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statistics and useful integrity-related information. All these data will be made freely available through the worldwide web (WWW). The second way to use the E-IPF is through specialised integrity experimentation. Here the E- IPF can be configured in a very flexible way to output relevant integrity-related diagnostic data and statistics. This way of usage, however, requires expert knowledge and is restricted to authorised users only. The first part of the paper presents the context and overall design of the E-IPF together with the core products that are generated by the E-IPF. There will be five main components in the E-IPF: interface server, processing kernel, configuration tool, monitoring agent and long-term statistics generator. Each of these components, their functionalities and interrelations are described in detail. The second part of the paper describes the implemented Galileo baseline algorithms as well as several alternate candidate core integrity algorithms and the possibilities for integrity testcase experimenting. Furthermore, simulation and manipulation algorithms that are used to contaminate the raw measurement data with different types of feared events as well as the necessary analysing algorithms are presented. As the operational phase of the GSTB processing centre and the routine data processing is about starting, some early results are also provided. EXPERIMENTAL IPF ARCHITECTURE The following figure 1 shows the architecture of the E-IPF: E-IPF Input Driver Modules Data Server Facility DSF I/F Server Interface Modules GIPA Kernel Algorithmic Models Config Tool Output Analysis Modules Remote I/F User I/F Local I/F Figure 1: Experimental IPF architecture User The E-IPF SW has been developed as platformindependent as possible, making use of Trolltech's Qt library. The heart of the E-IPF SW is the processing kernel. The processing kernel has integrated a set of around 230 algorithmic modules that perform all required processing tasks. Among these modules are: earth tidal correction, tropospheric and ionospheric correction, station synchronisation, carrier-phase smoothing, satellite anomaly detection, the integrity check modules, and quite a number of basic modules for low-level data transformation tasks or graphical displays. Also available are modules for data input and output as well as a certain set of simulation and statistical analysis modules. All the available modules can be inserted in a configuration and linked together as needed. This allows for a very high flexibility in experimenting with the algorithms. Figure 2: ExpIPFTool screen-shot (PC platform) The price to pay for this high flexibility is the complexity of the configurations. One complex configuration (which is used for the routine processing of the E-IPF) is shown in figure 2. For an easier configuration of the E-IPF, two different features have been implemented: a configuration tool that allows to graphically configuring the system, and a simplified configuration possibility that makes use of a simplified configuration file of a different format together with a "frozen" configuration file template. The following figure 3 shows the E-IPF SW components. These components are stand-alone executables that have a well-defined interface with each other and with the DSF, which is the central data archive and storage element of the GSTB-V1.
E-IPF C1: ExpIPFExec (E-IPF Executor) C2: ExpIPFKrnl (Processing Kernel) C3: ExpIPFTool (Configuration Tool) C4: ExpIPFSnmp (SNMP Subagent) C5: ExpIPFStat (Long-Term Statistics) Figure 3: Experimental IPF breakdown The E-IPF SW is divided into the following five components: • E-IPF Executor • Processing Kernel • Configuration Tool • SNMP Demon • Long-term statistics Each of these is briefly described in the following. Executor Component The E-IPF Executor is the SW component that realises the E-IPF operator interface for the routine data processing or for test case experiments, where monitoring and control capabilities have to be used. It is the SW component that will be called by the routine operator for performing the routine operations. The main functionalities of this SW component are: • Transfer E-IPF input data (via FTP) from DSF to the E-IPF session directory • Step through the multi-session file (see below) provided by the operator • Start the E-IPF kernel or statistics component with the appropriate configuration for each individual session • Transfer E-IPF output data (via FTP) back to DSF Dependent on the type of input configuration file, the executor either prepares a session for kernel processing, for long-term statistics computation or performs a "merge" between a simplified routine processing configuration file and the E-IPF resident "frozen" configuration file. The output of this "merge" process is a standard kernel configuration file that may be passed directly to the kernel component. An execution of the E-IPF is triggered via a systemlevel defined multi-session approach: A filename of a multi-session file is passed to the executor component. This multi-session file contains the filenames of a certain number of session files. Each session file defines a clear task for the E-IPF. In this way, the E-IPF can be used within a pre-defined regular processing schedule or even for some kind of backlog processing. This is a necessary feature, because after a change in the baseline algorithms or in the tuning of parameters for these baseline algorithms, all relevant processing has to be repeated, when consolidated long-term statistics must be evaluated. Finally, the executor component also performs all data housekeeping activities that are related to the E-IPF platform itself. Especially in cases, when there is insufficient disk space available, the GPC operator has to be warned. Kernel Component The kernel is the heart of E-IPF processing. It integrates a slim scheduling mechanism with a flexible linker mechanism and the full set of algorithmic modules. These modules are also included in the configuration tool component. This modular architecture allows easy expansion of the system via integration of new modules. The E-IPF allows also an integration of external modules that can be configured and, hence, included in the scheduling scheme. ExpIPFTool ExpIPFKrnl ExpIPFModl DataSrc DataDst DataFrm DataDsp ProcMod Class1 Class2 Module1 Class5 Class4 Module2 Class7 Class6 Module3 Class9 Class8 Module4 Class11 Class12 Module5 Figure 4: Algorithmic modules E-IPF components However, the interfaces of the modules as used by the kernel are different from the interfaces as used by the configuration tool. While the kernel mainly uses three virtual functions, called "Init", "Exec" and "Exit", the configuration tool uses a module
Page 1: Integrity Investigations Within the
Page 5 and 6: • Time Synchronisation Error Stat
Page 7 and 8: Category F: System Performance The
Page 9: Still a few algorithms have to be c

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