GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 1 GLAST Large...

EMI/EMC 1

GLAST LAT Project September 15, 2006: Pre-Shipment Review

Presentation 7 of 12

GLAST Large Area TelescopeGLAST Large Area Telescope

LAT Pre-Shipment Review

EMI/EMC

Michael Lovellette, Test DirectorNaval Research Lab

Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope

EMI/EMC 2



EMI/EMC The Bottom Line 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-TD08585-01

EMI/EMC 3



Purpose / ContentsPurpose / 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-00778– LAT Performance Verification Plan LAT-MD-00408-04c– EMI Test Plan LAT-MD-02726-02

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RE101 RE102 CE101 CECM CS102 CS06 RS101 RS103 St. MagTKR

ProtoFlight X X X X X X X X X 0Flight (Acpt) X X 0

CALProtoFlight X X X X X X X X X 0Flight (Acpt) X X 0

ACDQual BEA X X X X X X X X XProtoFlight (a)

T&DFQual X X X X X X X X X 3(b)Flight (Acpt) X X 0

Mech (Radiators)ProtoFlight X (c )

(c ) Radiator subsystem test of VCHP heater power source deferred to LAT level configuration

(a) ACD Subsystem EMI testing Waivered - LAT-XR-06733(b) Qual TEM/TPS, GASU exceeded radiated emissions spec (RE102) in S band, GPS notch; HCB exceeded CECM spec - Waiver approved, CCR 433-0374

Subsystem EMI/EMC Test SummarySubsystem EMI/EMC Test Summary

EMI/EMC 5



Radiator Subsystem EMI/EMC TestRadiator 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

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LAT EMI TestLAT 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

EMI/EMC 7



LAT Power InterfacesLAT 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

EMI/EMC 8



Test LimitationsTest 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)

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As Run Test SequenceAs 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

EMI/EMC 10



Deviations from EMI Test PlanDeviations 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

EMI/EMC 11



Deviations from EMI Test Plan - CS102Deviations 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

RFAmp

In Out

LAT-SIU Interface

VSC

ChamberBulkhead

Attenuator

≥100 H(if necessary)

(+)

(-)

SpectrumAnalyzer

Attenuator

≤ 5 cm

EMI/EMC 12



LAT GroundingLAT Grounding

Before Radiated Testing the LAT was positioned on copper sheets and all grounds were connected with 18” Cu sheets

EMI/EMC 13



Radiator EMI TestRadiator EMI Test

The radiator was connected to the special power supply

The first run showed power supply harmonics over the limit

EMI/EMC 14



So We Shielded the Power SupplySo We Shielded the Power Supply

EMI/EMC 15



Conducted EmissionsConducted Emissions

All conducted emissions tests passed comfortably – Representative plot

shown here.

EMI/EMC 16



Conducted SusceptibilityConducted 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

EMI/EMC 17



Conducted SusceptibilityConducted Susceptibility

EMI/EMC 18



CECM, CSCM, CS06CECM, 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 433-0374

EMI/EMC 19



Radiated EmissionsRadiated 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

EMI/EMC 20



Radiated Emissions - SGLS NotchRadiated Emissions - SGLS Notch

EMI/EMC 21



Radiated Emissions - GPS Notch Hor.Radiated Emissions - GPS Notch Hor.

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Radiated Emissions - GPS Notch Vert.Radiated Emissions - GPS Notch Vert.

EMI/EMC 23



Radiated Susceptibility - RS103Radiated Susceptibility - RS103

RS103 Test sweeps were performed and data analysis performed off line

ACD, CAL and TKR performance verified

EMI/EMC 24



Radiated Susceptibility - RS101Radiated Susceptibility - RS101

RS101 tested limited locations

Connectors Tracker

EMI/EMC 25



Radiated SusceptibilitiesRadiated 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 < 10-4

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

EMI/EMC 26



Radiated Susceptibility - TKRRadiated Susceptibility - TKR

EMI/EMC 27



PersonnelPersonnel

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

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GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 7 of 12 EMI/EMC 1 GLAST Large...

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