Viavi Solutions Inc. has launched the patent-pending Cesium-less ePRTC360+ holdover solution to safeguard at-risk critical power grids, transportation, aviation and public safety systems, 5G mobile networks and AI data center infrastructure against the increased threat of GNSS timing disruptions. It is the only alternative to Cesium clocks to meet ITU-T G.8272.1 standards.
The international ITU-T G.8272.1 standard stipulates that Enhanced Primary Reference Time Clock (ePRTC) holdover must have short-term drift of less than 30 ns when entering into holdover and a long-term drift of less than 100 ns over 14 days, all traceable to UTC. Previously achieved only by Cesium atomic clocks, VIAVI’s ePRTC360+ now also meets this standard.
The ePRTC360+ has been successfully tested across a range of live-sky defense and commercial jamming/spoofing environments, and has been integrated into VIAVI’s SecurePNT 6200 product series. The technology can maintain 100 ns accuracy during GNSS-denied threats through the resilient altGNSS GEO-L service with no time limit.
It also combines an augmented VIAVI SecureTime GEO anti-jamming antenna and an enhanced GNSS anti-spoofing antenna that also receive eGNSS GEO service with GPS/GNSS-NMA authentication for spoofing detection and mitigation.
Unlike conventional GNSS omni-directional signals, which can be drowned out by low-power interference, VIAVI’s GNSS-independent GEO-L service leverages encrypted and highly directional L-band signals transmitted from geostationary satellites. Coupled with the augmented VIAVI SecureTime GEO antenna, the altGNSS GEO-L service provides enhanced anti-jamming protection and a resilient timing reference for the ePRTC360+’s internal Rubidium holdover oscillator and enables smooth multi-orbit source switchover, even when primary GNSS frequencies are jammed, spoofed or subject to sophisticated meaconing attacks.
The affordability of ePRTC360+ clocks compared to Cesium clocks enable operators to deploy them beyond the core and across the network. They also complement non-RF Cesium clocks at the core. This boosts end-to-end sync network robustness and holdover reliability through meshed network PTP feeds as backup between the clocks, especially in case of local or regional jamming and/or spoofing threats.
In addition, the ePRTC360+ addresses constraints posed by the use of Cesium clocks for holdover timing. These include sensitivity to shock, delicate and multi-stage startup procedures that take days to complete, the need for ECCN 3A001.i licenses for export, long GNSS learning period of up to 40 days, as well as strict shipping and storage protocols. In addition, Cesium tubes need to be replaced approximately every seven years, and the dismantling and disposal of Cesium clocks are classified as a hazard due to their material content.
The ePRTC360+ eliminates these hurdles and has been designed for rapid and easy integration into any vendor’s grandmaster clock system. It enables operators to meet stringent ePRTC requirements while reducing total cost of ownership.
The ePRTC360+ will be demonstrated at VIAVI’s Stand 5B18 at Mobile World Congress (MWC) Barcelona 2026, March 2-5, in Barcelona, Spain.
Dedicated research and development, funded by European Union (EU) and European Space Agency (ESA) programs over the years, has played a key role in Galileo Second Generation.
Among the innovations that will benefit the new satellites are the development of new atomic clocks, links that allow the satellites to “talk” to one another in orbit and a prototype ground station that can precisely pinpoint satellites in the sky. These advanced technologies will ensure Galileo continues to provide world‑class positioning, navigation and timing to users worldwide.
The importance of R&D
Satellite navigation is constantly evolving, with new technologies being deployed. But before a technology can fly on a satellite, it must be derisked and qualified. This is where research and development (R&D) comes in, laying the groundwork for new technologies long before they see the light of day.
Horizon 2020 and Horizon Europe are R&D programs funded by the EU. A significant budget from these programmes is delegated to ESA for R&D to derisk new technologies for evolutions of Europe’s Galileo and EGNOS systems.
Complementing these EU R&D programs, ESA programs such as the General Studies Programme (now Discovery and Preparation), General Support Technology Programme and the former European GNSS Evolution Program (EGEP) have also performed R&D for future satellite navigation technologies.
R&D spurs the innovation that allows Galileo and EGNOS to modernise and develop new applications and services. Several activities funded through these programmes have contributed to Galileo Second Generation (G2). Some of these technologies will already fly on the G2 satellites when they are launched in the coming years.
New ways of keeping time
Galileo relies on highly precise onboard atomic clocks to ensure accurate global positioning and timing. Here, an iodine optical clock by SpaceTech, Germany (Credit: ESA)
Galileo delivers world-class positioning and timing, and its onboard clocks are the key to its performance. Each first generation Galileo satellite carries two passive hydrogen maser and two rubidium atomic frequency standard clocks. These clocks, developed by Leonardo and Safran Timing Technologies, respectively, are currently Galileo’s only space-qualified clocks.
A rubidium pulsed optically pumped (Rb POP) clock by Leonardo, Italy. (Credit: ESA)
To keep up with the latest technologies and allow for a broader diversity of European qualified clocks, R&D activities have encouraged European companies to develop new types of space-worthy atomic clocks. This investment is critical due to the time and expertise it takes to develop such complex and sensitive technologies. These activities aimed to develop alternative atomic clocks for Galileo that can improve performance and robustness and support Europe’s place as a leader in satellite navigation.
A Mercury ion clock (MIC) from Safran Timing Technologies, Switzerland. (Credit: ESA)
Seven innovative clock technologies were developed by European companies from France, Germany, Italy and Switzerland. After initial development activities, three of these clocks — proposed by Leondardo, SpaceTech and Safran Timing Technologies — were selected to progress to hardware development in preparation for a first flight.
Leonardo’s Rubidium Pulsed Optically Pumped clock is currently under development and planned to fly as an experimental clock on a Galileo Second Generation satellite. The Iodine Optical clock developed by SpaceTech is undergoing early development and shows potential for future use as an experimental clock on Galileo satellites. The Mercury Ion clock by Safran Timing Technologies recently launched its development activities.
Following an analysis of the clocks’ eventual in-orbit performance, a programme decision by the European Commission will be made before starting the operational phase of these new clock technologies.
Conversations in the sky
An intersatellite link transceiver by Thales Alenia Space. (Credit: ESA)
The Galileo system currently relies on links between satellites and ground stations to monitor and control the satellites and to determine the onboard clock skew. Clock skew occurs when a clock signal reaches different parts of a system at different times, which can cause errors in position calculations.
Galileo Second Generation will introduce inter-satellite links (ISL), allowing the satellites to ‘talk’ directly to one another in orbit. This will enable additional time synchronisation and ranging measurements that will improve knowledge of the satellites’ orbit and clock skew.
ISL will also allow faster data dissemination. If a particular satellite is not visible to a ground station, information can be sent to a different satellite and then passed on instead of waiting for the satellite to be visible.
An intersatellite link transceiver by Airbus Defence and Space. (Credit: ESA)
Two early models of ISL transceivers that are essentially identical to those which will fly on the Galileo Second Generation satellites were designed and developed. The transceivers, which can both send and receive signals, were developed by Thales Alenia Space (Spain) and Airbus Defence and Space (Germany).
One of these transceivers is about to enter the formal testing phase, while the other has undergone successful environmental qualifications. After the transceivers have completed their qualifications and testing, they will be ready for their trip to space.
Precisely pinpointing satellites
Accurate positioning, navigation and timing relies on knowing precisely where satellites are in their orbits. Galileo satellites are located by tracking their L-band antenna transmissions from the ground. Each satellite also has a laser retroreflector, which allows measurement of their orbit to within a few centimeters. Known as satellite laser ranging (SLR), this method measures the time it takes for a laser pulse to make the trip from a ground station, called an SLR station, to the satellite and back, then uses these measurements to determine the satellite’s orbit. Presently, SLR stations are owned and operated by scientific community users and serve multiple space missions.
One of the challenges of current SLR is the fact that the lasers are not safe for human eyes and cannot be used if an aircraft is flying nearby as the lasers could blind the pilots. This means SLR stations must coordinate with civil aviation and may not be allowed to use all parts of the sky. SLR stations also have limited availability due to local atmospheric conditions (clear skies are key), and low levels of automation (intensive need for human operators).
A prototype satellite laser ranging station in Matera, Italy. (Credit: ESA)
To mitigate these limitations, a modernized, eye-safe SLR station prototype for Galileo satellites has been developed by DiGOS (Germany) and commissioned in Matera, Italy. Due to the station design and laser wavelength used, there will be no need to coordinate with civil aviation. The station’s new technologies also explore increased automation using a predefined schedule to reach satellites. Although human operators are still needed, their workload is reduced.
A field campaign of the prototype SLR station is planned for this year as part of the Galileo Second Generation System Test Bed tasks. It will evaluate the potential benefits of SLR as a complement to L-band ground ranging. If the station is added to the Galileo ground segment, it could enhance the system’s robustness by providing an independent means of determining the satellites’ locations. In this case, interface design adjustments would need to be made to allow operational use of the station.
Beyond providing another method for determining Galileo satellite orbits, this station could also help contribute to the Galileo Terrestrial Reference Frame and could support ESA navigation scientific missions such as Genesis.
Microchip Technology has introduced its second-generation Low-Noise Chip-Scale Atomic Clock (LN-CSAC), model SA65-LN. It features a lower profile height and operates in a wider temperature range, providing low-phase noise and atomic clock stability in challenging environments.
Chip-scale atomic clocks (CSACs) offer precise and stable timing in situations where traditional atomic clocks are impractical due to size or power constraints or where satellite-based references may be unreliable.
The SA65-LN, featuring Microchip’s Evacuated Miniature Crystal Oscillator (EMXO) technology, offers significant advancements in oscillator design. With a profile height of less than half an inch, power consumption under 295 mW, and an operating temperature range from −40°C to +80°C, this compact device delivers impressive performance. These enhanced specifications make the SA65-LN an ideal choice for a wide array of aerospace and defense applications. It is particularly well-suited for use in mobile radar systems, dismounted radios, IED jamming equipment, autonomous sensor networks, and unmanned vehicles, where size, power efficiency, and temperature resilience are crucial factors.
The LN-CSAC combines a crystal oscillator and an atomic clock in a single device, offering a low-phase noise of 10 Hz < −120 dBc/Hz, an Allan Deviation (ADEV) stability of < 1E-11 at 1-second averaging time, and an initial accuracy of ±0.5 ppb. The LN-CSAC also demonstrates frequency stability with a < 0.9 ppb/mo drift and maximum temperature-induced errors of < ±0.3ppb. These features contribute to high-quality signal integrity and atomic-level accuracy, potentially extending mission durations and reducing maintenance requirements.
Clocks are at the heart of GPS. Advances in space-qualified atomic clocks that kept time to within 10 nanoseconds over a day were a key development that made GPS possible. It turns out that GPS must account for both special relativity and general relativity to deliver position at 1-meter level and time at 100-nanosecond level to its users. We’ll use these round numbers as user expectations from GPS.
In the simple engineering analysis below, we consider the problems that would have arisen if the engineers had ignored relativity in their design of GPS. The issues related to positioning and time transfer are distinct, so we treat them separately.
GPS is basically a bunch of synchronized, near-perfect clocks in orbit
It’s a mantra worth repeating: To measure ranges to GPS satellites with meter-level accuracy, the clocks on the satellites must keep time with nanosecond-level accuracy.
The clocks aboard GPS satellites are extraordinarily stable, typically to one part in 1013 over a day, which is another way saying that they could gain or lose on average 10-8 seconds, or 10 nanoseconds, over 105 seconds, which is roughly the length of a day. It’s a simple calculation. Suppose you measure a time interval of length with an oscillator advertised to have frequency f by counting its periods of oscillation. If the actual frequency is (f + Δf ), you’d measure the time interval as (T + Δt). It is easily shown that:
The fractional frequency stability (f / Δf ) is a key parameter. For an oscillator with stability (f / Δf ) of 10-13 over a day, as noted above, we can limit to 10 nanoseconds on average with data uploads to satellites once a day to re-sync the clocks. An error of 10 nano-seconds in time amounts to an error of about 3 meters in range computation and, speaking roughly, an error of about 3 meters in the position computed by the receiver. We can live with that.
Gravitational and motional effects on GPS clocks
Our previous calculation of the timekeeping error of a satellite clock would have been fine had we not overlooked an important fact: We pretended as though the clocks were at rest on Earth at mean sea level. So, let’s see what relativity has to say about clocks in 20,000-kilometer-high circular orbits around Earth. The satellite orbits are not perfectly circular, or identical, but for now let’s pretend that they are. We call that modeling. The clocks would move at a rate of about 4 kilometers per second and exist in an environment where Earth’s gravity is only about one-fourth that at sea level.
According to the theory of special relativity, a moving clock ticks more slowly when compared with one that’s stationary at sea level. A clock aboard a GPS satellite will lose about 7 microseconds per day. That is three orders of magnitude larger than our budget for satellite clock error discussed earlier, therefore we can’t simply ignore it.
According to the theory of general relativity, on the other hand, a clock in a weaker gravitational field will tick faster than one that’s stationary at sea level. Apparently, gravity weighs down time, too. A clock aboard a GPS satellite in a medium Earth orbit will gain about 45 microseconds per day over a clock that’s at sea level on the earth.
The net effect: A GPS satellite clock will gain about 38 microseconds per day over a clock at rest at mean sea level. This effect is secular, meaning the time offset will grow from day to day.
So, you ask: Can you show me how you came up with these numbers, 7 micro-seconds and 45 microseconds? No, but I can point you to the references listed below and I can come close using simple mathematical models: (i) Earth’s gravitational potential is complicated and to simplify things we model Earth as homogeneous in composition and spherical in shape with a radius (rE) of 6,400 kilometers; (ii) aGPS satellite orbit is a circle with radius 4 rE; and (iii) the satellites move at the rate of 4 kilometers/second. We saved ourselves a lot of trouble by agreeing on this simple model.
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The calculation of the fractional frequency stability (f / Δf ) due to the relativistic effects is now easy and given in the sidebar. The answers are only approximate, but surprisingly close to the numbers cited above. That’s the beauty of good models. To calculate time gained or lost over a day, multiply by the length of a day in seconds.
As an interesting aside, note that the effects predicted by special relativity and general relativity cancel each other for clocks located at sea level anywhere on Earth. Consider two clocks, one located at the North or South Pole, and the other at the equator. The clock at the equator would tick slower because of its relative speed due to Earth’s spin, but faster because of its greater distance from Earth’s center of mass (about 22 kilometers) due to Earth’s flattening. Because Earth’s spin rate determines its shape, the two effects are not independent, and it’s no coincidence that they cancel exactly.
What if GPS forgot about relativity?
What would have happened if the engineers responsible for designing GPS had disregarded relativity? If the GPS satellites were in fact in identical, circular or-bits, their clocks would have shown a puzzling, but identical, behavior of gaining time over clocks of the Control Segment on Earth at a steady rate, about 38 microseconds over a day, the combined effect of special and general relativity.
What would that do to range measurements? A GPS receiver would have meas-ured the ranges to all satellites in view as too short by a common amount (up to about 11 kilometers between daily uploads of clock corrections). However, GPS receivers don’t measure ranges. To measure ranges, the receiver clock would have to be synchronized with the satellite clocks, an onerous requirement. The receivers use inexpensive clocks that drift and have frequency stability no bet-ter than . The receivers measure pseudoranges, i.e., ranges with a common bias on account of the receiver clock offset relative to GPS Time. This bias is es-timated by the receiver, along with its three-dimensional position. The price of an inexpensive receiver clock is that we now have four parameters to estimate and need pseudorange measurements from four satellites.
So, what would that do to positioning? The answer is that the common bias introduced by the relativistic effects would get lumped with the typically much larger bias introduced by the offset in the receiver clock. The position estimate would be unaffected.
Now, what about time from GPS? A GPS receiver used for timing is typically stationary with its antenna location carefully surveyed. In principle, a single pseu-dorange measurement can sync it to GPS Time (and UTC). So, if the relativistic effects had been ignored, the timing accuracy would have suffered to the ex-tent of 38 microseconds per day between updates of the clock parameters. That’s a deal-breaker, considering that we expect 100-nanosecond accuracy.
The relativistic effects discussed so far can be compensated for easily by setting the frequency of the satellite clocks lower (by 0.0045674 hertz) in what’s called “factory offset”: The frequency of a satellite clock is set to 10.22999999543 megahertz so that it will tick in orbit at the same rate as a 10.23-megahertz atomic standard at sea level on Earth. What an ingenious solution!
This factory offset would have accounted for the relativistic effects completely if the GPS satellite orbits were perfectly circular and identical. They are not. You can’t control an orbit perfectly.
So, what about eccentric orbits?
Yes, that’s a complication.
Each orbit is distinct and slightly elliptical. A consequence of this is that the sat-ellite speed is not constant (due to Kepler’s second law): the farther away a sat-ellite gets from Earth in its elliptical orbit, the slower it moves; and the farther away the satellite, the lower is the gravity field. That means the clocks in differ-ent satellites are speeding up and slowing down at different times and at differ-ent rates. The effect for each clock is periodic and quasi-sinusoidal. Averaging the effect over an orbit, we get zero.
For a satellite in an orbit with an eccentricity of 0.02, the net effect is that a clock can be ahead or behind by as much as 45 nanoseconds. The corresponding range error would amount to ± 15 meters. This effect must be accounted for specifically for each orbit. It would require serious bookkeeping on where the satellite has been in its elliptical orbit since the last data upload to sync its clock. It’s a messy business but can be simplified. We’d leave it at that. See ICD-GPS-200C, Section 20.3.3.3.3.1, if you want to see how it is implemented in your GPS receiver.
There is more to relativity than the special theory and general theory. There is the Sagnac effect associated with our rotating reference frames attached to Earth, in which we’d like to determine a position. The principle of constancy of the speed of light cannot be applied in a rotating reference frame, where the paths of the radio rays are not straight lines, but spirals. (Receivers at rest on Earth are moving quite rapidly: 465 meters per second at the equator.) There is also the Shapiro delay associated with the slowing of electromagnetic waves as they near Earth, which amounts to a fraction of a nanosecond. See the refer-ences for more on these topics.
Final thought: Could Einstein have imagined one hundred years ago that a bil-lion people would unknowingly account for the effects of his esoteric theory in their everyday activities?
Refrences
Ashby (1993), “Relativity and GPS,” Innovation column in GPS World
Microchip Technology has released the 5071B cesium atomic clock that can perform autonomous timekeeping for months in the event of GNSS denials.
The 5071B is the next-generation commercial cesium clock to the 5071A. The 5071B is available in a three-unit height, 19-inch rackmount enclosure, making it a compact product for environments where it can be easily transported and secured.
The 5071B has upgraded electronic components to address possible obsolescence or non-RoHS circuitry. The clock provides 100 ns holdover for more than two months, maintaining system synchronization when GNSS signals, like GPS, are denied.
As a cesium beam tube product with no deterministic long-term frequency drift, the 5071B provides absolute frequency accuracy of 5E-13 or 500 quadrillionths over all specified environmental conditions for the life of the product. For military applications requiring rapid deployments for system radars, 5E-13 stability eliminates the need for the acquisition of external synchronization sources prior to radiating.
The 5071B is now fully compliant with the Restriction of Hazardous Substances Directive, making this device available in regions where regulatory policies are in place.
While I’m likely preaching to the choir here, GNSS cannot work unless we have an accurate description of the orbits of the satellites and the behavior of their atomic clocks. The accuracy with which this information is provided to a receiver or data processing software is the most important component of the error budget of GNSS positioning, navigation and timing and constitutes most of what is known as the signal-in-space (SIS) range error.
Each GNSS satellite broadcasts a description of its orbit or ephemeris along with the offset of its active clock from the system’s time standard in a navigation message decoded and used by the receiver. These data are predictions of the orbit and clock offset as computed by the system’s ground control segment and uploaded to each satellite. A recent assessment by U.S. Space Systems Command of the GPS SIS error averaged across all active satellites for a one-week period was about 50 centimeters, root-mean-square. While this is entirely adequate for many GNSS uses, it falls short of the required accuracy for high-demanding applications such as surveying, geodesy, atmospheric sensing, reference frame studies and tectonic monitoring. Which is why various organizations both private and public compute very accurate orbits and clocks and provide these to users. These computations, using data from global receiver networks, are very exacting and model the tiniest effects on the (primarily) carrier-phase measurements these receivers provide.
These effects include the offset in the electrical phase centers of a GNSS satellite’s transmitting antenna from the satellite’s center of mass and how that varies with the direction of the signal from the satellite to a receiver on Earth. Furthermore, this behavior must be calibrated and modeled for each radio frequency that the satellite transmits. Another effect that must be accounted for are the perturbations caused by non-perfect yaw-steering of a satellite’s solar panels. These panels continuously track the Sun but they have difficulty keeping up at orbit noon and midnight. Accurate models of the actual yaw angle are very important for high-precision GNSS orbits. As if these model requirements were not enough, the effect of solar radiation pressure on satellite orbits must also be modeled. While they don’t have (rest) mass, photons have energy and this can be imparted to satellites when they impinge on them. While a single photon has a negligible effect, the billions upon billions of photons making up sunlight do have a noticeable effect on a GNSS satellite’s motion and must be accounted for by orbit models.
One organization producing precise orbits for GNSS satellites – arguably the most precise in the world – is the International GNSS Service (IGS), a voluntary federation of more than 200 agencies, universities and research institutions across the globe. Several of these organizations each produce precise orbits, which they submit to the IGS to establish orbit products. One of these organizations is the Navigation Support Office (NSO) at the European Space Agency’s European Space Operations Centre. In this quarter’s Innovation column, a team of NSO engineers discusses how they have improved the orbit modeling of the GPS III satellites by around a factor of two with estimated orbit errors of about 2 centimeters or less. Wizardry? Not really – just rocket science.
Viavi Solutions has unveiled the PNT-6200 Series Assured Reference for resilient positioning, navigation and timing (PNT). Viavi acquired Jackson Labs Technologies in November 2022.
The PNT-6200 Series Assured Reference provides resiliency and robust cybersecurity for critical infrastructure.
The compact system can supplement or replace GPS signals based on connectivity to the broadcast range of timing sources in the market including other GNSS satellites, and commercial satellite, terrestrial, wireline, and atomic clock services. The PNT-6200 Series will draw the timing signal from the most reliable source and use it as a replacement for the GPS input, enabling continuous operation.
The PNT-6200 Series will be showcased at Mobile World Congress in Barcelona, Feb. 27-March 2.
Orolia developed the Skydel GSG-8, a PNT test solution in its GSG family of simulators, to deliver GNSS signal testing and sensor simulation performance in an easy to use, upgradable and scalable platform. (Photo: Orolia)
We discussed complementary PNT with Erik Oehler, marketing director at Orolia.
What are some of the most promising approaches to complementary PNT and how does simulation technology help?
5G is the most promising for the future. I believe the benefits in infrastructure, speed, precision, reliability, and the industry incentives 5G offer are superior to GNSS. Alternative signals of opportunity and new commercial satellite-based providers are always valuable as extra layers of resilience. However, PNT from 5G is not quite ready yet. There will be a transition period during which systems use GNSS and these signals of opportunity simultaneously, so simulation enables receivers of any complementary signal to be tested in the same environments and with the same potential threats faced by primary constellation signals.
How does Orolia fit in that mix?
Orolia has the most atomic clocks in orbit, including those aboard the Galileo constellation. We integrate anti-jam antennas and build Interference Detection and Mitigation (IDM) into our products. We partner with companies that offer alternative signals, such as STL from Satelles. Our SecureSync NTP and PTP time servers live in the world’s biggest data centers and support encrypted signals, such as M and Y code for our militaries. We innovate with industry leaders such as Meta on building a better PCIe Time Card. We offer edge time servers with the ability to automatically add Hoptroff’s Traceable Time as a Service. If 5G PNT becomes a standard, we are already providing industry leaders such as Anritsu with solutions for acceptance testing on a major carrier’s backbone. With our pending acquisition by Safran and access to a world-leading portfolio of INS components, we are one of the most qualified companies in the world to solve nearly any PNT challenge.
What kinds of complementary PNT are most useful in addressing specifically the challenges posed by jamming and spoofing, and how does simulation help?
In two technical notes published by NIST, they recognize STL as one of four recommended solutions for PNT resilience and the only one being both independent of GNSS and capable of sub-microsecond accuracy. Being closer to Earth, it is a stronger signal, making it 1,000 times less susceptible to jamming. Additionally, because it is encrypted it is inherently immune to spoofing. The aforementioned Hoptroff TTaS is time delivered over VPN, removing the outside environment component completely. For positioning and navigation, the integration of an IMU provides a contiguous PNT solution even during periods of GNSS denial, analogous to how an atomic clock provides precise time holdover during these denial periods. Combined with anti-jam antenna technology and IDM software, a robust PNT solution is always available.
Simulation helps by (1) identifying the vulnerabilities your PNT system might have (or could have in the future to evolving threats) and (2) verifying the total integrated resilient system. Our GSG-8 Advanced GNSS Simulator supports hundreds of GNSS full spectrum signals, custom signals, and hardware-in-the-loop testing of integrated IMUs at up to 1000 Hz iteration rate. Our Skydel Wavefront and Anechoic simulators can verify the most complex GNSS anti-jam antenna systems.
Service providers harnessing the solution can now offer GNSS/GPS- backup-as-a-service (GBaaS) with enhanced precision and availability
OSA 3300-HP. (Photo: ADVA)
ADVA has introduced its Oscilloquartz high-performance optical cesium atomic clock. The coreSync OSA 3300-HP is ADVA’s latest innovation in assured positioning, navigation and timing (PNT).
Following ADVA’s launch of an optical pumping timing solution two years ago, the OSA 3350 ePRC+, the OSA 3300-HP takes the technology to new levels. It has a 10-year lifetime compared to the five years offered by currently available high-performance magnetic clocks.
As a high-performance optical cesium clock, the OSA 3300-HP sets a new benchmark for precision and availability, ADVA claimed, providing the resilience required for PNT assurance in critical infrastructure and empowering service providers to deliver differentiated service-level-agreement timing offerings with integrated GNSS backup.
The feature-rich device has embedded Ethernet- and IP-based management as well as a user-friendly touchscreen graphical user interface.
“The launch of our coreSync OSA 3300-HP marks a key milestone in the design of atomic frequency and phase standards,” said Gil Biran, GM of Oscilloquartz, ADVA. “After many years of extensive work in our Swiss laboratories supported by the European Space Agency, we now have a mature, state-of-the-art technology that enables a major leap in the accuracy and stability of network timing while providing a substantially longer lifetime.”
Atomic clocks offer synchronization backup for networks that rely on GNSS-based timing, combining high accuracy with outstanding availability. The OSA 3300-HP commercial high-performance optical cesium atomic clock features an all-digital design and leverages optical-pumping techniques using laser diodes. This enables it to measure 100 times the number of atoms, making it more efficient compared to existing primary reference clock (PRC) technologies.
Thales and Syrlinks have signed a multi-year contract with the French defence procurement agency (DGA) to develop a new generation of tiny, high-performance atomic clocks.
Code-named Chronos, these new quantum clocks will meet the requirements of numerous civil and military applications. With their very high stability (error of less than 1 second in tens of thousands of years), defence electronics equipment will be able to operate when a GNSS signal is unavailable, for example due to hostile jamming.
Working with the procurement agency, the partners will help safeguard France’s technological sovereignty in GNSS-denied positioning, guidance, navigation and encrypted military communications. In civil applications (5G network synchronization, transport, energy, etc.), the Chronos quantum clocks will deliver low price and high performance to French and international customers.
Large swaths of the modern economy now rely on satellites for synchronization. GNSS technology provides the precise time reference for critical infrastructure such as 4G/5G networks, internet, air and rail transport, energy networks, global banking transactions and high-frequency trading, which would quickly fail if the signal were unavailable. In view of this high level of dependency, backup systems are needed to ensure that our civil and military infrastructure can continue to operate even if the GNSS timing signal is unavailable.
Thales’s industrial facility in Vélizy-Villacoublay and the Thales Research & Technology center in Palaiseau, both near Paris, have the industrial capabilities and talent to manufacture the atomic and optical core of these future quantum clocks.
Syrlinks — a French company based in Rennes, Brittany — specializes in satellite radiocommunications, radionavigation systems and miniature atomic clocks, and its products were selected to equip 650 satellites for the American operator OneWeb. The company will develop the electronic brain of the Chronos clock and guarantee its high-precision timing function.
The CNRS will provide critical scientific support for this project via its SYRTE (Observatoire de Paris) and Femto-ST (Université de Franche-Comté) joint research units.
Latest atomic clock designed for commercial, military and aerospace operations; launch webinar scheduled for July 7
Photo: Orolia
Orolia has introduced an upgraded edition of its low size, weight, power and cost (SWaP-C) miniaturized rubidium oscillator product line, the mRO-50 Ruggedized, to meet the latest military and aerospace requirements where time stability and power consumption are critical.
The mRO-50 Ruggedized provides a one-day holdover below 1 µs and a retrace below 1E-10 in a form factor (50.8 x 50.8 x 20mm) that takes up only 51 cc of volume (about one-third of the volume compared to standard rubidium oscillators) and consumes only 0.36 W of power, which is about 10 times less than existing solutions with similar capabilities, the company said.
With these competitive advantages, the new mRO-50 Ruggedized miniaturized rubidium oscillator provides accurate frequency and precise time synchronization to mobile applications, such as military radio-pack systems in GNSS-degraded or denied environments. Its wide-range operating temperature of -40°C to 80°C is also suitable for a wide range of applications such as underwater, military communications, radars, low Earth orbit, electronic warfare, airborne and unmanned vehicles.
“Our dedication and innovative design have contributed to the most accurate GNSS systems in service today,” said Jean-Charles Chen, Orolia Atomic Clocks Product Line director. “Orolia launched the mRO-50 in 2020, bringing the best rubidium technologies into one small form factor and ultra-portable packaging.”
The mRO-50 Ruggedized enhances this breakthrough technology with modifications providing wider thermal range, quicker lock and higher stability.
Orolia’s timing solutions support space agencies and research institutes worldwide, including the European Space Agency (ESA), NASA, Jet Propulsion Laboratory, SpaceX, Blue Origin, the Centre National d’Étude Spatiales (CNES France), the National Physics Laboratory (NPL UK), Deutsches Zentrum für Luft- und Raumfahrt (DLR Germany) and the Japan Aerospace Exploration Agency (JAXA).
ESA awarded Orolia two contracts to provide atomic clocks for the first 12 satellites for the Galileo Second Generation System. Each of the new satellites, designed to provide unprecedented accuracy worldwide, will contain three Orolia Rubidium Atomic Frequency Standards (RAFS) and two Orolia atomic clock physics packages integrated with Leonardo’s Passive Hydrogen Masers (PHM).
Chip-scale atomic clocks can supplement GNSS receivers to provide accurate and reliable time in GNSS-challenged environments. Photo: Microchip Technology
Accurate and reliable time is just as important as accurate and reliable location for a wide range of military and civilian applications — and GNSS receivers cannot provide either one when they are jammed. For timing, one solution is to supplement GNSS receivers with a miniature atomic clock. We asked Microchip Technology a few questions about their chip-scale atomic clock (CSAC) and Stewart Hampton, the company’s senior product line manager, responded.
How long was your SA65 CSAC in development before you announced it in August 2021? Typically, how often do you launch a new CSAC?
CSAC development started in 2001 under a contract from DARPA with Draper and Sandia laboratories. CSAC was first introduced to the commercial marketplace in 2011, and in 2016 we released an improved product design with an operating temperature range of –10 C° to +70 C°. Last year we released our CSAC SA65 with a wider operating temperature range, faster warm-up and improved frequency stability aimed at the defense and industrial marketplace. So, it has been about five years between major CSAC releases, but that may not be indicative of future products because we have also introduced specialized CSAC versions, such as the Low Noise CSAC (LNCSAC) in 2014 and the only commercially available radiation-tolerant CSAC (Space CSAC) in 2018.
What is the CSAC SA65’s drift rate?
Its typical drift rate is specified at <9 × 10–10 per month. Another key specification, particularly for many portable military applications, is total sensitivity of frequency to temperature (tempco) over a specified range. For the CSAC SA65, that specification is ±3 × 10–10 over the entire operating temperature range of –40 C° to +80 C °.
What are a few specific military use cases?
CSAC is designed into multiple military programs and used in a wide variety of military applications, particularly in GNSS-denied environments — including assured positioning, navigation and timing (APNT) modules, underwater unmanned and autonomous vehicles, software-defined radios, man-portable transceiver-based military communications, vehicle management computers, airborne reconnaissance/UAVs and GNSS-disciplined oscillators. It is also used in command, control, communications, computers, cyber, intelligence, surveillance and reconnaissance (C5ISR). The space CSAC variant is commonly used on low-Earth-orbit space defense payloads supporting such applications as low-latency communications networks, RF geolocation (geointelligence, or GEOINT), optical time transfer, alternative PNT satellites and Earth observation.
