PN Transmit/Receive Systems for Persistent Travel Time Measurements
Abstract
The structure and variability of atmospheric refractivity in the Marine Atmospheric Boundary Layer (MABL) can result in anomalous radio wave propagation. Environmental variability is driven by the physics of the coupling of the atmosphere with the ocean and controls the propagation of electromagnetic (EM) waves in the lower atmosphere. EM waves can become trapped when downward refracting conditions create a waveguide, allowing signals to propagate far beyond line of sight. This phenomenon (ducting) can augment communication performance by offering extended range. It can also cause problems for radar operators as ducting conditions will create erroneous radar returns. Knowing when ducting is occurring can provide communication system operators with context for variations in link performance. Historically ducting impacts have been considered in regards to signal strength, while time of arrival measurements have been sparse due in part to the difficulty of making the measurement. Much can be learned about the various paths traveled within the waveguide through examining travel times. For persistent, long-term observations of propagation conditions in the MABL, we proposeto design, procure equipment (e.g. electronics, hardware, software), and fabricate four new synchronized transmitter and receiver systems operating at 11 GHz that will utilize a coded pseudorandom noise (PN) sequence. The long-term, persistent travel-time measurements provided by these systems will be used to evaluate propagation conditions in the MABL in regions of interest offshore of southern California. The design of the PN transmit/receive system is based on lessons learned from the fabrication and field trials of a pilot PN system that was evaluated over variable and fixed-range links. The proposed systems will support existing ONR funded programs through the characterization of seasonal propagation conditions in the MABL in southern California. This abstract is publicly releasable.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142412769
Entities
People
- Eric Terrill
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego