GPS World

Tag: field trial

  • OneNav L5-direct navigates through GPS interference in field trial

    OneNav L5-direct navigates through GPS interference in field trial

    For the first time, the oneNav L5-direct receiver was flown on a UAV through a simulated electronic warfare GPS signal interference field. The assessment took place Feb. 12 at the Emerging Technology Lab at U.S. Special Operations Command (USSOCOM). This non-classified evaluation replicated battlefield conditions, including variable speeds, altitudes, maneuvers and robust L5 signal interference.

    Assessment Setup

    The assessment included two GNSS devices secured to the UAV, an onboard navigation computer and an onboard interference device. Two additional interference sources were located on the ground.

    A simplified block diagram of the assessment setup. (Credit: oneNav)
    A simplified block diagram of the assessment setup. (Credit: oneNav)

    The onboard navigation computer integrated data from both GNSS receivers to determine and maintain the vehicle’s position and guide its movement. GNSS 1 was a competitor L1/L5 dual-band receiver that uses the L1C/A signal for initial acquisition before adding L5 signals. GNSS 2 was the oneNav L5-direct receiver, which exclusively utilized modern L5-band signals for both acquisition and tracking.

    Test Conditions and Results

    The in-flight assessment, conducted on a UAV under real-world dynamic and RF interference conditions, demonstrated that the oneNav L5-direct receiver operates independently of legacy GNSS signals such as L1 and L2. While conventional dual-band receivers require L1 acquisition before transitioning to L5 tracking, the oneNav solution used only modern L5 signals for both functions6.

    The Emerging Technology Lab implemented comprehensive RF interference protocols, including both ground-based and airborne signal interference across multiple L5 frequencies. The oneNav L5-direct receiver maintained tracking capabilities during L5/E5a signal interference centered at 1176.45 MHz. This performance is attributed to the receiver’s wideband RF front-end architecture, which enables simultaneous processing across an extensive frequency range. The system leverages Galileo’s dual sideband configuration (E5a and E5b), automatically transitioning to E5b when E5a experiences interference—a feature unique to the oneNav technology. A brief six-second delay was observed during this transition, reflecting a three-second lock loss on E5a followed by a three-second acquisition of E5b. The ability to track E5b signals, despite a 10 dB power differential, highlights the receiver’s sensitivity.

    L5-direct FPGA attached to the assessment UAV. (Credit: oneNav)
    L5-direct FPGA attached to the assessment UAV. (Credit: oneNav)

    Key Findings

    • The oneNav L5-direct GNSS receiver acquired, tracked and provided location data to the drone flight computer under actual flight dynamics and through L5 band signal interference.
    • Direct acquisition and tracking using only L5-band signals was demonstrated, confirming immunity to L1 signal interference.
    • The receiver demonstrated resilience to L5 in-band signal interference at typical electronic warfare power levels, quickly adapting by switching to the E5b sideband when E5a was disrupted.
    • The receiver maintained stability and responsiveness when both E5a and E5b sidebands were blocked.
    • Continuous tracking functioned well with the BeiDou constellation off and the almanac on or off6.

    Technical Background

    The oneNav L5-direct technology was originally developed for consumer applications such as wearables, phones and surface vehicles. Its adaptability allows for rapid customization and deployment across a range of platforms, including those requiring robust performance in challenging environments.

    Because the L5-direct receiver uses signals exclusively within the L5 band, it can leverage the advanced features of these signals. L5-band signals offer greater power and increased resistance to RF interference compared to L1 signals. Industry experts, including Prof. Brad Parkinson, recognize the advantages of L5-only receivers for jam resistance.

    Currently implemented on FPGA architecture, a future L5-direct ASIC is expected to deliver performance improvements, including enhanced acquisition and tracking capabilities.

  • UrsaNav trials eLoran as GNSS backup with ADVA grandmaster clock

    UrsaNav trials eLoran as GNSS backup with ADVA grandmaster clock

    Successful eLoran field trial using ADVA’s OSA 5420 Series demonstrates same accuracy and stability as GPS with much-improved resilience

    UrsaNav and ADVA have conducted an enhanced long-range navigation (eLoran) field trial using UrsaNav’s eLoran receiver and ADVA’s Oscilloquartz grandmaster clock technology. The successful demonstration shows that eLoran offers a robust and reliable backup for GPS and other GNSS, and could be used to provide an assured position, navigation and timing (PNT) service.

    The trial follows U.S. PNT Executive Order 13905 aimed at strengthening national resilience through PNT services, including protecting critical infrastructure such as electrical power grid and communication networks from rising cyber threats. By harnessing ADVA’s flexible OSA 5420 series, designed with assured PNT (A-PNT) technology, UrsaNav has shown that eLoran can provide a new layer of protection and significantly boost timing resilience and security.

    “The success of this field trial demonstrates how eLoran, as part of ADVA’s assured PNT solution, can serve as a crucial backup for GPS,” said Charles Schue, CEO, UrsaNav. “We have shown how our technology enables ADVA’s grandmaster clock to receive UTC timing from the eLoran system for a period of several days with the same accuracy and stability as GPS. Of course, this capability is extensible to other GNSS as well. eLoran is far less vulnerable to unintentional jamming and spoofing disruptions or intentional attacks, thereby delivering nanosecond precision with even more resilience.”

    “By partnering with ADVA, we’ve been able to show that our eLoran receiver interoperates with the best network timing toolkit available,” Schue said. “The OSA 5420 Series is a great product — highly efficient and easy to operate. Together with ADVA, we’re paving the way for tomorrow’s more robust assured PNT synchronization architecture. Now that UrsaNav has demonstrated the power of our OSA 5420 Series to utilize eLoran in the event of outages, we have another very important tool to ensure the quality and availability of time-sensitive services.”

    UrsaNav’s latest trial used the OSA 5420 series grandmaster clock with built-in GNSS receiver. Timing stability from GPS was measured for several days. This was then replaced with eLoran for the same period with no loss of stability.

    The test was conducted indoors where GNSS signals are not usually available, potentially extending the availability of precise UTC timing to many more environments.

    “Commercially available GNSS jammers and spoofers are easy and cheap for attackers to acquire,” explained Nir Laufer, VP, product line management, Oscilloquartz, ADVA. “That’s part of the reason why we’re seeing a growing number of incidents across the world of blocked or misleading signals. If power utilities, enterprises, service providers and governments continue to rely on GNSS alone, it’s only a matter of time before the consequences become very serious. That’s why we’re committed to tackling GNSS vulnerabilities with advanced technologies like our ePRTC offering, cesium atomic clocks and our optical timing channel solution. Now that UrsaNav has demonstrated the power of our OSA 5420 series to utilize eLoran in the event of outages, we have another very important tool to ensure the quality and availability of time-sensitive services.”

    A demo showed how ADVA’s synchronization technology enables protection for critical infrastructure that needs ultra-reliable aPNT solutions. (Photo: Business Wire)
    The demo showed how ADVA’s synchronization technology enables protection for critical infrastructure that needs ultra-reliable aPNT solutions. (Photo: Business Wire)