1、Lessons Learned Entry: 0586Lesson Info:a71 Lesson Number: 0586a71 Lesson Date: 1998-04-24a71 Submitting Organization: JPLa71 Submitted by: R. Kuberry/D. OberhettingerSubject: Verify Vendor Certifications of Commercial Equipment (1996) Abstract: A commercial reference antenna used to test the Cassini
2、to-Probe RF link wrongly indicated that the spacecraft and probe antenna polarizations were both incorrect. The GSE reference antenna was then tested against other antennas of known polarization and found to be mislabeled. The functional attributes of vendor provided equipment cannot be assumed to
3、match specifications, particularly when an item is to be used as a reference standard. Assure independent testing of critical features of commercial instrumentation, review interface control documents and drawings, and conduct spacecraft-level tests of all telecom interfaces.Description of Driving E
4、vent: JPL required the use of a reference antenna to verify the Huygens Probe to Cassini high gain antenna (HGA) RF link. A test had been developed to use right and left-circular polarized (RHCP and LHCP) antennas to verify the polarization of both the Probe and HGA antennas, used for the transfer o
5、f science data during the probes descent to the surface of Titan. JPL purchased an off-the-shelf RHCP conical log spiral antenna for this test; the vendor provided a calibration certificate which certified the candidate ground support equipment (GSE) antenna to be right-circular polarized.When the c
6、ommercial antenna was used as a reference standard during a spacecraft-level RF compatibility test, it indicated that the spacecraft and probe antenna polarizations were both incorrect. When further investigation between international partners could not substantiate this indication, the GSE referenc
7、e antenna was tested against other antennas of known polarization and found to be mislabeled. The product featured a biwire winding which effectively reversed the polarization to LHCP, resulting in a left polarized emission from an apparently clockwise-wound spiral antenna.Provided by IHSNot for Res
8、aleNo reproduction or networking permitted without license from IHS-,-,-The manufacturer revealed that the antenna labeling was not in accordance with accepted standards, and that the product had been marketed as RHCP for over 10 years. Since the antenna had been used in EMC testing mostly as a broa
9、dband source or receiver, users were rarely concerned with polarization. As shown in Figure 1, the physical appearance of the reference antenna structure - a clockwise helix - supports the standard definition of RHCP, but the electrical performance indicates LHCP.refer to D descriptionD A Typical Co
10、nical Log Spiral Antenna Additional Keyword(s): COTS, Receiving InspectionReference(s):1. Cassini Problem/Failure Report No. Z23529, October 21, 1996.2. K. Kellogg & W. Moore, “Probe-Spacecraft Antenna End-to-End Failure Investigation Report,“ JPL IOM 3360-96-14, October 17, 1996.3. Lesson Learned #
11、11-121, Ground Support Equipment Failure Caused Damage to SEASAT-ALesson(s) Learned: The functional attributes of vendor provided equipment cannot be assumed to match specifications, particularly when an item is to be used as a reference standard.Recommendation(s): 1. Assure adequate independent tes
12、ting of critical features of any commercial instrumentation used in a test of flight or critical hardware.2. Continue present practice of reviewing interface control documents and drawings to determine whether they adequately define and control interface conflicts between subsystem Provided by IHSNo
13、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-and spacecraft elements. To prevent gaps in system-level interface control and monitoring, conduct spacecraft-level tests, where practical, of all telecom interfaces, including polarization.Evidence of Recurrence Contro
14、l Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Hardwarea71 Procurement Small Business & Industrial Relationsa71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1998-05-04a71 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-,-,-
