# Presentation: 582958

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

## 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

## 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

**L2 and L5 Civil Signal Industry Day**
**2 May 2001**
- Paul Novak
- SMC/CZC (SAIC)

## Civil Use of GPS

**Communications**

**Surveying &**
**   ****Mapping**

**Fishing &**
** ****Boating**

**Off shore**
**  ****Drilling**

**Recreation**

**Trucking & **
**  ****Shipping**

**Personal Navigation**

**Aviation**

**Railroads**

**Power Grid**
** ****Interfaces**

**“****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**

**Notes:**
You represent the largest community of GPS .  The CivilGPS community.

##  GPS Space Systems 

**Block IIF**

- 24-satellite (nominal) constellation
- Six orbital planes, four satellites per plane
- Semi-synchronous, circular orbits (~11,000 mi)

-  GPS Space Systems

**Notes:**
Your fathers GPS

## 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

## GPS Modernization Mission

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

_**Current Mission**_

**Anti-Jam/Anti-Spoof Protection, Civilian “Safety of Life” Signals, Upgraded & Redundant Control, **
** ****and demonstrate Legacy and Upgraded Military Receivers.**

_**Additional Modernization Mission**_

**Notes:**
-  Three Segments of GPS all effected by GPS modernization
	-Space Vehicle
	-Control Segment
	-User Equipment

## 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

***Military***
***code***
***L1 / L2***

***L2 Civil ***
***Signal ***

- Military User

*** ******L5 ***

## 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**

## GPS ModernizationBlock 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**_

## Modernized GPS Signal Evolution

**1227.60 MHz**

**1575.42 MHz**

**1176.45 MHz**

**L2**

**L1**

**L5**

**P(Y)**

**C/A**

**P(Y)**

**C/A**

**P(Y)**

**P(Y)**

**L2CS**

**P(Y)**

**C/A**

**P(Y)**

**L2CS**

**M**

**M**

- Present Signal
- (Block II/IIA/IIR)

- Next Generation
- Of Capability
- (Block IIR-M)

- Civil Safety of Life
- Applications
- (Block IIF and beyond)

**M**

**M**

## GPS III Architecture Studies

**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

## GPS Modernization 

- GPS Modernization
- Program Summary

## L2 Civil Signal

- LCDR Richard Fontana
- GPS Deputy Program Manager, DOT
- May 2, 2001

## Overview

- Background
-  Advantages of New Signal
- Design Considerations

## 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

## 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

## 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

## Design Considerations

- Enhance existing professional/commercial dual frequency applications
- Provide more robust iono correction signal
- Provide a more effective single frequency navigation signal
- Drives need for data
- Simple to implement in the SV and UE
- Schedule and Cost (both SV and UE)
- Replacement for C/A signal

## 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

## 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

## 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.**

## 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

## 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

## L2CS Summary

- TDM service for both single and dual frequency
- Significant improvements in
- Cross correlation performance
- Tracking threshold
- Data recovery threshold
- Acquisition Capability
- Modern signal for future GPS

## Back up