Previous Abstract Return to Session F3 Next Abstract

Session F3: Navigating in Challenged Environments (e.g., Urban, Indoor and Subsurface Navigation)

Advanced TDOA Techniques
Justin McIntosh, Clint Robison, Joe Paul Tupin Jr., Technology Advancement Group
Location: Room 6-8
Date/Time: Monday, Jun. 1, 2:50 p.m.

The world is extremely dependent on Global Navigation Satellite Systems (GNSS) but GNSS signals are sensitive to intentional and unintentional electrical interference as well as physical obstruction from natural or man-made obstacles. When GNSS is not an option, Alternative PNT (A-PNT) solutions are required to ensure navigation remains possible.
Signals of Opportunity (SoOp) technology can be employed to find an unknown transmitter using 3 or more synchronized receivers. Common applications include drone detection and tracking, wireless device detection and location, search and rescue, interference detection and hunting, ADS-B spoofing detection. In these instances, a set of time correlated receivers at known locations detect and analyse signals from an unknown or hostile transmitter. In this paper, the problem is reversed, two or more receivers can calculate their position from transmitters at known locations using time transfer and time difference of arrival (TDOA) technology.
TDOA systems typically use a reference node at a known location supplying reference data over a communications link to a “lost” node at an unknown location – similar to the RTK base-rover concept. TDOA requires a reference node and if that node is compromised or destroyed, the system collapses and PNT is lost.
TAG has developed an alternative to the traditional TDOA topology, eliminating the need for a reference node. Multiple nodes form a mesh network and self-locate based on time transfers between the nodes and received signals from transmitters with known locations. No one node becomes the critical link in the system. Our method constrains the TDOA location solution using the separation distance between nodes. The separation distance adds a sphere with a diameter equal to the distance between any two nodes to the 3-dimensional hyperboloids derived from the traditional TDOA calculations, providing a unique solution for the node locations.

Previous Abstract Return to Session F3 Next Abstract