1、Lessons Learned Entry: 0374Lesson Info:a71 Lesson Number: 0374a71 Lesson Date: 1995-01-25a71 Submitting Organization: JPLa71 Submitted by: Jim TaylorSubject: Higher Data Rates Possible Through Station Arraying Abstract: Because the MVM 73 project went to a degraded telemetry mode after failure of an
2、 onboard tape recorder, the project had to use DSN arraying schemes to provide higher mission telemetry data rates. The project and the DSN must foresee and plan the use of complex and previously unused capabilities sufficiently in advance to allow the proper analysis and configuration testing to be
3、 completed.Description of Driving Event: A previous failure of the onboard tape recorder had made the “full resolution, full frame 117.6 kbps“ mode the primary telecommunications mode at the second Mercury encounter. The increased Mercury to Earth range, relative to first Mercury encounter, required
4、 (1) a communications improvement of at least one dB over the performance obtained at the first Mercury encounter, and (2) commitment by the MVM 73 project to a bit error rate higher than .0333.The Telecommunications Division and the Deep Space Network (DSN) worked together to devise an arraying sch
5、eme to improve the signal-to-noise ratio. This consisted of real-time arraying of DSS-14, DSS-13, and DSS-12 at Goldstone through microwave connections. Testing one week before encounter showed a signal-to-noise ratio improvement of 0.8 dB; the actual improvement on encounter day was 1.0 dB. In addi
6、tion, non real-time arraying of the signals from DSS-14 at Goldstone and DSS-43 at Canberra was to be attempted. This would consist of combining the tape-recorded signals from each of these stations to gain additional signal-to-noise ratio. This was accomplished at the DSNs Compatibility Test Area 2
7、1 and in the Division 33 Telecommunications Development Laboratory. The bit error rate achieved in real time met the .0333 criterion for more than five hours during the encounter.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Additional Keyword(s):
8、Tracking StationLesson(s) Learned: The use of DSN arraying schemes can provide higher mission telemetry data rates than might otherwise have been possible.Recommendation(s): The project and the DSN must foresee and plan the use of complex and previously unused capabilities sufficiently in advance to
9、 allow the proper analysis and configuration testing to be completed. Otherwise, prediction accuracy is degraded.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Communication Systemsa71 Flight OperationsAdditional Info: Approval Info: a71 Approval Date: 1985-12-19a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
