# Presentation: 534112

## Global Positioning SystemModernization 

**Global Positioning System*****Modernization****** ***

**CGSIC **
**International Subcommittee Meeting**
- 
- 

**5 December, 2002**

## Overview

**Background**
**Constellation Status/Performance**
**   ****Standard**
**Modernization Program **
**The Way Ahead**

## 	     GPS Background

**Active program**** for over 25 years**
**Created from separate programs in 1973**
**Developmental satellites began launch in 1978**
**Operational satellites ****began launch**** in 1989**
**Initial Operational Capability - 1993**
**Full Operational Capability –1995**
**Open civil**** navigation service**
**Signal specification available to industry and all**
**   ****users, both US and International**
**Free of direct user fees**

## GPS Satellites

**  ****Block IIF**
**  ****In development**
**  ****Boeing**
**  ****6 already procured**
**  ****Options for 6 more**
**  ****MMD 11.35 yrs**

**Block IIR/IIR-M**
**  ****In production**
**  ****Lockheed/Martin**
**  ****21 procured**
**  ****6 operational**
**  ****1 destroyed on launch**
**  ****MMD 10.62/8.57 yrs**

**    ****Block II/IIA**
**  ****All have been launched**
**  ****Rockwell (now Boeing)**
**  ****First launch Feb 1989**
**  ****21 operational**
**  ****Mean Mission Duration**
**   ****(MMD) 9.6/10.23 yrs****   **

##            US Policy Goals

**Encourage ****acceptance**** of GPS into peaceful civil, commercial and scientific applications  **
**Promote ****safety and efficiency**** in transportation**
**Encourage ****private investment**** in/use of GPS**
**Strengthen and maintain ****national security**
**Promote ****international cooperation**** in using GPS for peaceful purposes**

## US Policy Principles

**No direct ****user fees**** **
**Open ****market competition**** for user equipment**
**Equal ****access**** for applications development and value added services**
**Common use of GPS time, geodesy, and signal structure ****standards**
**Interoperability**** of future systems with GPS**
**Recognition of ****security**** issues and protecting against misuse**
**Protect radionavigation ****spectrum**** from disruption and interference**

## GPS Civil Applications

**Enabling**** Technology**
**Unlimited growth potential**
**$16 Billion industry worldwide by year 2003**
**Japan projected to have 44% of customer market share**
**Expanding Use**** in Transportation Safety**
**Aviation, Maritime, Railroad, Highway, etc**
**Potential to reduce land-based navigation systems**
**Wide Range**** of Other Civil Uses**
**Telecommunications, Surveying, Law Enforcement, Emergency Response, Agriculture, Mining, etc.**
**Distress Alerting Satellite System (DASS), civil component of Global Personnel Recovery System **

## Overview

**Background**
**Constellation Status/Performance**
**   ****Standard**
**Modernization Program**
**The Way Ahead**

## 21 Block II/IIA satellites operational

6 Block IIR satellites operational
14 of 21 Block IIR satellites available
Modernizing up to 8 Block IIR satellites
Last launch:  31 Jan 01

Next Launch: On hold
Launch vehicle issues

Continuously assessing constellation health to determine launch need

**6 Block IIR**** satellites operational**
**14 of 21 Block IIR satellites available**
**Modernizing up to 8 Block IIR satellites**
**Last launch:  31 Jan 01**
**Next Launch****: ****On hold**
**Launch vehicle issues**
**Continuously assessing**** constellation health to determine launch need**

**27 Operating Satellites **
**(to ensure 24)**

*** *****GPS Constellation Status**

## GPS Constellation Age

**Block II MMD = 9.6**

**Block IIA MMD =10.23**

**Block IIR MMD = 12.67**

**Block IIA Predicted MMD**

**Block II Predicted MMD **

**Block IIR Predicted MMD**

## GPS SPS Performance Standard

**Defines the ****levels of performance**** the U.S. Government commits to provide to domestic and international civil GPS users**
**Not a requirements**** document**
**Current edition published ****October 2001**
**Updated performance as a result of discontinuing Selective Availability**
**Available**** on US Coast Guard Navigation Center website**
**http://www.navcen.uscg.gov/**

**A Commitment of Service**

**Notes:**
The purpose of the document is to define the levels of performance that the US Government commits to provide civil GPS users.

After considerable discussion during the development process, the document was restructured to focus on this purpose, and to clarify that it is NOT intended to define technical signal characteristics or specifications.  Therefore the document was renamed from ‘Signal Specification’ to ‘Performance Standard’, and most technical signal information (bit structures of the navigation message, for example) was removed, with references made to ICD-GPS-200C, the interface control document that does define the technical characteristics of the L-band carrier and C/A code. 

I would also like to make clear that the Performance Standard is not a requirements document.  It is neither a substitute for the Operational Requirements Document (ORD) we use to document GPS requirements, nor the military and civilian requirements processes.  Rather it is a document that expresses our commitment of service to GPS users.

## GPS SPS Performance Standard

**GPS SPS Performance Standard**

**Notes:**
This chart provides a summary of the key standards.  We have tried to express these in an ‘apples to apples’ comparison with parameters from the previous signed SPS Signal specification, and representative or typical recent performance.
You will see that the standard for horizontal worst site position accuracy has improved from 100m, to 36m, with performance typically in the range of 6 meters.  
The time transfer accuracy standard has improved from 340 nanoseconds to 40 nanoseconds, with typical performance below 10 nsec.
Availability of PDOP geometry below 6 has improved from slightly less than 96% to 98%, with typical performance about 99.9%.
We have added standards for range accuracy and constellation availability.
And finally, service reliability has remained the same, at basically 18 hours of service failure per year, where we have seen only a 2 hour service failure during the recent PRN 22 anomaly.
While the standards in some cases have improved from the 1995 version, there still is a significant margin between the standards and typical performance.  This margin is important;  first because typical performance is just that--typical, while we must meet the standard on the worst day.  Second, margin is important to allow the government to continue to meet its commitments, even in the face of possible problems that could be encountered during the many significant upgrades that are planned for the GPS system.    

## Overview

**Background**
**Constellation Status/Performance**
**   ****Standard**
**Modernization**** ****Program**
**The Way Ahead**

## GPS Modernization

**GPS IIA/IIR**

**GPS III**

**GPS IIR-M, IIF**

_**IIR-M**_**:  Improved on all IIA capabilities and added**
**2nd Civil Signal on L2**
**New L1 & L2 M-Code**
_**IIF:**_**  IIR-M capability and:**
**Add 3rd Civil Signal on L5**

**Standard Service (~100 m)**
**Precise Service (~16 m)**
**Two Nav frequencies **
**L1: Civil (C/A) & Precise **
**code, Navigation **
**L-2: P-code Nav**

_**GPS-III:**_
**Navigation Surety**
**Increased Accuracy**
**Assured Availability**
**Controlled Integrity**
**System Survivability **
_**Other Transformational needs **_
**Nav-related Messaging**
**Navigation Operations**
**Adjunct to BFT**

**Basic GPS**

**L2C on L2**
**M-Code (Earth)**

**NAVWAR Capable**
**Full Civil Rqmts**
**Add’l Capabilities**

**New Civil Signal – L5**

**GPS Modernization**

**Increasing System Capabilities**
**Increasing Defense/Civil Benefit**

**SA Set**
**to 0**

**Flex Power upgrade adds ability to increase power on both P and M code signals to defeat low level enemy jamming**

**Notes:**
GMSP concept is afforded by GPS-III modernization. As a GPS-III augmentation alternative, GMSP may provide a more efficient way to satisfy multiple space needs. 

## Setting SA to zero considered first step
Civil users currently limited to one GPS signal
C/A code at L1 frequency (1575.42 MHz)
Low power signal, not intended for precision nav
C/A = “Coarse Acquisition”; P = “Precise”
Adding a second civil signal
C/A-type code at L2 frequency (1227.60 MHz)
Low power signal, not intended for precision nav
Adding a third civil signal
P-type codes at L5 frequency (1176.45 MHz)
Higher power signal, intended for precision nav

**Civil users currently ****limited**** to one GPS signal**
**C/A code at L1 frequency (1575.42 MHz)**
**Low power signal, not intended for precision nav**
**C/A = “Coarse Acquisition”; P = “Precise”**
**Adding a ****second civil**** signal**
**C/A-type code at L2 frequency (1227.60 MHz)**
**Low power signal, not intended for precision nav**
**Adding a ****third civil**** signal**
**P-type codes at L5 frequency (1176.45 MHz)**
**Higher power signal, intended for precision nav**

***  ***
**Civil GPS Modernization**

## Second Civil Signal (L2C)

**More robust**** civil signal service**
**Civil users currently only have codeless/semi-codeless access to P(Y) on L2**
**Increased accuracy**
**Coded dual-frequency ionospheric corrections **
**    ****at the receiver**
**Advanced ****signal structure****  **
**Working Group defined signal characteristics**
**Better cross-correlation properties than C/A**
**Data-free component for robust tracking**
**Designated as primary L2 civil code versus C/A **
**   **

**Begin Launch in 2004; Projected for         Full Capability in 2012**

##  Third Civil Signal (L5)

**Improved ****signal structure**** for enhanced performance**
**~ 6 dB higher power relative to L1**
**Broadcast over the full registered 24 MHz band**
**Spectrum allocated for ****aeronautical radionavigation services**** (ARNS) (960 – 1215 MHz)**
**Co-primary allocation for RNSS received at the last World Radio Conference (1164 – 1215 MHz)**
**DME compatibility**** achieved by frequency reallocation, if required**
**L5 ****signal definition**
**RTCA SC 159, WG #1, developed L5 Specification**** **
**GPS JPO originated/coordinated ICD-GPS-705**

**Begin Launch in 2005; Projected Full Capability in 2015**

## Civil Benefits of GPS Modernization

**More ****robust**** GPS service**
**Reduces vulnerability to unintentional ****interference**** **
**Unlikely to simultaneously affect L1, L2 and L5**
**Worldwide dual frequency**** for en-route navigation and precision approach**
**Dual Frequency (L1, L5) allows ionospheric corrections in avionics onboard the aircraft**
**Fewer reference stations may be needed for space-based augmentation systems (e.g. WAAS)**
**Centimeter-level**** accuracy for scientific & survey applications **

## GPS Modernization Schedule

## Overview

**Background**
**Constellation Status/Performance**
**   ****Standard**
**Modernization Program**
**The Way Ahead**

## The Way Ahead (cont’d)

**The Way Ahead ****(cont’d)**

**Future**** of global satellite navigation services is bright**
**Compatibility/interoperability**** is critical between GPS and future systems**
**European Galileo**
**Japanese Quasi-Zenith**
**   **

**Seamless, global interoperability of future **
**systems with GPS is in best interest of all **
**navigation users**

## Summary

**Stable, consistent**** GPS policy and service**
**Expanding use**** in transportation safety **
**GPS Modernization is a ****multiple step**** process**
**Second civil signal (L2C) beginning in 2004**
**Third civil signal (L5) beginning in 2005**
**GPS III addressing future dual-use requirements**
**Continuing ****international outreach**** to be responsive to global user needs**
**Compatibility/interoperability with other future systems is critical   **

**Future GPS performance will dramatically improve as a result of modernization**

## Global Positioning SystemModernization 

**Global Positioning System*****Modernization****** ***

**GPS Symposium**
**Tokyo, Japan**
**November 12, 2002**
- 
- **Michael Shaw**
**U.S. Department of Transportation**

**Backups**

## Wide Area Augmentation System (WAAS)
Enroute thru near precision approach 
Signal in space currently available 
Use at your own risk until operational (2003)
Commissioning for aviation use by late 2003
Allows reduction in ground-based nav aids

Local Area Augmentation System (LAAS)
Terminal through CAT III Precision Approach
Research and development program 

**Enroute thru near precision approach **
**Signal in space currently available **
**Use at your own risk until operational (2003)**
**Commissioning for aviation use by late 2003**
**Allows reduction in ground-based nav aids**
**Local Area Augmentation System**** (LAAS)**
**Terminal through CAT III Precision Approach**
**Research and development program **

** ****GPS Augmentations**

##      GPS Augmentations (cont’d)

**Maritime Differential GPS ****(MDGPS)**** System**
**Accuracy better than 10 meters**
**Currently 40 nations implementing Maritime DGPS**
**Nationwide Differential GPS ****(NDGPS)**** System**
**Expanding MDGPS to cover entire U.S.**
**Positive Train Control for railroads**
**Intelligent Transportation Systems for highway use**
**23 stations currently operating**
**Full operational capability by end of 2007**

**MDGPS and NDGPS are one operating**
**system covering the US coast to coast**

##            GPS Satellite Status

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***           *****GPS Satellite Status**

_**Bottom Line**_
**16 vehicles are “yellow” (i.e. single string)**
**9 vehicles are yellow due to bus failures**
**13 vehicles are yellow due to nav failures**

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##       Constellation Summary

**Age Summary**
**7 satellites past updated mean mission duration**
**Health Summary **
**13 Satellites one component away from navigation mission failure**
**9 satellites one component away from **
**   ****bus failure**

**    ****Despite age and component issues, **
**     ****all satellites are providing a healthy nav signal**

## GPS Position Error Daily Performance – 

**GPS Position Error Daily Performance – **
**Global Assessment, 2002**

## Key GPS III Goals for Civil Signals

**Significant increase in ****system accuracy**
**Assured and improved level of ****unaugmented integrity**
**Improved availability of ****accuracy with integrity**
**Backward compatibility**** with existing receivers**
**IOC for L5**** (in combination with IIF satellites)**
**Smooth transition from ****GPS Block II to **
**   ****Block III**
**Flexibility to respond**** to evolving requirements **
**   ****with limited programmatic impacts**

##     GPS III Proposed Accuracy

-                        **Draft Systems Specification**

_**Threshold  **_

_**Objective**_

**Accuracy (95%)**

**Horizontal**

**Vertical**

** ****Timing**

**2.5 m**

**0.5 m**

**4.5 m**

**1.1 m**

**5.7 nsec**

**1.3 nsec**

**      ****Includes the effects of receivers**
** ****Threshold is for low-cost/low-performance receiver**
** ****Objective is for high-cost/high-performance receiver**