GPS World

Tag: time transfer

  • Research Roundup: Lunar GNSS applications

    Research Roundup: Lunar GNSS applications

    Artist's rendering of the Lunar Pathfinder. (Image: SSTL)
    Artist’s impression of the Lunar Pathfinder satellite built by Surrey Satellite Technology Ltd. (SSTL) that will provide communications and navigation services for the Moon.

    NASA and its international partners are planning a return to our natural satellite. The following three papers — presented at the Institute of Navigation (ION) GNSS+ conference Sept. 20–24, 2021 — discuss the role of GNSS in lunar exploration. The full papers are available at www.ion.org/publications/browse.cfm.

    Using GPS for Time Transfer

    NASA and the European Space Agency have conceptualized the initial framework for a GPS-like constellation for the Moon, which will ensure uninterrupted navigation and communication services for future lunar missions. The authors designed a smallsat-based Lunar Navigation Satellite System (LNSS) with time-transfer from Earth-GPS to alleviate the size, weight and power (SWaP) and timing stability requirements of the onboard clocks. A timing filter corrects the lower grade clock when Earth-GPS signals are available and propagates these clock estimates forward in time when no Earth-GPS signals are available. The authors analyzed their proposed time-transfer technique using high-fidelity simulations of an LNSS satellite with an onboard chip-scale atomic clock for three cases of elliptical lunar frozen orbits.

    Bhamidipati, Sriramya, Mina, Tara, Gao, Grace, “Design Considerations of a Lunar Navigation Satellite System with Time-Transfer from Earth-GPS,” https://doi.org/10.33012/2021.18021

    GNSS Nav for Moon Missions

    The authors show the potential of autonomous GNSS signal-based navigation for a set of Moon scenarios. This technology could be a game changer for the future of lunar exploration, representing an extremely low cost and effective alternative for Moon navigation. Results show that not only autonomous GNSS navigation for lunar orbiters is possible, but it also delivers good navigation performance. In fact, navigation with root-mean-square (RMS) errors on the order of 50–100 meters were obtained for scenarios of high interest, such as for the planned Lunar Pathfinder and near-rectilinear halo orbit of the Lunar Gateway space station around the Moon.

    Mangialardo, Marco, Jurado, María Manzano, Hagan, David, Giordano, Pietro, Ventura-Traveset, Javier, “The full Potential of an Autonomous GNSS Signalbased Navigation System for Moon Missions,” https://doi.org/10.33012/2021.18040

    Finding the best lunar orbit

    A continuous and reliable lunar positioning and timing system, such as a GNSS-like constellation, is considered essential infrastructure for lunar exploration. The authors focus on halo orbits with the aim of defining an optimal halo constellation for supporting and delivering a navigation service on the Moon. This paper shows the performance of a GNSS-like constellation deployed in Halo orbits around Earth-Moon L1 and L2 collinear libration points. Different phases have been considered, from a minimum number of satellites able to provide a local PNT service on the South Pole (Initial Operational Capability), to a final, extended constellation able to cover the whole lunar surface (Final Operational Capability).

    Musacchio, Daniele, Iess, Luciano, Carosi, Mattia, Capolicchio, Jacopo, Eleuteri, Massimo, Stallo, Cosimo, Di Lauro, Carmine, “Design of Earth Moon Halo Orbits for a Global Lunar PNT Service,” https://doi.org/10.33012/2021.18020

  • Orolia to acquire Seven Solutions for resilient PNT

    Orolia to acquire Seven Solutions for resilient PNT

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    Merger to deliver high-end performance and ultra-accurate timing and frequency products for commercial, critical infrastructure and defense markets worldwide

    Orolia has entered into a definitive agreement to acquire Seven Solutions, a global innovator in White Rabbit sub-nanosecond time transfer and synchronization technology. This transaction is subject to customary closing conditions and approvals required by the Spanish government and is expected to close before the end of the year.

    This is Orolia’s 11th acquisition in the past seven years.  

    The merger with Seven Solutions, based in Granada, will enhance Orolia’s portfolio for defense, aerospace, data centers, telecom, financial services, smart grids and other critical infrastructure industries, and will enable the next-generation applications dependent on ultra-precise, resilient timing and frequency technology.

    GPS World published an article about Seven Solutions and its White Rabbit technology in its October issue.

    “Orolia and Seven Solutions under one umbrella will combine our world-leading technologies to draw a new frontier in network timing to sub-nanosecond levels, delivering the most robust and accurate resilient PNT solutions for our customers,” said Orolia CEO Jean-Yves Courtois. “Seven Solutions’ long history of delivering cutting-edge time distribution solutions to sectors like telecommunications, smart grids, aerospace, defense and scientific facilities aligns perfectly with Orolia’s DNA.”

    Orolia and Seven Solutions will integrate global sales, marketing, product development and operations.

    Orolia’s full-scale, modular approach to resilient PNT includes atomic clocks with a combination of GNSS signals protected with interference detection and mitigation technology, together with low-Earth-orbit secure alternative signals. The addition of Seven Solutions’ products will deliver terrestrial sub-nanosecond time distribution from distant and potentially redundant locations.

    “We believe the union of our companies will produce the future of time transfer and frequency distribution solutions in terms of accuracy, reliability and interoperability,” said Rafael Rodriguez, chief technology officer and co-founder of Seven Solutions. “Finance, 5G telecommunications, data centers and hyperscalers have new and upgraded functionalities requiring ultra-accurate time distribution accuracy. To maximize interoperability, our solution for time transfer is based on the White Rabbit concept that has been pushed over the last decade to become the basis of the standard high accuracy time transfer profile (within the recent release of IEEE 1588 of precision time protocol).”

    Orolia and Seven Solutions are members of the Open PNT Industry Alliance. The international organization focuses on market concepts that strengthen economic and national security by supporting government efforts to implement resilient PNT capabilities for critical infrastructure.

  • Timing in Mission-Critical Systems

    Broadcast Date: March 31, 2016
    On-Demand Available Until: March 31, 2017
    Sponsor: Microsemi
    Summary: You’ll hear from our expert speaker panel about real-life timing challenges in mission-critical applications, such as satellite and military communications, test ranges and radar; time transfer accuracy and stability via GPS or PTP; and what technologies to look for in your next-generation instrument class clock to cost-effectively deliver accurate and stable time and frequency signal types, signal output flexibility and robust security.
    Speakers: Paul Skoog, Microsemi Corporation; Scott Williams, G.L. Williams Associates; and James L. Wright, Range Generation Next