AOC Airplane Calibrations According to SOW

Background

The U.S. Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), Aircraft Operations Center (AOC) at Lakeland, Florida, operates two Lockheed WP-3D aircraft in support of NOAA and national research.  This statement of work is to provide Evaluation, Repair, and Calibration for three Stepped Frequency Microwave Radiometers (SFMR) P/N SFMR2000-P  Serial Numbers US001, US002, and US003.

The SFMR is a wing-mounted, remote sensing, scientific instrument that is flown on both NOAA WP-3D aircraft as well as each of the 53rd Weather Reconnaissance Squadron’s WC-130J aircraft. The primary function of the SFMR is to derive surface level wind speed and rain rate in the tropical cyclone environment and does so through the measurement of brightness temperatures in six frequency bands from 4.6 to 7.2 GHz. The calibrated values of brightness temperatures are processed through a windspeed retrieval algorithm in real time and the values for surface level wind speed and rain rate are then generated.

A SFMR working group consisting of subject matter experts and stakeholders from across NOAA Line Offices convened during the 2024 Atlantic Hurricane Season and determined that, through thorough and careful quality assurance of SFMR surface level wind data compared to that derived from other sources (i.e. dropwindsondes, satellite, NOAA National Data Buoy Center (NDBC) buoys, etc.), SFMR brightness temperature behaviors were inconsistent leading to inconsistent SFMR surface-level wind retrievals.

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Objective

Evaluate, repair as required, and calibrate each of the NOAA AOC SFMR units (S/N: US001, US002, and US003). Provide AOC with three serviceable SFMRs as well as a set of calibration coefficients for each SFMR that, when used, will provide surface-level wind speeds and rain rates in a tropical cyclone environment.

Scope

1. Evaluate and Repair as Required, and Calibrate SFMR Serial Number US001. This work will include a full system checkup and all the necessary maintenance work to bring the SFMR back to operational specification.
2. Contractor shall replace all thermistors in SFMR Serial Number US002 as well as all associated internal wiring associated with each thermistor and the applicable electronics directly involved with translating the electronics signal to counts that are used to determine thermistor temperature. All components removed and replaced to be provided to the Technical Points of Contact, listed below, along with any associated findings and reports, and thermistor schematic diagrams so that the Technical Points of Contact can further understand how these measurements are taken as they are critical to continued satisfactory performance of the instrument.
3. Evaluate and Repair as Required, and Calibrate SFMR Serial Number US003. This work will include a full system checkup and all the necessary maintenance work to bring the SFMR back to operational specification.
4. Once each SFMR is performing to operational specifications Vendor will also perform the lab and sky calibration of the SFMR.
5. As a deliverable, Contractor will provide the SFMR raw data from the following calibration experiments:
   1. Thermal chamber at 20oC.
   2. Thermal chamber at 5oC.
   3. Sky experiment - SFMR ARU pointing at a cloudless sky (zenith).
6. Calibration will include testing of all associated thermistors within the unit ensuring that the final calibration equation considers all thermistor values.
7. Included in this price quote is a verification of the SFMR performance based on the data collected in a verification and calibration flight with the SFMR over a NDBC buoy or over an aircraft-deployed dropwindsonde. The verification will include a calibration flight, receive the coefficients from the Contractor, then a verification flight to ensure coefficients produce repeatable and accurate calculated values for wind speed.
8. Contractor shall finally release the agreed upon calibration coefficients to the latest SFMR4.cfg configuration file used by the Aircraft Operations Center.
9. Shipping of unit back to the AOC to be billed to NOAA AOC UPS Shipping Account; W81V41.
10. Work to be accomplished on each SFMR by 31 December 2025.
11. Contractor shall provide all labor, materials, equipment, and special tools to complete the repair and calibration. All work shall be in accordance with applicable maintenance manuals.

Government-Furnished Property

Step Frequency Microwave Radiometer P/N: SFMR2000-P, S/N: US001

Step Frequency Microwave Radiometer P/N: SFMR2000-P, S/N: US002

Step Frequency Microwave Radiometer P/N: SFMR2000-P, S/N: US003

SFMR Processor Unit P/N: SFMR2005W-P, S/N: US002

SFMR Processor Unit P/N: SFMR2005W-P, S/N: US003

SFMR Processor Unit P/N: SFMR2005W-P, S/N: US027

SFMR Shipping Container. Blue Custom made container. P/N: N/A, S/N: N/A

Performance Requirements

1. Technical Points of Contact (listed below) will be consulted and provided opportunities to do joint analysis and provide input during the diagnoses, repair, testing, and calibration activities for each SFMR unit.
2. The causes of brightness temperature anomalous behavior for each unit needs to be satisfactorily understood by the Technical Points of Contact (listed below) and a mitigation approach to resolve these behaviors agreed upon prior to the return and acceptance of each SFMR unit by AOC.
3. The Technical Points of Contact will be provided the raw lab calibration measurements for independent processing and analysis utilizing the SFMR reprocessing software.
4. Technical Points of Contact, and personnel deemed appropriate and necessary by the Technical Points of Contact, may visit the Vendor’s facility to better facilitate collaboration on analysis and testing of the SFMR units. Travel and incurred expenses for visitation would be at the expense of traveling personnel.
5. Vendor will characterize:
   1. Individual SFMR unit temperature performance from -47oC to +35oC.
      1. Characterization should include adjusting the temperature from low to high (heating up) and high to low (cooling down) since components might behave differently depending upon the temperature change direction (hysteresis).
      2. The Contractor will perform a thermal chamber time vs. temperature cycle test that covers the above temperatures. This time vs. temperature profile will be determined in conjunction with the Technical Points of Contact listed below and must be approved by the Contracting Officer’s Representative (COR) prior to the start of testing.
   2. Individual SFMR unit brightness temperature stability with time.
      1. This should include brightness temperature stabilization time dependent on temperature (i.e. Vendor’s prescribed wait time at each altitude during calibration flights).
      2. Vendor will prescribe acclimation time period prior to collection of mission data or how long recovery will take if passing through very warm/very cold regions along the flight track.
      3. Vendor will determine if a 10 minute acclimation period at mission altitude is sufficient for all high altitude regimes or if a different approach is warranted.
   3. SFMR unit-to-unit and channel-to-channel intercalibration.
      1. Ensure consistent performance of each SFMR unit to one another and consistent spreading of channels between each unit, which is necessary to obtain consistent and accurate wind speed and rain rate retrievals.
   4. Frequency drift error with voltage control oscillator error.
6. The Contractor shall verify the serviceability and operational stability of the microprocessor-based thermal control device integrated within each SFMR unit.
   1. The Contractor shall provide empirical evidence that confirms proper thermal regulation, including:
      1. A graph of thermistor readings from the heated radome or enclosure, showing how temperature changes over time.
      2. A representative sample of electrical current draw while the heater is active (such as during startup or a cold-soak condition).
      3. The data should clearly show heater activation, thermal response time, and whether the system cycles on/off as expected.
7. Within 10 calendar days of contract award, the Contractor shall provide the Government with the following for review and approval:
   1. A Minimum Performance Specification that defines the key parameters used to evaluate each SFMR.
   2. An Acceptance Test Procedure or Test Sheet outlining test steps, expected results, and pass/fail criteria.
8. These documents must be approved by the COR before any SFMR evaluations begin.
9. Final performance data and test results for each SFMR shall be delivered with the unit, and should reference the approved test documentation used during evaluation.

Place of Performance

ProSensing, Inc.

107 Sunderland Rd

Amherst, MA 01002

Delivery/Period of Performance

Work to be accomplished on SFMR Serial Numbers US001, US002, and US003 by 31 December 2025. The SFMR shall be delivered to 3450 Flightline Dr., Lakeland, FL 33811. Shipping shall be via UPS Ground using NOAA’s Shipping Container and billed to NOAA AOC’s UPS Account W81V41. SFMR will be shipped to Contractor in NOAA’s Shipping Container. P