Global Navigation Satellite Systems, Inertial Navigation, and Integration E-Book

Mohinder S. Grewal

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch
• Veröffentlichungsjahr: 2020

Seitenzahl: 872

Beschreibung

Covers significant changes in GPS/INS technology, and includes new material on GPS, GNSSs including GPS, Glonass, Galileo, BeiDou, QZSS, and IRNSS/NAViC, and MATLAB programs on square root information filtering (SRIF) This book provides readers with solutions to real-world problems associated with Global Navigation Satellite Systems, Inertial Navigation, and Integration. It presents readers with numerous detailed examples and practice problems, including GNSS-aided INS, modeling of gyros and accelerometers, and SBAS and GBAS. This revised fourth edition adds new material on GPS III and RAIM. It also provides updated information on low cost sensors such as MEMS, as well as GLONASS, Galileo, BeiDou, QZSS, and IRNSS/NAViC, and QZSS. Revisions also include added material on the more numerically stable square-root information filter (SRIF) with MATLAB programs and examples from GNSS system state filters such as ensemble time filter with square-root covariance filter (SRCF) of Bierman and Thornton and SigmaRho filter. Global Navigation Satellite Systems, Inertial Navigation, and Integration, 4th Edition provides: * Updates on the significant upgrades in existing GNSS systems, and on other systems currently under advanced development * Expanded coverage of basic principles of antenna design, and practical antenna design solutions * More information on basic principles of receiver design, and an update of the foundations for code and carrier acquisition and tracking within a GNSS receiver * Examples demonstrating independence of Kalman filtering from probability density functions of error sources beyond their means and covariances * New coverage of inertial navigation to cover recent technology developments and the mathematical models and methods used in its implementation * Wider coverage of GNSS/INS integration, including derivation of a unified GNSS/INS integration model, its MATLAB implementations, and performance evaluation under simulated dynamic conditions Global Navigation Satellite Systems, Inertial Navigation, and Integration, Fourth Edition is intended for people who need a working knowledge of Global Navigation Satellite Systems (GNSS), Inertial Navigation Systems (INS), and the Kalman filtering models and methods used in their integration.

Leseprobe

Global Navigation Satellite Systems, Inertial Navigation, and Integration

Mohinder S. Grewal

California State University at FullertonFullerton, California

Angus P. Andrews

Rockwell Science Center (retired)Thousand Oaks, California

Chris G. Bartone

Ohio UniversityAthens, Ohio

Fourth Edition

Copyright

This fourth edition first published 2020

© 2020 John Wiley & Sons, Inc.

Edition History

Wiley‐Interscience; 1st edition 2006

Wiley‐Interscience; 2nd edition 2011

Wiley‐Interscience; 3rd edition 2013

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.

The right of Mohinder S. Grewal, Angus P. Andrews, and Chris G. Bartone to be identified as the authors of this work has been asserted in accordance with law.

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Limit of Liability/Disclaimer of Warranty

MATLAB® is a trademark of The MathWorks, Inc. and is used with permission. The MathWorks does not warrant the accuracy of the text or exercises in this book. This work's use or discussion of MATLAB® software or related products does not constitute endorsement or sponsorship by The MathWorks of a particular pedagogical approach or particular use of the MATLAB® software. While the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.

Library of Congress Cataloging‐in‐Publication Data

Names: Grewal, Mohinder S., author. | Andrews, Angus P., author. | Bartone,

 Chris G., author. | John Wiley & Sons.

Title: Global navigation satellite systems, inertial navigation, and

 integration / Mohinder S. Grewal, California State University at

 Fullerton, Angus P. Andrews, Chris G. Bartone.

Description: Fourth Edition. | Hoboken : Wiley, 2020. | Third edition

 published 2013. | Includes bibliographical references and index.

Identifiers: LCCN 2019038560 (print) | LCCN 2019038561 (ebook) | ISBN

 9781119547839 (Hardback) | ISBN 9781119547846 (Adobe PDF) | ISBN

 9781119547815 (ePub)

Subjects: LCSH: Global Positioning System. | Inertial navigation. | Kalman

 filtering.

Classification: LCC G109.5 .G74 2020 (print) | LCC G109.5 (ebook) | DDC

 910.285‐‐dc23

LC record available at https://lccn.loc.gov/2019038560

LC ebook record available at https://lccn.loc.gov/2019038561

Cover design by Wiley

Cover image: © Busakorn Pongparnit/Getty Images

M.S.G. dedicates this book to the memory of his parents, Livlin Kaur and Sardar Sahib Sardar Karam Singh Grewal.

A.P.A. dedicates his contributions to his wife Jeri, without whom it never would have happened.

C.G.B. dedicates this work to his wife Shirley and two sons, Christopher and Stephen, for their never‐ending support over the years.

Preface to the Fourth Edition

This book is intended for people who need a working knowledge of Global Navigation Satellite Systems (GNSS), Inertial Navigation Systems (INS), and the Kalman filtering models and methods used in their integration. The book is designed to provide a useable, working familiarity with both the theoretical and practical aspects of these subjects. For that purpose we have included “real‐world” problems from practice as illustrative examples. We also cover the more practical aspects of implementation: how to represent problems in a mathematical model, analyze performance as a function of model parameters, implement the mechanization equations in numerically stable algorithms, assess its computational requirements, test the validity of results, and monitor performance in operation with sensor data from GPS and INS. These important attributes, often overlooked in theoretical treatments, are essential for effective application of theory to real‐world problems.

The companion Wiley website (www.wiley.com/go/grewal/gnss) contains MATLAB® m‐files to demonstrate the workings of the navigation solutions involved. It includes Kalman filter algorithms with GNSS and INS data sets, so that the reader can better discover how the Kalman filter works by observing it in action with GNSS and INS. The implementation of GNSS, INS, and Kalman filtering on computers also illuminates some of the practical considerations of finite‐word‐length arithmetic and the need for alternative algorithms to preserve the accuracy of the results. If the student wishes to apply what she or he learns, then it is essential that she or he experience its workings and failings – and learn to recognize the difference.

The book is organized for use as a text for an introductory course in GNSS technology at the senior level or as a first‐year graduate level course in GNSS, INS, and Kalman filtering theory and applications. It could also be used for self‐instruction or review by practicing engineers and scientists in these fields.

This fourth edition has been updated to include advancements in GNSS/INS technology since the third edition in 2013, as well as many improvements suggested by reviewers and readers of the second edition. Changes in this fourth edition include the following:

Updates on the significant upgrades in existing GNSS systems and on other systems currently under advanced development.

Expanded coverage of basic principles of antenna design and practical antenna design solutions are included.

Expanded coverage of basic principles of receiver design, and an update of the foundations for code and carrier acquisition and tracking within a GNSS receiver.

Examples demonstrating independence of Kalman filtering from probability density functions of error sources beyond their means and covariances, and how this breaks down with nonlinearities.

Updated coverage of inertial navigation to cover recent technology developments and the mathematical models and methods used in its implementation.

Updated dynamic models for the propagation of inertial navigation errors, including the effects of drifting sensor compensation parameters and nonlinearities.

Greatly expanded coverage of GNSS/INS integration, including derivation of a unified GNSS/INS integration model, its MATLAB implementations, and performance evaluation under simulated dynamic conditions.

The companion Wiley website has also been augmented to include updated background material and additional MATLAB scripts for simulating GNSS‐only and integrated GNSS/INS navigation. The companion website (www.wiley.com/go/grewal/gnss) includes satellite position determination, calculation of ionospheric delays, and dilution of precision.

Chapter 1 provides an overview of navigation in general, and GNSS and inertial navigation in particular. These overviews include fairly detailed descriptions of their respective histories, technologies, different implementation strategies, and applications.

Chapter 2 covers the fundamental attributes of satellite navigation systems in general, the technologies involved, how the navigation solution is implemented, and how satellite geometries influence errors in the solution.

Chapter 3 covers the fundamentals of inertial navigation, starting with its nomenclature, and continuing through to practical implementation methods, error sources, performance attributes, and development strategies.

Chapters 4–9 cover basic theory of GNSS for a senior‐level class in geomatics, electrical engineering, systems engineering, and computer science. Subjects covered in detail include basic GNSS satellite signal structures, practical receiver antenna designs, receiver implementation structures, error sources, signal processing methods for eliminating or reducing recognized error sources, and system augmentation methods for improving system integrity and security.

Chapter 10 covers the fundamental aspects of Kalman filtering essential for GNSS/INS integration: its mathematical foundations and basic implementation methods, its application to sensor integration in general, and to GNSS navigation in particular. It also covers how the implementation includes its own performance evaluation, and how this can be used in performance‐predictive design of sensor systems.

Chapter 11 covers the basic errors sources and models for inertial navigation, including the effects of sensor noise and errors due to drifting inertial sensor error characteristics, how the resulting navigation errors evolve over time, and the resulting models that enable INS integration with other sensor systems.

Chapter 12 covers the essential mathematical foundations for GNSS/INS integration, including a unified navigation model, its implementation in MATLAB, evaluations of the resulting unified system performance under simulated dynamic conditions, and demonstration of the navigation performance improvement attainable through integrated navigation.

Appendix A contains brief descriptions of the MATLAB® software, including formulas implementing the models developed in MATLAB® different chapters and used for demonstrating how they work. Appendix B and Appendix C (www.wiley.com/go/grewal/gnss) contains background material on coordinate systems and transformations implemented in the software, including derivations of the rotational dynamics used in navigation error modeling and GNSS/INS integration.

For instructors that wish to cover the fundamental aspects of GNSS, Chapters 1–2 and 4–9 are recommended. Instructors for a course covering the fundamental concepts of inertial navigation can cover Chapters 1, 3, 10, and 11. A follow‐on class or a more advanced course in GNSS and INS integration should include Chapter 12 as well as significant utilization of the software routines provided for computer‐based GNSS/INS integration projects.

October 2019

Mohinder S. Grewal, Ph.D., P.E.California State University at FullertonFullerton, California

Angus P. Andrews, Ph.D.Rockwell Science Center (retired)Thousand Oaks, California

Chris G. Bartone, Ph.D., P.E.Ohio UniversityAthens, Ohio

Acknowledgments

We acknowledge Professor John Angus, Jay A. Farrell, and Richard B. Langley for assistance and inspiration on the outline of this edition. We acknowledge the assistance of Mrs. Laura A. Cheung of the Raytheon Company for her expert assistance in reviewing Chapter 8 (Differential GNSS) and with the MATLAB® programs. Special thanks goes to Dr. Larry Weill for his contribution to Chapter 7 on multipath mitigation algorithms.

A. P. A. thanks Andrey Podkorytov at the Moscow Aviation Institute for corrections to the Schmidt–Kalman filter; Randall Corey from Northrop Grumman and Michael Ash from C. S. Draper Laboratory for access to the developing Draft IEEE Standard for Inertial Sensor Technology; Dr. Michael Braasch at GPSoft, Inc. for providing evaluation copies of the GPSoft INS and GPS MATLAB Toolboxes; Drs. Jeff Schmidt and Robert F. Nease, former Vice President of Engineering and Chief Scientist at Autonetics, respectively, for information on the early history of inertial navigation; and Edward H. Martin, member of the GPS development team awarded the 1992 Robert J. Collier Trophy by the National Aeronautics Association, and winner of the 2009 Captain P.V.H. Weems Award presented by the Institute of Navigation for his role in GPS receiver development, for information on the very early history of GPS/INS integration.

C. G. B. would like to thank Ohio University and many of its fine faculty, staff, and students that I have had the pleasure to interact with in my research and teaching over the years. Such a rich environment has enabled me to develop a wide variety of classes and research efforts that these writings draw upon. Thanks also goes to Neil Gerein and Jerry Freestone from NovAtel, Dave Brooks from Sensor Systems, James Horne from Roke, and Herbert Blaser from u‐blox for providing antenna information.

About the Authors

Mohinder S. Grewal, Ph.D., P.E., is well known for his innovative application of Kalman filtering techniques to real world modeling problems and his ability to communicate this complex subject to his students. His original research appears in IEEE and ION refereed journals and proceedings. He holds patents in GUS clock steering and L1/L5 differential bias estimation. Dr. Grewal is Professor of Electrical Engineering at California State University, Fullerton, which awarded him its 2008-2009 Outstanding Professor Award. His consulting associations include Raytheon Systems, Boeing Company, Lockheed‐Martin, University of California, Riverside, staff of the US Department of the Interior, Geodetics, and Northrop. He is a Senior Member of IEEE and member of the Institute of Navigation. His Ph.D. in Control Systems and Computers is from University of Southern California.

Angus P. Andrews derived the first electrostatic bearing torque parametric models for calibrating electrostatic gyroscopes in 1967 at the Autonetics Division of Rockwell International, and then saw its development through two generations of strapdown inertial navigation systems to the N73 competitor for the US Air Force Standard Navigator. His career in inertial navigation also included derivations of new square root filtering formulas. His undergraduate degree is from MIT and his Ph.D. in mathematics is from University of California, Los Angeles.

Chris G. Bartone, Ph.D., P.E., is a professor at Ohio University with over 35 years experience in communications, navigation, and surveillance systems. He received his Ph.D., E.E. from Ohio University, M.S.E.E. from the Naval Postgraduate School, and B.S. E.E. from The Pennsylvania State University. Dr. Bartone has developed and teaches a number of GNSS, antenna, and microwave classes. He is a recipient of the RTCA William E. Jackson award, the ION Captain P.V.H. Weems award, and is a Fellow of the ION. His research concentrates on all aspects of navigation systems.

Acronyms

A/D

analog‐to‐digital (conversion)

ADC

analog‐to‐digital converter

ADR

accumulated delta range

ADS

automatic dependent surveillance

AGC

automatic gain control

AHRS

attitude and heading reference system

AIC

Akaike information‐theoretic criterion

AIRS

advanced inertial reference sphere

ALF

atmospheric loss factor

ALS

autonomous landing system

aItBOC

alternate binary offset carrier

AODE

age of data word, ephemeris

AOR‐E

Atlantic Ocean Region East (WAAS)

AOR‐W

Atlantic Ocean Region West (WAAS)

AR

autoregressive or axial ratio

ARMA

autoregressive moving average

ARNS

aeronautical radio navigation services

ASD

amplitude spectral density

ASIC

application‐specific integrated circuit

ASQF

application‐specific qualification facility (EGNOS)

A‐S

antispoofing

ATC

air traffic control

BD

BeiDou

bps

bits per second

BOC

binary offset carrier

BPSK

binary phase‐shift keying

BS

base station

C

civil

C/A

coarse acquisition (channel or code)

C&V

correction and verification (WAAS)

CDM

code‐division multiplexing

CDMA

code‐division multiple access

CEM

computational electromagnetic model

cps

chips per second

CEP

circle error probable

CL

code long

CM

code moderate

CNAV

civil navigation

CNMP

code noise and multipath

CONUS

conterminous United States, also continental United States

CORS

continuously operating reference station

COSPAS

Cosmicheskaya Sistyema Poiska Avariynich Sudov

CBOC

combined BOC

C/NAV

commercial navigation

CRC

cyclic redundancy check

CRPA

controlled reception pattern antenna

CWAAS

Canadian WAAS

DGNSS

differential GNSS

DGPS

differential GPS

DME

distance measurement equipment

DOD

Department of Defense (USA)

DOP

dilution of precision

E

eccentric anomaly

ECEF

Earth‐centered, Earth‐fixed (coordinates)

ECI

Earth‐centered inertial (coordinates)

EGNOS

European Geostationary Navigation Overlay System

EIRP

effective isotropic radiated power

EKF

extended Kalman filter

EMA

electromagnetic accelerator or electromagnetic accelerometer

ENU

east–north–up (coordinates)

ESA

European Space Agency

ESG

electrostatic gyroscope

ESGN

electrostatically supported gyro navigator (US Navy)

EU

European Union

EWAN

EGNOS wide‐area (communication) network

FAA

federal aviation administration (USA)

FDMA

frequency division multiple access

FEC

forward error correction

FLL

frequency‐lock loop

FM

frequency modulation

FOG

fiber optic gyroscope

FPE

final prediction error (Akaike's)

FSLF

free‐space loss factor

F/NAV

free navigation

FT

feet

GAGAN

GPS and GEO augmented navigation (India)

GBAS

ground‐based augmentation system

GCCS

GEO communication and control segment

GDOP

geometric dilution of precision

GEO

geostationary Earth orbit

GES

GPS Earth station COMSAT

GIC

GPS integrity channel

GIPSY

GPS infrared positioning system

GIS

geographic information system(s)

GIVE

grid ionosphere vertical error

GLONASS

global orbiting navigation satellite system

GNSS

global navigation satellite system

GOA

GIPSY/OASIS analysis

GPS

global positioning system

GUS

GEO uplink subsystem

GUST

GEO uplink subsystem type 1

HDOP

horizontal dilution of precision

HEO

highly inclined elliptical orbit or high earth orbit

HMI

hazardously misleading information

HOW

handover word

HRG

hemispheric resonator gyroscope

ICAO

International Civil Aviation Organization

ICC

ionospheric correction computation

ICD

interface control document

IDV

independent data verification (of WAAS)

IF

intermediate frequency

IFOG

integrating or interferometric fiber optic gyroscope

IGP

ionospheric grid point (for WAAS)

IGS

international GNSS service

ILS

instrument landing system

IMU

inertial measurement unit

Inmarsat

international mobile (originally “Maritime”) satellite organization

I/NAV

integrity navigation

INS

inertial navigation system

IODC

issue of data, clock

IODE

issue of data, ephemeris

IONO

ionosphere, ionospheric

IOT

in‐orbit test

IR U

inertial reference unit

IS

interface specification

ISA

inertial sensor assembly

ITRF

International Terrestrial Reference Frame

JPALS

Joint Precision Approach and Landing System

JT1DS

Joint Tactical Information Distribution System

LAAS

local‐area augmentation system

LADGPS

local‐area differential GPS

LAMBDA

least‐squares ambiguity decorrelation adjustment

LD

location determination

LLMSE

linear least mean squares estimator

LHCP

left‐hand circularly polarized

LORAN

long‐range navigation

LOS

line of sight

LPV

lateral positioning with vertical guidance

LSB

least significant bit

LTP

local tangent plane

M

mean anomaly, meter or military

MBOC

modified BOC

MCC

mission/master control center (EGNOS)

MCPS

million chips per second

MEDLL

multipath‐estimating delay‐lock loop

MEMS

microelectromechanical system(s)

MEO

medium Earth orbit

MS

mobile station (i.e. cell phone)

MMSE

minimum mean‐squared error (estimator)

MMT

multipath mitigation technology

MOPS

minimum operational performance standards

MSAS

MTSAT satellite‐based augmentation system (Japan)

MSB

most significant bit

MTSAT

multifunctional transport satellite (Japan)

MVDR

minimum variance distortionless response

MVUE

minimum‐variance unbiased estimator

MWG

momentum wheel gyroscope

NAS

National Airspace System

NAVSTAR

navigation system with time and ranging

NCO

numerically controlled oscillator

NED

north–east–down (coordinates)

NGS

National Geodetic Survey (USA)

NLES

navigation land Earth station(s) (EGNOS)

NPA

nonprecision approach

NSRS

National Spatial Reference System

NSTB

National Satellite Test Bed

OASIS

orbit analysis simulation software

OBAD

old but active data

OD

orbit determination

OPUS

online positioning user service (of NGS)

OS

open service (of Galileo)

PA

precision approach

PACF

performance assessment and checkout facility (EGNOS)

P‐code

precision code

PDF

probability density function

pdf

portable document format

PDI

pre‐detection integration

PDOP

position dilution of precision

PI

proportional and integral (controller)

PID

process input data (of WAAS) or proportional, integral, and differential (control)

PIGA

pendulous integrating gyroscopic accelerometer

PLL

phase‐lock loop

PLRS

position location and reporting system (US Army)

PN

pseudorandom noise

POR

pacific ocean region

PPS

precise positioning service or pulse(s) per second

PR

pseudorange

PRN

pseudorandom noise or pseudorandom number (=SVN for GPS)

PRS

public regulated service (of Galileo)

PSD

power spectral density

QZS

Quasi‐Zenith Satellite

QZSS

Quasi‐Zenith Satellite System

RAAN

right ascension of ascending node

RAG

receiver antenna gain (relative to isotropic)

RAIM

receiver autonomous integrity monitoring

RF

radiofrequency

RHCP

right‐hand circularly polarized

RIMS

ranging and integrity monitoring station(s) (EGNOS)

RINEX

receiver independent exchange format (for GPS data)

RLG

ring laser gyroscope

RM A

reliability, maintainability, availability

RMS

root‐mean‐squared or reference monitoring station

RNSS

radio navigation satellite services

RPY

roll–pitch–yaw (coordinates)

RTCA

radio technical commission for aeronautics

RTCM

radio technical commission for maritime service

RTOS

real‐time operating system

RVCG

rotational vibratory coriolis gyroscope

s

second

SAP

space adaptive processing

SAR

synthetic aperture radar, or search and rescue (Galileo service)

SARP

standards and recommended practices (Japan)

SARSAT

search and rescue satellite‐aided tracking

SAW

surface acoustic wave

SBAS

space‐based augmentation system

SBIRLEO

space‐based infrared low Earth orbit

SCOUT

scripps coordinate update tool

SCP

Satellite Correction Processing (of WAAS)

SDR

software defined radio

SF

scale factor

SI

system international (metric)

SIS

signal in space

SM

solar magnetic

SNAS

Satellite Navigation Augmentation System (China)

SNR

signal‐to‐noise ratio

SOL

safety of life service (of Galileo)

SPS

standard positioning service (GPS)

sps

symbols per second

SSBN

ship submersible ballistic nuclear (USA)

STAP

space–time adaptive processing

STF

signal task force (of Galileo)

SV

space vehicle

SVN

space vehicle number (= PRN for GPS)

SWR

standing wave ratio

TCS

Terrestrial Communications Subsystem (for WAAS)

TCXO

temperature‐compensated Xtal (crystal) oscillator

TDOA

time difference of arrival

TDOP

time dilution of precision

TEC

total electron content

TECU

total electron content units

3GPP

3rd generation partnership project

TLM

telemetry word

TMBOC

time‐multiplexed BOC

TOA

time of arrival

TOW

time of week

TTA

time to alarm

TTFF

time to first fix

UDRE

user differential range error

UERE

user‐equivalent range error

UKF

unscented Kalman filter

URE

user range error

USAF

United States Air Force

USN

United States Navy

UTC

universal time, coordinated (or coordinated universal time)

UTM

universal transverse mercator

VAL

vertical alert limit

VCG

vibratory coriolis gyroscope

VDOP

vertical dilution of precision

VHF

very high frequency (30–300 MHz)

VOR

VHF omnirange (radionavigation aid)

VRW

velocity random walk

WAAS

wide‐area augmentation system (USA)

WADGPS

wide‐area differential GPS

WGS

world geodetic system

WMS

wide‐area master station

WN

week number

WNT

WAAS network time

WRE

wide‐area reference equipment

WRS

wide‐area reference station

About the Companion Website

This book is accompanied by a companion website:

www.wiley.com/go/grewal/gnss

The website includes:

Solution Manual for Instructors only

MATLAB files for selected chapters

Appendices B and C

1Introduction

A book on navigation? Fine reading for a child of six!1

1.1 Navigation

During the European Age of Discovery, in the fifteenth to seventeenth centuries, the word navigation was synthesized from the Latin noun navis (ship) and the Latin verb stem agare (to do, drive, or lead) to designate the operation of a ship on a voyage from A to B – or the art thereof.

In this context, the word art is used in the sense of a skill, craft, method, or practice. The Greek word for it is τεχνυ, with which the Greek suffix ‐λoγια (the study thereof) gives us the word technology.

1.1.1 Navigation‐Related Technologies

In current engineering usage, the art of getting from A to B is commonly divided into three interrelated technologies:

Navigation

refers to the art of determining the current location of an object – usually a vehicle of some sort, which could be in space, in the air, on land, on or under the surface of a body of water, or underground. It could also be a comet, a projectile, a drill bit, or anything else we would like to locate and track. In modern usage, A and B may refer to the object's current and intended dynamic

state

, which can also include its velocity, attitude, or attitude rate relative to other objects. The practical implementation of navigation generally requires observations, measurements, or sensors to measure relevant variables, and methods of estimating the state of the object from the measured values.

Guidance

refers to the art of determining a suitable trajectory for getting the object to a desired

state

, which may include position, velocity, attitude, or attitude rate. What would be considered a “suitable” trajectory may involve such factors as cost, consumables and/or time required, risks involved, or constraints imposed by existing transportation corridors and geopolitical boundaries.

Control

refers to the art of determining what actions (e.g. applied forces or torques) may be required for getting the object to follow the desired trajectory.

These distinctions can become blurred – especially in applications when they share hardware and software. This has happened in missile guidance [1], where the focus is on getting to B, which may be implemented without requiring the intermediate locations. The distinctions are clearer in what is called “Global Positioning System (GPS) navigation” for highway vehicles:

Navigation

is implemented by the GPS receiver, which gives the user an estimate of the current location (A) of the vehicle.

Guidance

is implemented as

route planning

, which finds a route (trajectory) from A to the intended destination B, using the connecting road system and applying user‐specified measures of route suitability (e.g. travel distance or total time).

Control

is implemented as a sequence of requested driver actions to follow the planned route.

1.1.2 Navigation Modes

From time immemorial, we have had to solve the problem of getting from A to B, and many solution methods have evolved. Solutions are commonly grouped into five basic navigation modes, listed here in their approximate chronological order of discovery:

Pilotage

essentially relies on recognizing your surroundings to know where you are (A) and how you are oriented relative to where you want to be (B). It is older than human kind.

Celestial navigation

uses relevant angles between local vertical and celestial objects (e.g. the Sun, planets, moons, stars) with known directions to estimate orientation, and possibly location on the surface of the Earth. Some birds have been using celestial navigation in some form for millions of years. Because the Earth and these celestial objects are moving with respect to one another, accurate celestial navigation requires some method for estimating time. By the early eighteenth century, it was recognized that estimating longitude with comparable accuracy to that of latitude (around half a degree at that time) would require clocks accurate to a few minutes over long sea voyages. The requisite clock technology was not developed until the middle of the eighteenth century, by John Harrison (1693–1776). The development of atomic clocks in the twentieth century would also play a major role in the development of satellite‐based navigation.

Dead reckoning

relies on knowing where you started from, plus some form of heading information and some estimate of speed and elapsed time to determine the distance traveled. Heading may be determined from celestial observations or by using a magnetic compass. Dead reckoning is generally implemented by plotting lines connecting successive locations on a chart, a practice at least as old as the works of Claudius Ptolemy (∼85–168 CE).

Radio navigation

relies on radio‐frequency sources with known locations, suitable receiver technologies, signal structure at the transmitter, and signal availability at the receiver. Radio navigation technology using land‐fixed transmitters has been evolving for about a century. Radio navigation technologies using satellites began soon after the first artificial satellite was launched.

Inertial navigation

is much like an automated form of dead reckoning. It relies on knowing your initial position, velocity, and attitude, and thereafter measuring and integrating your accelerations and attitude rates to maintain an estimate of velocity, position, and attitude. Because it is self‐contained and does not rely on external sources, it has the potential for secure and stealthy navigation in military applications. However, the sensor accuracy requirements for these applications can be extremely demanding [

2

]. Adequate sensor technologies were not developed until the middle of the twentieth century, and early systems tended to be rather expensive.

These modes of navigation can be used in combination, as well. The subject of this book is a combination of the last two modes of navigation: global navigation satellite system (GNSS) as a form of radio navigation combined with inertial navigation. The key integration technology is Kalman filtering, which also played a major role in the development of both navigation modes.

The pace of technological innovation in navigation has been accelerating for decades. Over the last few decades, navigation accuracies improved dramatically and user costs have fallen by orders of magnitude. As a consequence, the number of marketable applications has been growing phenomenally. From the standpoint of navigation technology, we are living in interesting times.

1.2 GNSS Overview

Satellite navigation development began in 1957 with the work of William W. Guier (1926–2011) and George C. Weiffenbach (1921–2003) at the Applied Physics Laboratory of Johns Hopkins University [3], resulting in the US Navy Transit GNSS [4]. Transit became operational in the mid‐1960s, achieving navigational accuracies in the order of 200 m and remained operational until it was superseded by the US Air Force GPS 28 years later. The Transit navigation solution is based on the Doppler history of the received satellite signal as the satellite passed overhead from horizon to horizon – a period of about a quarter of an hour. The US Navy also developed the TIMATION (TIMe/navigATION) in the mid‐1960s to explore the performance of highly accurate space‐based clocks for precise satellite‐based positioning. While Transit and TIMATION were “carrier‐phase” only‐based systems, the US Air Force 621B experimental program validates the use of ranging codes for a global satellite‐based precision navigation system. These programs were instrumental in the concepts and techniques in the development of GPS as well as other satellite‐based GNSS that we know today.

Currently there are several GNSS in various stages of operation and development. This section provides a brief overview of these systems, where a more detailed discussion is given in Chapter 4.

1.2.1 GPS

The GPS is part of a satellite‐based navigation system developed by the US Department of Defense under its NAVSTAR satellite program [5–16].

1.2.1.1 GPS Orbits

The fully populated GPS constellation includes 31 active satellites with additional operational spares, in six operational planes. The satellites are in circular orbits with four or more satellites in each orbital plane. The orbital planes are each inclined at an angle of 55° relative to the equator and are separated from each other by multiples of 60° right ascension. Each satellite is in a medium Earth orbit (MEO), is nongeostationary, and is approximately circular, with radii of 26 560 km, with orbital period of one‐half sidereal day (≈11.967 hours). Four or more GPS satellites will always be visible from any point on the Earth's surface, where the GPS satellites can be used to determine an observer's position, velocity, and time (PVT) anywhere on the Earth's surface 24 h/d.

1.2.1.2 Legacy GPS Signals

Each GPS satellite carries a cesium and/or rubidium atomic clock (i.e. frequency reference oscillator) to provide timing information for the signals transmitted by the satellites. While each satellite carries several internal clock, all navigation signals are generated from one clock. Satellite clock corrections are provided to the users in the signals broadcast by each satellite, with the aid of the GPS Ground Control Segment. The legacy GPS satellite transmits two L‐band spread spectrum navigation signals on – an L1 signal with carrier frequency f1 = 1575.42 MHz and an L2 signal with carrier frequency f2 = 1227.6 MHz. These two frequencies are integral multiples f1 = 154f0 and f2 = 120f0 of a base frequency f0 = 10.23 MHz. The L1 signal from each satellite is binary phase‐shift keying (BPSK) modulated by two pseudorandom noise (PRN) codes in phase quadrature, designated as the C/A‐code and P(Y)‐code. The L2 signal from each satellite is BPSK modulated by only the P(Y)‐code. A brief description of the nature of these PRN codes follows, with greater detail given in Chapter 4.

Compensating for ionosphere propagation delays. The time delay from when a navigation signal is transmitted, to when the signal is received, is used to eventually estimate the distance between the satellite and the user. This signal propagation delay is affected by the atmosphere. As the signals pass through the ionosphere, the delay chances with frequency. This is one motivation for use of two different carrier signals, L1 and L2. Because delay through the ionosphere varies approximately as the inverse square of signal frequency f (delay ∝ f−2), the measurable differential delay between the two carrier frequencies can be used to compensate for the delay in each carrier (see Ref. [16] for details).

Code‐division multiplexing. Knowledge of the PRN codes allows users independent access to multiple GPS satellite signals on the same carrier frequency. The signal transmitted by a particular GPS signal can be selected by generating and matching, or correlating, the PRN code for that particular satellite. All PRN codes are known and are generated or stored in GPS satellite signal receivers. For legacy GPS there are two PRN codes transmitted from each satellite. The first PRN code from each GPS satellite, sometimes referred to as a precision code or P‐code, is a relatively long, fine‐grained code having an associated clock or chip rate of f0 = 10.23 MHz. A second PRN code from each GPS satellite, sometimes referred to as a clear or coarse acquisition code or C/A‐code, is intended to facilitate rapid satellite signal acquisition and handover to the P‐code. It is a relatively short, coarser‐grained code having an associated clock or chip rate of f0 = 1.023 MHz. The C/A‐code for any GPS satellite has a length of 1023 chips or time increments before it repeats. The full P‐code has a length of 259 days, during which each satellite transmits a unique portion of the full P‐code. The portion of P‐code used for a given GPS satellite has a length of precisely one week (seven days) before this code portion repeats. Accepted methods for generating the C/A‐code and P‐code were established by the satellite developer (Satellite Systems Division of Rockwell International Corporation) in 1991 [17].

Navigation signal. The GPS satellite bit stream includes navigational information on the ephemeris of the transmitting GPS satellite and an almanac for all GPS satellites, with parameters providing approximate corrections for ionospheric signal propagation delays suitable for single‐frequency receivers and for an offset time between satellite clock time and true GPS time. The legacy navigational information is transmitted at a rate of 50 baud. Further discussion of the GPS and techniques for obtaining position information from satellite signals can be found in chapter 4 of Ref. [18].

Precise positioning service(PPS). Formal, proprietary service PPS is the full‐accuracy, single‐receiver GPS positioning service provided to the United States and its allied military organizations and other selected agencies. This service includes access to the encrypted P(Y)‐code.

Standard positioning service(SPS). SPS provides GPS single‐receiver (stand‐alone) positioning service to any user on a continuous, worldwide basis. SPS is intended to provide access only to the C/A‐code and the L1 carrier.

1.2.1.3 Modernization of GPS

GPS IIF, GPS IIR–M, and GPS III provide the legacy and new modernized signals. These may include L2 civil (L2C) signal and the L5 signal (at 1176.45 MHz) modulated by a new code structure, as well as, the M and L1C codes. These modernized GPS signals improve the ionospheric delay calculation, ranging performance, ambiguity resolution, and overall PVT accuracy.

The GPS Ground Control Segment monitors the GPS signals in space, interfaces with the US Naval Observatory for timing information, and has remote monitor/uplink transmitter sites throughout the globe. Over the years, the GPS GCS has been upgraded and the Next‐Generation Operational Control System (OCX) will monitor all legacy and modernized GPS signals to provide for enhanced PVT solutions for the user segment. See Sections 4.2.8 and 10.5.5.5 and Ref. 18, Chapter 4.

1.2.2 Global Orbiting Navigation Satellite System (GLONASS)

A second system for global positioning is the Global Orbiting Navigation Satellite System (GLONASS), placed in orbit by the former Soviet Union and now operated and maintained by the Russian Republic [19,20].

1.2.2.1 GLONASS Orbits

GLONASS has 24 satellites, distributed approximately uniformly in three orbital planes (as opposed to six for GPS) of 8 satellites each. Each orbital plane has a nominal inclination of 64.8° relative to the equator, and the three orbital planes are separated from each other by multiples of 120° right ascension. GLONASS orbits have smaller radii than GPS orbits, about 25 510 km, and a satellite period of revolution of approximately 8/17 of a sidereal day.

1.2.2.2 GLONASS Signals

The legacy GLONASS system uses frequency‐division multiplexing of independent satellite signals. Each GLONASS satellite transmits two navigation signals in the L1 and L2 frequency bands, corresponding to f1 = (1.602 + 9k/16) GHz and f2 = (1.246 + 7k/16) GHz, where k = −7, −6, … 5, 6 is the satellite number. These frequencies lie in two bands at 1.598–1.605 GHz (L1) and 1.242–1.248 GHz (L2). The L1 code is modulated by a C/A‐code (chip rate = 0.511 MHz) and by a P‐code (chip rate = 5.11 MHz). The L2 code is presently modulated only by the P‐code. The GLONASS satellites also transmit navigational data at a rate of 50 baud. Because the satellite frequencies are distinguishable from each other, the P‐code and the C/A‐code are the same for each satellite. The methods for receiving and analyzing GLONASS signals are similar to the methods used for GPS signals. Further details can be found in the patent by Janky [21].

1.2.2.3 Modernized GLONASS

The first of next‐generation GLONASS‐K satellites was first launched on 26 February 2011 and continues to undergo flight tests. This satellite transmits the legacy FDMA (frequency division multiple access) GLONASS signals and a L3OC code‐division multiple access (CDMA) signal at a frequency of 1202 MHz. Other GLONASS CDMA signals are under development within the legacy L1 (L1OC signal) and L2 (L2OC signal) bands.

1.2.3 Galileo

The Galileo system is satellite‐based navigation system currently under development by the European Union (EU). This development has completed definition and development phases and is nearly complete with launching operational satellites to achieve a 30 satellite constellation. Galileo operates in the L‐band with MEO satellites at height slightly above the GPS MEO satellites (23 222 km for Galileo versus 20 180 km for GPS). Galileo satellites operate in three orbital planes at an inclination angle similar to GPS. Galileo operates in three spectral bands known as E1 (1559–1592 MHz), E5 (1164–1215 MHz), and E6 (1260–1300 MHz).

1.2.3.1 Galileo Navigation Services

The EU intends the Galileo system to provide various levels of services.

Open service(OS). The OS provides signals for positioning and timing, is free of direct user charge, and is accessible to any user equipped with a suitable receiver, with no authorization required. The OS provides dual‐frequency operation in the L1/E1 and L5/E5 frequency bands. The Galileo E1 L1C signal centered at 1575.42 MHz is compatible with the modernized GPS L1C signal transmitted by GPS III satellites. The Galileo E5a signal at 1176.45 MHz is part of a combined AltBOC signal. Modernized GNSS receiver equipment may use a combination of Galileo and GPS signals, thereby improving performance in severe environments such as urban canyons and heavy vegetation.

Commercial service(CS). The CS service is intended for applications requiring performance higher than that offered by the OS. Users of this service pay a fee for the added value. CS is implemented by adding two additional signals to the OS signal suite. The additional signals are protected by commercial encryption, and access protection keys are used in the receiver to decrypt the signals. Typical value‐added services include service guarantees, precise timing, multifrequency ionospheric delay measurements, local differential correction signals for very high‐accuracy positioning applications, and other specialized requirements. These services will be developed by service providers, which will buy the right to use the multifrequency commercial signals from the Galileo operator.

Public regulated service(PRS)