# Presentation: 672339

## “ANY TIME, ANY PLACERIGHT TIME, RIGHT PLACE”
Civil GPS Service Interface CommitteeCol James B. Armor, Jr.System Program Director 15 September 1997

**Civil GPS Service Interface Committee****Col James B. Armor, Jr.****System Program Director**** ****15 September 1997**

**NAVSTAR GLOBAL****POSITIONING SYSTEM**

## GPS Block IIR Schedule

- ‘95	‘96	‘97	‘98	‘99	‘00	‘01

- SV Delivery

- Launch

- CY

- SV Production

**Jul**

**Jul***

**Feb**

- *Jan 97 Launch Failed

**SV01**
**Aug 94**

**Notes:**
Begin with Overview
Formally Rockwell International
Go in to the two areas we evaluated--Fixed Price and Cost Plus Award Fee

## Block IIR Success

**Successful Launch on 23 Jul 97 @ 0343Z from Cape**
**Near Flawless LEO & Handover to 2SOPS 13 Aug 97**
**L-Band Turn-on 13 Aug 97**
**Received Signal Power Comparable to Block II/IIA**
**Rubidium Clock (RAFS 1/3) Turn-on Complete 22 Aug**
**Nav/NDS Initialization Completed on 26/31 Aug 97**
**On-Orbit Verfication still On-going (ETC: 3 Dec 97)**
**Extended Operations Starts 26 Sep 97**

## GPS Block IIF Schedule

- Contract Award

- ‘96     ‘98     ‘00     ‘02     ‘04    ....   ‘12

- Final Design Complete

- SV1 Delivery

- First Launch

- CY

- Final Delivery

- 22 Apr 96

- 23 Dec 97

- Apr 01

- Mar 02

- Aug 12

**Notes:**
Begin with Overview
Formally Rockwell International
Go in to the two areas we evaluated--Fixed Price and Cost Plus Award Fee

## Block IIF Good News Story

**Preliminary Design Complete, 21 Feb 97**
**Box Testing - Results Excellent to Date!**
**Frequency Synthesizer EDU Assembled**
**Rubidium Clock EDU Assembled**
**On Track for Final Design Complete, 23 Dec 97**

## Year 2000 Rollover Concerns

**Year 2000 Rollover Concerns**

**GPS has two “rollover” issues**** **
**Year 2000 “Millennium” problem with computer implementations**
**GPS End of Week (EOW) Rollover at 0000 hrs UTC, 22 Aug 99**
**GPS as a total system must account for both cases by design and operate through sucessfully**
**Much negative speculation--these are the facts**

**Testing questions for non-GPS JPO procured equipment:**
**Capt Jason J. Christ, SMC/CZE, (310)363-2212**
**Christjj@gps1.laafb.af.mil**
**http://www.laafb.af.mil/SMC/CZ/homepage/y2000/index.html**

## Current Status

**Current Status**

**GPS Satellites**
**All generations of GPS **_**satellites**_** are **_**unaffected**_
**Some satellite support system software is not Y2K compliant and is scheduled to be repaired or replaced**
**Operational Control System **
**Operates on a mainframe legacy system **_**affected**_** by Y2K Rollover**
**Analysis by Lockheed Martin to be completed Sep 97 **
**Estimate $3.5 - $7.6M in software repairs--funds in budget **
**Complete before Y2K Rollover**

## Current Status (cont)

**Current Status (cont)**

**GPS User Equipment**
**Fully validated capability available to test GPS receivers for both Rollover phenomena**
**Test of all JPO-procured receiver designs complete-Aug 97 **
**Rollover test capability is available to all DoD & commercial GPS developers on a fee/non-interference basis**
**Interface considerations now under investigation**
**GPS JPO is widely publicizing both problems and corrective actions to DoD and civil users**
**GPS performance will be unaffected by the either rollover**** **

**Y2K compliant output of GPS receivers doesn’t relieve users responsibility to verify components that use GPS as an input**

## Back-Up Charts

## “Millennium” (Y2K) Rollover

**“****Millennium” (Y2K) Rollover**

**Computer programs using two digits for the year**
**2000 becomes “00”**
**Could be interpreted as 1900 for calculations**
**Could be treated as invalid date**
**Millennium (Y2K) rollover will occur 132 days after next GPS End of Week (EOW) rollover**

## GPS “END OF WEEK” (EOW) ROLLOVER PHENOMENON

**GPS “END OF WEEK” (EOW)**** ROLLOVER PHENOMENON**

**GPS system time counts weeks from midnight 5-6 Jan 1980 in modulo 1024 (0-1023) **
**No year or century data is included in the Navigation Message - Subframe 1 (Word 3)**
**GPS week rolls over from week 1023 to week 0000 at midnight 21-22 August 1999 and approximately every 20 years thereafter**
_**Clearly**_** **_**documented**_** in ICD-GPS-200, para  3.3.4(b)**
**GPS receiver manufacturers responsible for their designs  conforming to ICD-GPS-200 **