Exchanging Databases with Dissimilar Systems Using

CCSDS XTCE CCSDS Spacecraft Monitoring & Control WG

and

OMG Space Domain Task Force

Presented by Mario Merri, ESA

GSAW 2006 2

Outline

• Where does XTCE come from?

• Its goals and benefits

• How does it work?

• Usage so far

• Conclusions

GSAW 2006 3

XTCE History

• Object Management Group (OMG) standard originally developed by

• European Space Agency• US Air force/Mission Operations (Lockheed Martin)• Boeing Communications & Satellites• NASA & JPL

• Being adopted by CCSDS via Agency Review under responsibility of SM&C WG

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CCSDS SM&C and XTCE• ESA

– M Merri (chairman), M Schmidt, A Ercolani, J Muller, I Dankiewicz, S Cooper

• BNSC– R Thompson (deputy

chairman), B Harnett• CNES

– B Béhal, E Poupart, R Soumagne

• CSA – P Melanson

• DLR– H Hofmann

• INPE– PG Milani, AM Ambrosio

XTCE Splinter Group

• JAXA– T Yamada

• NASA/GSFC– DC Lokerson, F Johnson,

JK Marquart, JS Gal-Edd, C Fatig, R Jones , K Rice

• NASA/JPL– A Oyake, P Shames, J Moholt

• ASI– C Labonia

• OMG– G Simon (Lockheed Martin),

B Kizzort (Harris Corp.)

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XTCE Goal

• XML-based non-proprietary standard format for exchanging TM/TC databases that will reduce• human errors • ambiguities, confusion, and • lost time and money in difficult, sometimes

lousy (painful) conversions between dissimilar systems

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XTCE Format

• Exchange between– working teams– missions– systems– agencies

►Adapt only I/O►Reuse legacy systems►Reduce costs

Application Field

PlanningScheduling

CommandManagement

Real time

Trending

Analysis

Simulators

SpacecraftManufacturers

InstrumentManufacturers

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XTCE Benefits• Allows better interoperability

– Across organisations (e.g. JWST)

– Within a mission (e.g. S/C prime -> operations)

• Lets different philosophies collaborate in one data model

• Separates “pure” telemetry and telecommand data from dedicated/proprietary processing data

• Able to extend for data items not currently defined

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XTCE in a nutshell (1/8)• An XML Schema language describing data for:

– Telemetry definitions– Data transmission and packaging– TM/TC parameter properties– Telecommand definitions

• Non TM&TC data is not considered part of XTCE (e.g. dedicated software instructions, SW configuration variables, page definitions, real-time scripts, etc.)

• TM and TC definitions are 80% similar between space systems

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XTCE in a nutshell (2/8)

• XTCE describes a “SpaceSystem” - command & telemetry descriptions, in a hierarchical format

• The granularity of a space system’s description is left to the user, e.g. SpaceSystem may contain SpaceSystem(s)

• The hierarchy allows integration of multiple databases into one overall database– E.g.: multi-satellite missions, multi-instrument satellite

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XTCE in a nutshell (2*/8)

Space System

Space System Space System

Space System Space System

Spacecraft level

Instrument level

Device level

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XTCE in a nutshell (2**/8)

Space System

Space System Space System

Space System Space System

Constellation level

Satellite level

Instrument level

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XTCE in a nutshell (3/8)

• A space system in XTCE is able to describe:– Telemetry parameters, their packaging and dedicated

processing– Telecommand parameters, commands, its packaging

and dedicated processing– Streams (up and down, with coding information)– Maintain minimal configuration information– Conversion information– Limits and pre/post command checks

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XTCE in a nutshell (4/8)

• Header for configuration data

• Default for generic settings• Telemetry for core data • Telecommand for core data• Services for frames

identification

Space System

Header

Defaults

Telemetry

Services

Telecommand

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XTCE in a nutshell (5/8)

• Telemetry data is distributed in several elements:– Parameter types– Parameters (instances of parameter types)– Containers (aka packets)– Messages– Streams– Algorithms

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XTCE in a nutshell (6/8)

• Logical sequence of definitions:– Parameter types (alarms, calibrations)– Parameter instances– Containers (Packets)– Streams, messages and algorithms

• Example: CCSDS TM frames, packets and XTCE containers

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XTCE in a nutshell (7/8)

• Parameters are put in sequence to form packets (containers)

• Packets are put together to form frames• Streams are defined on top of generic frames

Frame primary header

Frame secondary header

Frame data field

Op.ctrl Err.ctrl

Packet header Packet data field

Ver # Type P.hdr f APID Gr. f SSC P.h.len

Frame

Packet

Packet header

GSAW 2006 17

XTCE in a nutshell (8/8)

• Telecommand data is distributed in several elements:– Parameter types– Parameters– Containers– Messages– Streams– Algorithms

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XTCE Applications so far

• James Webb Space Telescope XML Schema have been converted– Future work includes exchanging database with other

archive systems and control center real-time systems

• SCOS-2000 ASCII files have been converted• Hardware vendors deliver the database

information in XTCE format to the spacecraft integrator on some US programs

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CCSDS Documentation

• Draft CCSDS Green book release along with XTCE1.1 for internal CCSDS review

• CCSDS Magenta book (detailed user guide) is being written

• CCSDS Red Book released

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Conclusions• XML self-describing nature reduces learning curve and errors

• XML is easy to work with, due to the amount of libraries, tools, and broad industry acceptance

• XTCE powerful concepts are ideal for exchanging legacy, current and future TM & TC databases to planning systems, engineering analysis tools, and real-time command and control systems

• Easily translated between the project XML database format and XTCE, no longer just a concept but being used internationally

• XTCE covers about 80% of the TM/TC definitions reducing the errors between dissimilar systems

GSAW 2006 21

Questions and Answers

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