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Looking Ahead for GPtS ---

Bradford ParkinsonEmeritus ProfessorStanford University

Department of Aeronautics and Astronautics

With New Satellite Systems: The promise of Many Signals

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GPS L1 C/AOnly Fully

Operational World-wideCivil Signal

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Q: What must we do to insurethat the Trust in GPtS

is not misplaced?

A: We should address Three Issues:

– Sustainment

– Robustness

– Interchangeability

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GPtS Issue #1 – (Sustainment ) Constellation Availability

• Average GPS on-orbit life 9.4 years (Max is 19.8 yrs.)

• First IIF launched: May 2010 (when do we see next 11?)

• First GPS III (First “All-signal” GPS) currently available for Operations - August 2015

• When will Galileo be “certifiable”?

• Will GLONASS or Compass be completely available?

Needed: Sustained, high-level support for -

• Earliest GPS III delivery and availability

• Development of Low-cost version of

All-signal GPS only Satellite (GPS-IIIS)

• Insisting on dual GPS launch (Triple ?)

It is imperative the we avoid “GPtS Brownouts”

Is the Interference Problem Significant?

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– Fri Sep 3, 3:01 am ET

A (US) federal court recently validated the police's right to

attach GPS tracking devices to vehicles without a warrant.

Portable GPS supplier Chinavasion says people who

value their privacy need GPS Jammers.Unit

Price: $33.00

Handheld GPS Jammer GJ02

GPS L1 - 1575.42MHzOutput power: 0.5 Watt

y_newsprweb/201/article/y_narticle1orion166dfeRGnszm60en-USus

Nibbling at the GNSS Interference Problem

• Signal Power Solutions– GPS satellite increased Power

(GPS-III L5 >-157dBW on two channels)

– Pseudolites (local only/Near-Far/Jammer?)

• Receiver Solutions– Beam antennas (gain and rejection)

– Processing Gain (Use of codeless channel)

– Integration with MEMS/INS(Coasting and extending averaging time)

– Integration with CSAC (coasting and extending averaging time)

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Nibbling at the GNSS Interference Problem (2)

• Signal Frequency Diversity– Use of all “certified” Phase-Locked GNSS signals

– “Vector” receivers – all signals single filter

– Use communication signals of opportunity

• Back-up Solution– eLoran recommended at National Level/ DME for FAA?

• Regulation – DHS and FCC (little help to date)

– Detect/Locate interference (Cell Phones – 911GPS ?)

– Shut down Interference

– Prosecute Interferers

– Stop Internet sales of Jammers

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Summarizing: GPtS Issue #2 –GPS Robustness (Deterrence?)

• Affordable GPS Receiver Interference Rejection Technology

• Locating/Mitigating/Eliminating Interference and Prosecuting Offenders

• GPS Backup – eLoran or Residual DME?

Needs positive decisions/funding

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Levels of Cooperation - New Systems:Can’t we just get along?

• Degrees of “Getting Along”– Compatible

• Lets not hurt each other

– Interoperable• I’ll try yours, you can try mine

– Interchangeable• Any four will do

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GPtS Issue #3 –GPS and Galileo-Interchangeability: “Mix and Match”

Prerequisites:

– L1C (the new international signal) defined, implemented,

demonstrated and operable – including all details

– Seamless WAAS/EGNOS/+ ?

– True clock Synchronization (Common Clock) and

common grid

• Payoff – Availability, Accuracy and Robustness

for Worldwide Users

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Summary : What must we do to insure that the

Trust in GPtS is not misplaced?

Ans: Address the ThreeIssues:

• Sustainment• Robustness• Interchangeability

•Backups

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GLONASS –(Russia)

Galileo(European)

GPS(USA)

QZSS(Japan)

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• Delayed• Cost Challenges

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Compass (Beidou China)

• Moving Ahead• Technical Details not

clear

• Many Very Old Satellites

• IIF very Late• III ahead of schedule

but 1st launches 2014, 2015

• Delayed• Working Longevity

We may be Facing Availability Challenges