Augmented Message Research Articles

USER IMPLEMENTATION AND ASSESSMENT OF BDS-3 PRECISE POINT POSITIONING AUGMENTATION SERVICE WITH NO ECONOMIC COST

Abstract. The satellite-based precise point positioning (PPP) service enables users with high accuracy positions without Internet connections. Currently, two types of satellite-based PPP services are available. One type is commercial service, such as Trimble CenterPoint RTX service. The second type is non-commercial and cost-free service, including the BDS-3 satellite-based PPP service based on PPP-B2b signals. This service is currently open access to all receiver manufacturers. This contribution firstly presents a detailed instruction on how to apply PPP-B2b signals into positioning. Afterwards, the performance of BDS-3 PPP service is validated with both static and kinematic experiments carried out in Wuhan, China, during day of year 168 and 172, 2022. Results indicate that PPP-B2b signals mainly improve BDS-3 clock precision and GPS orbit accuracy. With BDS-3 PPP-B2b augmentation messages, the static satellite-based PPP shows 3.9/6.9/10.3 mm daily solution repeatability in E/N/U directions, respectively. An average of 13.9 min convergence time and 3.42/2.16/6.65 cm E/N/U positioning accuracy are achieved in the simulated kinematic mode. During a 28-min stepper motor driven movement test, 3.48/14.88 cm 2D/3D kinematic positioning accuracy is obtained using the BDS-3 PPP service.

Comparison of Satellite Positioning Augmentation Messages Broadcast from Michibiki and Galileo

Comparison of Satellite Positioning Augmentation Messages Broadcast from Michibiki and Galileo

Exploring characteristics of BDS-3 PPP-B2b augmentation messages by a three-step analysis procedure

Exploring characteristics of BDS-3 PPP-B2b augmentation messages by a three-step analysis procedure

Performance analysis of the BDSBAS-B1C message in trial operation stage

BeiDou Satellite-based Augmentation System (BDSBAS) has come into the trial operation stage since July, 2020. To evaluate the characteristic of the augmentation message in BDSBAS-B1C signal, the effectiveness of the message content was firstly analyzed, and then the validity of the broadcasting strategy was estimated. Finally, the accuracy of the user equivalent ranging error (UERE) and the single frequency positioning error with different correction parameters in BDSBAS-B1C message was evaluated. Based on the above analysis, the effectiveness of the augmentation message was preliminarily verified with the results showing that: (1) the BDSBAS-B1C message type, information content and update interval have basically met the international standard; (2) the accuracy of the UERE obtained with the augmentation message had an obvious improvement in contrast to that of the UERE obtained with the usual navigation message of the GPS satellites, and the ionospheric delay was one of the important factors which affected the accuracy of the UERE; (3) the positioning accuracy obtained with the augmentation message was also improved, and the improvement was more obvious in the service areas with high availability of the ionospheric parameters.

GNSS global real-time augmentation positioning: Real-time precise satellite clock estimation, prototype system construction and performance analysis

Lots of ambiguities in un-differenced (UD) model lead to lower calculation efficiency, which isn’t appropriate for the high-frequency real-time GNSS clock estimation, like 1Hz. Mixed differenced model fusing UD pseudo-range and epoch-differenced (ED) phase observations has been introduced into real-time clock estimation. In this contribution, we extend the mixed differenced model for realizing multi-GNSS real-time clock high-frequency updating and a rigorous comparison and analysis on same conditions are performed to achieve the best real-time clock estimation performance taking the efficiency, accuracy, consistency and reliability into consideration. Based on the multi-GNSS real-time data streams provided by multi-GNSS Experiment (MGEX) and Wuhan University, GPS+BeiDou+Galileo global real-time augmentation positioning prototype system is designed and constructed, including real-time precise orbit determination, real-time precise clock estimation, real-time Precise Point Positioning (RT-PPP) and real-time Standard Point Positioning (RT-SPP). The statistical analysis of the 6h-predicted real-time orbits shows that the root mean square (RMS) in radial direction is about 1–5cm for GPS, Beidou MEO and Galileo satellites and about 10cm for Beidou GEO and IGSO satellites. Using the mixed differenced estimation model, the prototype system can realize high-efficient real-time satellite absolute clock estimation with no constant clock-bias and can be used for high-frequency augmentation message updating (such as 1Hz). The real-time augmentation message signal-in-space ranging error (SISRE), a comprehensive accuracy of orbit and clock and effecting the users’ actual positioning performance, is introduced to evaluate and analyze the performance of GPS+BeiDou+Galileo global real-time augmentation positioning system. The statistical analysis of real-time augmentation message SISRE is about 4–7cm for GPS, whlile 10cm for Beidou IGSO/MEO, Galileo and about 30cm for BeiDou GEO satellites. The real-time positioning results prove that the GPS+BeiDou+Galileo RT-PPP comparing to GPS-only can effectively accelerate convergence time by about 60%, improve the positioning accuracy by about 30% and obtain averaged RMS 4cm in horizontal and 6cm in vertical; additionally RT-SPP accuracy in the prototype system can realize positioning accuracy with about averaged RMS 1m in horizontal and 1.5–2m in vertical, which are improved by 60% and 70% to SPP based on broadcast ephemeris, respectively.

Improved tagged visual cryptography by random grids

Tagged visual cryptography (TVC) is a brand new type of visual cryptography (VC) in which additional tags are concealed into each generated share. By folding up each single share, the associated tagged pattern is visually revealed. Such additional tag patterns greatly enrich extra abilities of VC, such as augmented message carried in a single share, user-friendly interface to manage the shares, and/or evidence for verifying consistency among those shares cooperating in a decryption instance. However, reported (k, n) TVC proposed by Wang and Hsu still suffers from the defects such as pixel expansion, code book required in the encoding phase and low image quality. In this work, a (k, n) TVC by adopting the concept of random grid (RG) is introduced. The proposed method can solve the pixel expansion and code book needed problems. Further, cheating activity can be prevented by the proposed algorithm. Superior visual quality of both the recovered secret image and reconstructed tag image is provided as well according to the theoretical analysis and demonstrated experiments.

Tagged Visual Cryptography

This letter presents a method for implementing visual cryptography (VC) in which an additional tag is attached to each generated share. The proposed (t, n), 2 ≤ t ≤ n tagged visual cryptography (TVC) scheme works like a traditional VC scheme does, where the original image is encoded in n shares in such a way that the secret can be revealed by superimposing any t or more shares, but knowledge of less than t shares gets no secret information. A notable characteristic of TVC is that an extra tag can be revealed by folding up each share, which provides users with supplementary information such as augmented message or distinguishable patterns to identify the shares. The tagging property can easily be applied to any reported VC scheme to endow the generated shares with more capabilities. Construction methods and simulation results of the proposed (t , n) TVC based on conventional matrix-based VC and probabilistic-VC are illustrated in the letter.

Network system for wide area DGNSS

A differential global navigation satellite system (DGNSS) is always used to broadcast augmentation messages for GNSS to receivers in the covering areas through geostationary earth orbit (GEO) satellites to improve the accuracy, reliability, and integrity of navigation. GEO broadcasting is an efficient strategy for avionic applications and other modes of transport. For some applications though, it may be of interest to broadcast additional augmentation messages through other transmission means. For instance, it may be difficult for GEO reception in cities or indoors because of building obstacles. Real-time broadcasting of navigation augmentation messages through the internet is an important hot-spot of research. Based on characteristics of navigation augmentation messages, combined application layers multicast with i3 (internet indirection infrastructure) multicast, is presented herein with a hierarchy mix multicast system based on node heterogeneity to broadcast differential correction messages. The qualities of the system network structure are analyzed. After the securities requirements are analyzed, the types and solutions of security issues were briefly studied.

Augmented message-matrix approach to deterministic dense-coding theory

A useful method for deriving analytical results applicable to the standard two-party deterministic dense-coding protocol is introduced and illustrated. In this protocol, communication of $K$ perfectly distinguishable messages is attainable via $K$ selected local unitary operations performed on one qudit from a pair of entangled qudits of equal dimension $d$ in a pure state $|\ensuremath{\psi}⟩$ with largest Schmidt coefficient $\sqrt{{\ensuremath{\lambda}}_{0}}$. The method takes advantage of the fact that the $K$ message states, together with ${d}^{2}\ensuremath{-}K$ augmenting orthonormal state vectors, yield a unitary matrix, thereby implying properties of the $K$ message states which otherwise are not readily recognized. Employing this augmented message matrix, we produce simple proofs of previously established results including (i) ${\ensuremath{\lambda}}_{0}\ensuremath{\le}d/K$, (ii) ${\ensuremath{\lambda}}_{0}<d/K$ when $K=d+1$, and (iii) the impossibility of finding a $|\ensuremath{\psi}⟩$ that can enable transmission of $K={d}^{2}\ensuremath{-}1$ messages but not ${d}^{2}$. Additional results obtained using the method include proofs that the ${\ensuremath{\lambda}}_{0}\ensuremath{\le}d/K$ bound is reduced to at least (i) ${\ensuremath{\lambda}}_{0}\ensuremath{\le}(1/2)[1+\sqrt{(d\ensuremath{-}2)/(d+2)}]$ when $K=d+1$ and (ii) ${\ensuremath{\lambda}}_{0}\ensuremath{\le}(K\ensuremath{-}m)/(2K\ensuremath{-}m\ensuremath{-}d)$ whenever $(d+1)\ensuremath{\le}K\ensuremath{\le}2d$ and the selected local unitaries include the first $m$ non-negative integral powers of the shift operator $X$.

Development of the EGNOS Pseudolite System

In order to access the Satellite Based Augmentation System (SBAS) service, the end user needs to have a direct line of sight to at least one of the Geostationary Earth Orbit (GEO) satellites transmitting the augmentation messages. This requirement is critical for users in environments such as city canyons, valleys and fjords since high buildings and mountains in the vicinity of the end user can easily block the lines of sight to the GEO satellites. The situation becomes worse at high latitudes because of the low elevation angles to the GEO satellites. Even a very low obstacle can block the lines of sight to the GEO satellites. This limitation reduces SBAS Signal in Space (SIS) availability significantly at high latitude especially for land applications. This paper presents a solution of transmitting the European Geostationary Navigation Overlay Service (EGNOS) SIS using a pseudolite. The EGNOS pseudolite functions in a similar way as a GEO satellite. It will provide not only a terrestrial-based solution for transmitting the EGNOS SIS, but also a ranging measurement for the navigation solution. The EGNOS pseudolite system mainly consists of a Master Control Station, an EGNOS Data Server, EGNOS pseudolites and the user terminal. A preliminary test on a surveyed site has been carried out to verify the functionalities of the system. The data set collected from the test has been processed with two scenarios: one with four GPS satellites, while the other with three GPS satellites plus an EGNOS pseudolite. Both data processing scenarios have similar satellite geometries. The test result shows that the positioning accuracies are similar for both scenarios.

Expressional reprogramming of survival pathways in rat cardiocytes by neuregulin-1β

Neuregulin/ErbB2-induced kinase signaling provides essential survival and protection clues for functional integrity of the adult heart and skeletal muscle. To define the regulatory pathways involved in neuregulin-dependent muscle cell survival, we set out to map the largely unknown transcript targets of this growth/differentiation factor in cardiocytes. Freshly isolated adult primary rat cardiocytes were treated for 24 h with recombinant human neuregulin-1beta (NRG-1beta, 30 ng/ml). Transcript level alterations in NRG-1beta-treated and control cardiocytes (n = 6) were identified with Atlas Rat Toxicology 1.2 cDNA arrays (BD Clontech) and established permutation L1 regression analysis. Selected transcriptional adjustments were confirmed by RT-PCR and Western blotting. Involvement of MAPK pathways was verified with the inhibitor PD-98059. Application of the single dose of NRG-1beta to quiescent cardiocytes induced expressional reprogramming of distinct cellular processes. This response included a prominent 50-100% increase in transcripts of multiple redox systems. It also involved a comparable mRNA augmentation of protein synthetic and folding factors together with augmented message for the trigger of cardiac hypertrophy, cyclin D1 (CCND1). First evidence for a role of neuregulin in promotion of mitochondrial turnover, voltage-gated ion channel expression, and the suppression of fatty acid transporter mRNAs was revealed. Subsequent analysis confirmed a corresponding upregulation of redox factor proteins thioredoxin and the thioredoxin reductase 1, GSTP-1, and CCND1 and demonstrated downregulation of the related transcripts by PD-98059 in neuregulin-stimulated cultures. These MAPK-dependent expressional adjustments point to novel oxidative defense and hypertrophy pathways being involved in the longer lasting protective function of neuregulin in the heart.

Influence of length of augmented message on children's attitudes toward Peers who use augmentative and alternative communication

The influence of conversational phrase length on the attitudes of two groups of grade-schoolaged children (i.e., those familiar and unfamiliar with children with disabilities) was studied. Length did not influence the attitudes of familiar children but did influence the attitudes of unfamiliar children in grades 3 and 5. The unfamiliar children who saw a videotape of a child communicating with two- to four-word augmented messages had more positive attitude responses than did the children who saw a videotape of a child communicating with one-word augmented messages. Theoretical and clinical implications are discussed.