Avionics News - September 2023 - 24

HOW BRAD PARKINSON SAVED GPS
Continued from page 23
On Parkinson's first combat mission, the mission
commander (Major Ron Terry) was standing next to him.
The major had logged hundreds of gunship combat missions,
looked tense and for good reason. The North Vietnamese
had set a trap on the Ho Chi Minh trail with stationary trucks
left with engines running. The lethal part of the trap was 57
mm anti-aircraft guns that had been dragged into position on
surrounding mountains. All of the big AAA guns were firing
at Parkinson's AC-130.
Major Terry ignored Air Force guidance for gunships to
not duel with AAA sites and knocked them all out as well as
the idling trucks in the valley below. Their aircraft returned
to base safely. These gunship combat experiences gave
Parkinson a " visceral, personal understanding of the value of
precision weapons delivery. "
While Parkinson pursued his Air Force career, ideas
and developments in the world of military navigation were
percolating behind the scenes to create his future job and his
rendezvous with destiny. Dr Ivan Getting, president of the
Aerospace Corporation, sold the Air Force on the need for
a new satellite-based navigation system. It would provide
positioning in 4D (latitude/longitude/altitude/time) 24/7/365.
Getting had designed a microwave tracking system near the
end of World War II that allowed allied AAA batteries to
shoot down German V-1 flying bombs aimed at London.
Getting's persistent advocacy of a new satellite navigation
system spurred the Air Force to study alternatives under a
program later named 621B. At the Aerospace Corporation,
space system engineers James Woodford and Hideyoshi
Nakamura studied alternative systems. The most capable
alternative they found used four satellites for passive ranging
and would have atomic clocks on the spacecraft. This did not
require an atomic clock on user equipment.
Between 1966 and 1972, more than 90 U.S. Air Force
and Aerospace Corporation studies had examined this
opportunity. Doctors Fran Natali and Jim Spilker of PhilcoFord
and Dr. Charlie Cahn of Magnavox synthesized the best
passive ranging technique for the ranging signal. It was called
Code Division Multiple Access. CDMA is also called spread
spectrum because the energy of the signal is spread over a
wide range of radio frequencies.
By late 1972, Parkinson had graduated from the Naval War
College and was the director of engineering for the Advanced
Ballistic Reentry Systems Program at the Space and Missile
Systems Organization. Also, at SAMSO, the 621B satellitebased
navigation program was floundering, with inadequate
support in the Pentagon.
In November, Parkinson's boss, the SAMSO commander,
24 avionics news * september 2023
Lt. Gen. Kenneth Schultz, asked if he wanted to transfer
to the 621B program. Parkinson said only if he could be in
control of the project, something Shultz said he couldn't
promise. Parkinson said he therefore would not volunteer, but,
as he left Schultz's office, the general was already directing
his reassignment. Parkinson was pleased to discover soon
after that he was firmly in charge of the struggling program,
and the issue never came up again. Parkinson, then 37, was
one of the youngest colonels in the Air Force.
At that point, the USAF's 621B was locked in a death
struggle with the Naval Research Lab on the design for a
new satellite navigation system. Military consensus was that
neither program would gain approval.
A Pentagon committee was formed to study alternatives,
but Parkinson as the new program manager had no respect
for this particular group. His skill at navigating bureaucracies
would be tested immediately by what country singer Kenny
Rogers once sang, " You got to know when to hold' em, know
when to fold 'em, know when to walk away, and know when
to run. " He ignored the blathering of the committee. But he
also knew there were more than a few wolves in the senior
ranks roaming the halls of the Pentagon who could kill his
fledgling program.
One reason he was able to ignore the committee was
because he had protection from a high-level Pentagon official
who became the " Godfather of GPS. " Parkinson said every
innovative program, like the one that became GPS, needs
such a champion to make it to the finish line in the Pentagon
acquisition process. But how did he gain the support of this
powerful person?
Luck. About four months after reassignment to 621B,
Parkinson was tapped to spend an afternoon briefing the
No. 3 Pentagon official, Malcom Currie, undersecretary of
research and engineering for the Department of Defense.
Dr. Currie, who had previously led all space programs for
the Hughes Aircraft aerospace company, flew each week
between Washington, D.C., and Los Angeles. General Schultz
had run out of subjects to present to Currie, so he sent him
to Parkinson's office. The subsequent 2 ½-hour discussion
took place in Parkinson's small 9-by-12-foot office, with no
one else present. Discussion was lively and technically deep.
Later, Parkinson heard that Currie was quoted by someone at
the Pentagon saying GPS was now his favorite program.
The death struggle: NRL wanted a two-dimensional
system, and Parkinson and the Air Force wanted three
dimensions plus time. The NRL patent called for atomic
clocks in the user equipment, which would have made them
prohibitively expensive. Parkinson and the Air Force wanted
atomic clocks on the satellites instead, which would greatly
Continued on page 26
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