned to 5.4 MHz. An improvement on the mean bit energy-to-noise power spectral density (Eb/N0) was received and the bit error rate (BER) was achieved. The results obtained showed that the extraordinary mode had a higher availability throughout the day (15% more availability), but a delayed spread (approximately 0.3 ms mean value), similar to those of the ordinary wave. Furthermore, an improvement of up to 4 dB was achieved with the usage of polarization diversity, thus reducing transmission errors.

scholarly journals Evaluaciónde OPS para la Reducción de la PAPR en un SistemaOFDM conCanal Multitrayecto

2020 ◽  
Vol 44 (2) ◽  
pp. 35-42
Author(s):  
María Peñaherrera ◽  
Diego Reinoso
Keyword(s):  
Bit Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
Density Ratio ◽  
Average Power ◽  
Noise Power ◽  
Power Ratio ◽  
Frequency Division ◽  
Complementary Distribution ◽  
Noise Power Spectral Density ◽  
Power Spectral

OFDM (Orthogonal Frequency Division Multiplexing) es una tecnología de comunicacióninalámbrica que tiene ventajas como alta eficiencia espectral, alta tasa de transmisión y es robusta a la propagación por mulitrayecto. Sin embargo, su principal desventaja es que tienealta PAPR (Peak-to-Average Power Ratio).Este artículo presenta la evaluaciónde la técnica OPS (Orthogonal Pilot Sequence) para la reducción de la PAPR en un sistema OFDM con canal multitrayecto. Para la evaluación se consideran dos tipos de canalesmultitrayecto selectivos en frecuencia, con y sin línea de vista. Se evalúa la técnica OPS obteniendola gráfica del BER (Bit Error Rate)vs Eb/No (energy per bit to noise power spectral density ratio) y la gráfica de la CCDF (Cumulative Complementary Distribution Function) para distintos parámetros. Losresultados muestran una reducción de la PAPR cuando se utiliza la técnica OPS y una mejora en el BER.

scholarly journals Wide-Band Interference Mitigation in GNSS Receivers Using Sub-Band Automatic Gain Control

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 679
Author(s):  
Johannes Rossouw van der van der Merwe ◽  
Fabio Garzia ◽  
Alexander Rügamer ◽  
Santiago Urquijo ◽  
David Contreras Franco ◽  
...  
Keyword(s):  
Interference Mitigation ◽  
Automatic Gain Control ◽  
Low Cost ◽  
Poor Performance ◽  
Wide Band ◽  
Band Noise ◽  
Gnss Receivers ◽  
Interference Signals ◽  
Wide Band Noise ◽  
The Impact

The performance of GNSS receivers is significantly affected by interference signals. For this reason, several research groups have proposed methods to mitigate the effect of different kinds of jammers. One effective method for wide-band IM is the HDDM PB. It provides good performance to pulsed and frequency sparse interference. However, it and many other methods have poor performance against wide-band noise signals, which are not frequency-sparse. This article proposes to include AGC in the HDDM structure to attenuate the signal instead of removing it: the HDDM-AGC. It overcomes the wide-band noise limitation for IM at the cost of limiting mitigation capability to other signals. Previous studies with this approach were limited to only measuring the CN0 performance of tracking, but this article extends the analysis to include the impact of the HDDM-AGC algorithm on the PVT solution. It allows an end-to-end evaluation and impact assessment of mitigation to a GNSS receiver. This study compares two commercial receivers: one high-end and one low-cost, with and without HDDM IM against laboratory-generated interference signals. The results show that the HDDM-AGC provides a PVT availability and precision comparable to high-end commercial receivers with integrated mitigation for most interference types. For pulse interferences, its performance is superior. Further, it is shown that degradation is minimized against wide-band noise interferences. Regarding low-cost receivers, the PVT availability can be increased up to 40% by applying an external HDDM-AGC.

scholarly journals Analisis Unjuk Kerja Improved Sinc Power Pulse pada Sistem OFDM Melalui Kanal Frequency Selective Fading

2019 ◽  
Vol 18 (3) ◽  
pp. 323
Author(s):  
Kadek Agus Mahabojana Dwi Prayoga ◽  
NMAE Dewi Wirastuti ◽  
Nyoman Pramaita
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Density Ratio ◽  
Pulse Frequency ◽  
Noise Power ◽  
Selective Fading ◽  
Frequency Selective Fading ◽  
Power Pulse ◽  
Noise Power Spectral Density ◽  
Frequency Selective

Kombinasi antara sistem OFDM (orthogonal frequency division multiplexing) dan Pulse Shaping mampu mengurangi Inter Carrier Interference (ICI) dan error yang terjadi. Penelitian ini bertujuan untuk mengetahui perbandingan performansi dari sistem OFDM tanpa pulse shaping dan OFDM dengan pulse shaping Improved Sinc Power (ISP) pulse yang melalui kanal Frequency Selective Fading, ditinjau dari BER (bit error rate) berbanding Eb/No (energy per bit to noise power spectral density ratio). Penelitian ini menggunakan metode simulasi dengan menggunakan program Matlab R2018a. Hasil dari simulasi didapat unjuk kerja sistem OFDM dengan pulse shaping ISP pulsememiliki hasil yang lebih baik dari OFDM tanpa pulse shaping. Pada kanal transmisi Frequency Selective Fading untuk mencapi nilai BER sebesar 10-1 sistem OFDM dengan pulse shaping ISP pulse dibutuhkan Eb/No sebesar 2 dB. Sedangkan pada sistem OFDM tanpa pulse shaping dibutuhkan Eb/No sebesar 10 dB. Kata Kunci — OFDM, Pulse Shaping, ICI, ISP pulse, Frequency Selective Fading.

Reducing multipath effect of low-cost GNSS receivers for monitoring by considering temporal correlations

2020 ◽  
Vol 14 (2) ◽  
pp. 167-175
Author(s):  
Li Zhang ◽  
Volker Schwieger
Keyword(s):  
Low Cost ◽  
Ground Plane ◽  
Single Frequency ◽  
Spatial Correlations ◽  
Raw Data ◽  
Multipath Effect ◽  
Temporal Correlations ◽  
Multipath Effects ◽  
Gnss Receivers ◽  
Multipath Signals

AbstractThe investigations on low-cost single frequency GNSS receivers at the Institute of Engineering Geodesy (IIGS) show that u-blox GNSS receivers combined with low-cost antennas and self-constructed L1-optimized choke rings can reach an accuracy which almost meets the requirements of geodetic applications (see Zhang and Schwieger [25]). However, the quality (accuracy and reliability) of low-cost GNSS receiver data should still be improved, particularly in environments with obstructions. The multipath effects are a major error source for the short baselines. The ground plate or the choke ring ground plane can reduce the multipath signals from the horizontal reflector (e. g. ground). However, the shieldings cannot reduce the multipath signals from the vertical reflectors (e. g. walls).Because multipath effects are spatially and temporally correlated, an algorithm is developed for reducing the multipath effect by considering the spatial correlations of the adjoined stations (see Zhang and Schwieger [24]). In this paper, an algorithm based on the temporal correlations will be introduced. The developed algorithm is based on the periodic behavior of the estimated coordinates and not on carrier phase raw data, which is easy to use. Because, for the users, coordinates are more accessible than the raw data. The multipath effect can cause periodic oscillations but the periods change over time. Besides this, the multipath effect’s influence on the coordinates is a mixture of different multipath signals from different satellites and different reflectors. These two properties will be used to reduce the multipath effect. The algorithm runs in two steps and iteratively. Test measurements were carried out in a multipath intensive environment; the accuracies of the measurements are improved by about 50 % and the results can be delivered in near-real-time (in ca. 30 minutes), therefore the algorithm is suitable for structural health monitoring applications.

scholarly journals Bio-Separated and Gate-Free 2D MoS2 Biosensor Array for Ultrasensitive Detection of BRCA1

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 545
Author(s):  
Yi Zhang ◽  
Wei Jiang ◽  
Dezhi Feng ◽  
Chenguang Wang ◽  
Yi Xu ◽  
...  
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Chemical Vapor ◽  
Signal Interference ◽  
Ultrasensitive Detection ◽  
Chemical Vapor Deposition Growth ◽  
Biosensor Array ◽  
Growth Method ◽  
Biological Modification ◽  
Biological Solutions

2D molybdenum disulfide (MoS2)-based thin film transistors are widely used in biosensing, and many efforts have been made to improve the detection limit and linear range. However, in addition to the complexity of device technology and biological modification, the compatibility of the physical device with biological solutions and device reusability have rarely been considered. Herein, we designed and synthesized an array of MoS2 by employing a simple-patterned chemical vapor deposition growth method and meanwhile exploited a one-step biomodification in a sensing pad based on DNA tetrahedron probes to form a bio-separated sensing part. This solves the signal interference, solution erosion, and instability of semiconductor-based biosensors after contacting biological solutions, and also allows physical devices to be reused. Furthermore, the gate-free detection structure that we first proposed for DNA (BRCA1) detection demonstrates ultrasensitive detection over a broad range of 1 fM to 1 μM with a good linear response of R2 = 0.98. Our findings provide a practical solution for high-performance, low-cost, biocompatible, reusable, and bio-separated biosensor platforms.

Real-time and near real-time ZTD from a local network of low-cost dual-frequency GNSS receivers.

2021 ◽  
Author(s):  
Tomasz Hadas ◽  
Grzegorz Marut ◽  
Jan Kapłon ◽  
Witold Rohm
Keyword(s):  
Water Vapor ◽  
Real Time ◽  
Low Cost ◽  
Weather Prediction ◽  
Local Network ◽  
System Component ◽  
Dual Frequency ◽  
Lower Accuracy ◽  
Gnss Receivers ◽  
The Impact

<p>The dynamics of water vapor distribution in the troposphere, measured with Global Navigation Satellite Systems (GNSS), is a subject of weather research and climate studies. With GNSS, remote sensing of the troposphere in Europe is performed continuously and operationally under the E-GVAP (http://egvap.dmi.dk/) program with more than 2000 permanent stations. These data are one of the assimilation system component of mesoscale weather prediction models (10 km scale) for many nations across Europe. However, advancing precise local forecasts for severe weather requires high resolution models and observing system.   Further densification of the tracking network, e.g. in urban or mountain areas, will be costly when considering geodetic-grade equipment. However, the rapid development of GNSS-based applications results in a dynamic release of mass-market GNSS receivers. It has been demonstrated that post-processing of GPS-data from a dual-frequency low-cost receiver allows retrieving ZTD with high accuracy. Although low-cost receivers are a promising solution to the problem of densifying GNSS networks for water vapor monitoring, there are still some technological limitations and they require further development and calibration.</p><p>We have developed a low-cost GNSS station, dedicated to real-time GNSS meteorology, which provides GPS, GLONASS and Galileo dual-frequency observations either in RINEX v3.04 format or via RTCM v3.3 stream, with either Ethernet or GSM data transmission. The first two units are deployed in a close vicinity of permanent station WROC, which belongs to the International GNSS Service (IGS) network. Therefore, we compare results from real-time and near real-time processing of GNSS observations from a low-cost unit with IGS Final products. We also investigate the impact of replacing a standard patch antenna with an inexpensive survey-grade antenna. Finally, we deploy a local network of low-cost receivers in and around the city of Wroclaw, Poland, in order to analyze the dynamics of troposphere delay at a very high spatial resolution.</p><p>As a measure of accuracy, we use the standard deviation of ZTD differences between estimated ZTD and IGS Final product. For the near real-time mode, that accuracy is 5 mm and 6 mm, for single- (L1) and dual-frequency (L1/L5,E5b) solution, respectively. Lower accuracy of the dual-frequency relative solution we justify by the missing antenna phase center correction model for L5 and E5b frequencies. With the real-time Precise Point Positioning technique, we estimate ZTD with the accuracy of 7.5 – 8.6 mm. After antenna replacement, the accuracy is improved almost by a factor of 2 (to 4.1 mm), which is close to the 3.1 mm accuracy which we obtain in real-time using data from the WROC station.</p>

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