Resilient Positioning, Navigation and Timing (PNT)

The Challenge

GPS is an enabler of our fast-moving highly mobile world. Yet, it has vulnerabilities that require detecting and mitigating interference:

  • GPS is weak because signals come from 20,000 km above the Earth.
  • GPS is easily disrupted by interference from benign sources like terrestrial-based transmitters and atmospheric or astronomic events.
  • GPS is susceptible to intentional spoofing and jamming.

We have been working aggressively to integrate resilient positioning, navigation and timing (PNT) technologies into Spectracom products, to make them more reliable, secure, and fault-tolerant.

Let us help you understand the risk of vulnerabilities.

We can help you analyze the impacts of interference and other GPS disruptions.

The Resilient PNT Solution

The issue of interference detection and mitigation is integral to our entire portfolio of solutions.

  • Resilient Timing solutions that include the integration of secure signals of opportunity to complement GPS and other GNSS satellite signals
  • High-reliability holdover timing references, including rubidium atomic clocks, to maintain system time in the absence of external reference signals
  • For navigation systems, inertial sensors that offer a level of stand-alone performance in the absence of GPS references
  • Hardened products that extend into harsh operational environments and are resistant to cyber attacks
  • GNSS Vulnerability Test Systems with the ability to evaluate the effects of interference, jamming and spoofing on systems that rely on GNSS signals
  • Smarter use of the entire GNSS eco-system including feature-rich GPS reception hardware and intelligent software techniques, reception from multiple constellations, multi-frequency signals, and augmentation systems
  • Technology that extends GPS-like performance to GPS-denied environments​

The Resilient Timing Solution

Satellite Time and Location Signal Technology (STL) can be used as a secure signal of opportunity to complement GPS and other GNSS satellite signals, making the applications more accurate and secure and less prone to interference and attack.

Originating from the Iridium® constellation of 66 low-earth-orbiting satellites, STL is 1,000 times stronger than GPS/GNSS, reaching deep into buildings and penetrating GPS/GNSS jamming without the aid of local infrastructure. Cryptographic security features of STL also provide exceptional resilience to intentional spoofing.

Spectracom precision timing products integrated with STL reference sources can be used to augment GPS/GNSS and other reference signals. The energy grid, data networks, financial exchanges and military operations that depend on GPS/GNSS can be fortified by the integration of Spectracom's Resilient PNT technology.

Resources

Presentation and Articles

More Info
Signals from Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS), are very weak and usually cannot be seen indoors or underground. A common method to overcome the problem of receiving GNSS signals indoors or underground is to use a GPS/GNSS repeater with an antenna located outdoors to receive the GNSS signals and an amplifier/antenna to re-transmit the signal indoors. This paper describes the technologies and methods for creating an intelligent repeater system including time synchronization at the nanosecond, microsecond, and millisecond levels, how each synchronization level affects the overall system and methods for achieving each, power level considerations including power level requirements between zones and how they affect transitions from one zone to another, data transfer and example system configurations. While GPS is primarily demonstrated and tested, the possibility for adding other GNSS constellations such as QZSS, BeiDou, Galileo, and GLONASS are also presented.
pdf - 270 KB
Wednesday, November 18, 2015
By: Lisa Perdue - Spectracom
More Info

It has been a continuous trend that all aerospace and payload programs require more and more parameters to be measured during flight tests, at increasing sampling rates. Contextual data, associated with measurements – like timestamp, geolocation, attitude - are instrumental to performing a relevant analysis of measured data. Therefore flight test teams, in charge of engineering high speed measurement systems, need to ensure proper time alignment amongst all on-board systems, facing two challenges:

  • Distribute precise time (better than 1 μs), even in case of GPS loss, over the whole test mission duration
  • Distribute precise position and attitude, which are time-stamped consistently with the distributed time

In this paper, we demonstrate how a combined position & attitude measurement sensor and precise time server can meet all “Positioning, Navigation and Timing (PNT)” needs for a complex observation payload like an on-board test system and a SAR imagery radar, with benefits in terms of architecture simplification, and overall performance increase in terms of time and attitude accuracy. We also review the benefits of associating a high stability clock with a GPS receiver, in terms of improvement of some GPS reception performances.


pdf - 573 KB
Tuesday, June 9, 2015
By: Spectraccom
More Info

This article was originally presented at the 2014 PTTI conference. It describes various approaches to a disciplining algorithm to detect and mitigate the effect of GNSS spoofing on precision time signals.


pdf - 914 KB
Monday, December 1, 2014
By: Spectracom