Statement_of_Work.pdf

STATEMENT OF WORK

OPTICAL ENCODERS

The National Weather Service (NWS) Radar Operations Center (ROC) has a requirement to procure optical encoders to replenish logistics spares, which are used in the Weather Surveillance Radar 1988 Doppler (WSR-88D). The ROC supports the Next Generator Weather Radar (NEXRAD) program, which is a network of 160 high-resolution S-Band Doppler weather radars jointly operated by the NWS, the Federal Aviation Administration (FAA), and the United States Air Force known as the Tri-Agency. The NEXRAD program provides the NWS with the ability to accurately detect, analyze, and forecast weather events in support of local warning and forecast and safety of flight operations overseen by the Tri-Agency. The NEXRAD program provides essential data needed to achieve Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), and NWS objectives and goals. NEXRAD data underpins NWS forecast/warning services-critical for meeting WeatherReady Nation goal to protect life and property, and reduce disruption from high-impact weather events. The continuous availability of stock is a critical element supporting the NWS mission.

The optical encoders National Stock Number (NSN) 7050-01-388-0992, Agency Stock Number (ASN) Reference Identification R400-2A1A1A2A1 are used within the NEXRAD Radar. The associated equipment Source Control Document part number is 14636-5017 has been provided within this document to be referenced for manufacturing. Additionally, the information below is considered to be the minimum technical requirements that optical encoders must meet to be used in the NWS ROC WSR-88D.

● 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 can not 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 70 microseconds or less 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

APPL CATION R; VISIONS

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14636-5017 PROPERTY OF THE U.S. GOVERNMENT (NATIONAL WEATHER SERVICE) Status:Production

L PURPOSE

This specificotion defines an absolute optica1 encoder to be used in an antenna pos itioner ope rat 1 nq in a sheltered envf rorment.

2.0 REQUIREMENTS

2.1 Encoder 1/0 Definition

The encoder's elect r1 ca1 character1 sties shal 1 confonn t o the requirements fden t ified fnTable 1.

2.2 Mechanical Data

The mechanical definft;on sl'lal l c001ply with the descrfptfon depicted in the drawing shown in Figure 1 or Figure 2 and the requ4 reme!lts of Table 2.

2 .• 3 Design Life

The rated life of the bearings shalt be 1 E 9 revolutio~s minfm~m. The rated life of the LED's shall be 100,000 hours minimum, The encoder MTBF shall be greater than 300.000 hours as calculated per Mll-HOBK-217 for ground fixed use.

2.4 Resolution and Accuracy

The encoder shall have 14-bit resolution (0.02 degrees). aro 13-bit RMS accuracy ( o. 04 degrees).

Accuracy and r~olutfon sha11 be warranted by the manufacturer.

2.5 Packaging for Shipment

The encoder shal 1 be supplied as a complete assembly per F1gure 1 or Figure 2.

2,6 Material

Only material conside red corrosiori resistant shal 1 be used.

When di ssim1lar metals are in contact. the effects of galvanic corrosion shall be controlled by selecting compatible materials from Table 2 of Mll•E-16400.

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TABLE 1. ELECTRICAL DATA

Conditfon1: a. Anf>1ent Temperature

b. Free Air

Jnputs: Read, Cl ocic

Outputs:

a. Differential Input rmpedance "' 180 oh11 m1 n1mum

b. Pulse W1dth :c 0.5 micro-sec ■inimun

c. Interrogation Rate= 5 kHz fflin1mum

d. Sn1ft Freque~cy • z.o MHz minimum

e. ~otatfon (for fncreasf119 count)~ Clockwise fa~tn9 the mo11nt ing surf ace (or shaft ertd} f, r,ming Relationsn1p - see figure 3

9. Power. •5 Vdc +0.Z5 Vdc at 1500 m1 m4xirun -0.50

a. Ser1al Natural 81nary - LS•TTL Compatit>le

1. Angle Fomat: Natural b1nary w1th Least S1griif1cant Bit (LSB) f1rst out.

Bite: A log1~ •111 in fi!ISS+l in MS8+1 position indicates normal operatfon. a •o• would ftl:1fcate an eneoder f'~fl ura.

2. Binary •1• • 2,5 Vdc 111n1mum at -20 ma

3. B1n11ry 11 0• • O.S Vdc m11:,c,imum at 20 ma

b. Tfmfng Relat1<1Mhtp - see ftgure 3

c. Electrical signaling characteristics should comply with ANSI Standard TIA-422 (RS422).

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Figure 1.

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E - L Tab le 2. Mechanical Data

a. 14-Bit Optical Absolute Position Encoder

b. Solf d Shaft

c. Self-Contained Electronics i d. Weight=< 10 Oz

L e. Starting Torque at 25 Deg Cm 1.5 Oz-In Maximum

f. Running Torque at 25 Deg C = 1.5 Oz-In Maximum

9. Dimensions •• See Figure 1 or Figure 2

Tab le 3. Electrical Connection

Connector: OASF15P with Strain Relief SR029-8757-015 (ITT Cannon) or equivalent

Cable: 36 inch minimum. No. 28 AWG, Shielded Jacketed Ribbon Cable (0.050 conductor spacfng)

·-------·······------···--··-·-------·---------··--------·--~·------·---------WIRE NO. PIN NO. FU~CTION

1 1 GND ( +5 Vdc RTN) 2 9 Not Used 3 2 Not Used 4 10 Update ~Read I Command ~ :~ 5 3 Update Read Command 6 11 Shfft Clock +1 7 4 Shfft Clock -) 8 12 Ser1 al Data Ouput ~+) 9 5 Serial Data Ouput -)

10 13 Update Canplete ~+!

11 6 ugdate C001plete - 12 14 + Vdc 13 7 Not Used 14 15 Not Used 15 8 Not Used Shield -- Shield to be tem1nated at the encoder end only• cut and 1 nsulate at the connector end

DRAWN --1000E a:NT NO.,IIDWG NO. 10 A 1U7M4 14636-6017 a

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SH CLOCK

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I I 7 ,- 80C nSEC MAX ---n • 2.5 uSEC MIN

I . 104 1.1SEC MA><

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NOTE: BIT O IS NOT USED

• I II 500 .s,:r. _ , _

U7__J7 ---u-

I BIT 1 I BIT 2 I

( L SB) (lSll • 11 (MSB)

Figure 3. Seria1 Mode Update Conf1guration

2.7 ENVIRONMENTAL

2.7.1 Alrtlient Temperature

The encoder sha11 operate, without degraded perfonnance. o.-er the temperoture range of -40 deg C to +49 deg c.

2. 7 .2 Long Term Storage

The encoder shall survive long tenn storage within a tefllperature range of -62 deg C to +60 deg. C wf thout damage or degraded perfonnance.

2.7.3 Hum1dity

The encoder sha11 rraintain the specified perfonnance when exposed to a relative humidfty of 15 percent to 100 percent for both continuous and 1ntermft.tent periods, avo1dfng condft1ons where condensation takes place fn and on the equip ment in the form of water or frost. This hum1d1ty can occur during both opera tion and long term shortage, IC>RAWN NO. N!!V

14636-so11 D

- 2.7.4 Fungus

The encoder shall be resistant to fungi in both operating and non-operating modes. It sha1 l be comp11 ant w1th Requ1 rement 4 (Fungus Inert Materials) of

MI L-ST0-4 54.

2.7,5 Shock and Vibration

The encoder sha11 be capable of w1thstand1ng without damage the vibration, shock and atrrospher1c pressure encountered during transporation by canm;:,n sur face, air, or sea urrier.

2. 8 MARKI t«i

Each encoder shall be pennanently and legibly marked and shall include, but not be li111ited to, manufacturer's name or sylli>ol, manufacturer's part nunt>er, DRS part nunt>er and serial nunt>er.

The :ORS-sss: part nunter and serial nunt> er s na 11 be on the body or the enc oder such that it 1s visible when installed i n a m unt1ng plate. The DRS.SSS- part nunt>er shall be 14636-5017-1. •

2.9 TEST

Each unit shall be tested ~o assure compliance with this specification prior to shipment. Test data by serial nurrber sha.11 be shipped with each encoder.

Test a.nd test data (measured at roooi temperature) sha11 include at least the fo l1 owi n9 : • • •

a. Weight

b. Mechanical dimensions

c. Start and run torque

d. Electrical:

1. P1n functions

2. S1gna1 form ard levels (fnclude count d1rect1on vs. rotation )

3. La11p fun ct ton

e. Standard accuracy and resolution

2.10 I NS?ECTION SYSTEM

The vendor shal 1 ma1nta1n an inspection system wh1ch meets the requ1 rements of Ml L•l-4 6208.

DRAWN SIZE COOE IOENT N01DWG NO. I REV

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2.11 WORKMANSHIP

Workmanship shall be in accordance with best industry commercial practice.

2.12 SO~CE

Identification of suggested source(s) hereori is not to be construed as a guarantee of present or continued ava11ab111ty as a source of supply for 1tem(s).

BEi Motion Sytems Company. Inc.

Digital Products Division P .o, Bo>< 3838 Little Rock, AR 72203

ITEK Measurement Systems 27 Christina Street Newton, HA 02161

Sequential Electronic Systems 249 North Saw Hf 11 River Road Elsford, NY 10523

FARRAND OPTICAL COMPONENTS & INSTRUMENTS (CAGE CODE: 25792)

DIVISION OF RUHLE COMPANIES, INC

99 WALL STREET

VALHALLA, NY 10595

DRAWN

SCAL£