There Exists a US Program to Identify, Geolocate, and Mitigate Sources of GPS

Interference

But are we serious?

Terry McGurn/Consultant

Presented to the SoCal ION Chapter

Meeting of 14 September 2010

Background & Motivation

• Motivation: Fact Sheet of NSPD-39, Dec 2004– Maintain Continuity of GPS service in an

interference environment– Deny hostile exploitation of this service.

• NSPD-39 Actions (From Fact Sheet)– Establish a PNT EXCOM to address these issues,

among others– Establish the EXCOM Advisory Board– Establish Agency Roles

CONCLUSIONS

• Language of the NSPD-39 Fact Sheet is vague.

• Open to Various Interpretations of Assignments.

• NSPD-39 Muddies the Issues (friendly protection & hostile denial).

• The Program may be Headed in the Wrong Direction.

• But I believe we can get back on track.

The Bottom Line• No one tasked to develop sensors and

array them to detect and geolocate interferers.

• The Fact sheet seems to reflect a belief that we have assets in place, and the task is primarily to coordinate these assets.

• There are assets available that could be netted to support the program, but these are only mentioned in passing.

DHS: The Action Agency• DHS has taken action on this program.

– DHS developed an IDM paper to address this issue, published in 2007.

– DHS/CIP group, as part of a periodic review, also addressed this issue.

– The DHS persons specifically tasked to implement a response to this program, and their contractors, have been very forthcoming on their program.

BUT• The several high level appointees in the

responsible DHS body for this program were (in late 2009) not yet in place.

• I believe the present DHS approach may be putting the cart before the horse. (i.e., developing a “data repository” before developing the sensors that will provide the “reposing” data.)

• In fact, the sensors should dictate the degree of processing to be done at the repository vice in the field.

So: What Can We Do Now?

• DHS should address the pieces of the issue. The “one size fits all threats” approach not practical.

• Unintentional interference, intentional jamming, spoofing, are different problems.

• But (at present) unintentional jamming is the most frequent source of signal loss.

Examples of Unintentional Jamming

• Rome ADC (3 days/5 watts/ several hundred kilometers)

• St. Louis Airport (1990s)• Butte, Montana (? days, spurious harmonics)• Monterey Bay (2001) Many months/ VHF/UHF

TV antenna radiating above the L-band noise floor)

• Mesa, Arizona (2 days before reporting, traffic steered into incoming. Interference operated for 4.5 days before shutdown.

• Puerto Rico FAA Facility (? days, INMARSAT) • San Diego navy Test Center (4 hrs, 500 mw)

DGPS SiteInoperative

2 Hours

AIS Display ConsoleAnomaly

Cell Provider Network150 sites detected error

2 sites inoperative

Medical Services Paging Provider Network

Inoperative

1.5 Hours – 20 sites

General AviationPilot Report GPS

Malfunction

Potential for First Responder Impacts

Interference Case Study

SoLet’s develop a capability to minimize the occurrence of unintentional jamming? You don’t get partial credit if you lose a critical function unintentionally.

So

• Let’s develop a capability to minimize the occurrence of unintentional jamming.

• You don’t get partial credit if you lose a critical function unintentionally.

• Situational awareness?

Recommendations• Define Specific Responsibilities for the

Various Components of the Network. (An EXCOM role?)

• Suggest Several Small Funded Efforts. (Requires more selective expertise/less PPT.)

• Responsible Dept/Agency should have System Engineering Support.

• Let’s Get a Significant Start. First Address

the Unintentional Jamming Issue.

Introduction - Typical digital GNSS receiver block diagram

RF

Antenna

LOs

Digital IF

Analog IF

N2

Regulated DC power

Unregulated input power

Navigation processing

User interface

Power supply

Receiver processing

AGC

Frequency synthesizer

Reference oscillator

1 Digital receiver

channel

A/D converter

Down converter

Pre amp

RF front end

Introduction - GNSS receiver front end with Digital Gain Control

ADC

Digital Gain

Control

Analog IF

J/N Meter

Digital IF

DownConverter

Antenna

PreampDigital

Attenuator

Gain Controlled Analog IF

Final Thoughts

• Mitigation:– Where possible, geolocate and prosecute– Otherwise:

• Back-up Systems– Inertial (short term only. Present inertial trends

are for poorer performance, low-cost systems.– Loran e: Provides high availability, good anti

jam, and good timing performance (sigma about 30 nsec).

– Smart receivers, for situational awareness.– Land-line for time?

Final Thoughts (Continued)

• “When everyone’s in charge, no one’s in charge”. (Relevance to Fact Sheet)

(A retired Russian Colonel, in discussing the problems in the GLONASS program)

• Give a clear charter to DHS/(DOT?) This problem is:– Hard– Challenging– Fun