LAT EMI Test

1
LAT EMI Test

• LAT test levels derived from LAT-SS-0778
• Use CAL EMI test procedure as template
• LAT-PS-03929-03
• Test Suite
• CE102 Conducted Emissions, Power Leads, 10 kHz to
  10 MHz, MIL-STD-462, CE03
• CECM 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

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LAT Power Interfaces

• SC-LAT Power Interfaces
• SC PRU (P) - LAT PDU
• SC PRU (R) - LAT PDU
• SC PRU (P) - LAT SIU (P)
• SC PRU (R) - LAT SIU (R)
• SC PRU (P) - LAT VCHP Y
• SC PRU (P) - LAT VCHP -Y
• SC PRU (R) - LAT VCHP Y
• SC PRU (R) - LAT VCHP -Y
• SC PDU (P) - LAT MAKEUP
• SC PDU (R) - LAT MAKEUP

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Test Limitations

• RS103 upper limit of 18GHz (40GHz)
• 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
• Limited B side conducted testing
• Emissions tests and susceptibility only where
  noted on A side
• Limited VCHP htr testing
• Emissions only

4
EMI Test Configurations

• Split EMI test
• Conducted tests performed in the high bay
  integration area
• Radiated testing performed in anechoic chamber
• Conducted emissions and susceptibility tests with
  SIU and PDU do not require radiators, but do
  require good access to connectors

• LAT z axis vertical to provide access to LAT
  connectors with 2m cable lengths

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Radiated Test Configuration
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Radiated Test Configuration
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LAT Cable Feedthrough
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Conducted Test Considerations

• Fully test
• SC PRU (P) - LAT PDU
• SC PRU (P) - LAT SIU (P)
• Limited test
• SC PRU (R) - LAT PDU
• SC PRU (R) - LAT SIU (R)
• Need to resolve operating constraints on VCHP
  htrs
• Can they be run for extended periods of time at
  ambient temp?
• Thermostatic overtemp protection
• Limited power, 4W/circuit
• No plan to test PDU - LAT Makeup
• Thermostatic control, open circuit at ambient
  temp
• Conducted susceptibility tests may require
  disabling bus protection unit

9
Conducted Test Harness

• Require access to power harness 2m from LAT I/F
• CE102, CS102 (10kHz - 150kHz), CSCM (30Hz -
  150kHz), CECM
• All conductors of power circuit must be connected
  to a single 1/4 lug on line conditioner
• All conductors must be gathered into a bundle so
  that a current probe may be connected around them
• Require access to power harness 5cm for LAT I/F
• CS102 (150kHz - 150MHz), CS06, CSCM (150kHz -
  150MHz)
• Small bare section of a single conductor to
  attach clip lead for hf injection
• EMI shielding not required on harnesses

10
Radiated Test Harness

• No access to conductors required
• Harness must be fully shielded
• Includes all connector savers
• Any test ports must be closed out or have
  shielded harnesses
• back door
• Test harnesses must be shielded
• Accelerometers
• TCs thermistors
• Harness supports not directly connected to the
  LAT should be nonconducting material, wood or PVC

11
Test Software

• Emissions Testing
• Utilize the FSW Charge Injection Calibration
  function to inject charge into a large number of
  detectors. The number of channels into which
  charge can be injected will be limited by a) FSW
  design (which is not yet complete) and b) The
  number of channels which can physically be
  injected with charge in any given one second
  cycle. The one second cycle is required to
  provide repeatability during the Emissions
  frequency sweeps.
• Susceptibility Testing
• A variation of the test described in the
  End-to-End (ETE) Test Plan, LAT-MD-03489,
  paragraph 2.2.1, item 4, "Nominal Rate Cosmic Ray
  Test" will be used. This test is run at ambient
  temperature and at nominal voltage, timing,
  threshold, and trigger configurations. Both
  Cosmics and the external trigger function are
  used to create on-orbit trigger rates. The
  external trigger rate will be set so that the
  total trigger rate will be at or near the nominal
  expected on-orbit values.
• The externally triggered events should have very
  low occupancy, monitor to see if occupancy goes
  up
• The cosmic ray events should remain constant,
  monitor to see if rate goes up.

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Test EGSE Software Tools

• Displays of natural trigger rates and occupancy
  of externally triggered events should be strip
  chart type
• Other error status, checksum, etc. should latch

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RE102 - Integrated LAT
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RE101 All LAT Equipment
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CE102 Spacecraft PRU LAT DAQ
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CE102 Spacecraft PRU LAT SIU (IL), VCHP Heaters
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CE102 Spacecraft PDU LAT Anti-freeze and
Make-up Heaters
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Conducted Emissions Common Mode All LAT
Equipment
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RS103 Perform BEA and Tracker Tower
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RS101 Perform BEA and Tracker Tower
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CS102 Spacecraft PRU LAT DAQ
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CS102 Spacecraft PRU LAT SIU (IL), VCHP Heaters
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CS102 Spacecraft PDU LAT Anti-freeze and
Make-up Heaters
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Conducted Susceptibility Common Mode All LAT
Equipment
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CS06 Operate All LAT Equipment
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CS06 Perform All LAT Equipment
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Back-up Slides
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CE 102 LAT PDU TPS (TEM, CAL, TRKR), EPU
(IL),GASU (ACD BEA, IL), PDU (IL)
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CS102 LAT PDU TPS (TEM, CAL, TRKR), EPU
(IL),GASU (ACD BEA, IL), PDU (IL)