Photo: SandboxAQ

SandboxAQ has been awarded an SBIR Phase 2B Tactical Funding Increase (TACFI) by the United States Air Force (USAF) to further develop its dual-use AQNav magnetic navigation (MagNav) system. Under the contract, SandboxAQ and its partner AFWERX will explore new configurations of the AQNav technology, including a pod-based attachment, for use on a broader range of aircraft platforms, such as unmanned aerial systems.

AQNav navigation technology combines proprietary artificial intelligence (AI) Large Quantitative Models (LQMs), powerful quantum sensors and the Earth’s crustal magnetic field, resulting in a solution that operates effectively in all weather conditions, day or night and across any terrain. AQNav technology is completely passive and operates in real-time, offering an unjammable and un-spoofable alternative to traditional navigation methods. This system functions entirely independently of GNSS, offering a secure and dependable navigation option in environments where satellite signals may be compromised or unavailable. This is a key example of applying quantitative AI – AI models trained on quantitative data and not language. SandboxAQ is a leader in Large Quantitative Models (LQMs), in this case to pull the signal from the background magnetic noise for navigation.

This funding increase extends a prior Direct-to-Phase-II SBIR contract awarded to SandboxAQ in January 2023. To date, SandboxAQ’s AQNav technology has logged more than 200 flight hours and more than 40 sorties across multiple regions on four different aircraft types, ranging in size from single-engine planes to large military transport aircraft. In this process, AQNav was successfully tested in two USAF exercises – Exercise Golden Phoenix and Exercise Mobility Guardian – Air Mobility Command’s largest exercise at the time.

AQNav uses a powerful quantum magnetometer system to acquire data from Earth’s crustal magnetic field, which exhibits geographically unique patterns – similar to a human fingerprint. AQNav uses proprietary LQMs to compare this data against known magnetic maps, enabling the system to quickly and accurately find its position. Due to the high sensitivity of foundational quantum sensors, AI algorithms are applied to improve the signal-to-noise ratio, removing any mechanical, electrical, or other interference that would impact the system’s ability to acquire its location.

AQNav is available worldwide and can be used in air, land, and sea applications. The system does not rely on visual ground features or satellite transmissions to function and is not affected by weather conditions. Additionally, AQNav’s passive technology emits no electronic signals, which reduces the aircraft’s detectability. It operates at room temperature, requires no shielding, and has a small form factor that can be integrated into a wide variety of platforms, from multi-engine airliners to unmanned aerial vehicles.

SandboxAQ is developing AQNav as a dual-use solution to address the need for resilience to GPS vulnerabilities, which extends societally and economically. In addition to the USAF, SandboxAQ is engaged with several aerospace leaders to test and develop AQNav, including other allied governments, Boeing and Acubed — Airbus’s Silicon Valley research and innovation center.

<p>The post US Air Force and SandboxAQ address GPS jamming and spoofing first appeared on GPS World.</p>

Photo: TrustPoint

TrustPoint, a commercial GPS and navigation technology company, has been awarded a Phase II Small Business Technology Transfer (STTR) contract by AFWERX, totaling $1.6 million. The contract focuses on the development of advanced, resilient navigation applications to meet the challenges faced by the Department of the Air Force.

In collaboration with the Naval Postgraduate School, TrustPoint aims to enhance its GNSS capabilities and pave the way for applications that will boost the national defense of the United States.

The Air Force Research Laboratory (AFRL) and AFWERX have partnered to optimize the Small Business Innovation Research (SBIR) and STTR processes. Their efforts aim to provide quicker proposal-to-award timelines, broadening the applicant pool to include more small businesses and reducing bureaucratic overhead through ongoing process improvements. Since the initiation of the Open Topic SBIR/STTR program in 2018, the DAF has expanded the scope of innovations it funds, with TrustPoint’s project commencing on April 2, 2024.

<p>The post TrustPoint improves GNSS solutions for US Air Force first appeared on GPS World.</p>

Between Feb. 7, 05:02 UTC and Feb. 8, 12:30 UTC, 2017, all seven operational GPS Block IIR-M satellites were consecutively subject to short periods of unavailability. These official outage periods, when the satellite signals were set unhealthy and deemed unusable, were announced ahead of time through Notice Advisories to Navstar Users (NANUs). An overview of the outage periods and the corresponding NANUs for each satellite identified by their pseudorandom noise code (PRN) assignment and space vehicle number (SVN) is provided in TABLE 1.

Table 1. GPS Block IIR-M satellite outage periods and corresponding 2017 NANUs.

An analysis of the measured signal-to-noise-density ratio (C/N₀) from several tracking stations of the International GNSS Service (IGS) indicates that the satellites’ transmit powers were increased during the outage periods. The effect is visible in the plots in FIGURES 1 and 2, which show C/N₀ of the L1 C/A-code over time for satellite passes on the three consecutive days Feb. 6, 7 and 8, 2017.

Figure 1 shows the results for PRN 17 as tracked by a Septentrio PolaRx4TR receiver (USN8) located in Washington, DC. The pass on the outage day Feb. 7 is plotted in blue. Obviously, the receiver is configured to not track unhealthy satellites, since no observations are available during the outage period. However, a clear increase in the C/N₀ is visible from about 50.5 dB-Hz before the outage to approximately 52 dB-Hz after the outage. The C/N₀ level of the day before is similar to the level prior to the outage. The C/N₀ level on the following day is very similar to the C/N₀ after the outage, which indicates that the satellite continues to transmit with an increased power.

Figure 1. Plot of L1 C/A-code C/N₀ over time for consecutive satellite passes of satellite PRN 17 (SVN 53) tracked by a Septentrio PolaRx4TR receiver located in Washington, DC, on Feb. 6–8, 2017. The satellite’s unhealthy period on Feb. 7 is indicated by the gray shaded area.

The plot in Figure 2 shows the same analysis, this time for PRN 05 and for a Leica GR10 receiver (KOUG) located in Kourou, French Guiana. This receiver continues to track the satellite during the unhealthy period. The distinct step in C/N₀ is clearly visible shortly after the satellite is set unhealthy. Also, this satellite continues to transmit with increased power during the pass on the following day. The same observations as in Figure 1 and Figure 2 can also be made for all other Block IIR-M satellites and other receivers.

Figure 2. Plot of L1 C/A-code C/N₀ over time for consecutive passes of satellite PRN 05 (SVN 50) tracked by a Leica GR10 receiver located in Kourou, French Guiana, on Feb. 6–8. The satellite’s unhealthy period on Feb. 7 is indicated by the gray shaded area.

The difference between the measured C/N₀ before and after the unhealthy period is typically 1–2 dB-Hz depending on the receiver and the satellite (see TABLE 2). On average, a power increase of 1.5 dB with a scatter of ±0.25 dB among the various satellites is suggested by the measured data.

Furthermore, it may be noted that different receivers respond with a different change in C/N₀ for a given change in transmit power. At the average 1.5 dB power increment, C/N₀ changes between 1 dB and 2 dB are reported by the different types of receivers. This indicates manufacturer-specific algorithms for C/N₀ estimation that impact the use of measured C/N₀ as a reliable indicator of received signal power strength.

Table 2. Changes in C/N₀ (dB-Hz) obtained from differences of days before and after the increase of the transmit power.

It is interesting to notice in this context that NANU 2017005 issued Jan. 19, 2017, states that “The 2d Space Operations Squadron (2 SOPS) periodically conducts configuration changes on GPS satellites to assess current capabilities, validate future capabilities and ensure continued interoperability.”

Furthermore, the Civil GPS Service Interface Committee Executive Secretariat released the following statement on Jan. 25, 2017: “Beginning 25 January 2017, Air Force Space Command (AFSPC) will conduct a limited duration test implementing an increase of the L1 C/A power level on the GPS Block IIR-M and IIF satellites (19 vehicles).”

However, no maintenance has been announced so far for any of the Block IIF satellites, and no obvious increase in the measured C/N₀ could be found for these satellites. A repeated analysis for the Block IIR-M satellites on Feb. 22, 2017, confirmed that the L1 C/A-code power levels were still at their increased levels.

Measurements with the German Aerospace Center’s (DLR’s) 30-meter-diameter high-gain antenna at Weilheim, Germany, have been recorded to independently confirm the GPS Block IIR-M transmit power increase of the L1 C/A-code. FIGURE 3 shows the L1 spectral flux density for March 4, 2017 (blue line), and a previous measurement taken on Dec. 7, 2015 (red line). The sharp peak in the middle of the spectrum represents the C/A-code. A clear increase of the power in the measurement of March 2017 compared to Dec. 2015 is visible. Further analysis of the high-gain antenna data yields a power increase of about 2 dB.

Figure 3. L1 spectral flux density of PRN 29 (SVN 57) for Dec. 7, 2015 (red, normal C/A-code power level) and March 4, 2017 (blue, increased C/A-code power level).

However, the M-code flux density with main lobes near 1565 and 1585 MHz is reduced in March 2017 compared to Dec. 2015, whereas the P(Y)-code signal strength remains essentially unaltered. The total transmit power in the L1 frequency band is the same for both time periods. Therefore, the analysis reveals a redistribution of transmit power from M-code to C/A-code for the Block IIR-M satellite PRN 29 (SVN 57).

Authors Peter Steigenberger, André Hauschild and Steffen Thoelert are from the German Aerospace Center (DLR).

Richard B. Langley is from the University of New Brunswick and authors the monthly Innovation column for GPS World magazine.

<p>The post U.S. Air Force puts more power into GPS Block IIR-M C/A-code first appeared on GPS World.</p>