THIS IS A REQUEST FOR INFORMATION (RFI) SOURCES SOUGHT (ONLY). This RFI is issued solely for information and market research planning purposes and does not constitute a solicitation or a promise to issue a solicitation or Request for Proposals (RFP). This request for information does not commit the Government to contract for any supply or service. The Government does not intend either to award a contract based on this RFI or to pay for the information that is submitted. No solicitation, statement of work, specification, or requirements package exists at this time. Issuance of this notice does not constitute any obligation on the part of the Government to procure support services for, or install existing/modified software, and/or for any associated documentation development/deployment or to issue a solicitation. Responses to this notice cannot be accepted as offers. Vendors are advised that the Government will not pay for any information or pay administrative costs vendors may incur in responding to this RFI; therefore, all costs associated with responding to this RFI will be borne solely by the interested party. Respondents are advised that the NWS is under no obligation to acknowledge receipt of information received, or provide feedback to respondents with respect to any information submitted under this RFI. Any information that the vendor considers proprietary should be clearly marked as such. Clearly marked responses to this RFI indicating that information therein is proprietary or represents confidential business information will be received and held in confidence for U.S. Government use only. The information provided in this RFI is subject to change and is not binding on the Government. All submissions become the property of the Federal Government, and will not be returned.

1.  Purpose of this RFI:

The NWS, Radar Operations Center (ROC) WSR-88D Next Generation Weather Radar (NEXRAD) Program located in Norman, OK is conducting market research seeking information regarding future development or replacement of the OPTICAL ENCODER (herein called “Encoder”), National Stock Number (NSN) 7050-01-388-0992, Agency Stock Number (ASN) Reference Identification R400-2A1A1A2A1, used within the NWS WSR-88D NEXRAD Doppler Radar Antenna/Pedestal (UD2). The NWS is seeking to gather ideas, recommendations, and best practices from industry on how to advance and/or redesign this encoder set in order to meet future technology advancements. 

2.  Background:

The NWS, ROC NEXRAD Program is responsible for the life cycle support of the WSR-88D NEXRAD Radar and related systems. There are 159 operational radars located within the continental United States and selected sites overseas. Each radar system consists of three parts; Radar Data Acquisition (RDA), Radar Product Generator (RPG), and various end product display systems. The NWS utilizes the encoder in the two-axis (Azimuth & Elevation) Pedestal of the RDA to translate position to electrical signals for antenna position control. The antenna and pedestal assembly as a whole rotates continuously within the WSR-88D on a 24 hour - 7 days a week schedule to collect radar weather data in order to support the NWS weather forecasting mission.

The current optical encoders (R400-2A1A1A2A1) used within the NEXRAD Radar were obtained from the following sources; BEI Motion Systems Company, INC, ITEK Measurement Systems, or Sequential Electronics. The associated equipment Source Control Document part number is 14636-5017, propriety of DRS Technologies and is not provided in this notice. Although this document establishes the minimum requirements that future optical encoders must meet to be used in the NWS ROC WSR-88D NEXRAD Doppler radar, Section 4 of this notice will provide a discussion of the minimum requirements.

3.  Discussion:

The current encoder is in short supply and approaching non-availability in the marketplace. The encoder is critical to the overall operation of the radar and sufficient quantities of encoders are needed in sufficient quantities in order to be stocked in the NWS National Logistics Supply Center as spares in case of a failure at any of the radar sites. The NWS therefore desires to ensure replacement encoders are available in the future marketplace for use within the NWS ROC WSR-88D NEXRAD Doppler Radar.

4.  Requirements:

Any future optical encoder will require the following minimum technical aspects for use within the NWS ROC WSR-88D NEXRAD Doppler radar:

• Mechanical

Each unit shall be constructed as follows:

• Size must be 1.60 inches in diameter at least 1.25 inches from the mounting surface; the unit cannot exceed 2.53 inches in diameter more than 1.25 inches from the mounting surface
  • Unit length must be at least 2.74 inches long from the mounting surface, and cannot exceed 10 inches long from the mounting surface
  • Shaft size must be at least .75 inches long, and .2497 + 0.0000, -0.0005 inches in diameter
  • There must be a groove below the mounting surface, as viewed looking down on the shaft end of the encoder
• Electrical

Each unit shall include the following standards:

• Each unit must adhere to Figure 1,  Encoder Timing Relationships below with the following exception
  • Signal “RDY (OUT)” is not required.  That is, the data output will begin upon reception of the “SH CLOCK” signal, which begins 104 microseconds after the “READ (IN)” signal is sent
  • Each unit must adhere to the following electrical performance, valid over a temperature range from -49 to +50 C without forced-air cooling:
    • Inputs (Interrogate and Clock)
      • Differential input impedance: 180 Ohms minimum
      • Pulse width: 1.0 microsecond minimum
      • Interrogation rate: 5 kHz minimum
      • Shift Clock Frequency: 2.0 MHz minimum
      • Rotation for increasing count: Clockwise facing the mounting surface (i.e. shaft end)
      • See Figure 1 below for timing relationships
      • Power: +5 VDC (+0.25/-0.5), sourcing no more than 1.5 Amperes
    • Outputs
      • Serial natural binary, LS-TTL compatible
      • Angle format: Natural binary with least-significant bit (LSB) first out
      • BITE: A logic “1” at most-significant bit (MSB) + 1 position indicates normal operation; a logic “0” indicates a failure
      • Binary “1”: +2.5 VDC minimum at -20 milliamperes
      • Binary “0”: +0.5 VDC maximum at +20 milliamperes
    • Electrical signaling characteristics will comply with ANSI Standard TIA-422 (RS-422)

Each unit electrical interface must adhere to the following:

• The data cable must be at least 36 inches long; it is not required that it be a ribbon cable
• The data cable must be shielded
• The data connector interface connector must be a two-row, 15-pin D-subminiature plug (male) with strain relief
  • DASF15P with SR029-8755-015 strain relief, or equivalent
• Electrical pinout is provided below:
  • Pin 1: GND (+5 VDC Return)
  • Pin 2: Not used
  • Pin 3: Interrogate Command Neg
  • Pin 4: Shift Clock Neg
  • Pin 5: Serial Data Out Neg
  • Pin 6: Update Complete Neg
  • Pin 7: Not used
  • Pin 8: Not used
  • Pin 9: Not used
  • Pin 10: Interrogate Command Pos
  • Pin 11: Shift Clock Pos
  • Pin 12: Serial Data Out Pos
  • Pin 13: Update Complete Pos
  • Pin 14: +5 VDC
  • Pin 15: Not used
  • Shield: Terminated at encoder end ONLY; terminate and insulate at connector

Figure 1: Encoder Timing Relationships

Interested parties are requested to provide an information package addressing their approach to meeting the requirements listed in the above sections. Interested parties are requested to include basic company information, including business size, in addition to any knowledge and experience levels regarding their approach to meeting the aforementioned requirements. 

The response date for this RFI is March 13, 2023. No phone calls or collect calls will be accepted. All responses to this RFI should be sent to the following: Tammy Buie: [email protected]; Contracting Officer Jackie Shewmaker: [email protected]; and Contract Specialist Holly Ferguson: [email protected].

Note: Ensure that all responses have “NEXRADENCDR0001” in the title of the email. Avoid providing proprietary information in your questions as our intent is to post all questions and answers to the SAM.gov website. Submission of questions will be deemed permission to post the questions with a response at https://www.SAM.gov.