1 L2 and L5 Civil Signal Industry Day 2 May 2001 LCDR Richard Fontana GPS Deputy Program Manager, DOT.

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L2 and L5 Civil Signal Industry Day

2 May 2001

LCDR Richard Fontana

GPS Deputy Program Manager, DOT

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GPS L2 Civil Signal Industry Day Agenda

ITEM BRIEFER TIME

Welcome and Introductions LCDR Fontana 0900-0910

Overview of GPS Modernization Paul Novak 0910-0920

Advantages of a New L2 CS LCDR Fontana 0920-0945

BREAK 0945-1000

Technical Description of L2CS Tom Stansell 1000-1100

Laboratory and Simulation Dr Dafesh 1100-1130

Results

Almanac Karl Kovach 1130-1200

Question and Answer Session LCDR Fontana 1200-1215

LUNCH 1215-1330

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GPS L5 Civil Signal Industry Day Agenda

ITEM BRIEFER TIME

Welcome and Introductions Lt Victoria 1330-1340

L5 Design Background Dr Hegarty 1340-1400

L5 Design Background Dr Van Dierendonck 1400-1445

L5 Environmental Studies Dr Hegarty 1445-1500

BREAK 1500-1515

ICD-GPS-705 Organization Dr Slattery 1515-1540

ICD-GPS-705 Review Process Lt Victoria 1540-1600

Question and Answer Lt Victoria 1600-1630

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L2 and L5 Civil Signal Industry Day

2 May 2001

Paul NovakSMC/CZC (SAIC)

Communications

Surveying & Mapping

Fishing & BoatingOff shore

Drilling

Recreation

Trucking & Shipping

Personal Navigation

Aviation

Railroads

Power Grid Interfaces

Civil Use of GPS

“The nation’s reliance on GPS has become an issue of national security -- national security in its broadest sense, that goes beyond merely national defense.” -- Dr. James Schlesinger, March 1997

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Block IIR

Block II/IIA

Block IIF

24-satellite (nominal) constellation

Six orbital planes, four satellites per plane

Semi-synchronous, circular orbits (~11,000 mi)

GPS Space Systems GPS Space Systems

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Civil GPS, Summary of Key Events

• 1978 - First Global Positioning System satellite launch

• 1983 - President Reagan offers GPS to the world “free of charge”

• 1993 - GPS Standard Positioning Service available

• 1994 - FAA approves GPS for use in National Airspace System

• 1996 - Presidential Decision Directive, first National GPS policy

• 1998 - Two new GPS civil signals (L2 and L5) announced

• 1999 - Third civil signal (L5) at 1176.45 MHz announced

• 2000 - Congress funds GPS Modernization in DoD budget

• 2000 - Selective Availability set to zero

• 2000 - GPS JPO begins modifications to IIR-M and IIF satellites

• 2000 - JPO awards Boeing and Lockheed Martin GPS III contracts

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GPS Modernization Mission

Precise & Continuous, 3-D Position, Velocity and Timing Information to an unlimited number of military and

civil users

Current MissionAnti-Jam/Anti-Spoof Protection, Civilian “Safety of Life” Signals, Upgraded & Redundant Control,

and demonstrate Legacy and Upgraded Military Receivers.

MS

GAMCS

L-Band NDSDownlink

S-band

Alternate MCS

UHF Crosslink

Additional Modernization Mission

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GPS Users “Wants”

• More jam resistance• More security

• Anti-spoof• User discrimination

• Shorter “time to first fix”• Backward compatibility

• Accuracy• Availability• Coverage• Integrity• Robustness

• Redundant signals• More power

• Higher power• New military signal

• Spectral separation from civil signals• Faster signal acquisition• Improved security codes

• Selective Availability (SA) to zero• Second civil signal

• Ionospheric correction• Redundancy

• Third civil signal• High accuracy real-time applications

• Spectrum protection for “safety of life” applications

Civil User

Militarycode

L1 / L2

L2 Civil Signal

Military User

L5

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Why Modernize GPS?The Civil GPS Perspective

• Better support to civil GPS customers worldwide• New civil signals for improved accuracy, integrity and

continuity of service = robustness• Global utility = economic enabler• Optimize GPS PVT and augmentation systems in a

overall national network architecture

Presidential Decision Directive - Mar 96

Vice Presidential Announcements - Mar 98 and Jan 99

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GPS ModernizationBlock II Space Vehicles

L1 Enhancements New developmental

Military code (M-code) L2 Enhancements

New L2 civil signal New developmental M-

code

L1 Enhancements Similar to IIR-M Operational M-code

L2 Enhancements Similar to IIR-M Operational M-code

L5 New civil signal at

1176MHz

Block IIR-M Block IIF

121227.60 MHz 1575.42 MHz1176.45 MHz

L2 L1L5

P(Y)P(Y)

C/AC/A

P(Y)P(Y)

C/AC/A

P(Y)P(Y)

P(Y)P(Y)

L2CSL2CS

P(Y)P(Y)

C/AC/A

P(Y)P(Y)

L2CSL2CS

MM MM

Present Signal(Block II/IIA/IIR)

Next GenerationOf Capability(Block IIR-M)

Civil Safety of LifeApplications

(Block IIF and beyond)

Modernized GPS Signal EvolutionModernized GPS Signal Evolution

MM MM

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GPS III Architecture Studies

Military missions• Precision bombing• Mine clearing• Situational awareness

Civilian missions• Precision farming• Building/ urban canyon personnel tracking• Global Air Traffic Management (GATM)• Time synchronization for utilities/

telecommunications

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SystemMilestones

Space Segment

Control SegmentFunctionality

User Equipment

1801 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 19CY

M-Code (IIRM/IIF) Launches

UE Fielding

Heritage Launches

SAASM Capable

M-Code Capable

M-Code + Power Capable

1st LRIP RCVRs

SAASMOA

M-Code UE Development

M-CodeIOCM-Code

IOCL2CS&M-Code

IOC

M+PowerFOC

L2CS& M-code

FOC

M+PowerIOC

GPS III Launches1st IIR Mod 1st IIF

GPS III Launches

L5IOC

L5FOC

EMD

Dev Test

Dev Test

Dev Test

SAASM UE Producton / Platform Installs

1st LRIP RCVRs

High Power AE Development1st LRIP AE

Inc

rea

sin

g P

erc

en

t Fie

ldin

g

Production / Platform Installs

Production / Platform Installs

GPS Modernization Program Summary

L2 Civil Signal

LCDR Richard FontanaGPS Deputy Program Manager, DOT

May 2, 2001

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Overview

Background

Advantages of New Signal

Design Considerations

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Background

Option to implement a new signal

Did not want to limit future GPS by what is implemented on

IIR/IIF

Overcome some limitations of C/A coded signals

Can make significant improvements with new technology

signal

C/A code designed as an acquisition signal

1070s technology

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Advantages of a New Signal

Improved Cross Correlation Properties

Improves ability to transmit more signals (SBAS,Pseudolytes)

Improves the tolerance to interference

Improves susceptibility to self interference

Improves the dynamic rage of receivers

• Can receive weaker signals without self interference

Enables operation in more stressful environments (wooded area,

buildings, urban canyons)

Enables ability for higher power signals on future satellites

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Advantages of a New Signal

Improved Tracking capability Enables operation in more stressful environments (wooded area,

buildings, urban canyons)

Improved Data Demodulation Want equivalent to tracking threshold

Again, enables operation in more stressful environments

Acquisition Capability Dependent on user equipment

Design trade with code length

Not limited by code. With right UE, can acquire signal in more stressful environments than C/A code

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Design Considerations

Enhance existing professional/commercial dual frequency applicationsProvide more robust iono correction signal

Provide a more effective single frequency navigation signalDrives need for data

Simple to implement in the SV and UESchedule and Cost (both SV and UE)Replacement for C/A signal

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Design Considerations (continued)

Compatible with L2 M-code Spectral Separation

Ensure no detriment to Codeless/Semi Codeless L2 P(Y) receivers As a result of two earlier objectives Same power level and spectral shape as C/A code…no

additional testing required

Risk Mitigation Design schedule short, IIR implementation schedule short,

coordination process short C/A code switch

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Design Considerations (continued)

What is optimum in the future (GPS III) to determine the best step now. Did not want to artificially constrain thinking due to possible

IIR/IIF perceived limitations. Perceived cost/schedule limitations. Design for future, provide natural migration path

Then determine what portion could be implemented on IIR and IIF

L2 C/A code compatibility Assess impact on both military and civilian receivers Not a design driver but have C/A switch as risk mitigation

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Signal Characteristics

Two codes one with & one without data Serves single and dual frequency users

Signal characteristics: Codes longer than C/A to minimize cross correlation Separated by time – Time Division Multiplexed (TDM) Narrow band signal – Spectral separation Improved data structure – Enhanced Data demodulation

Enhance cross correlation, tacking threshold, data demodulation threshold.

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Signal Comparison

L2 splits power 50/50 between data and data-less channels

Medium Code with Data, Long code no data

Higher effective L2 channel for tracking

3db higher than C/A on L2

Approximately 3dB better Data demodulation capability

Enhanced data structure

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Signal Comparison

24dB better cross-correlation protection. C/A code cross correlation “protection” is ~21 dB. The L2CS signal is ~45dB

“protection”

Dynamic range improvement. Better capability to receive both weak and strong signals

Acquisition threshold Given assumptions of improved UE, not harmed Under stressful conditions improved

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L2CS Summary

TDM service for both single and dual frequency Significant improvements in

Cross correlation performanceTracking thresholdData recovery thresholdAcquisition Capability

Modern signal for future GPS

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