VLF Nighttime Data Analysis

This paper documents a VLF/LF Data Analysis task by the Naval Ocean Systems Center to improve the modeling of the nighttime ionosphere when making propagation predictions with the LWPC computer program. The task utilizes an extensive database of VLF measured data recorded during the 1985-1986 trips...

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Bibliographic Details
Other Authors: TELECOMMUNICATION SCIENCE ASSOCIATES INC SAN DIEGO CA
Format: Text
Language:English
Published: 1991
Subjects:
Plasma Physics and Magnetohydrodynamics
Radiofrequency Wave Propagation
*DATA PROCESSING
*NIGHT
*OCEAN ENVIRONMENTS
COMPUTER PROGRAMS
DATA BASES
FREQUENCY
IONOSPHERE
PROPAGATION
POSITION(LOCATION)
SHIPS
PREDICTIONS
NAVY
TIME
OCEANS
RANGE(DISTANCE)
MERCHANT VESSELS
NORTH ATLANTIC OCEAN
PLOTTING
VERY LOW FREQUENCY
*IONOSPHERIC PROPAGATION
*ELECTRON DENSITY
LOW FREQUENCY
COLLISION FREQUENCY
DATA ANALYSIS
NIGHTTIME
North Atlantic
Online Access:http://www.dtic.mil/docs/citations/ADA234006
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA234006
Description
Summary:This paper documents a VLF/LF Data Analysis task by the Naval Ocean Systems Center to improve the modeling of the nighttime ionosphere when making propagation predictions with the LWPC computer program. The task utilizes an extensive database of VLF measured data recorded during the 1985-1986 trips of the merchant ship GTS Callaghan in the North Atlantic area. By constraining the Callaghan data to those periods when both the ship and the distant transmitters were in time zones consistent with all-nighttime propagation, and by eliminating data from trips outside the principal area of interest, an aggregated set of recorded data was assembled for each frequency of concern. Four frequencies were examined: 16.0, 19.0, 21.4 and 24.0 kHz. Recorded data sets were graphed as signal vs. distance plots, computing distance from the transmitter for each ship's location. The LWPC program was then utilized to compute signal vs. distance along a typical path in the same ocean area, and the predicted and recorded data were compared. By changing the LWPC parameters different propagation predictions were compared with the recorded data until a best fit was obtained.

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