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Stream real-time tracking data with support for delayed delivery. Transfer TDM content efficiently to minimize bandwidth. Explore ways to optimize TD-CSTS operations for varied data needs.
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Tracking Data Cross Support Transfer Service Status John Pietras 16 October 2008 Berlin
Tracking Data Cross Support Transfer Service • Aimed at “real time” streaming tracking data • However, delayed complete delivery also supported • Service goals • Transfer valid TDM content • Minimize bandwidth required
DATA_START Record DATA_START Record DATA_START Record Tracking Data Record(s) Tracking Data Record(s) Tracking Data Record(s) Tracking Data Record(s) Tracking Data Record(s) Metadata n Metadata 2 Tracking Data Record(s) DATA_STOP record Tracking Data Record(s) DATA_STOP record NOTIFY ‘data stopped’ NOTIFY ‘metadata updated’ TRANSFER-DATA TRANSFER-DATA Mapping TDM Segment to TD-CSTS Operations TD Operation TDM TDM Partitions Invocations Header Header NOTIFY ‘tdm header’ Header Partition Metadata 1 NOTIFY ‘start time metadata’ Metadata 1 Metadata Partition Data 1 TRANSFER-DATA Data Partition(s) DataStop Partition Metadata Partition Data Partition Data Partition Data Partition Data Partition DataStop Partiton Metadata Partition Data Partition Data Partition Final Partition NOTIFY ‘data stopped’ Metadata 2 NOTIFY ‘metadata updated’ Data 2 TRANSFER-DATA TRANSFER-DATA . . . . . . Data n-1 TRANSFER-DATA TRANSFER-DATA Metadata n Data n . DATA_STOP record NOTIFY ‘data stopped’ NOTIFY ‘end of data’
Issue with Current Approach • TDM parameter names are qualified by the metadata. E.g; • The link is identified in the Metadata • The parameter is named in the Data • If a spacecraft has 2 links (e.g., S and X band) and Transmit Frequency and Receive Frequency are being used concurrently, the metadata has to change for every pair of reported values
Possible Approaches • Repeat metadata for each measurement pair • Fully supported by TDM specification • Higher bandwidth requirements – is this a problem? • Modification to TDM • Modify TDM keywords • E.g., allow multiple indexed PATHs to exist • Let Data keywords reference the indexed PATHs • Allow partial Metadata respecification • Where to apply these modifications? • Part of TDM specification? • TD-CSTS-specific compression? • Run separate TD-CSTS instances for each tracking PATH • Reasonable for separation of radiometric from meteorological data • Not so good for separate RF links
Fundamental Question • How important is minimizing TD-CSTS bandwith?