Space-based Telemetry And Range Safety (STARS) StudyJames Rash - GSFC

Ed Criscuolo - CSCKeith Hogie - CSCRon Parise - CSC

2004 Space Internet Workshop

OverviewBrief Description of STARSGoals of the STARS IP FormatterKey issues using standard HW for constant-rate TelemetryDesign and DevelopmentTesting and PerformanceStatus

2004 Space Internet Workshop

Space-based Telemetry and Range SafetyThe STARS project is investigating the use of a reliable communication link between flight vehicles and satellites in order to support range operations such as those used in flight termination systems.The project goals are to evaluate the system's reliability and performance, and to define a detailed design for the range system user that will reduce costs associated with dedicated groundstations. Previous flights evaluated the reliability of satellite communication links with TDRSSNext flights will incorporate the use of Internet Protocol (IP) for all downlink telemetry, and use a phased-array antenna to track TDRSS

2004 Space Internet Workshop

Space-based Telemetry and Range SafetyNASA Photo / Tony Landis

2004 Space Internet Workshop

IP Formatter GoalsTransport all range user telemetry to groundsystem using standard Internet ProtocolsBuild on previous flight experienceIncrease Flexibility, Reduce CostsOff-The-Shelf PC-104 hardware Open-Source operating-system (Linux 2.4.18)Standard "C" code and scripting languages Simplify Telemetry Systemdata captureonboard loggingdata transferSimplify Ground Systemdata routing and distributiondata logging

2004 Space Internet Workshop

Key Issues Using Std Sync Serial H/WIssue: Telemetry FramingSync Serial I/O cards are designed to handle discrete frames which may arrive asynchronouslyPCM telemetry has continuous nonstop framesSolution:Use hardware to initially locate syncUse back-to-back reads and software to flywheel & check syncUse hardware to re-acquire sync if lostIssue: Bit orderPCM telemetry is msb firstCommunications industry (eg - hdlc/frame-relay) uses lsb firstSolution:Use hi-speed software bit-reversal via table lookup

2004 Space Internet Workshop

Telemetry FormatsF-15 PCM Telemetry StreamIP Header (20)UDP Header (8)UDP/IP Telemetry Packet156 byte telemetry frame4 byte Seq #8 byte timestamp

2004 Space Internet Workshop

Telemetry FormatsF-15 TelemetryRange Safety TelemetryAntenna TelemetryIP FormatterStatusInOutIP Formatter1 Mbit/secPCM stream156 byte framesw / 3 byte syncFixed size UDP packetswith 1 frame per packet.Includes sync chars.10Kbit/secPCM stream124 byte framesw / 4 byte syncFixed size UDP packetswith 1 frame per packet.Includes sync chars.Fixed size UDP packets with one 80-byte frame per packet.Fixed size UDP packets with one 80-byte frame per packet.UDP packets with one ascii text line per packet.

2004 Space Internet Workshop

IP Formatter System ArchitectureGround Use OnlyPowerIRIG-BChar-SerNet-SerEthernetCPUConsoleNetworkWANPhased Array StatusUDP/IP packetsEthernet DB-9Formatter OutputUDP/IP packetsHDLC Sync serialRS-422DB-37IRIG-B timecodeLinux ConsoleCharacter terminal9600 baud N81RS-232DB-9Network Int.IP-192.168.0.11EthernetRJ-45Enerdyne MuxAudioVideoCoding PCBGDDSAntennaControlPhasedArrayControlPCM frames in bitstreamSynced PCM framesIndividual PCM frames in UDP/IP packetsCoded Enerdyne muxed data bitstreamTDRSConvDecodePort 40000PhasedArrayAntennaF-15 TelemRS Telem

2004 Space Internet Workshop

F-15 PCM DataReceiverF-15 DataR/S PCM DataReceiverRange Safety DataPhased Array Antenna Data

Linux Operating System2.4.18 kernel

Telemetry Sync Serial Driver

NetworkHDLC SyncSerial Driver

IRIG-B DriverRS-422RS-422RS-422RS-422EthernetIRIG-BEthernetDriverF-15RangeSafetyTestAccessIRIGSerial toEnerdyne MuxMinimal Kernel &File SystemIP FormatterStatus GenIPTime Stamps111.222.0.xPort10000UDPcapture #2UDPcapture #4UDPcapture #3192.168.0.11Port20000111.222.0.xPort20000192.168.0.11Port30000111.222.0.xPort30000192.168.0.11Port40000111.222.0.xPort40000RS-232ConsoleDriverTestAccessFLAPSRouterEnerdyneEnerdyne111.222.0.xPorts10000, 20000, 30000, 40000Packets addressed to specific UDP ports on FLAPS systemSwitch192.168.0.11RFSystemLANPhasedArrayAntennaIP FormatterSoftwareArchitectureTimekeeper

2004 Space Internet Workshop

RS-422 Breakout BoxRouterSTARS IP Formatter PC/104 stackPC/104 Proto BoardSerial line to Enerdyne/Router384MBDisksOnChipPC/104 Cable KitIP Formatter Development Bench

2004 Space Internet Workshop

Testing"Gizmo" programmable telemetry generator used to simulate F-15 PCM telemetryParaScope serial line analyzer used to playback simulated Range Safety PCM telemetryCustom data-generator program (provided by STARS) used to simulate Antenna telemetry data in UDP packets sent over ethernetTrueTime 800 timecode generator for IRIG-BEtherpeek network monitor SW used to monitor performancePost-run analysis of captured telemetry on groundstation to determine packet loss rate

2004 Space Internet Workshop

TestingPowerIRIG-BChar-SerNet-SerEthernetCPUF-15 TelemRS TelemGizmoParaScopeAntenna SimTimecode GeneratorRouterHDLCLinkEthernet LANGround SystemEtherPeekIP FormatterPC/104Stack

2004 Space Internet Workshop

PerformanceTest Conditions:Full telemetry rates on all inputs (1.45 Mbits/sec aggregate)HDLC output clock at 1.8 Mbits/sec (35 Kbits/sec headroom)Onboard logging of all telemetry except F-15Results:40 - 50% CPU UtilizationAll telemetry ingested with NO lossFull output rate (average) with 1 - 2% packet lossAttempted Mitigations:DMA output driver: Reduced CPU usage, but loss unchangedReduced F-15 rate to 500 Kbits/sec: Loss reduced to 0%Analysis:Insufficient kernel buffer pool causing dropped packets on output

2004 Space Internet Workshop

StatusIP Formatter delivered to STARS project on March 5, 2004Currently being integrated at the STARS facility at Dryden Flight Research Center (DFRC)

2004 Space Internet Workshop