Interface Control Document Research Articles

Derivation of the Sagnac (Earth-rotation) correction and analysis of its accuracy for GNSS applications

AbstractGlobal Navigation Satellite Systems (GNSS) applications require computation of the geometric range between the satellite vehicle at the time-of-signal transmission and the receiver antenna location at the time-of-signal reception. This computation requires attention to the frames of reference due to the rotation of the Earth-Centered Earth-Fixed (ECEF) frame during the time-of-signal propagation. Three range computation approaches are commonplace and will be discussed herein. The first is the Global Positioning System Interface Control Document recommendation to rotate the ECEF frames to a common reference time. The other two are forms of the Sagnac correction. The Sagnac derivations already in the literature are either limited to stationary receivers or lack the connection between the Earth-centered inertial (ECI) and ECEF frames. Neither form of the Sagnac correction exactly reproduces the geometric range. They are approximations. The literature does not currently contain an analysis of the error involved in using either form of the Sagnac correction. This article makes two contributions: (1) it presents derivations for both forms of the Sagnac correction that are valid for moving receivers and that maintain the connection between the ECI and ECEF frames; and (2) it analyzes the error of the Sagnac correction for orbits of different radius. The analysis shows that Sagnac corrections introduce range errors less than $$7.57\times 10^{-4}$$ 7.57 × 10 - 4 meters for GNSS satellites at medium Earth orbit.

Improving hardware/software interface management in systems of systems through documentation as code

ContextThe management of Interface Control Documents (ICDs) has shown to be a major pain point in the architecting processes of Systems of Systems (SoS).ObjectiveThis work aims to improve on previously identified ICD management issues using the documentation-as-code philosophy as a potential basis for a treatment, and in collaboration with practitioners.MethodWe conducted a Technical Action Research (TAR) study with a group of engineers at the Netherlands Radio Astronomy Institute (ASTRON), in the context of the LOFAR radio telescope. An additional research instrument, in the form of an expert panel, was used to evaluate the transferability of the proposed treatment to alternative domains.ResultsIn-depth insights on previously identified interface management issues were gained. Based on these insights a functional proof-of-concept was developed aimed at addressing these issues following the documentation-as-code principles. In addition to receiving overall positive reviews from practitioners and experts, further areas of improvement and transferability considerations for future work were identified.ConclusionsThe proposed approach, which to our knowledge has not been explored before in this context, is promising to address some of the recurring interfacing-related issues with directed SoS in multiple engineering domains. This could be done mainly by enforcing consistency and completeness on both text-based and formal elements of the ICDs, and turning ICDs into single sources of truth for the architecting processes of large scale SoS.

Analysis of BDS-3 PPP-B2b Positioning and Time Transfer Service

With the completion of the BeiDou global navigation satellite system (BDS-3), the BeiDou Navigation Satellite System Signal In Space Interface Control Document Precise Point Positioning Service Signal PPP-B2b (Version 1.0) was officially announced, and BDS-3 officially broadcast PPP-B2b correction to broadcast ephemeris through geostationary earth orbit (GEO) satellites to provide precise point positioning services for users in the Asia–Pacific region. This study comprehensively analyzes the application of the PPP-B2b product to time transfer and positioning. On a daily basis, the PPP-B2b positioning accuracy after convergence is calculated using the four ionosphere-free (IF) combinations in static and simulated kinematic modes: BDS B1I/B3I, BDS B1C/B2a, BDS B1I/B3I + GPS, and BDS B1C/B2a + GPS. Observations of time laboratories including the National Time Service Center of the Chinese Academy of Sciences (NTSC) and the Telecommunication Laboratories (TL) are employed to conduct zero-baseline common clock difference (CCD) time comparison experiments and long-baseline time comparison experiments using the PPP-B2b product and the GBM product. The results indicate that the PPP-B2b position accuracy in static mode by only BDS is 1.5/2.7/3.9 cm, and by GPS + BDS is within 1.5/2.5/3.5 cm in North, East, and Up directions, respectively. Regarding simulated kinematic PPP-B2b, the average root mean square (RMS) values of the position errors in the North, East, and Up directions for the combination of BDS B1I/B3I + GPS and BDS B1I/B3I are 3.4/5.8/7.6 cm and 3.8/6.6/7.8 cm, respectively. Simultaneously, the average RMS values of position errors using BDS B1C/B2a + GPS and BDS B1C/B2a are 3.6/4.9/8.1 cm and 4/6.1/8.5 cm. In the time comparison study, the results of zero-baseline CCD using the PPP-B2b product and the GBM product are within the fluctuation range of 0.1 ns, respectively. Particularly, the long-baseline time comparison difference between results employing the PPP-B2b product and the GBM product is within the range of ±0.5 ns.

Uporaba variacij pospeška zaradi vpliva Lune in Sonca pri izračunu tirnic satelitov GLONASS

In the differential equation system describes the motion of GLONASS satellites (rus. Globalnaya Navigazionnaya Sputnikovaya Sistema, or Global Navigation Satellite System ), the acceleration caused by the luni-solar traction is often taken as a constant during the period of the integration. In this work-study, we assume that the acceleration due to the luni-solar traction is not constant but varies linearly during the period of integration following this assumption; the linear functions in the three axes of the luni-solar acceleration are computed for an interval of 30 min and then implemented into the differential equations. The use of the numerical integration of Runge-Kutta fourth-order is recommended in the GLONASS-ICD (Interface Control Document) to solve for the differential equation system in order to get an orbit solution. The computation of the position and velocity of a GLONASS satellite in this study is performed by using the Runge-Kutta fourth-order method in forward and backward integration, with initial conditions provided in the broadcast ephemerides file.

BDGIM performance evaluation based on iGMAS global tracking network

The third phase BeiDou Navigation Satellite System (BDS-3) provides a BeiDou Global broadcast Ionospheric delay correction Model (BDGIM) for single-frequency navigation and positioning applications. According to the BDS Interface Control Document (ICD) Signal B1C (Version 1.0), the BDGIM contains nine parameters and was broadcast in December 2018. The BDGIM will gradually replace the BDS-2 ionospheric 8-parameter Klobuchar model (BDSKlob). A preliminary evaluation of the BDGIM was conducted using data collected at multiple stations across the international GNSS Monitoring and Assessment System (iGMAS) global tracking network. The high-precision global grid ionospheric delay sequences obtained from the Center of Orbit Determination in Europe (CODE) were selected as references to evaluate the BDGIM performance worldwide. The synthetic analysis and comparison results show that the BDGIM provides the best global description of the ionosphere and improves the nocturnal performance of the Klobuchar model and its sharp increase in the Polar Regions. The VTEC (Vertical Total Electron Content) calculated by the BDGIM exhibited the smallest RMS (Root Mean Square) values, the highest precision, and better performance for most northern hemisphere latitudes. BDGIM RMS values for most world regions were generally less than 5 TECU (Total Electron Content Unit), and its ionospheric delay correction rate reached nearly 80%.

Performance analysis of BDS-3 B1C and GPS L1C data/pilot component pseudo random noise codes

Abstract The Pseudo Random Noise (PRN) codes is an important part of the GNSS system based on Codes Division Multiple Access (CDMA), and it is the key to channel separation and satellite distinction. The GNSS system excellent performance characteristics of multiple access and spread spectrum are realized by the PRN codes. According to the officially released Interface Control Documents (ICDs), the Beidou global navigation satellite system (BDS-3) B1C and GPS L1C have chosen the Weil codes as PRN codes whose generation is based on the number theoretic method. The Weil codes has the advantages of flexible codes length, good performance and large candidate set, therefore, this paper mainly studies 63 pairs of data/pilot channel PRN codes for BDS-3 B1C and GPS L1C. On the basis of introducing BDS-3 B1C and GPS L1C PRN codes, mainly for the Weil codes generation principle, codes evaluation criteria and intra-system and inter-system odd/even auto-correlation and cross-correlation characteristics are simulated in detail. The experimental results show that the upper limit value, lower limit value, the mean and standard deviation of the odd auto-correlation and cross-correlation of the PRN codes of the BDS-3 B1C signal were better than those of the GPS L1C PRN codes. The performance of odd and even cross-correlation are almost similar between BDS-3 B1C and GPS L1C signal inter-systems, which are slightly worse than the intra-system, and the upper limit value of the inter-system is lower than 2.94 dB in the GPS L1C intra-system.

Requirements and design structure for Surya Satellite-1

Currently, there are various references on the manufacture of nanosatellite specifications weighing 1KG - 10KG.The Surya Satellite-1 is the first nanosatellite made by universities in Indonesia. The Surya Satellite-1 team gets a launch offer from Japan Aerospace Exploration Agency (JAXA) and, all the nanosatellites manufacturer racers at ICD (Interface Control Document) obtained from JAXA. The formation of the Satellite-1 Surya framework is also based on the provisions of JAXA. The various specifications and requirements specified by the JAXA space agency consisting of specific specifications such as the mass of nanosatellite 1U (10cm x 10cm x 11.65cm) size of at least 0.13KG and a maximum of 1.33KG, with the determination of a gravity point not exceeding 2 cm from the nanosatellite geometry center point. In the case of preventing solar radiation in space, there is a requirement that the structure of satellite structures on hard black anodization should be more than 10 meters in the surface of the satellite structure. In terms of detail, the satellite structure is a black hard anodized aluminum after its manufacturing process derived from the MIL-A-8625 document, type 3.

Model-based software engineering for an optical navigation system for spacecraft

The project Autonomous Terrain-based Optical Navigation (ATON) at the German Aerospace Center (DLR) is developing an optical navigation system for future landing missions on celestial bodies such as the moon or asteroids. Image data obtained by optical sensors can be used for autonomous determination of the spacecraft’s position and attitude. Camera-in-the-loop experiments in the Testbed for Robotic Optical Navigation (TRON) laboratory and flight campaigns with unmanned aerial vehicle (UAV) are performed to gather flight data for further development and to test the system in a closed-loop scenario. The software modules are executed in the C++ Tasking Framework that provides the means to concurrently run the modules in separated tasks, send messages between tasks, and schedule task execution based on events. Since the project is developed in collaboration with several institutes in different domains at DLR, clearly defined and well-documented interfaces are necessary. Preventing misconceptions caused by differences between various development philosophies and standards turned out to be challenging. After the first development cycles with manual Interface Control Documents (ICD) and manual implementation of the complex interactions between modules, we switched to a model-based approach. The ATON model covers a graphical description of the modules, their parameters and communication patterns. Type and consistency checks on this formal level help to reduce errors in the system. The model enables the generation of interfaces and unified data types as well as their documentation. Furthermore, the C++ code for the exchange of data between the modules and the scheduling of the software tasks is created automatically. With this approach, changing the data flow in the system or adding additional components (e.g., a second camera) have become trivial.

Tailoring a ConOps for NASA LSP Integrated Operations

AbstractAn integral part of the Systems Engineering process is the creation of a Concept of Operations (ConOps) for a given system, with the ConOps initially established early in the system design process and evolved as the system definition and design matures. As Integration Engineers in NASA's Launch Services Program (LSP) at Kennedy Space Center (KSC), our job is to manage the interface requirements for all the robotic space missions that come to our Program for a Launch Service. LSP procures and manages a launch service from one of our many commercial Launch Vehicle Contractors (LVCs) and these commercial companies are then responsible for developing the Interface Control Document (ICD), the verification of the requirements in that document, and all the services pertaining to integrating the spacecraft and launching it into orbit. However, one of the systems engineering tools that have not been employed within LSP to date is a Concept of Operations. The goal of this paper is to research the format and content that goes into these various aerospace industry ConOps and tailor the format and content into template form, so the template may be used as an engineering tool for spacecraft integration with future LSP procured launch services. This tailoring effort was performed as the author's final Masters Project in the Spring of 2016 for the Stevens Institute of Technology and modified for publication with INCOSE (Owens, 2016).

Monitoring and evaluation algorithm of GNSS signal in space availability

In civil aviation and other navigation application fields, the availability of Global Navigation Satellite System (GNSS) in Signal in Space (SIS) is a key indicator to evaluate the performance. In this paper, the SIS availability of Global Positioning System (GPS) and BeiDou Navigation Satellite System (BDS) are evaluated and analyzed. The model of satellite availability algorithm is constructed based on the Markov process, with its reliability investigated. Moreover, the evaluation algorithm of constellation availability is developed. Based on the evaluation models, the performance of GPS SIS and BDS SIS is evaluated by using the measured data, respectively. Combined with the availability standard of GPS Standard Positioning Service (SPS) performance standards and BDS Signal In Space Interface Control Document (Version 2.0), the proposed evaluation models of SIS availability are effective and the performance of GPS SIS and BDS SIS conform the availability of performance standards, respectively. Meanwhile, the results are instructive for the study of the availability performance monitoring and the evaluation of global BDS.

M&C ML: A modeling language for monitoring and control systems

The use of System Engineering (SE) language such as SysML [1,20] is common within the community of control system designers. However the design handoff to the subsequent phases of the control system development is carried out manually in most cases without much tool support. The approach to agreeing on the control interface between components is a good example where engineers still rely on either manually created Interface Control Documents (ICD) or one off tools implemented by individual projects. Square Kilometer Array (SKA) [2] and International Thermonuclear Experimental Reactor (ITER) [3] are two good examples of such large projects adopting these approaches. This results in non-uniformity in the overall system design since individual groups invent their own vocabulary while using a language like SysML which leads to inconsistencies across the design, interface and realized code. To mitigate this, we propose the development of a Monitoring and Control Modeling Language (M&CML), a domain specific language (DSL) [4,22] for specifying M&C solutions. M&C ML starts with defining a vocabulary borrowing concepts from standard practices used in the control domain and incorporates a language which ensures uniformity and consistency across the M&C design, interfaces and implementation artifacts. In this paper we discuss this language with an analysis of its usage to point out its benefits.

Software Implementation of BeiDou B1I Code Generator Using Matlab/Simulink

Conventional Matlab implementation of software ranging code generator requires code shifts to produce the ranging codes assigned to different satellites. Unfortunately, it is unable to implement software BeiDou B1I code generator using this method, because the B1I code shifts are unknown. Based on the generator revealed in BeiDou Interface Control Document (BICD), a software generator is implemented by using Simulink blocks in conjunction with Matlab programs in this paper. The Simulink blocks enable the generator to compute the BeiDou B1I code shifts, as well as reducing the complexity of the implementation. Simulation results show that the implementation is feasible and reliable. All B1I code shifts are calculated, which can be used for both software and hardware implementation in the future. Patents describing a wide range of applications based on the BeiDou system have also been proposed and implemented. Keywords: BeiDou system, the B1I code, software generator, Matlab/Simulink, code shift.

비행시험 발사통제 시스템의 신호처리 알고리즘

The Missile Flight Test Launch Control System is to operate in conjunction with the Fire Control System during flight test to guided weapons. Also, this is a system for the test control and situation monitoring depending on the type of guided weapons and testing purposes. Message structure, communication protocols, such as data types for interworking with the fire control system and the Missile Flight Test Launch Control System are defined in the Launch Control ICD(Interface Control Document). ICD are composed differently of each guided weapons system and each test object. Previously, in order to interwork with the Fire Control System, the interlocking software was developed, which had a variety of problems. Therefore, we developed a new parsing algorithm in order to recognize the variety of Launch Control ICD and verified that the algorithm operates normally by checking transmitting and receiving various message in conjunction with the fire control system.

DGNSS RSIM을 위한 GPS/Galileo 의사거리 보정기법

본 논문에서는 위성항법시스템(GNSS)의 다양화에 따른 DGNSS 기준국(RSIM, Reference Station and Integrity Monitor)의 재구축을 위하여, 유럽연합(EU) 위성항법시스템인 Galileo의 E1 의사거리 보정정보 생성 알고리즘과 GPS/Galileo 시뮬레이션을 통한 성능검증에 대해 다룬다. 먼저 DGPS RSIM에서 DGNSS RSIM으로 전환을 위한 운영적 측면에서의 기술 및 메시지 표준과 사용자 방송 측면에서의 메시지 표준에 대해 살펴본다. 일반적으로 GNSS의 의사거리 보정을 위해서는 정확한 GNSS 위성위치와 사용자 위치를 알아야만 한다. 그러므로 Galileo 위성위치를 정확하게 계산하기 위해서, Galileo ICD 문건의 위성위치 계산식을 이용하여 사용자 수신기에서 제공하는 궤도력 정보를 기반으로 해당 위성 위치를 추정한다. 그리고 위성시계 옵셋과 사용자 수신기의 시각오차, GPS와 Galileo 위성의 시스템 타임 옵셋을 계산하여 GPS/Galileo 의사거리 보정정보를 생성한다. GPS/Galileo 시뮬레이터를 연동한 성능검증 플랫폼을 기반으로 GPS/Galileo 보정정보의 오차를 분석하고, 측위정확도를 분석하여 그 성능을 검증하였다. 국제기구(RTCM)에서 요구하는 기준국 운영을 위한 측위 성능을 충족할 수 있음을 확인하였다. In order to prepare for recapitalization of differential GNSS (DGNSS) reference station and integrity monitor (RSIM) due to GNSS diversification, this paper focuses on differential correction algorithm using GPS/Galileo pesudorange. The technical standards on operation and broadcast of DGNSS RSIM are described as operation of differential GPS (DGPS) RSIM for conversion of DGNSS RSIM. Usually, in order to get the differential corrections of GNSS pesudorange, the system must know the real positions of satellites and user. Therefore, for calculating the position of Galileo satellites correctly, using the equation for calculating the SV position in Galileo ICD (Interface Control Document), it estimates the SV position based on Ephemeris data obtained from user receiver, and calculates the clock offset of satellite and user receiver, system time offset between GPS and Galileo, then determines the pseudorange corrections of GPS/Galileo. Based on a platform for performance verification connected with GPS/Galileo integrated signal simulator, it compared the PRC (pseudorange correction) errors of GPS and Galileo, analyzed the position errors of DGPS, DGalileo, and DGPS/DGalileo respectively. The proposed method was evaluated according to PRC errors and position accuracy at the simulation platform. When using the DGPS/DGalileo corrections, this paper could confirm that the results met the performance requirements of the RTCM.

Acquisition and Tracking of Galileo IOV E5 Signals: Experimental Results and Performance Evaluation

Abstract An assessment of the Galileo In-Orbit Validation (IOV) signals on the E5 band is presented in this paper, investigating the signal features compared with the expected characteristics as described in the Galileo Interface Control Document (ICD) specifications. In detail, the results in terms of signal acquisition and tracking during multiple satellite passes are discussed, providing also a description of the experimental setup used in order to separately receive and process E5a and E5b signals. The analysis covers the received signal strength versus the satellite elevation, the modulation format, and the presence of navigation data and secondary code chips. Since at time of writing both the two Galileo IOV satellites (PFM and FM2) are broadcasting E5 signals, the results obtained processing their E5a and E5b signals are discussed. In addition, these signals are also compared with those currently transmitted by the two experimental Galileo satellites, GIOVE-A and GIOVE-B.

GIOVE Satellites Pseudorange Error Assessment

Galileo is a global civil navigation satellite system developed in Europe as an alternative to the GPS controlled by the US Department of Defense and GLONASS controlled by Russian Space Forces. It is scheduled to be operative in 2013 and it will have 30 satellites orbiting on three inclined planes with respect to the equatorial plane at an altitude of about 24 000 km. The aim of this work is the study of the pseudorange error of the GIOVE satellites. To achieve this goal, the specifications defined in Giove A-B Navigation Signal in Space Interface Control Document (ICD) are used to develop a suitable software tool in MATLAB® environment. The tool is able to compute GIOVE A and GIOVE B position from the broadcast ephemerides, to calculate the pseudorange error and to process it. From the known receiver position and the computed satellite coordinates, the geometric range is obtained and compared with the pseudorange measurement, in order to obtain the pseudorange error.

갈릴레오 GIOVE-A E1 신호 분석 및 RF 프론트엔드 대역폭 영향 분석

갈릴레오는 유럽에서 개발하고 있는 민간 주도의 새로운 위성항법시스템이다. 갈릴레오 시스템의 성능을 테스트하기 위한 테스트 위성인 GIOVE-A 위성이 현재 지구 상 궤도에서 항법신호를 송출하고 있다. 갈릴레오 시스템의 성능을 평가하고 향후 갈릴레오 수신기를 개발하기 위해서는 GIOVE-A 위성 신호를 분석할 필요가 있다. 본 논문에서는 GIOVE-A 위성신호를 수신 한 후 이를 GIOVE-A 신호 규격문서에 정의된 정보를 이용하여 신호 처리하였다. 신호 획득, 추적 및 항법 메시지 디코딩의 과정을 수행하여 현재 GIOVE-A 위성의 항법정보 제공 상황을 파악하였다. BOC 신호 사용에 따른 항법신호 대역폭의 증가가 갈릴레오 신호가 GPS와 다른 점 중의 하나이며 RF 프론트엔드의 대역폭에 따른 항법 신호 수신 성능을 평가하여 현재 사용되고 있는 GPS L1 RF 프론트엔드를 사용할 수 있는지를 검토하였다. Galileo is a new civil Global Navigation Satellite System(GNSS) developed by Europe. GIOVE-A, a satellite to test Galileo system performance, transmits navigation signal on orbit. Evaluation of Galileo system and development of Galileo receiver needs to analyze GIOVE-A signals. In this paper, we received GIOVE-A signals and processed it using GIOVE-A Interface Control Document(ICD). Signal acquisition, tracking and navigation message decoding made grasping current signal status possible. Bandwidth increase by BOC modulation is one of the difference from GPS. Therefore, we investigated feasibility of conventional GPS L1 RF front-end to receive GIOVE-A E1 signal by evaluation of receiving performance of navigation signal on each bandpass filter of RF front-end.

AUTOMATING THE MANAGEMENT OF INTERFACE DATA

AbstractGeneration and maintenance of interface data are a significant part of the Systems Engineering effort on most programs. Typically the control is accomplished through Interface Control Documents (ICD's). The data used to generate the ICD has many other applications, such as wire lists, loads analysis, weights reports, etc. In most applications the ICD is actually a subset of the available interface data, and control and maintenance of this data is a multifarious task. Using an electronic database to record all interface data and generate the ICD and other required data from the resulting database cannot only save a significant amount of effort, but can improve the quality and data consistency. This process can enhance the Systems Engineering effort throughout all phases of the program from inclusion of initial interface Requirements, through Functional Allocation, Design Synthesis, Interface Management, and Verification.This approach was used to generate interface documentation for an Unmanned Air Vehicle to Automatic Test Equipment (ATE) interface. The process has proven to be less labor intensive than previous methods, and has shown significant savings in updates and generating related documents from the same database. When maintained on a network, it allowed the systems engineers working the interfaces access to the latest data, without having to generate and control printed copies. This paper will discuss the factors that must be considered in implementing an interface management database, such as selection of a DBMS program, data formats, control of the database, and will discuss the experience gained from this application, and will provide examples of the results.