GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 1 GLAST Large Area Telescope LAT Pre-Shipment Review EMI/EMC Michael Lovellette, Test Director Naval Research Lab Gamma-ray Large Area Space Telescope

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 2 EMI/EMC The Bottom Line  No emissions excesses found in any LAT system level test, CE or RE  One susceptibility found –Tracker occupancy specification of <10 -4 violated at ~100 MHz vertical polarization in RS Nothing on the vehicle radiates in this frequency band Also unlikely for external radiation Not considered a problem, waiver submitted  EMI report in preparation, LAT-TD

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 3 Purpose / Contents  Demonstrate LAT complies with all EMI/EMC requirements: –Conducted and radiated emissions below required levels –LAT does not exhibit susceptibilities when exposed to conducted or radiated energy at required levels  Test Categories –Conducted emissions (CE) –Radiated emissions (RE) –Conducted susceptibility (CS) –Radiated susceptibility (RS)  Requirements flowdown –Mission System Spec  433-SPEC-0005 –LAT Environmental Requirements Spec  LAT-SS –LAT Performance Verification Plan  LAT-MD c –EMI Test Plan  LAT-MD

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 4 Subsystem EMI/EMC Test Summary

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 5 Radiator Subsystem EMI/EMC Test  VCHP heater Radiated Emissions testing –S/C power source for LAT VCHP heaters is an unfiltered DC- DC converter. –Concern is the conducted noise for this power source will become radiated emission issue for LAT system test. –This issue shall be resolved by special subsystem (Radiator) test – RE102 – using simulated S/C power source. –The test was performed just prior to LAT RE102 test.  Not formally part of the LAT level EMI test, performed on an STR

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 6 LAT EMI Test LAT test levels derived from LAT-SS-0778  Test Suite: –CE102 Conducted Emissions, Power Leads, 10 kHz to 10 MHz, MIL-STD-462, CE03 –CECM & CEDM* Conducted Emissions, Time Domain, 150 MHz Bandwidth –CS102 Conducted Susceptibility, Power Leads, 10 kHz to 10 MHz, MIL-STD- 462, CS02 –CSCM Conducted Susceptibility, Common Mode, 30 Hz to 150 MHz, MIL-STD- 462, CS02 –CS06 Conducted Susceptibility, Spike, Power Leads, MIL-STD-462 –RE101 Radiated Emissions, Magnetic Field, 20 Hz to 50 kHz –RE102 Radiated Emissions, Electric Field, 10 kHz to 18 GHz, MIL-STD-461E –RS101 Radiated Susceptibility, Magnetic Field, 20 Hz to 50 kHz –RS103 Radiated Susceptibility, Electric Field, 30 MHz to 18 GHz  Verify by Analysis: –RS103 Radiated Susceptibility, Electric Field, 18 GHz to 40 GHz –Static Magnetic Field * Not required but we did it anyway

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 7 LAT Power Interfaces  SC-LAT Power Interfaces –SC PRU (P) - LAT DAQ –SC PRU (R) - LAT DAQ –SC PRU (P) - LAT SIU (P) –SC PRU (R) - LAT SIU (R) –SC PRU (P) - LAT VCHP +Y Heaters –SC PRU (P) - LAT VCHP –Y Heaters –SC PRU (R) - LAT VCHP +Y Heaters –SC PRU (R) - LAT VCHP –Y Heaters –SC PDU (P) - LAT Makeup Heaters (Survival) –SC PDU (R) - LAT Makeup Heaters (Survival) Makeup circuit power interfaces are not tested. VCHP heater testing limited to RE102

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 8 Test Limitations  RS103 upper limit of 18GHz (40GHz) –18 – 40 GHz addressed by analysis.  Limited area of RS101 test –Requires scanning each 10cm x 10cm area, ~16min/scan –~1450 scans for the LAT, another ~1200 for the radiators (~29 days) –Scan selected locations around connectors, PMTs, BEA  Redundant side testing limited to Conducted Emissions (CE102) and Conducted Susceptibility (CS102)

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 9 As Run Test Sequence  12 June - High Bay –CE102 DAQ hot & ret redundant bus –CE102 SIU hot & ret redundant bus  13 June –CS 102 DAQ ret redundant bus –CS102 SIU hot & ret redundant bus  15 June - Anechoic Chamber –RE 102 calibration –RE102 Test  16 June –RE102 continued  17 June –RS103  19 June –RS103 continued  20 June –RS103 –RE101 –RS103 retest  21 June –RS103 retest –RS101  22 June –CSCM DAQ primary bus –CSCM SIU primary bus –CS06 DAQ primary bus –CS06 SIU primary bus –CS102 DAQ primary bus –CS102 SIU primary bus  23 June –CS06 SIU primary bus –CS102 DAQ primary bus –CS102 SIU primary bus  24 June –CS102 DAQ redundant bus –CE102 DAQ primary bus –CE102 SIU primary bus –CECM SIU primary bus –CEDM SIU primary bus –CS06 retest –CECM DAQ primary bus –RS101 retest  10 July - High Bay –CS102 retest DAQ & SIU primary bus

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 10 Deviations from EMI Test Plan  UHF Notch shown in Figure 36 not included in RE102 requirement –Table 6 Gives correct notches  CS102 pulse level 10 V as indicated in text, not 20V as shown in Figures 27 and 30.  CEDM test not required –We did it anyway  During initial RE testing some radiator connectors not connected –No change noted once they were connected  During redundant side CS test 150kHz to 10MHz signal injection was lead was inadvertently connected to a thermistor lead –Incorrect lead stripped for access –Thermistor passed CS testing with flying colors –Test successfully repeated during primary side CS testing using correct pin number

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 11 Deviations from EMI Test Plan - CS102  Impossible to locate current probe between injection point and LAT connector due to the twisted pair type wiring  Current probe was located at LSC –Reduced current feedback sensitivity  Pre calibrated current limits used LSC RF Generator RF Amp InOut LAT-SIU Interface VSC Chamber Bulkhead Attenuator ≥100  H (if necessary) (+) (-) Spectrum Analyzer Attenuator ≤ 5 cm

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 12 LAT Grounding  Before Radiated Testing the LAT was positioned on copper sheets and all grounds were connected with 18” Cu sheets

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 13 Radiator EMI Test  The radiator was connected to the special power supply  The first run showed power supply harmonics over the limit

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 14 So We Shielded the Power Supply

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 15 Conducted Emissions  All conducted emissions tests passed comfortably –Representative plot shown here.

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 16 Conducted Susceptibility  The only susceptibilities detected during conducted testing were additional noise on RTD temperature measurements –This imposed ± 2 or 3 degrees noise on the temperature readout –Some of the readouts affected were VCHP reservoir temperatures used by the thermal control software –Does not violate any requirements, but worth noting for thermal control software design  This additional noise can be accommodated by a modification to the digital filter in the thermal control system –D. Wood has modified filter and tested against noise data taken during EMI CS test

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 17 Conducted Susceptibility

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 18 CECM, CSCM, CS06  All LAT system tests nominal  There was an exceedence during subsystem CECM test on the heater control box (HCB) VCHP reservoir heater feed. –No retest performed at system level –Waiver approved by project office, CCR

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 19 Radiated Emissions  All radiated emissions, RE101 & RE102, were below required levels  All broad band was well below the limit  SGLS notch also passed easily  GPS notch required some additional shielding of test harnesses, connectors and connector savers to get below limits

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 20 Radiated Emissions - SGLS Notch

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 21 Radiated Emissions - GPS Notch Hor.

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 22 Radiated Emissions - GPS Notch Vert.

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 23 Radiated Susceptibility - RS103  RS103 Test sweeps were performed and data analysis performed off line  ACD, CAL and TKR performance verified

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 24 Radiated Susceptibility - RS101  RS101 tested limited locations  Connectors  Tracker

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 25 Radiated Susceptibilities  LAT exhibited increased tracker occupancy at ~33, 66, & 99 MHz during testing with vertical polarization –Effect noted during post test processing –Only the 99 MHz frequency violated tracker occupancy requirement of <  There are no sources of EM radiation on the S/V at these frequencies and the frequency is below most external sources  Considered not to be a problem  Waiver submitted to project office

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 26 Radiated Susceptibility - TKR

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 27 Personnel  EMI/EMC Test Director - Michael Lovellette  EMI/EMC Facility Operations –Mike Obara - Test Conductor –Tony Gray - Test Conductor  LAT Instrument Operations –Brian Grist – Operations Lead –Standard LAT I&T Operators and Online analysis support –Anders Borgland – Offline instrument analysis lead –Elliott Bloom – LAT181 analysis lead