New Millennium EO1 Advanced Land Imager 23 January 1998

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Spacecraft Testing EMI / EMC
Bob Vernot EO-1 Electrical Engineer Swales
Aerospace
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Agenda

• EMC Related System Tests to Date
• Planned System Level EMC Tests
• Transient Tolerance Testing
• Power Profile Testing
• RE02 (NB Radiated Emissions)
• RE02 (BB Radiated Emissions)
• Limited Radiated Susceptibility Test
• Magnetic Survey Plan
• Issues

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EMC Related System Tests to Date

• Power Service Current Balance
• Turn-On/Turn-Off Transients
• Operational Transients
• Powered SADA rotation

4
Planned System Level EMC Tests

• S/C Self Compatibility Tests
• Transient Tolerance Test
• Power Profile Test
• RF Compatibility Test
• Quantitative Testing
• RE02 Narrowband Radiated Emissions Test
• RE02 Broadband Radiated Emissions Test
• Limited Radiated Susceptibility Test

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Transient Tolerance Testing

• Goal - Demonstrate that worst case EMI from each
  S/C subsystem has no detrimental effect on any
  other subsystem
• Test Description
• S/C must be in flight like configuration
• All S/C subsystems begin test in normal on-orbit
  operational mode considered to be most
  susceptible to (and/or most indicative of) EMI
• Each subsystem (individually) is exercised
  through normal modes of operation considered to
  produce worst case EMI
• All other subsystems monitor telemetry and
  science data for anomalies which may correlate to
  EMI from other subsystems. Some off-line data
  evaluation is required

6
Power Profile Testing

• Goal - Provide a Quantitative measure of S/C
  Conducted Emissions under worst case conditions
• Test Description
• S/C must be in flight like configuration
• S/C Power Bus is instrumented with Oscilloscope
  and Spectrum Analyzer (accomplished via isolated
  test point at PSE)
• All Subsystems are configured for orbital mode of
  operation creating maximum EMI
• S/C power bus is monitored for compliance with
  CE01 and CE03

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RE02 (NB Radiated Emissions)

• Goal - Demonstrate that EO-1 S/C RE will not
  interfere with Delta II avionics
• Test Description
• S/C will be configured for the worst case mode of
  operation during launch and ascent
• RF probe is used to determine locations of worst
  case RE
• Biconical test antenna will be placed one meter
  from these locations and configured at 45 degree
  angle to the horizontal
• One sweep (14 KHz - 18 GHz) required for each
  location identified

8
RE02 (BB Radiated Emissions)

• Goal - Demonstrate that EO-1 S/C RE will not
  interfere with Delta II avionics
• Test Description
• S/C will be configured for the worst case mode of
  operation during launch and ascent
• Biconical test antenna will be placed one meter
  from locations determined previously, and
  configured at 45 degree angle to the horizontal
• One sweep (14 KHz - 18 GHz) required for each
  location identified

9
Limited Radiated Susceptibility Test

• Goal - Demonstrate that S/C is not susceptible to
  RF energy that it may be exposed to On-Stand
• Test Description
• All S/C subsystems powered On and in most
  susceptible mode
• Various test antennae used to emulate RF energy
  which may result from LV transmitter and launch
  site specific sources. Test antennae locations
  are dependent on RF source locations relative to
  S/C frame of reference on-stand.
• Test antennae will be powered individually to
  provide no more than 10 V/m of RF energy at the
  S/C
• Telemetry shall be monitored for any anomalous
  behavior associated with Radiated susceptibility

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Issues

• Not all components have undergone EMC testing
• Some qualified by simularity
• Waivers issued for some components within S-Band
  Notch
• ECU
• Exceedances in broadband emission

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Magnetic Survey Plan
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Magnetic Survey Plan

• Analysis and ALI STM Magnetic Test indicate
  magnetic self-combatability is not an issue
• Clean area magnetically , and evaluate and
  measure external sources such as lights and
  filter blowers
• Perform an un-powered survey with the compass,
  noting any changes in needle direction when the
  compass is approximately 6 inches from a
  potential source
• For dipoles that may be vertical and/or
  inaccessible within 6 inches of the source (e.g.
  ALI), use the test TAM. Any field change greater
  than 35 mGauss from 1 foot away is significant,
  and would equate to a field change greater than
  280 mGuass from 6 inches away
• The center of the dipole (within the box) is best
  found by aligning one axis of the test TAM along
  the dipole, and recording the measurements from
  at least two points along the dipole
• Repeat on powered spacecraft