GPS - GPS World: GPS Insights -- January 2008

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GPS World: GPS Insights -- January 2008

Sam Wormley

2008-01-23, 10:33 pm

GPS Insights -- January 2008
The real hook is the historical context and the revelations of the mysterious influences that drove the workings of the
"inner sanctum." The inventions and breakthroughs that came just in time are incredible. Each and every one was a piece
of the puzzle that has become the GPS we enjoy today.

http://mg.gpsworld.com/gpsmg/conten...p.jsp?id=486315

Jan 23, 2008
By:Don Jewell
GPS World

A Review of "Global Positioning System -- Systems Engineering Case
Study"

When was the last time you sat down in your favorite chair, in a nice
quiet room with a warming fire in the fireplace and the snow falling
gently outside, to read your favorite government report? I mean, when
no one was holding a gun to your head? I can hear your responses now
(with the expletives deleted).

Seriously, according to interviews in the Wall Street Journal,
luminaries such as Milton Friedman and Alan Greenspan did/do this,
respectively, on a regular basis. But I must admit it was not something
I anticipated doing (or enjoying), until this GPS case study was
released recently. Don't get me wrong, the title and the first few
pages of this historical case study are as you might expect: barely
modified boilerplate, bureaucratic and really somewhat boring, and like
a great many historical government masterpieces (was that an oxymoron?)
you have to wait and wait for the hook.

Almost immediately, I found myself taking issue with the caveat that
appears on the majority of such studies, because it reads: "The views
expressed in this Case Study are those of the author(s) and do not
reflect the official policy or position of the United States Air Force,
the Department of Defense, or the United States Government."

Fortunately for us, that lawyer-inspired insertion doesn't hold water
in this case, because this study accurately reflects what the
prevailing views and policies of the U.S. government were at the time,
when the GPS system we know and love today was in its infancy. So
ignore the admonition this time, because the authors have got it mostly
correct -- or as correct as possible while still having the
document appear in the public domain.

If you care at all about the history of modern navigation, or the
history of time, or about GPS in general, you will find this report an
interesting read. I won't say I couldn't put it down, but I did read it
cover-to-cover in one sitting. And now I hear you saying, sure, that's
your job -- but in truth I have the latitude, thanks to a great
editor, to write about any endeavor as long as it somehow ties into
GPS, and preferably government and military users. This GPS case study
accomplishes that in spades.

Yes, it is a government report, but it is riveting in certain places,
and funny in others (and downright boring in some sections that can be
easily skipped). It has its dry moments, but the insight it grants into
how GPS came about is really extraordinary, and unprecedented for a
government report from that repository of literary thrillers, the Air
Force Institute of Technology (AFIT). (Just be happy it's not a
doctoral thesis, which is the normal output of this aerospace venue of
higher learning for frustrated engineers and would-be Norman Mailers.)
So, my hat's off to AFIT, and all those who worked so hard to publish
this seminal masterpiece of navigational history as it relates to GPS.

One obstacle you can't get around or over is the title: "Global
Positioning System -- Systems Engineering Case Study." Not exactly
riveting. Truthfully, if I have to read a government publication I
would prefer it to be a case study, because I usually learn something.
In this case study, if the authors had dug just a little deeper into
the history of GPS, they might have titled this study something like
"Lighthouses In the Sky -- A GPS Case Study." There's a title you
can sink your teeth into, and it piques your interest because it makes
you immediately wonder, "Why 'Lighthouses In The Sky'?"

Why? Because if you dig deep into the history of NAVSTAR GPS, you will
learn that there are at least five well-known and prestigious
individuals throughout the years who have claimed, or had it claimed
for them, that they were the "Father of GPS" -- which is, of
course, the mother of all navigation systems today -- and several
of them used this phrase to describe what has become that ubiquitous
global utility we all know as GPS.

It was not always that way, however. As the case study points out, the
NAVSTAR GPS of the 70s, 80s, and first half of the 90s was a
military-only system; it is not evident that anyone in the 70s had the
slightest premonition of what the GPS was to become, or of the
importance it holds in our global society today. As far as I can tell
there was never a business case or a cost-benefit analysis for civilian
use.

Certainly no one looked into their crystal ball -- not even Dr.
Ivan Getting, one of the five "fathers" -- and said, "In the
future, nine out of ten of the world's GPS users will use this PNT
(position, navigation, and timing) system to determine time." That's
right, 90% of the global users of GPS today use it because of the
extremely accurate and reliable timing signal, not for position
accuracy or navigation. Surprised?

But back to the specifics of this case study: It is conveniently broken
down into major sections, with the appropriate subsections that are
required in a normal case study. Nowadays it seems that acquisition
case studies all fall under the moniker of "Friedman-Sage," which
simply refers to the two authors who developed the case study format
and not necessarily, as you might think, to the veracity or wisdom of
the system itself. (Although I do have to admit that in this case, it
works quite well.)

For me, the insights into the establishment of the first GPS JPO (Joint
Program Office), headed by its first director, Bradford Parkinson
-- a doctor, Stanford physics professor, USAF colonel, and old and
esteemed friend of mine -- are worth the read. Brad and his
nefarious minions are mentioned no less than 43 times in this case
study; the number should probably be 143, but fortunately we can all
read between the lines.

Colonel Parkinson and his immediate staff -- which was unbelievably
joint in nature, a true portent of things to come -- carried the
future of the GPS program on their broad shoulders as they trolled the
corridors of the Pentagon and the then-hallowed halls of Congress
casting about for support, funding, and sometimes, anyone who would
listen. The perspicacity and perseverance of Colonel Parkinson and his
staff are now legendary to those who know the "rest of the story" and
in truth, that story is merely hinted at in this case study, but
hopefully it will be enough to make you want to know more.

The case study is primarily about systems engineering, and is broken
down into individual segments labeled Learning Principles that
encompass the critical aspects of systems engineering and lead us into
an explanation of how this originally military-only navigation system
became a truly global system of systems.

For the systems engineers among you, this engineering section of the
case study will undoubtedly be a rollicking good read, but for myself
and (I hope) others, the real hook is the historical context and the
revelations of the mysterious influences that drove the workings of the
"inner sanctum." The inventions and breakthroughs that came just in
time are incredible. Each and every one was a piece of the puzzle that
has become the GPS we enjoy today.

There are also historical tidbits like this one:

"The genesis of GPS occurred soon after the Russians launched Sputnik
on October 4, 1957. While the satellite circled the Earth broadcasting
its tone, an engineer at the Applied Physics Laboratory at Johns
Hopkins University postulated that he could use the Doppler effect from
an orbiting satellite to actually compute where something was located
on the Earth. The Navy and the Air Force established separate programs
to satisfy their unique service needs. Under these programs, key
technologies such as precise atomic clocks, quartz oscillators, spread
spectrum signals, precise ephemeris, tracking and prediction, and
reliable space systems were developed and demonstrated."

Who knew that the Russian launch of Sputnik in 1957 caused a scientist
at John Hopkins Applied Physics Laboratory to think of using the
Doppler effect for position determination or rudimentary navigation? A
true history buff would answer that by saying, since Sputnik was the
first object ever launched into Earth orbit, it spawned a great many
other firsts, such as the United States' response to Sputnik with
Explorer One just a few months later on January 31, 1958. The Space
Race was on, and fortunately someone was again thinking about
"lighthouses in the sky."

As far as I can determine, that phrase was first coined (or used in
print, anyway) by author and navigational educator extraordinaire
Captain George Mixter (USNR), known to many of us who used his textbook
Primer of Navigation, which was originally written in 1943 and is now
in its seventh edition. Mixter frequently used the phrase "lighthouses
in the sky," referring to stars for celestial navigation. But the term
was adopted by two other luminaries of that time, Dr. Ivan Getting and
Dr. James Schlesinger. Getting, and this phrase, were honored with a
plaque attached to the recently launched 50th GPS satellite. The
tribute reads:

Lighthouses In The Sky
Serving All Mankind
Dr. Ivan Getting
1912-2003

All of us that knew and respected Getting wish that he could have
lived to see his tribute, but these accolades are all too often
accomplished posthumously. And it is certainly interesting, and
probably not coincidental, that this case study was released and the
50th GPS launch occurred at about the same point in time.

Coincidences aside, the historical documentation (and certainly the
really fascinating part of this report) does not appear until page
85. The report is 139 pages long, minus the executive summary, and
the last 54 pages are an unprecedented and unpretentious look at the
documentation that brought GPS into being. For example, a look at the
initial Requirements Document, which for today's GPS payload is
several hundred pages in length, reveals that the initial
requirements for GPS were built around two main goals, one of which
was very much an effects-based requirement (have you heard that
phrase recently?) and the other was economics-based. In short they
were, according to Dr. Bradford Parkinson, "to put five bombs in the
same hole, one after another, in rapid succession and to develop user
equipment that cost less than $10,000 per unit."

As I considered these goals/requirements drivers, several thoughts
came to mind. Of course "five bombs in the same hole" transports me
back to World War II and the bunker buster technologies they sought
so desperately to develop, but at the same time it equates well with
today's requirements for that bunker buster technology and the
effects-based results that compose our current metric for the success
of a new weapons system.

As for the $10,000 receiver, the report correctly points out that you
can buy a commercial receiver today for less than $100, while our
less-capable, but hardened military receivers that, grant you, do
have special properties, are still in the $1,000 range; a 90%
decrease in price in 30 years is not bad in the scheme of things
electronic.

I revealed what drove the requirements, but the actual GPS System
Performance Requirements were expressed like this:

Table 1. Expected GPS System Performance Requirements
See: http://mg.gpsworld.com/gpsmg/conten...p.jsp?id=486315

To put the parameters in historical context, the goals and
requirements were certainly admirable for their time, especially when
you consider that the driving force for en route position and weapons
accuracy for the USAF resided in the Strategic Air Command at the
time, and for navigation was one mile left or right of centerline
within a corridor that stretched five miles left or right for a total
corridor ten miles wide. In CONUS (the Continental United States)
this was usually accomplished with ground-based navigation aides, but
over water it was accomplished with a sextant and a compass. And if
you coasted in to your ADIZ (Air Defense Identification Zone) for
your destination only four miles right or left of centerline, you
were considered an expert navigator indeed. So, while an en route
position accuracy of 5-30 meters seems incredibly large to us today,
it was hard to even comprehend in the mid-70s.

Remember that inertial systems were at best good for drift rates of
1nm (nautical miles) per hour, so on an over-water flight of eight
hours you could easily bust your navigation corridor and be the
subject of an unwelcome fighter escort unless you also used that
eternal standby, celestial navigation, your old friend, those
naturally occurring lighthouses in the sky. With the advent of GPS
theory there was promise of new manmade lighthouses that promised an
unheard-of accuracy. And it was all accomplished by clocks in the
heavens. All you really needed to know to solve the problem of where
you were located was an assembly of extremely accurate celestial
clocks, in this case atomic clocks.

Think of the mariners of old, that had been using sextants and other
methods for centuries to determine latitude and a crude magnetic
compass for heading information, but what they really needed was
simply a reasonably accurate clock that worked on board a pitching
and careening ship in the middle of the ocean to determine longitude.
Weights and pendulums do not work well in rough seas. For the ancient
mariners an accurate clock solved the longitude problem, increased
the accuracy of the latitude calculation and added precision to many
of the calculations related to velocity, just as it did for us in the
1970s. But I will stop here, because I don't want to spoil the ending
for you.

So, is this one government case study that you should read from cover
to cover? I obviously believe it is, but don't be too concerned
because truth be told it is actually only a 139-page synopsis to whet
your appetite for more. In truth it could be (and probably should be)
1,139 pages long, but then, it is only a case study. My hope it that
it will inspire you to learn more about the miraculous "lighthouses
in the sky" that impact our lives in incredible and unforeseen ways
every day. Indeed, you can view this as only the first chapter in an
historical novel that remains to be finished. Read it today at these
two AFIT Websites.

http://www.afit.edu/p/news.cfm?AFITID=233

http://www.afit.edu/cse/cases.cfm?case=13&a=detail

Mark F

2008-01-25, 10:33 am

In the mid 80s, an IEEE sponsored conference on sat nav and comms
highlighted ETAK and others' displays of prototype automotive
systems similar to those in wide use today, which suggests that
there were a lot of forward thinking folks spending money on
the future of civilian GPS from about '80 onward....

I recall being laughed out of a late 80s planning session
for proposing that GPS signals be used for real-time synchronization
of signals from geographically separated radio paging transmitters.
I take no joy from the company's subsequent demise.... /mark

Sam Wormley wrote:

> It was not always that way, however. As the case study points out, the
> NAVSTAR GPS of the 70s, 80s, and first half of the 90s was a
> military-only system; it is not evident that anyone in the 70s had the
> slightest premonition of what the GPS was to become, or of the
> importance it holds in our global society today. As far as I can tell
> there was never a business case or a cost-benefit analysis for civilian
> use.
>
> Certainly no one looked into their crystal ball -- not even Dr.
> Ivan Getting, one of the five "fathers" -- and said, "In the
> future, nine out of ten of the world's GPS users will use this PNT
> (position, navigation, and timing) system to determine time." That's
> right, 90% of the global users of GPS today use it because of the
> extremely accurate and reliable timing signal, not for position
> accuracy or navigation. Surprised?
>

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