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Session C5: Military PNT User Equipment Test Results

PNT Assessment Exercise (PNTAX) Results from Aiding Acquisition for an Increment 1 MGUE Receiver Using a Frequency-Hop Acquisition Using Secure TRANSEC (FAST) Prototype
Terry Ferrett and Philip Dafesh, The Aerospace Corporation
Location: Ballroom C
Date/Time: Wednesday, Jun. 14, 8:35 a.m.

A number of Frequency Hop Acquisition Using Secure TRANSEC (FAST) signal experiments will be broadcast from the Navigation Technology Satellite (NTS) 3 satellite in 2022. The FAST signal aids direct acquisition of military receivers by providing a secure, jam resistant means to acquire GPS satellite timing, greatly reducing the burden for subsequent direct acquisition of Military GPS signals to greatly enhance TTFF and J/S performance and reduce SWAP for future military GPS receivers [1,2].
A FAST transmitter and receiver prototype [2] were taken to the PNT assessment exercise (PNTAX) to characterize the acquisition performance of FAST under real-world operating conditions [3]. The test setup included a FAST transmitter that was synchronized to a GPS time server to emulate the reception of FAST from a future NTS-3 satellite. A FAST receiver prototype was also developed and used to provide hot start data in the form of a 1pps signal and time mark, conforming to a standard time transfer interface used to initialize GPS receivers.
The acquisition performance of the FAST prototype was evaluated under various simulated jamming environments provided at the PNTAX exercise. In all cases, the FAST prototype was demonstrated to greatly speed up the Time to First Fix (TTFF) compared to what is theoretically expected from unaided receivers. The results show that FAST can provided time aiding that enables a receiver to acquire at TTFF levels approaching expected hot start performance.
This work will describe the prototype system, the test setup at PNTAX and measurement scenarios. TTFF performance and related measurements conducted during the PNTAX test exercise will be presented. The results illustrate the great benefit that FAST can provide to enable GPS receivers to achieve warm start performance that approaches hot start TTFF levels under field conditions.
[1] Philip Dafesh, “Enhancing GPS PNT Resiliency with a Frequency Hop Acquisition (FA) Signal, ”ION JNC 2018.
[2] Philip Dafesh, Eugene Grayver and Terry Ferrett, “Software Radio Prototype of a Frequency Hop Acquisition Using Secure TRANSEC (FAST) Receiver,” ION JNC 2022.
[3] Caitlin ONeill, “Army Hosts second annual PNT assessment exercise,” https://www.army.mil/article/240634/army_hosts_second_annual_pnt_assessment_exercise ,Nov 5, 2020.
Approved for public release; distribution is unlimited. Public affairs release approval #AFRL-2023-0595.

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