1、Public Lessons Learned Entry: 2737Lesson Info:a71 Lesson Number: 2737 a71 Lesson Date: 2010-04-26 a71 Submitting Organization: KSC a71 Submitted by: Annette Pitt Subject: Launch Processing System - Unprocessed Data Recording Abstract: While radio frequency (RF) Shuttle Main Engine telemetry data was
2、 being recorded during the vehicle ascent phase of STS-123, off-nominal noise in the data stream, combined with the use of a predefined and preset pulse code modulation (PCM) bit synchronizer, invalidated some of the Shuttle Main Engine data. Investigations revealed a deficiency in the telemetry sta
3、tion recording process, which was subsequently resolved by changing the RF data recording format from digital to analog. Description of Driving Event: As a primary element of the Launch Processing System at Kennedy Space Center, the Record and Playback System (RPS) is a general-purpose telemetry dat
4、a recording and reduction facility capable of recording low-data-rate PCM in either digital format (synchronized to a PCM bit sync) or analog format. For the STS-123 launch countdown, RPS was nominally configured to record Shuttle Main Engine 60 KB RF data in the digital format, using PCM bit syncs
5、as a front end to the recording process. After launch, when requested to confirm “Decom Lock” status of the RF Main Engine data links during ascent, RPS discovered one of the Merritt Island Launch Area (MILA) Main Engine data links was not valid. Lesson(s) Learned: Preconfigured, operator-specified
6、bit sync parameters compensate for nominal frequency and bit jitter variations in PCM data, allowing the bit sync to recover data from an imperfect stream. However, RF data is often very noisy and can be further degraded by vehicle exhaust plumes. These factors preclude the effective use of predefin
7、ed bit sync parameters. To eliminate this problem, RPS started recording the PCM signal in analog (unprocessed) format, eliminating all PCM signal processing and the potential for invalid data. Recommendation(s): Whenever feasible, PCM data sources should be recorded in an unprocessed format. Beside
8、s eliminating front-end problems with bit sync, raw data is extremely valuable as a troubleshooting tool, especially for the isolation of system data errors (problems) between vehicle and ground systems. Evidence of Recurrence Control Effectiveness: N/A Documents Related to Lesson: IFA STS-123-K-022
9、 In Flight Anomaly presentation Click here to download communication document. Mission Directorate(s): a71 Space Operations a71 Exploration Systems Additional Key Phrase(s): a71 1.Ground Operations a71 1.Configuration control and data management a71 1.Human factors impact on mission design a71 1.Eng
10、ineering design and project processes and standards a71 0.Crew Survival Systems a71 1.Ground support systems a71 1.Ground Equipment Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 1.Launch support systems a71 1.Test & Verification a71 1.Security a71 1.Software Additional Info: a71 Project: Space Shuttle Program Approval Info: a71 Approval Date: 2010-08-09 a71 Approval Name: mbell a71 Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
