VOACAP Quick Guide by Jari Perkiömäki, OH6BG

WWW www.voacap.com

High-Frequency (HF) Ionospheric Communications Propagation Analysis and Prediction

Updated: 15 February 2008

This is a brief, a work in progress, guide to using VOACAP - a free professional HF propagation prediction program from NTIA/ITS, originally developed for Voice of America (VOA). This guide should get you well started with VOACAP. A more comprehensive discussion about the finer details of using the software can be found in George Lane's recently-published book Signal-to-Noise Predictions Using VOACAP. A User's Guide (Rockwell Collins).

Table of Contents

1. Downloading VOACAP

• Download from the home of VOACAP, NTIA/ITS, this ITSHFBC page has not been updated for long
• Download from Greg Hand's site, all new updates of the ITSHFBC package are available here
• Alternative direct download, 3 Sep 2007 version (4.5 MB)
• What's New?
  • The 03 Sep 2007 version
  • The 17 May 2007 version
  • The 13 May 2007 version
  • The 18 Nov 2006 version
  • The 31 Jul 2006 version
  • The 20 Jul 2006 version
  • The 18 Apr 2006 version
  • The 04 Mar 2006 version
  • The 09 Feb 2006 version
  • The 19 Dec 2005 version
  • The 18 Dec 2005 version
• Download the Fortran source codes of the VOACAP Propagation Prediction Engine, 3 Sep 2007 version, in a special directory as ZIP files.
• VOACAP on Linux by J.A.Watson (M0DNS), an exciting project to make VOACAP available for Linux users. Please contribute!
  • Release 2 is out!: Download the new VOACAP Linux GUI, Release 2! (1.1 MB gzipped file; this software is supplied 'as is' without any warranty, implied or otherwise. right-click and save the target). All users of Release 1 are strongly encouraged to upgrade, due to the bugs in R1.
  • The Linux voacapl application: voacapl-0.3.1.zip (to be compiled with GFortran)
  • The Linux itshfbc files: itshfbcFiles.zip
  • The VOACAP Linux plotting scripts, written in Python

2. Space Weather & the Sun

• Current International Smoothed Sunspot Numbers, Ri, to be used in VOACAP, from NOAA/NGDC (now updated until the year 2018!)
• Current Space Weather: Solar Wind, Magnetogram, X-Rays, Protons
• Today's Sunrise and Sunset Times by DXCC country
• Today's Ionospheric Grayline by DXCC country
• Today's Sunrise and Sunset at Global HF BC Transmitting Sites

3. VOACAP-related Papers

• Another Way to View Propagation Predictions for DXing and Contesting [2006] Visalia 2006 presentation by Dean Straw, N6BV.
• In Search of the Ultima Thule. Can VOACAP Help Find the Ultimate QTH? [2006] CCF/OHDXF presentation by Jari Perkiömäki & George Lane.
• Improved Guidelines for Automatic Link Establishment Operations [2005] by George Lane
  • Graphs for the paper [2005]
• Review of the High Frequency Ionospheric Communications Enhanced Profile Analysis & Circuit (ICEPAC) Prediction Program [2005] by George Lane
• Required Signal-to-Interference Ratios for Shortwave Broadcasting, [7.2 MB] by George Lane, 1997
• Predicting Signal-to-Interference Probability in the High Frequency Band, [60 kB] by George Lane and Greg Hand, 1997
• Strategies Using Propagation Predictions for DXing and Contesting, by Dean Straw, N6BV
• What is VOACAP Trying to Tell Me? by Dean Straw, N6BV
• How Does VOACAP Compare With These Measurements, by Dean Straw, N6BV

4. VOACAP - Backgrounds & Running the Prediction

General

• VOACAP Overview
• Screenshots of VOACAP
• Modelling the real-life HF communication system into VOACAP
• Setting VOACAP input parameters
• Textual circuit prediction (Run > Circuit)
• Graphical circuit prediction (Run > Graph)
• Area coverage prediction (VOAAREA)

The calculation engine, VOACAPW

• An introduction to VOACAPW.EXE
• The FREQUENCY card in VOACAPX.DAT

Graphs & Colours

• VOACAP & VOAAREA contours
• VOACAP & VOAAREA plot colors
• Y-axis scaling for VOACAP Time & Distance graphs

5. NTIA/ITS HF software HELP Topics

• General information on the NTIA/ITS HF Propagation Analysis Package
• VOACAP. General information - Point-to-Point - Area Coverage - Signal-to-Interference.
  Voice of America Coverage Analysis Program
  • VOACAP Frequently Asked Questions (22-Feb-96 Version)
• ICEPAC. General information - Point-to-Point - Area Coverage - Signal-to-Interference.
  Ionospheric Communications Enhanced Profile Analysis and Circuit Prediction Program
• REC533. General information - Point-to-Point - Area Coverage.
  ITU-RS Recommendation 533. This has been updated to the ITU 1996 Version 3.
• Data Files Frequently Asked Questions
• Helpful documents on using the propagation models
  • History (Part 1) of HF propagation models by Ray Rosich, 1978
  • Introduction to the ICEPAC Technical Description
  • Excerpts from Original ICEPAC User's Manual
  • Corrections to Man-made Noise
  • Note on MUFDAYs
  • High Latitude Errors
  • Corrected Signal-to-Noise Ratio Distribution
  • A Comparison of Broadcast Quality to VOACAP using Methods 21, 22, and 30
  • VOACAP Method 30. A Long Path/Short Path Smoothing Function

6. VOACAP - Understanding the Prediction

General

• Ten Common Mistakes in Using VOACAP
• Field Strength vs. Signal-to-Noise
• Choosing the correct Sunspot Number
• VOACAP Predictions at Low Frequencies
• Comparing VOACAP, ICEPAC and REC533
• Method 25: Ionospheric Parameters and Semi-thickness

MUF, SNR and REL

• The MUF and SNR Distribution: Choosing the Best Frequency
• Understanding Above-the-MUF Predictions
• Calculating the MUFdays
• Maintaining the Required Grade of Service: Calculating the Circuit Reliability for a Given Hour

Signal Power & Noise Power

• Summing Signal Power from Multiple Modes
• Calculating the Received RF Noise Power

Antennas & Radiation Angles

• Method 15, or Transmitter & Receiver AntennaPatterns
• VOACAP Angle Predictions
• Minimum Angle in VOACAP
• Predicting the Takeoff Angle Parameter TANGLE

Conversions

• S DBW to S Meter Correlation Table
• The Z Tables

7. VOACAP - Case Studies

• VOACAP Case: Make your beacon predictions
• VOAAREA Case: RUV Gufunes

8. HamCAP User's Guide

• HamCAP v1.5 User's Guide
• HamCAP and Type 13 & 14 Antennas

9. Articles of interest

English

• The Woody Woodpecker Story, Part 3 [PDF, 115 kB] by V. K. Lehtoranta, OH2LX
• Jamming, or deliberate interference against radio broadcasting stations [PDF, 140 kB] by V. K. Lehtoranta, OH2LX
• www.radiojamming.info by Rimantas Pleikys

Finnish

• Kokeiluja Faroksella - automaattinen kelimajakoiden kuuluvuudenmittaus vs. keliennusteet
• Tee-se-itse täsmäennuste YLE Radio Finlandin lähetyksille
• VOACAP ennustaa kuuluvuuden signaali-kohinasuhteen avulla
• VOACAP taajuussuunnittelun työkaluna
• Avaruussään vaikutuksesta HF-keliin
• Avaruussään tarkkailua IonoProbella

Swedish

• VOACAP förutspår hörbarheten med hjälp av signal-noiseförhållandet

Japanese

• HamCAP 1.5 User's Guide [PDF, 49 kB]

10. Tools & downloadable files for use with VOACAP

Find coordinates and Maidenhead grid locators just by pointing and clicking

• Browse the World with Google Maps, (start view: World)
• Browse the World with Google Maps, (start view: Scandinavia)
• QTH Locator (Google Maps), updated!

Downloadables

Software

• Windows program (zipped, 830 kB) for conversion of on-line CTY.DAT to CTY.GEO [9 Dec 07]. Mac and Linux versions available upon request!
• Perl source code for conversion of WL_CTY.DAT to CTY.GEO

Coordinate files

Save the coordinate files (*.GEO) at C:\ITSHFBC\GEOCITY\

• New country coordinate list from CTY.DAT by AD1C. [9 Dec 07]
• GEO file for all Zones (WAZ). Courtesy of Peter Ackermann DL3NAA.
• Latest Global HF Transmitter Site List. [5 Aug 06]
• Latest country coordinate list by OH6BG. [30 Jul 06]
• Latest NCDXF beacon coordinate list [30 Jul 06]
• Finland city coordinate list

Antenna and configuration files

• A collection of antennas and coordinate lists for use with VOACAP is available. If you wish to contribute, please let me know.
• Fine-tuned VOACAP Point-to-Point parameter auto scaling settings, English. Save as C:\ITSHFBC\DATABASE\Voacap.gph
• Fine-tuned VOACAP Point-to-Point parameter auto scaling settings, Finnish. Tallenna nimellä C:\ITSHFBC\DATABASE\Voacap.gph
• Fine-tuned Y-axis scaling for VOACAP Time & Distance graphs. Save as C:\ITSHFBC\DATABASE\voadist.gph
• Fine-tuned colors for auto-contour shading for Point-to-Point plots. Save as C:\ITSHFBC\DATABASE\Colors.gph

Special Thanks I wish to thank Mr George Lane for his friendship, invaluable comments and guidance - and his patience in this project. A special thank-you to Greg Hand who still maintains the code.

© 2003-2007 Jari Perkiömäki, OH6BG.