Special Sensor Ultraviolet Limb Imager (SSULI)

SSULI The Special Sensor Ultraviolet Limb Imager (SSULI) was designed and built by the Naval Research Laboratory's Thermospheric and Ionospheric Physics Branch (Code 7623) to study the "weather" of the upper atmosphere and ionosphere using satellite and rocket-based optical remote sensing of naturally occuring dayglow and nightglow. NRL has developed five ultraviolet remote sensing instruments for the Air Force Defense Meteorological Satellite Program (DMSP) . These SSULI instruments will launch aboard the DMSP block of 5D3 satellites starting in 2000, followed by launches approximately every 18 months.

Silver Engineering, Inc. designed the SSULI Control Electronics (SCE) CPU Card, Telemetry Interface Card (TCI), Spacecraft Interface Card (SCI), SEE SEM-E type backplane, and SCE Enclosure. All cards utilized surface mount technology and used Field Programmable Gate Arrays (FPGA) to reduce the number of cards and reduce power comsumption thereby maintaining the tight weight and power budget requirements.

Silver Engineering, Inc. particiated in testing and simulations during the SSULI experiments intergration and test. We designed and built the SSULI Aerospace Ground Equipment (SAGE) which simulates all of the interfaces to the SCE. We also designed and built the SSULI Stepper Motor Driver Simulator which is used to drive the door mechanism during calibration testing of the SSULI instrument and we provided two suitcase size test units, SAGE2 and the USA Test Set Unit for SSULI ground support.


SSULI Control Electronics - SCE

  • Compresses & Formats Spectrograph Data
  • Controls Scan Mirror, Detector Door & Dust Cover Operation
  • Provides All Command, Telemetry & Power Interfaces To The DMSP Spacecraft Converts
  • Spacecraft Power To Secondary Power For Subsystems
  • Dual Redundant DSP Architecture
  • FPGA's Utilized To Reduce Size & Weight
  • Operates On Less Than 25 Watts
  • Seven SEM-E Circuit Cards
  • CPU Card (SEI designed)
    • ADSP-2100 DSP Processor, Flight Code, Actel 1020
  • Telemetry Interface Card (SEI designed)
    • Actel 1020, Stepper Motor Control, A/D Telemetry Acquisition, Paraffin Actuator Control
  • Spacecraft Interface Card (SEI designed)
    • Actel 1020, DMSP OLS Interface Logic
  • Backplane and Enclosure (SEI designed)
    • SEM-E format, Single element thermal path, Weight of 9 pounds

SSULI Simulator

SEI designed and delivered five SSULI Simulators to be used in place of the flight SSULI components to faithfully simulate the SSULI instrument during the DMSP satellite maintenance testing.

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