ITSHF  Propagation Analysis Package                       Date: 7 Feb 1997

ICE_GEN   General information on the ICEPAC propagation prediction model

The Ionospheric Communications Enhanced Profile Analysis and Circuit Prediction
Program (ICEPAC) 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 ICEPAC (a descendent of IONCAP), 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 ICEPAC are provided:
	ICEPAC -produces point-to-point predictions.
		Tabular output or contours of any output variable on a 24-hour
		by 30MHz graph.
	ICEAREA-produces area coverage predictions.
		Contours of any output variable on world maps.
	S/I ICEPAC - calculates Signal-to-Interference in Point-to-Point mode.

See the appropriate HELP file 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 Version 3.x, 95, or NT.

**************
* BACKGROUND *
**************
For many years, numerous organizations have been employing the HF spectrum to
communicate over long distances.  It was recognized in the late 1930's that
these communication systems were subject to marked variations in performance.
The effective operation of long-distance HF systems increased in proportion to
the ability to predict variations in the ionosphere, since such an ability
permitted the selection of optimum frequencies, antennas, and other circuit
parameters.  Research demonstrated that most variations in HF system performance
were directly related to changes in the ionosphere, which in turn are affected
in a complex manner by solar activity, seasonal and diurnal variations, as well
as latitude and longitude.  Various organizations developed computer models to
analyze HF circuit performance.  The Ionospheric Communications Analysis and
Prediction Program (IONCAP) developed by ITS and its predecessor organizations,
became one of the more accepted and widely used models for HF propagation
predictions.  However, IONCAP demonstrated poor performance in the polar region
and used some of the older electron density profile structures.  To correct
these problems, IONCAP was transformed into ICEPAC by adding the Ionospheric
Conductivity and Electron Density (ICED) profile model described in Tascione
(1987).  The ICED profile model is a statistical model of the large-scale
features of the northern hemisphere.  The model recognizes the different
physical processes that exist in the different regions of the ionosphere. 
It contains distinct algorithms for the sub-auroral trough, auroral zone, and
polar cap.

**************
* REFERENCES *
**************
Tascione, T.F., K.W. Kroehl, and B.A. Hausman, A technical description of the
	  ionospheric conductivity and electron density profile model (ICED,
	  version 196-II), Syst. Doc Vol. VII, Air Weather Serv., U.S. Air
	  Force, Scott Air Force Base, Ill., 1987.
--------------------------End-of-HELP-for-ICE_GEN-------------------------------