Frequency-Agile Distributed-Sensor System (FADSS) Deployment in the Western 
United States: HF Results 
J. Vincent Eccles, Donald D. Rice, Jan J. Sojka, Robert D. Hunsucker, and John 
W. Raitt 
 
A distributed-sensor deployment of inexpensive, frequency-agile, beacon monitors 
is currently being developed to provide a real-time description of space weather 
effects on ionospherically-dependent systems.   This array of software radios is 
dynamically programmed to measure GPS variations and received signal strengths 
from select beacons from VLF through HF along a multitude of propagation paths.   
Through a real-time network, the information is processed to both optimize the 
frequency selection of the sensors as well as to provide information on the 
prevailing ionospheric weather conditions. 
 
We describe the HF signal strength results of our initial deployment, receiving 
the five frequencies (2.5-20 MHz) from the standard time transmitter WWV (Fort 
Collins, Colorado).  The multi-sensor deployment consists of six receivers in 
the Western United States:  KFO (Klamath Falls, Oregon), BLO (Bear Lake 
Observatory, Utah), PRV (Providence, Utah), LGN (Logan, Utah), TUC (Tucson, 
Arizona), and SEC (at SEC office in Providence, Utah.)  A relocatable beacon 
monitor is also available for field campaigns.  The FADSS system provides in 
real-time ray-traced predictions of these measured signal strengths.  A 
comparison of the observations and predictions leads to FADSS ability to specify 
the ionospheric weather. The various baselines between the deployed monitors and 
the WWV beacon are used to determine the correlation length associated with 
ionospheric horizontal structuring associated with phenomena such as TIDs and 
gravity waves.  This information is crucial in determining the optimal distance 
of monitor spacing needed to resolve horizontal ionosphere structure. The prototype 
study provides insights on sporadic E spatial scales and discusses the monitor 
distribution requirements for the possibility of mapping these transient structures 
in real-time.