Adtran and Satelles, a provider of secure time and location technology using low-Earth-orbit (LEO) satellites, have partnered to offer operators of critical infrastructure a timing network device with satellite, time and location (STL) technology. The partnership aims to provide an alternative to GNSS by integrating STL technology from Satelles into Adtran’s Oscilloquartz network synchronization products.
Through its partnership with Satelles, Adtran’s Oscilloquartz division will incorporate STL into its end-to-end timing toolkit. The companies will also integrate STL into its grandmaster clocks to develop miniature M.2 form factor STL receiver modules for third-party product integration.
With the ability to deliver precise position, navigation and timing (PNT) service in GNSS-denied applications, STL is suitable for mobile operators, power utility companies, government, scientific research and more. STL technology also offers accurate, secure and augmented Iridium LEO-based PNT services for indoor applications and as backup for GNSS outdoors.
Jackson Labs Technologies PNT-6200 Series, an STL-based time and frequency reference system installed in a 5G application. Photo: Satelles
We discussed Satellite Time and Location (STL) services and complementary PNT with Michael O’Connor, CEO at Satelles.
What is the problem with GPS/GNSS that Satelles aims to solve?
GPS and GNSS are amazing. We designed Satellite Time and Location (STL), the service that we offer, to complement those capabilities. We have focused on three unique aspects in the areas where GPS could use complementary service. First, we provide a fully independent backup. We all know that things can happen, so we aim to provide an independent source of position navigation, and timing (PNT). Second, we focused the high-power aspect of STL to enable us to reach indoors and other places where GPS does not reach. Because STL comes from low Earth orbit (LEO) satellites, the signals are naturally at a higher power.
We also focused on improving the indoor penetration capability by enhancing the signal design and doing some other things. Third, we use modern cryptographic techniques to ensure the security and resilience of the system, specifically to intentional misdirection attacks. If you can ensure that the signal is coming from the satellite and not from a third party you can have a more secure and resilient solution.
To what extent can you replace GPS during an extended outage?
We have never considered LEO PNT as a replacement for MEO (medium Earth orbit) GNSS. GNSS are the primary domain of PNT but there are applications that have additional needs. The more independence you can get, the fewer the common modes of failure, if you can at least have some survivability in the absence of GNSS. That’s one of the services we can offer. It is probably not the most important thing to our customers, honestly. The service we offer is similar to GPS and GNSS in that we have a space segment (the satellites), a ground segment, and a user segment. We have space vehicles, user equipment, and ground infrastructure that supports the space infrastructure.
What’s interesting about the way we work with the Iridium satellite constellation is that the satellites themselves include inter-satellite links. That provides a lot of resilience to ground-based events. The satellites themselves have a time transfer capability between them. So, we don’t require a direct connection to every satellite to propagate a time throughout the network. That’s one unique aspect we can take advantage of with this particular network, Iridium, which is pretty amazing.
Additionally, we have multiple ground infrastructure and monitoring sites and multiple sources of time at those ground monitoring and control stations. For example, some of them rely on GNSS combined with atomic clocks as their master timing source but we also have one installed at the National Institute of Standards and Technology facility in Boulder, Colorado. So, we have multiple primary time sources that we can integrate into our filtering across the network. That, combined, with satellite links, allows us to maintain time for substantial periods independent of GNSS.
How do you define “complementary PNT” and how does Satelles fit in that mix?
Several applications have additional needs beyond what GNSS offer. There are many technologies that can come to bear on that. There’s the LEO satellite base, which is where Satelles fits in, but there are also local and wide-area terrestrial radio navigation sources, network-based time transfer, signals of opportunity, and so on. They all have something important to offer, depending on the application. Satelles’ LEO satellite solution is available today, has global coverage, and is relatively affordable. It leverages the capital investments that have been made to launch the satellites to provide this service globally. The industry is working together to make sure that an awareness of these capabilities is propagated throughout the industries that we serve.
Besides the orbit height, which requires many more satellites, how does your system differ from GNSS?
We do not consider LEO PNT as something that might replace MEO PNT. The fundamental difference is being in lower Earth orbit, which results in a higher received power. That is what allows us to penetrate, just based on the 1/r2 losses. The measurable Doppler signatures give additional observables for PNT calculations, and higher satellite dynamics that can help with multipath. This service relies on many of the same physics and geometry as GPS. We measure the time of arrival of a very similar signal. The signals from the Iridium satellites are even in the L band. Very often we’re using a GPS chip that’s been reprogrammed to track and utilize our service as well as GPS or instead of GPS.
If I explained how GPS works to, say, a high school science class, how much of that basic explanation—about trilateration, spread spectrum, etc.—would also apply to your system?
It’s fundamentally the same. It relies on a lot of the same physics and geometry. We measure the time of arrival of a very similar signal. The signals from the Iridium satellites are even in the L band. Very often we’re using a GPS chip that’s been reprogrammed to track and utilize our service as well as GPS or instead of GPS. There are subtle differences—for example, a lower Earth orbit is faster—but it is very similar.
How would GPS user equipment have to be modified to make use of your service?
We don’t think of STL as something where we are modifying GPS user equipment. Rather, we think about what must be done in an end-user application to meet their needs. For example, one of our partners, Orolia, has a GNSS + STL secure synchronization product that we have delivered to customers in data centers and major stock exchanges around the world. Those are operational and in service. They integrate through standard interfaces, such as PPS or PTP, depending on the type of equipment to which they are connecting.
Ultimately, we don’t think of it is as replacing GPS user equipment. Rather, where a user has a need for PNT, they’re opting for this GNSS + STL solution because they have an indoor need, such as a data center, or they have a need for resilience in the case of a stock exchange.
Another example is Jackson Labs. The Jackson Labs 2600 is also a GNSS + STL solution that generally is integrating with existing 5g. It has a specialized transcoder interface that can work with any existing GNSS-type equipment. In some cases, we’ve taken a chip that was originally designed for GPS and modified its firmware.
Who are the earliest adopters?
Satelles’ LEO satellite solution is available today, has global coverage, and is relatively affordable. It leverages the capital investments that have been made to launch the satellites to provide this service globally. Data centers, stock exchanges and cell phone providers are implementing these capabilities today. The major wireless operators are seeing that more and more of the 5G infrastructure they roll out is going indoors, where GPS doesn’t reach. We provide a solution that integrates with their existing solutions and can provide reliable timing capabilities.
If your solution can survive on its own, why does it need GNSS at all?
In some cases, the user is not using GNSS at all. The product itself has a GNSS capability. User equipment is very affordable and the service is taxpayer-funded. In many cases, especially for indoor installations, the equipment that is installed is capable of tracking GNSS and STL signals, but often it relies on the STL signal itself for timing.
How do you predict STL spreading through various applications and industries?
We have our hands full with the markets we’re going after now, but there are certainly going to be other markets in which the customers will recognize that they have a critical need to implement a backup solution.
In the long run, could LEO satellites replace MEO ones for GNSS?
Sometimes there have been misperceptions in the industry. I’ve never considered that LEO PNT satellites might replace MEO ones. There are excellent reasons why Brad Parkinson, Jim Spilker, Gaylord Green and others decided almost 50 years ago to put GPS in MEO. Those physics haven’t changed. You can cover a large portion of Earth with each satellite. LEO will not replace MEO, but it has unique characteristics that make it a great complement to the GNSS MEO solutions.
Do you have any additional comments about complementary PNT?
It’s good to see that the federal government is encouraging the adoption of complementary PNT, which they often call “GPS backup.” It is encouraging to see the amount of activity on this issue that’s been going in Washington over the last couple of years. Although our company is very focused on delivering a LEO-based PNT service, which has several advantages for customers that need a global capability, many technologies can play an important role in those solutions.
The U.S. Department of Transportation did a fantastic job of looking at several of those technologies across those different categories. The European Union has also had a similar activity recently. Some reports will be coming out soon about that. It is very important that the government understands that this is an important issue for our society and encourages industry to adopt these solutions and is even starting to make some investments toward that. That includes executive order 13905 and some recent funding increases by Congress.
All of that has been very important and positive, as has modifying some of the legislation to be more inclusive of multiple technologies, such as removing the words “land-based” from the National Timing, Resilience, and Security Act this year.
I am involved in an industry consortium, the Open PNT Industry Alliance, with several other companies whose CEOs are in alignment that there is no single answer. Having a thriving ecosystem of technologies and companies trying to solve this important problem is incredibly important and it’s exciting to see.
Cooperative agreement expands precision timing distribution options for critical infrastructure and verifies STL’s agreement with UTC via UTC(NIST)
This March 30, 2022, chart of Satelles and NIST testing verifies that STL timing agrees with UTC. (Chart: Satelles)
Satelles Inc., provider of highly secure satellite-based time and location services, has entered a cooperative agreement with the U.S. National Institute of Standards and Technology that directly connects STL’s operational infrastructure to the source of UTC(NIST), the national standard for time and frequency in the United States produced in coordination with the U.S. Naval Observatory.
The agreement calls for Satelles to provide its STL service to NIST. Reciprocally, the agreement includes the introduction of a connection between an STL Ground Monitoring Station (GMS) provided by Satelles to the NIST collection of extremely accurate atomic clocks that maintains the official time scale for UTC(NIST).
The Cooperative Agreement was described in NIST Technical Note 2187, “A Resilient Architecture for the Realization and Distribution of Coordinated Universal Time to Critical Infrastructure Systems in the United States,” published in November 2021.
In February 2021, Satelles delivered and configured an STL GMS at NIST’s Time and Frequency Division in Boulder, Colorado. This facility is home to the ensemble of high-precision cesium beam and hydrogen maser atomic clocks that maintains UTC(NIST).
After conducting a series of successful preliminary tests in the spring of 2021, NIST then directly connected the STL GMS to its primary clock ensemble in June 2021. Comparing timing provided by STL to UTC(NIST), the testing confirmed STL’s long-term stability of better than 25 nanoseconds with short-term time deviation of 50 nanoseconds.
STL from Satelles is a resilient, alternative PNT service from low-Earth-orbit (LEO) satellites that enterprise customers rely on as a primary timing source. Telecom operators, for example, use STL for 5G wireless network deployments where GPS is unavailable indoors or when other timing solutions cannot provide the required level of accuracy.
STL’s agreement with UTC also is important for critical infrastructure and other applications that require an essential contingency capability to protect the operations of PNT-dependent systems and ensure survivability and resilience.
“Satelles has a network of GMS nodes positioned around the world to receive STL signals and calculate the position and timing of the satellites for purposes of producing timing corrections, and
now we are fortunate to have a GMS connected inside NIST’s main time lab,” said Gregory Gutt, president and CTO of Satelles. “It’s an honor to be given direct access to UTC(NIST), especially in an arrangement that delivers benefit to both our customers and NIST.”
Visit satelles.com/nist for more information about NIST reports that detail the performance of STL and collaborations between Satelles and NIST.
The trial for the U.S. Department of Homeland Security showcases the precise, resilient timing capabilities of NextNav’s TerraPoiNT service in the event GPS is unavailable.
NextNav has successfully demonstrated the timing precision and resilience of its terrestrial positioning, navigation and timing (PNT) system, TerraPoiNT, in a recent evaluation by the Science and Technology Directorate of the Department of Homeland Security (DHS S&T).
The trial tested the timing redundancy of the TerraPoiNT system in a number of scenarios, including instances of GPS outages, spoofing and jamming. It validates TerraPoiNT’s capabilities as a terrestrial, GPS-free network capable of powering critical national infrastructure in the event of GPS failure.
During a simulated 72-hour GPS outage, the TerraPoiNT service was able to deliver a timing accuracy better than 50 nanosecond in urban and semi-urban environments, successfully meeting timing requirements for various applications including 5G networks, the synchronization of the power grid, and more.
In addition, TerraPoiNT provided precise timing and redundancy utilizing two alternate absolute timing sources — atomic clock (Cesium/Rb) and LEO satellite (Satelles).
“GPS is critical infrastructure, but it has its limitations,” said Ganesh Pattabiraman, co-founder and CEO of NextNav. “In working with DHS S&T, we’ve validated that TerraPoiNT can serve as an important backup to GPS and ensure the resilience and continuity of our nation’s most critical systems, including next-generation telecommunications networks, financial services, and power grids.”
Satelles STL
STL from Satelles was one of two alternate absolute timing sources for the trial. Available today on a global basis, STL is a service that provides alternative PNT independent of GPS, supporting PNT-reliant applications such as 5G communications networks, high-frequency trading in financial markets, and electrical grids throughout the United States and around the world.
“Satelles applauds NextNav for conducting a successful field demonstration of its resilient PNT service, and we were delighted to have played an instrumental part in the exhibition,” said Christina Riley, vice president of Commercial PNT.
NextNav’s selection of STL to help demonstrate their own technology’s operation in the absence of GPS was a natural fit. That’s because earlier this year the U.S. National Institute of Standards and Technology (NIST) confirmed STL as an accurate and reliable source for the wide-area delivery of Coordinated Universal Time independent of GPS/GNSS.
Previous TerraPoiNT evaluations
The successful trial builds on recent evaluations of TerraPoiNT conducted by independent bodies. Earlier this year, the Department of Transportation (DOT) evaluated 11 alternate PNT solutions, in which each was rigorously tested across applications and scenarios. As a result of the evaluation, the DOT named TerraPoiNT the best and only performing solution across all PNT categories.
Spartacus. In June, NextNav entered into a definitive merger agreement with Spartacus Acquisition Corporation in a transaction that would result in NextNav being listed on the Nasdaq. The transaction is expected to close late in the third quarter of 2021 or early in the fourth quarter of 2021, subject to satisfaction of customary closing conditions.
Study by U.S. government agency responsible for maintaining national time scale shows that Satelles provides a signal that is independent of GNSS and delivers exceptional timing stability
Following a detailed performance study in 2020, the U.S. National Institute of Standards and Technology (NIST) determined that Satellite Time and Location (STL) is a reliable source of timing highly consistent with Coordinated Universal Time (UTC). The secure STL services are provided by Satelles Inc.
STL is based on a signal independent from GPS and other GNSS. The STL service was able to deliver this consistent performance in a deep indoor environment where GNSS signals did not reach.
The results of the study were shared by Elizabeth Donley, chief of the Time and Frequency Division at NIST, in a keynote speech at the Workshop on Synchronization and Timing Systems (WSTS) conference on April 1.
Donley articulated the details of the NIST study, in which a GPS-disciplined clock and a Satelles EVK-2 evaluation unit with a quartz oscillator were compared to UTC for 50 days. In this evaluation, the GPS device received its signal from an outdoor antenna, whereas the Satelles device was connected to an indoor antenna in a deep indoor environment where GNSS signals were not able to reach.
Time deviation calculations estimated the stability of the two signals with respect to the UTC time scale. Based on one day of averaging, the GPS instability was less than two nanoseconds, and the STL instability was only slightly higher at under three nanoseconds (see chart). These measurements demonstrated that STL delivers stability comparable to GNSS and does so in an indoor location where GPS signals usually cannot penetrate.
Image: NIST
STL delivers a positioning, navigation and timing (PNT) service from satellites in low Earth orbit (LEO) to back up or augment GPS and other GNSS. The evaluation by NIST confirms that users of PNT-reliant applications can obtain accurate and reliable timing without using GNSS.
“We are thrilled that NIST has performed these independent tests that confirm what we have long known, which is that STL delivers an independent timing source that is reliable and highly consistent with UTC,” said Gregory Gutt, president and CTO of Satelles. “This report complements and reinforces the findings of the U.S. Department of Transportation, which identified STL as a top-ranked PNT system in its technology demonstration report released earlier this year, and showed STL to be the only solution that demonstrated a wide-area timing capability that works indoors and out.”
The STL-2600 STL-capable receiver provides a GNSS-independent low SWaP-C UTC-time and location capability
Jackson Labs Technologies Inc. (JLT), a designer and manufacturer of GNSS, timing and frequency equipment, has announced the availability of the STL-2600 Satellite Timing and Location (STL) receiver designed in partnership with Satelles Inc., the STL service provider.
The STL-2600 commercial receiver provides a completely GNSS-independent, low-cost capability to generate UTC nanosecond timing and meters-accurate positioning anywhere in the world. It operates in a way similar to GPS, but without GPS or GNSS. The STL signal has 30-db (1,000 times) higher power compared to GPS signals, allowing the receiver to operate deep indoors independent of any GPS/GNSS signal.
“Useful for non-GNSS-based E911 location and UTC(NIST) timing applications, the STL-2600 receiver is deployable today to fulfill critical infrastructure PNT objectives such as those outlined in Executive Order 13905 on the responsible use of PNT in the U.S. and the emerging mandates for a GNSS-independent backup solution in Europe,” said Said Jackson, president of JLT.
The STL-2600 receiver is also useful in marine applications where GNSS signals are regularly denied or manipulated and for stationary high-accuracy timing applications such as 5G.
The STL-2600 receiver can be directly connected to JLT’s GPS Transcoder products for glue-less retrofit capability of existing customer legacy GPS-only receiver systems to Galileo, GLONASS, BeiDou, QZSS and SBAS as well as adding the STL and optional atomic holdover capability to these legacy systems.
The receiver module combines a custom-designed STL L1 LEO receiver and a latest-generation concurrent-GNSS receiver with a disciplined high-stability reference oscillator sub-system on one circuit board.
Features and specifications of the STL-2600
Photo: JLT
Form factor: 1.4″ x 2.0″ x 0.5″ (36mm x 51 mm x 13mm)
Switching modes: User-selectable automatic and manual switching between GNSS and STL signal reception during jamming or manipulation events
Integration: Incorporates into user systems just like a legacy GNSS receiver would using NMEA and SCPI serial messages, with the use of standard NMEA messages for STL positioning and timing features making system integration trivially easy
Oscillator options and performance: Internal high-stability TXCO standard; capable of directly and gluelessly disciplining numerous optional DOCXO, CSAC and rubidium oscillators for holdover capability, with ultra-stable ADEV performance from 0.1s to infinity with better than 10E-12 stability when using a DOCXO or Rubidium as the holdover oscillator
Low-power consumption: Ranges between 0.7 W to 1.45 W (depending on configuration) allowing for long-term battery operation for use cases without AC power
Antenna support: One GNSS/STL combined standard; optional support of a second antenna for diversity
Interfaces: TTL serial port standard; optional USB serial port allow easy evaluation and design-in
Upgrades: One-button firmware updates performed in situ through any of the serial ports
The receiver includes JLT’s proven frequency and timing disciplining and holdover IP deeply embedded into the entire signal chain for ultra-low phase noise performance and high-stability 1PPS and 10 MHz operation, even when using only the built-in TCXO oscillator.
The unit operates fully autonomously from just a USB cable and is compatible with a customized version of the GPSCon software — offered at no cost to JLT customers — for monitoring and control.
The STL signal has been deployed worldwide since 2016 and can be evaluated and implemented SWaP-C-effectively today via this receiver module.
The STL-2600 is available now. Contact Jackson Labs Technologies for configuration and pricing information.
Jackson Labs Technologies (JTL) has launched the PNT-6220 Assured Reference — a product combining low-Earth-orbit (LEO) signals, GNSS, terrestrial, wireline and atomic clock services in one small solution, specifically designed for critical infrastructure applications.
The PNT-6220 reference seamlessly combines concurrent L1, L2, L3 and L5 GNSS reception with a custom JLT-designed LEO-based Satellite Time and Location (STL) timing receiver. It also includes terrestrial receivers and PTP/IEEE-1588 edge grandmaster (EGM) and PTP/IEEE-1588-slave capability.
The PNT-6220 provides assured PNT for critical infrastructure applications such as those described in the directives of Presidential Executive Order 13905.
It can serve as a timing reference for 5G equipment, an ePRTC-capable reference, or a high-performance disciplined reference that supports PTP/IEEE-1588, STL, RF distribution and multi-frequency GNSS capability.
The PNT-6220 will be able to select the most optimal UTC reference input automatically and auto-switchover among its numerous reference inputs if one or more of them are jammed or spoofed, as well as average several references for additional stability and accuracy.
If all external references are jammed, the unit can provide UTC timing from its internal holdover oscillator with options that have less than 100-ns drift over 24 hours. The unit is also capable of outputting a GPS RF distribution signal driven by the internal flywheel oscillator, which allows glue-less retrofitting of any GPS-based legacy user equipment to the state-of-the-art reference sources the PNT-6220 can receive by simply plugging into the legacy equipment GPS antenna input.
Available Options
Numerous options are available for the half-width 19-inch-wide rack-mount box.
The U.S. Department of Homeland Security (DHS) issued a report on alternative sources of PNT on May 6. It was submitted to U.S. congressional committee leaders on April 8.
Section 1618 of the 2017 National Defense Authorization Act (NDAA) of Dec. 23, 2016, required the DHS to address the need for a GPS backup by identifying and assessing viable alternate technologies and systems.
The report is a summary and analysis of that assessment by the Homeland Security Operational Analysis Center (HSOAC) of PNT systems currently used by critical infrastructure. It also provides recommendations for the federal government’s next steps to increase the resilience of critical infrastructure to disruption of GPS services.
In the report, DHS offers the following recommendations to address the nation’s PNT requirements and backup or complementary capability gaps:
Temporary GPS disruptions: End users should be responsible for mitigating temporary GPS disruptions. For example, the Federal Aviation Administration maintains sufficient PNT capabilities to assure the continued safe operation of the national airspace, albeit at a reduced capacity, during GPS disruptions. The federal government can facilitate this mitigation for various critical infrastructure sectors, but should not be solely responsible for it.
PNT Diversity and Segmentation: The federal government should encourage adoption of multiple PNT sources, thus expanding the availability of PNT services based on market drivers. Encouraging critical infrastructure owners and operators to adopt multiple PNT systems will diffuse the risk currently concentrated in wide-area PNT services such as GPS. Federal actions should focus on facilitating the availability and adoption of PNT sources in the open market.
System Design: PNT provisioning systems, assets, and services must be designed with inherent security and resilience features. Critical infrastructure systems that use PNT services must be designed to operate through interference and to identify and respond to anomalous PNT inputs. These attributes are applicable to the PNT receivers and the systems that use them.
Pursue Innovation that Emphasizes Transition and Adoption: Incorporating PNT signal diversity into the PNT ecosystem should be pursued with an emphasis on research and development that prioritizes successful transition and adoption into existing GPS receivers, taking into account factors such as business case considerations, financial costs, technical integration, and logistical deployment.
Table 1 shows timing requirements for critical infrastructure are, according to the report.
Table 1. (Image: DHS report)
Table 2 from the report shows proposed timing solutions submitted by industry to DHS during a Request for Information (RFI) in December 2018. Systems that can meet or exceed timing requirements for critical infrastructure are indicated in green.
Table 2 (Image: DHS report)
Satelles responds
The Satelles company, which offers STL, issued a statement on the report. “This important report highlights the urgent need for GPS backup for critical applications, and it identifies and characterizes a variety of solutions that are available to meet this need today,” said Michael O’Connor, CEO of Satelles. “The report also describes the essential role of the federal government in urging industry to implement multiple technologies, without making the mistake of providing or selecting a single PNT solution.”
Continued O’Connor, “DHS goes on to define a baseline requirement for timing services accuracy for critical infrastructure. Not only does Satelles meet or exceed the precision timing specifications stated by DHS, but also our solution provides national coverage (including Alaska, Hawaii, and U.S. territories) and is commercially available now.”
Satelles Inc., provider of highly secure satellite-based time and location services, has raised $26 million in Series C funding. C5 Capital led the round, with participation from Iridium Communications and existing investors.
The new investment brings Satelles’s total funding since the launch of its platform to $39 million and will help the company expand its sales and marketing efforts, broaden its partner network, and accelerate product development.
In 2016, Satelles demonstrated sub-microsecond timing using its Satellite Time & Location (STL) service with a stand-alone TCXO-based receiver. In February 2018, the company released new tests using configurations with a differential source and with a more accurate OCXO clock, producing timing accuracy of 160 nanoseconds.
Industry and government requirements for positioning, navigation, and timing (PNT) are expanding at a rapid pace, and the Satellite Time and Location (STL) broadcast signal from Satelles provides assured PNT across a range of applications and at scale.
“Today’s world runs on systems requiring trusted time and location information, and C5 Capital shares our commitment to make it a more secure and better place,” said Michael O’Connor, CEO of Satelles. “We are delighted that C5 led this latest investment round because they bring great insight into cybersecurity, and their international network is unparalleled.”
Attacks such as jamming and spoofing — where a radio transmitter near the target is used to interfere with legitimate GPS or GNSS signals — and hacking are becoming more of a threat because of the key role that GPS and GNSS play in the operation of critical infrastructure.
The STL signal strength is much greater than GNSS because the LEO satellites are much closer. (Slide: Satelles)
According to the company, the Satelles STL platform brings security to telecommunications networks, financial exchanges, electrical grids, maritime transportation systems, and many other sectors that depend on timing or location information.
Downtime or malfunctions in these systems due to such attacks would be very costly. A June 2019 report sponsored by the National Institute of Standards and Technology estimated a $45 billion loss to the U.S. economy if GPS were to experience a 30-day service disruption.
The Satellite Time and Location broadcast service from Satelles is encrypted to thwart malefactors aspiring to spoof or otherwise disrupt the STL signal, which is delivered via the low-Earth-orbit (LEO) satellite constellation operated by Iridium, an investor in this financing round.
“STL addresses a critical and growing need across many applications and industries, so Iridium’s investment in Satelles aligns with our strategic vision,” said Matt Desch, CEO of Iridium Communications. “Satelles’s technology is unique and powerful, and we are proud to host such an innovative service that solves important problems and leverages the unique capabilities of our network.”
The Iridium satellite constellation-based system offers many advantages:
A signal 1,000 times stronger than GPS/GNSS is better at reaching users and facilities in GPS/GNSS-challenged environments such as inside buildings, underground locations, and urban canyons.
Overlapping and constantly moving spot beams enable revolutionary cybersecurity solutions that can rely on trusted time and location for authentication and data access.
Polar-orbiting, cross-linked satellites ensure truly global coverage.
The L-band frequency range allows small, low-cost equipment to receive the Satelles STL signal.
“The capabilities of Satellite Time and Location are enhanced by the technical and service delivery attributes of low-Earth-orbit satellites,” said Dr. Gregory Gutt, President and CTO of Satelles. “An extraordinary constellation such as Iridium’s gives us an incredible platform from which to deliver our trusted PNT solutions, so we remain committed to LEO technologies going forward.”
Commenting on the closure of the Series C investment in Satelles, Andre Pienaar, Managing Partner of C5 Capital, said, “Space is a rapidly developing battleground for cyber threats to critical infrastructure, and GPS is unable to meet all these challenges. Satelles has developed a powerful solution which not only prevents attacks but provides a stronger and more effective service through STL. We are pleased to have led this funding round and look forward to working closely with this remarkable business.”
Growing awareness of the vulnerabilities of GNSS signals — weak, unencrypted and easily jammed or spoofed — have made GNSS less important to steering the driverless vehicle. What’s up with that?
Extensive visual map databases are being created that, when coupled with cameras, radars and lidars on the vehicle and processed by artificial intelligence (AI) algorithms, enable the driverless car to be steered much the way humans drive. Pattern recognition processing in the vehicle allows it to “read” street signs and recognize landmarks, registering its position on the map.
This is the way a person drives in his or her home town, where they always know their orientation and don’t need GNSS. The AI processing “brain,” with access to huge map databases, either through local storage or a network connection, will always be in its familiar home environment: continuously knowing its own position and properly oriented for navigation.
So, will GNSS become unnecessary in the car of the future? Probably not.
First, no one method of navigation is foolproof, and today, GNSS is our primary method of navigating our cars. It is a cost-effective, accurate way of determining position in real time, and with the integration of inertial navigation sensors to handle cases when GNSS is intermittently unavailable, it is improving.
Second, it is not just the car itself that needs to know its location for navigation, but also others outside the car. Ride-sharing apps like Uber and Lyft, car-sharing, usage-based insurance apps, dynamic toll charging, and parking apps all depend on knowing where the car is at all times. GNSS offers sufficient accuracy for all these apps by providing location coordinates. Therefore, a GNSS receiver will most likely remain in the car.
The case for jamming and spoofing
Recall, however, that one of the weaknesses of GNSS is its open, unencrypted format. It is becoming increasingly easier to spoof these signals. Car-sharing, usage-based insurance and dynamic toll charging apps all create a monetary incentive for fraud that can be implemented with a spoofer. For example, a car in a car-sharing network can report a fake position indicating that it is safely parked in a secure area — while in reality, a thief is busy driving it away.
(Image: Orolia)
Let’s assume that all wireless connections to and from the car are secure. This is a reasonable assumption, although recently there have been demonstrations of carjacking via unsecure remote links. Standard SSL encryption, similar to what is used to enter credit card information on the internet, works well here. We have both the awareness and the technology now to prevent such carjackings from ever reoccurring.
However, even if communication links are secure, a GNSS spoofer in the car can fool the GNSS receiver into reporting a fake “safe” position right as it is being stolen. The same is true for insurance or toll apps. And the fraud does not have to be sophisticated. A simple, low-cost jammer can deny proper position just long enough to skirt payment. A secure location method is needed.
Other signals for localization
What would an ideal signal for localizing a driverless car look like?
It needs to be much stronger than GNSS so it is not easily jammed.
It needs to be encrypted so it cannot be spoofed.
It must be ubiquitous, available worldwide.
It must be reliable and robust — with 99.999% availability or better.
It must be practical and priced for the mass-market automotive application.
Though accuracy is always important, the signal used for localization does not have to be as accurate as GNSS is today. Accuracy to 10s of meters is sufficient for all these applications needing fraud protection since it would not be used for steering the car, but rather, only localization. It can also be used in tandem with GNSS to authenticate a reported position when a GNSS signal is available.
Such a signal is available today, worldwide: STL (Satellite Time and Location). Carried on the Iridium satellites, it is a special purpose signal that is more than 30 dB stronger than GNSS and encrypted for anti-spoof protection. Decoding of this signal is available via a subscription model to users.
Here’s how it would work using a car-sharing example. A group of people subscribe to a car-sharing service that provides X number of cars to serve Y number of people, where X is less than Y. The service optimally schedules people when and where a car will be available. The service provider needs to know the whereabouts of the cars at all times to maximize utilization of the fleet, so every car has a GNSS receiver in it.
But to ensure the authenticity of these reports, they also have a secure localization receiver. This receiver is assigned a unique ID that is authorized to decode the encrypted signal. (Eventually, we expect this receiver and GNSS to converge into one device much the way multi-GNSS receivers operate today).
If a position report does not agree with the authentic localization report, the fleet manager can act to recover the car immediately. Insurance providers who cover secure localization-equipped cars would also give preferential rates as an anti-theft device.
(Image: Pavel Vinnik/Shutterstock.com)
Could PRS do it?
The new Public Regulated Service (PRS) from Galileo is encrypted and could provide a similar level of authentication protection, if made available. However, it is still a weak GNSS signal that can easily be jammed. Of course, any signal can be jammed, even one that is a thousand times stronger than GNSS.
However, given the robust nature of a very strong signal, the managing system that is monitoring the cars — the insurance, toll or car-sharing system, for example — can alarm upon the loss of positioning information. Such alarms on a GNSS-only car would be frequent and often erroneous due to simple fades, yielding so many false alarms that it would render the monitoring system useless. But a loss of both the strong localization signal and GNSS would likely be considered suspicious and result in a valid alarm.
GNSS navigation is truly one of the great advances of the modern era, giving us precise time and location for any place in the world. Its two major weaknesses — that it is easy to jam and spoof — can be overcome by augmenting it with other stronger encrypted signals, such as STL, providing robust jam-resistance and positive authentication.
Results from new tests of the Satellite Time and Location (STL) service, using equipment configurations with a differential source and with a more accurate OCXO clock, show timing accuracy of 160 nanoseconds.
The STL service uses a signal from the low-Earth orbit (LEO) Iridium constellation.
In 2016, Satelles demonstrated sub-microsecond timing using a stand-alone TCXO-based receiver (see “Innovation: Navigation from LEO,” July 2017 GPS World).
New testing employed three different configurations of equipment, services and environment, including a Stanford Research Systems (SRS) rubidium vapor frequency reference, based on the PRS10 module, and a Satelles Evaluation Kit (EVK2) STL receiver, comprising a Maxim RF chip, Xylinx Spartan-3 FPGA, TI dual-core DSP chip, and internal OCXO (oven-controlled crystal oscillator) or external clock.
Parameters and equipment for the three tests are:
Optimal. Outdoor antenna, Rubidium clock powered on for months prior to data collection, receiver configured in static mode with a known location, and high-quality antenna.
Sub-optimal. Indoor antenna, Rubidium clock powered on six hours prior to data collection, receiver configured in static mode with an unknown location, and low-quality antenna.
Three independent receivers collecting data, receiver on-board OCXO, indoor antenna, receiver configured in static mode with an unknown location, low-quality antenna. Tests performed: 10 days with no local reference station running; 10 days with local reference station, 20-kilometers away from test receivers, providing timing corrections to STL ground segment.
See Figure 1 for more extensive test results. Also see a previous article.
FIGURE 1. OCXO timing result with base station.
The 66-satellite Iridium LEO constellation transmits overlapping spot beams, which provide location-specific data that changes every few seconds.
Air Force Issues GPS III Follow-on Contract
The U.S. Air Force Space Command released its request for proposals to build 22 new GPS III satellites, called the GPS III Follow-On Phase 2 contract.
The contract will be awarded to a single bidder, and has an estimated dollar value of $10 billion including all options.
Phase 2 is planned as a single, predominantly fixed-price incentive-type contract awarded via full and open competition for production of 22 GPS III satellites. Deadline for proposals is April 16. Delivery of the first satellite is to be in 2026.
Phase 1 contracts awarded in May 2016 to Boeing, Northrop Grumman and Lockheed Martin (builder of the first 10 GPS III satellites) “determined that viable, low-risk, high-confidence sources exist to conduct a full and open competition for Phase 2, the production of 22 GPS III SVs [space vehicles] starting in the FY19 timeframe.”
BeiDou’s Long March
On Feb. 12, BeiDou-3 28 and 29 were launched into medium-Earth orbits, following the launch of a pair of BeiDou satellites on Jan. 11. The satellites form part of a third phase of BeiDou deployment, taking BeiDou coverage from regional to covering the countries along the Belt and Road initiative by the end of 2018, and global by 2020.
Per Enge, Professor and Director, Stanford university Center for Position Navigation and Time
Satelles, a secure time and location solutions company, has appointed Per Enge to its board of directors. Satelles provides a time and location solutions delivered over the Iridium constellation of 66 low-earth-orbiting satellites.
Enge is the Vance and Arlene Coffman Professor of Aeronautics and Astronautics for Stanford University, where he is also the director of the Stanford Center for Position Navigation and Time.
“I am eager to join the Satelles Board of Directors and look forward to supporting the management team,” Enge said. “I am encouraged by the progress Satelles has made and continue to have confidence in the leadership team and future growth of the business.”
Enge’s laboratory has worked with the U.S. Coast Guard to design a medium frequency radio system to broadcast differential GPS corrections to maritime users, and this system has been implemented as a worldwide standard.
His laboratory also worked with the U.S. Federal Aviation Administration to develop WAAS, the Wide-Area Augmentation System that provides GPS integrity data to airborne users. Today, WAAS is carried by more than 100,000 aircraft, and similar systems have been implemented in Europe, India and Japan.
Enge also serves on the board of directors of Amida Technologies, and he serves as a technical advisor to Polaris Wireless.
He has received the Kepler, Thurlow and Burka Awards from the Institute of Navigation for his work. He is a Fellow of the Institute of Electrical and Electronics Engineers. He is a member of the National Academy of Engineering and a fellow of the Institute of Navigation.
Enge received his Ph.D. in electrical engineering from the University of Illinois in 1983. In 2012, the U.S. Air Force inducted Enge into the GPS Hall of Fame.
“It is with great pleasure that we welcome Per to Satelles Board of Directors,” said Michael O’Connor, Satelles CEO. “Per has distinguished himself as a technology innovator and brings to our board of directors deep expertise in global navigation satellite systems. His wealth of experience and expertise in GPS and other technologies adds new depth to our board as we continue to deliver Satellite Time and Location to users around the world. We look forward to working with Per on our mission is to deliver trusted time and location solutions that augment and enhance existing solutions — including GPS.”
