ITSHF  Propagation Analysis Package                       Date: 7 Feb 1997

VOA_GEN   General information on the VOACAP propagation prediction model

The Voice of America Coverage Analysis Program (VOACAP) predicts the expected
performance of high frequency (HF) broadcast systems, and in doing so is useful
in the planning and operation of HF transmissions for the four seasons,
different sunspot activities, hours of the day, and geographic location.

This current version of VOACAP running on a PC under Windows, incorporates a
colorful, user-friendly interface to easily modify input variables and produce
the desired results.
Three implementations of VOACAP are provided:
	VOACAP -produces point-to-point predictions.
		Tabular output or contours of any output variable on a 24-hour
		by 30MHz graph.
	VOAAREA-produces area coverage predictions.
		Contours of any output variable on world maps.
	S/I VOACAP - calculates Signal-to-Interference in Point-to-Point mode.

See the appropriate HELP file (within the program) for more details of each model.

The information provided within this program via the HELP windows is written
with the assumption that anyone executing these programs has a basic understanding
of HF radio broadcasting, the propagation prediction model, and the Windows
operating system.

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* BACKGROUND *
**************
In 1985, the Voice of America (VOA) adopted the Ionospheric Communications
Analysis and Prediction Program [Teters et al.,1983] as the approved engineering
model to be used for broadcast relay station design and antenna specification.
As the program was modified for these purposes, the name was changed to the
Voice of America Coverage Analysis Program (VOACAP) to distinguish it from the
official National Telecommunications and Information Administration (NTIA)
IONCAP program.  The development of VOACAP was accomplished for VOA by the
Naval Research Laboratory and the Institute for Telecommunication Sciences
(Department of Commerce, NTIA). 

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* REFERENCES *
**************
Teters, L.R., J.L. Lloyd, G.W. Haydon and D.L. Lucas, Estimating the Performance
	  of Telecommunication Systems Using the Ionospheric Transmission
	  Channel, Institute for Telecommunication Sciences NTIA Report 83-127,
	  July 1983.
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