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precision farming.
HSOAC’s research determined that other sectors and applications are also willing to pay for
increased precision, such as surveying, construction, shipping
(containerized), and location7 The user-needs analysis (PNT data) is
attached as Appendix C of this report.
9
based services. Not surprising, these were some of the same industries RTI International assessed
to have the highest economic impacts from a GPS outage.
Provisioning Position and Navigation Services
Table 5 depicts real-time position and navigation solutions submitted by industry during the RFI
process compared to examples of application-specific precision requirements. Additional
comparisons are contained in HSOAC’s report submitted to DHS.
Table 5*
Real-Time Precision Requirement Examples with Bounded Precision
Solutions
Precision
Agriculture/
Construction
Port
Operations
(Automated
containers)
Consumer
LBS
Over the
Road
Navigation
Open
Water
Navigation
Open
Water
Navigation
<10cm =10cm–< 1m 1–< 5m = 5–10m 10–20m >20m
GPS (Aug) Meets Precision Meets Precision Meets Precision Meets Precision
Meets Precision Meets Precision
GPS (UnAug) Not close to req. precision Not close to req. precision Not
close to req. precision Meets Precision Meets Precision Meets Precision
eLORAN Not close to req. precision Not close to req. precision Not close to req. precision Not close to req. precision Not close to req. precision Meets Precision
STL Not close to req. precision Not close to req. precision Not close to
req. precision Not close to req. precision Not close to req. precision Meets Precision
NextNav Not close to req. precision Not close to req. precision Meets
Precision Meets Precision Meets Precision Meets Precision
Locata Meets Precision Meets Precision Meets Precision Meets Precision Meets Precision Meets Precision
Meets Precision Precision within factor of 5 Not close to req. precision *System performance parameters are as reported by the submitter and have not been validated by the
government. Actual system performance must be assessed as part of any acquisition effort.
As mentioned earlier, GPS alone cannot meet many of the precision position
and navigation
requirements without augmentation. Generally, any precision requirement
below 5m will require
some form of augmentation (this may change soon with dual frequency, carrier phase-based
GNSS chips). As Table 5 depicts, only two systems can meet this requirement, but only in the
areas they are deployed. Even if the backup requirements are expanded to the
5m that GPS can
provide, it will not expand the available backup options or significantly reduce risk. While some
position and navigation systems can outperform GPS, they are localized applications and face
challenges scaling to a national or regional level (see Table 3).
Industries adopt high-precision position and navigation services only when there is a business
case to do so. However, even within industries heavily dependent on
precision position and
navigation, not all users will adopt precision applications due to the increased cost. For example,
a farm would need to be sufficiently large to offset the cost of equipment
and fees associated
with precision farming. A 2014 U.S. Department of Agriculture report
estimated that 70 percent
of U.S. farms were under 197 acres.8 HSOAC assessed that a farm would need
to have a
minimum acreage between 200 and 2,100 acres to justify the expense
associated with precision
8 United States Department of Agriculture, National Agricultural Statistics Service, Farms and Farmland, Census of
Agriculture Highlights (Washington, D.C.: United States Department of Agriculture, 2014).
10
farming.9
Consequently, it is not cost effective for 70 percent of U.S. farms to
adopt precision
farming. This highlights the price sensitivity associated with the adoption
of additional position
and navigation systems.
Understanding the Augmentation Market Space
By whatever means funded, all augmentation systems require interested
investors or sponsors. In
the public sector, per NSPD-39, agencies requiring augmentations to GPS are required to fund
the augmentation in their budgets. In the private sector, companies have developed, and continue
to develop, capabilities to deliver high-accuracy position and navigation services through GPS
augmentation or other means. These services are sold to industries who are willing to pay for this
level of accuracy. If the U.S. Government were to provide a free backup and complementary
system, similar to the free utility of GPS, the government would have to consider the
repercussions of such a system in the marketplace. A free government system would negatively
impact commercially available PNT systems by directly competing with them.
V. Backup Considerations
Up to this point, this report has detailed PNT accuracy and precision requirements and the
systems that can deliver PNT to meet those requirements, relying primarily
on HSOAC’s
research. To assist with an analysis of alternatives on viable backup system(s), HSOAC
delineated the risks that critical infrastructure users are attempting to mitigate and analyzed how
a backup impacts said risks. DHS frames this risk in three general
scenarios. This unclassified
report will not discuss potential causes, only the effects on GPS and GNSS availability.
• Scenario 1: Signals in the GPS band are unavailable or unreliable due to spectrum
interference (jamming or spoofing) within the United States. This
interference is limited
in geographic area and duration.
• Scenario 2: GPS and GNSS systems are unavailable nationwide due to events such as a
geomagnetic disturbance. GPS and GNSS are expected to return to normal operations
within days.
• Scenario 3: GPS signals are no longer available, and restoration of
services cannot be
determined.
Temporary Disruptions
Though the U.S. Government provides GPS for free, this does not remove the obligation of the
end user to plan for its short-term disruption. Since no utility is
perfectly reliable, users plan
appropriately, implementing backups and contingency plans to assure
continuity of business. In
the case of electricity during major disasters such as hurricanes, critical functions continue
despite power outages because users made appropriate contingency plans and
are able to use
alternate power sources until mainline power is restored. In the first two scenarios critical
9 Richard Mason et al., Analyzing a More Resilient National Positioning, Navigation, and Timing (PNT) Capability
(Washington, D.C.: Homeland Security Operational Analysis Center, 2019).
11
infrastructure users can use this traditional utility disruption mitigation approach—resorting to
local power backups.
Planning for temporary disruptions can vary depending on the nature of the function. At one end
of the spectrum, there are safety-of-life applications that require
significant investment to enable
graceful degradation and maintenance of an acceptable level of performance. Returning to the
electricity example, hospitals invest significant resources ensuring backup power sources are
available and maintained. On the other end of the spectrum, there are applications that will
simply be deferred until signals are available, similar to retailers being unable to serve patrons
until power is restored.
Long-Term Disruptions
The unique nature of GNSS systems requires the United States Government to consider a
scenario where GPS and other GNSS are no longer available. Addressing this issue requires an
entirely different approach to backup capabilities. Returning to the electricity model, end users
assume that electricity will eventually be restored and delivered in the
same format as before the
disruption (direct current). Users do not plan for a backup delivery system which would
necessitate not only the construction of a new distribution model, but the replacement or
modification of all end user equipment. In contrast, should GNSS become unavailable and
critical infrastructure be required to move to an alternate PNT source, it would not only likely
require a new delivery system, but also widespread adoption of the alternate system’s end user
equipment, such as the procurement of upgraded receivers and antennae that would receive a
signal other than GNSS.
If the Federal Government plans to require backup capabilities for a sudden, long-term disruption
to GPS, the concept for a backup must change. If the Nation is to react to
such an event, then
there must not only be a distribution system in place, but also the end user equipment. If either
the delivery method or the ability to receive the PNT data is unavailable,
the system will not
work. Moving users to this model will be challenging. There are three ways
to influence user
willingness to adopt alternate systems:
1. Availability of a PNT service that is at least as economically or operationally beneficial
as GPS.
2. Require (through regulation or government policy) adoption of alternate
PNT sources.
3. Availability of a non-GPS PNT service that is compatible with GPS
equipment, and
would be therefore transparent to most GPS users.
Option (1) represents the current operating environment where GPS is ineffective, and industry
adopts alternate systems to provide PNT sources. In applications where safety-of-life requires
PNT assurance, industry uses alternate and backup systems to maintain that assurance. In
addition, one backup service is unlikely to meet all PNT requirements.
Because of these
dynamics, providing a government alternate to existing PNT systems is
unlikely to significantly
change the nation’s risk profile unless it is heavily subsidized (and
therefore anti-competitive) or
there are other incentives to adopt.
12
Option (2) could provide incentives necessary to reduce the nation’s risk profile. Currently there
is no authoritative or regulatory requirement for adopting any backup or complementary system
to GPS. However, the U.S. Government could regulate public/private entities that own and
operate critical infrastructure assets that rely on PNT to adopt alternate sources for
backup/complementary purposes. Doing so would not necessarily require
fielding additional
complementary PNT capabilities but it would set an outcome-oriented
framework to require
certain critical infrastructure to invest in resilience.
Option (3) is a different approach where government and industry would collaborate to enable
behavioral and design changes to enhance resilience. For example, as foreign GNSS systems,
such as Galileo, come online, industry is integrating the new systems on the same chipset and
using the same antenna as GPS. By emulating form factor and not
significantly changing the
size, weight, and power requirements, Galileo will provide some degree of backup capability
depending on the cause for disruption.
If, for example, a commercially available PNT system were integrated with existing GNSS
chipsets and hardware, the U.S. Government could incentivize inclusion of
these capabilities
onto GNSS chipsets sold in the U.S. During normal operations, these capabilities would only be
available to subscribers. Should a largescale GPS disruption occur, the government would then at
least have the capability to deliver service to all users in an emergency regardless of subscription
based on need. If the government pursues this option, the requirements would expand to:
• GPS and backup receivers co-exist within the current GNSS form factors.
• GPS and backup receivers are integrated on a PNT chipset.
• Antennas and other hardware support both GNSS and backup signals.
• The system can provide PNT data to all users regardless of subscription status during a
long-term disruption to GPS.
If any of the systems that can meet critical infrastructure’s timing requirements can be effectively
integrated with GPS equipment, there could be significant risk reduction benefits for timing
applications. Since none of the systems meet all position and navigation requirements, the impact
to position and navigation resilience will be less substantial. To ensure widespread adoption,
newly adopted systems must have capabilities matching GPS and would be more readily adopted
if they provide capabilities not native to GPS.
Conclusion
The department’s analysis leads it to conclude there are steps the U.S. Government can take in
the near term, in concert with industry, to enhance PNT resilience that
would be more effective
than endorsing and investing in a single backup system. Government and
industry can achieve
effective risk mitigation by influencing owner and operator planning and investment, broadening
education efforts about the criticality of PNT services, enabling innovation
in the market space,
working to promote technical interoperability and adopting the principles contained in Executive
Order 13905, Strengthening National Resilience Through Responsible Use of Positioning,
Navigation, and Timing Services.
13
Furthermore, overreliance on a government endorsed or provided system can
cause negative
impacts. For example, telecommunications providers deploy high-quality oscillators (clocks) that
enable systems to operate without an external timing source for days, weeks, and potentially
months before services are significantly degraded. If operators deploy a primary timing system
(GPS), an alternate timing system (foreign GNSS), and an “un-jammable” third system endorsed
by the government and paid for by the operator, will they continue to
install high end oscillators?
The U.S. Government must assess how businesses will react to changes in the
PNT ecosystem to
guard against undesirable, unintended consequences.
As the research detailed in this report demonstrates, there is no single intervention that the U.S.
Government can make to ensure risk elimination of a GPS disruption. However, there are smart,
market-oriented solutions that will contribute to enhanced resilience that
the U.S. Government
should continue to promote, enable and stimulate.
VI. Departmental Plan for Meeting the Requirements
Department of Homeland Security
Since the enactment of the FY17 NDAA, DHS has aggressively pursued efforts
to define the
PNT operating environment for U.S. critical infrastructure. Most of the work
in this report is
based on DHS efforts. Based on our findings throughout these studies, CISA
has provided valueadded information at various interagency and private
sector outreach conferences (when
available). CISA has posted Information Papers and Best Practice information
on the website
gps.gov. As DHS transitions from the “requirements” definition phase, the department looks to
governing documents to define roles and responsibilities.
DHS will continue its efforts to fulfill requirements established in PPD-21, Critical Infrastructure
Security and Resilience, as they relate to PNT. DHS will continue to work
with the interagency
and the private sector to identify vulnerabilities associated with use of
PNT services and work to
minimize the associated risk to infrastructure. Because DHS has been
actively engaged in the
identification and mitigation of risk associated with PNT, DHS does not
foresee any significant
changes to our resourcing requirements in this mission space. The department will maintain
current PNT resourcing levels to support security and resilience efforts.
DHS will continue coordination with DOT to support DOT as they execute their responsibilities
under the National Timing Resilience and Security Act of 2018.
14
A. List of Abbreviations/Acronyms
AoA Assessment of Alternatives
CISA Cybersecurity and Infrastructure Security Agency
DHS U.S. Department of Homeland Security
DOD U.S. Department of Defense
DOT U.S. Department of Transportation
FY Fiscal Year
GLONASS Globalnaya navigatsionnaya sputnikovaya Sistema
GNSS Global Navigation Satellite System
GPS Global Positioning System
HSOAC Homeland Security Operational Analysis Center
LORAN Long-Range Navigation
LTE Long-Term Evolution
MBS Metropolitan Beacon System
NDAA National Defense Authorization Act
NIST National Institute of Standards and Technology
NRMC National Risk Management Center
NSPD National Security Presidential Directive
PL Public Law
PNT Position, Navigation, and Timing
RF Radio Frequency
RFI Request for Information
STL Satellite Time and Location
USNO U.S. Naval Observatory
UTC Coordinated Universal Time
15
B. Bibliography
Mason, Richard, James Bonomo, Timothy Conley, Ryan Consaul, David Frelinger, David
Galvan, Dahlia Goldfeld, et al. Analyzing a More Resilient National Positioning,
Navigation, and Timing (PNT) Capability (Washington, D.C.: Homeland Security Operational Analysis Center, 2019).
O’Connor, Alan, Michael Gallaher, Kyle Clark-Sutton, Daniel Lapidus, Zack Oliver, Troy Scott,
Dallas Wood, Manuel Gonzalez, Elizabeth Brown, Joshua Fletcher. Economic Benefits
of the Global Positioning System (GPS) (Research Triangle Park, NC: RTI International,
2019), ES-4. https://www.rti.org/sites/default/files/gps_finalreport.pdf. President’s Commission on Critical Infrastructure Protection. Critical Foundations: Protecting
America's Infrastructures (Washington, D.C.: United States Government,
1997), A-19.
https://www.hsdl.org/?abstract&did=986.
Sadlier, Greg, Rasmus Flytkjaer, Farooq Sabri, Daniel Herr. The economic
impact on the UK of
a disruption to GNSS (London, UK: London Economics, 2017), iii. https://www.gov.uk/government/publications/the-economic-impact-on-the-uk-of-adisruption-to-gnss.
United States Department of Agriculture, National Agricultural Statistics Service. Farms and
Farmland, Census of Agriculture Highlights (Washington, D.C.: United States Department of Agriculture, 2014). https://www.agcensus.usda.gov/Publications/2012/Online_Resources/Highlights/Farms_a
nd_
United States Department of Homeland Security. National Risk Estimate: Risks
to U.S. Critical
Infrastructure from Global Positioning Disruptions (Washington, D.C.: United States
Department of Homeland Security, 2010), 3.
United States Government. National Security Presidential Directive 39: U.S. Space-Based
Position, Navigation, and Timing Policy (Washington, D.C.: United States Government,
2004).
Additional reference not used in the report:
Socio-Economic Benefits Study: Scoping the value of CORS and Grave D (Irving Levenson
Revised 2009) https://www.ngs.noaa.gov/PUBS_LIB/Socio-EconomicBenefitsofCORSandGRAV-D.pdf
16
C. User Needs Framework
Reported User Needs for Timing Accuracy
Critical Sector Application Accuracy Range
Communications /
Mobile Applications10 Billing, alarms 1 to 500 µs
Internet Protocol delay monitoring µ 5 to 100 µs
Call handoff/continuation11 10 to 30 µs
Node-to-node communication 7 to 9 µs
Network routers and switches, network backhaul12 4 to 5 µs
Time stamping/event management 2 to 5 µs
Long-term evolution (LTE) Time -Division Duplexing (TDD)
(large cell) WiMax-TDD (some configurations) 1.5 to 5 µs
ULTRA-TDD 1 to 1.5 µs
LTE-TDD (small-cell) 1 to 1.5 µs
Handoffs in WiMax-TDD (some configurations) 1 µs
Wired
Communications13 Conversational video (livestreaming) 1 µs
Conversational voice 150 µs
Mission-critical data 100 µs
Mission-critical delay sensitivity signaling 75 µs
Vehicle-to-Everything messages 50 µs
Network routers and switches14 50 µs
Grandmaster clock15 1.5 µs to 50 µs
Electricity Physical/video security 1 s
Network security 1 µs
Sequence of event recorder 1 µs
Protective relays-coordinated controls 1 µs
Phasor Measurement Unit (PMU) – offline 1 µs
Emergency Services Public safety answering point Sub 1 s
Simulcast Land Mobile Radio (LMR) Systems 2 µs
First Responder Network Authority (FirstNet) 1.5 µs
Financial Services Manual security trading 1 s
Automated security trading 50 µs
Computer system clocks and time stamping 100 µs to 50 µs
Non-high-frequency trading (ESMA MiFID-2) 1 µs
High-frequency trading (ESMA MiFID-2) 50 µs
Source: Cavitt, et al. (2018)
10 Applies to 20, 30, LTE-FDD, and LTE-A, except where otherwise noted. 11 Applies to 20, 30, LTE-FDD, and LTE-A, except where otherwise noted. 12 Violation of timing requirement expected to have relatively minor impact. 13 Applies to Synchronous Optical Networking (SONEn, Time-Division Multiplexing (TDM), Ethernet, and ultrahigh-speed Ethernet. 14 Violation of timing requirement expected to have relatively minor impact. 15 Violation of timing requirement expected to have relatively minor impact.
17
Reported User Needs for Positioning Accuracy
Critical Sector Application Position Accuracy Range
Chemicals Tracking chemicals through supply chain 1-5 m
Inspection and monitoring of equipment, pipes,
and assets Sub 1 m
Chemical Cleanup Sub 1 m
Commercial Facilities Construction Sub 1 m
Location-based marketing and sales Sub 5 m
Communications Geographical service extension Sub 5 m
Wireless signal strength measurement Sub 5 m
Service and fleet management Sub 5 m
Public safety alert management Sub 10 m
Dams Monitoring deformations in dams and
infrastructure (structural integrity) 1 cm horizontal 2 cm vertical
Monitoring deformations in landforms and
waterways Sub 0.5m
Construction of dams Sub 10 cm
Emergency Services Strategic deployment of resources (large
incidents) Sub 1 m
Dispatch and routing (routine incidents) Sub 1 m
Public safety alert management Sub 10 m
Energy Seismic exploration (land and marine)
1 m for seismic exploration
10 cm for hydrographic mapping
1 m for docking
Dynamic positioning – drilling 10 cm for dredging and
construction
Construction 1 m for cable and pipe laying
Financial Services Tracking assets such as cash 15 m
Risk assessment
1 m for drone to evaluate specific
properties
5 to track consumer auto
behavior
Loan loss mitigation/ measurement
1 m for drone to evaluate specific
properties
5 to track automotive collateral
Food and Agriculture Mapping farms Sub 1 m
Piloting farm equipment Sub 1 m
Variable rate technology Sub 1 m
Food sourcing Sub sm
Food control Sub sm
Government Facilities Workforce/asset tracking Sub 1 m
Base planning/coordination Sub sm
Student tracking systems Sub sm
Defendant/parolee tracker Sub 1 m
Healthcare and Public
Health Health data mapping Sub 1 m
Location-based services to direct patients to
health services Sub 5 m
Telemedicine and response Sub sm
Nuclear Reactors,
Materials, and Waste
Tracking materials and waste through supply
chain 1-5 m
Inspection and monitoring of facilities 1 cm
Monitoring crustal deformations at nuclear waste Sub 1 m
18
Critical Sector Application Position Accuracy Range
disposal site
Water and Wastewater Equipment mapping, monitoring, and tracking Sub 1 m
Survey and mapping of landforms and waterways 1 cm
Fleet management Sub 5 m
Source: Thompson, et al. (2018).
Reported User Needs for Navigation Accuracy in Transportation
Critical Sector Application Position Accuracy Range
Aviation Oceanic phase of flight 7.4km
En route flight 3.7km
Terminal flight 750m
Non-Precision Approach (NPA) 220m
Approach Procedure with Vertical Guidance (APV)
16 m horizontal
20 m vertical (APV-I)
8m vertical (APV-II)
Maritime Cat-I landing 16 m horizontal 4-6m
vertical
Cat-II landing 7.5 m horizontal 1 m
vertical
Cat-III landing 3 m horizontal 1 m
vertical
Road Vehicle to
Infrastructure Ocean navigation 10m
(V21) Applications Pot approach and restricted waters 10m
Road Vehicle to
Vehicle (V2V) Inland waterways 2-10m
Applications Port 1m
Road 5m
Lane 1.1m
Where-in-lane 0.7m
Road 5m
Lane 1.5m
Where-in-lane 1.0m
Source: Tralli, et al. (2018b).

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