VOACAP Quick Guide

HF Propagation Prediction and Ionospheric Communications Analysis

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by Jari Perkiömäki, OH6BG/OG6G

This is a work-in-progress guide to using VOACAP (Voice of America Coverage Analysis Program) - free professional HF propagation prediction software 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 book Signal-to-Noise Predictions Using VOACAP. A User's Guide. The book is now available on CD-ROM.

What's New?

• VOACAP Online - an easy-to-use web-based tool for making professional HF predictions
  • Current International Smoothed Sunspot Numbers, Ri, to be used in VOACAP, from NOAA/NGDC (updated until 2018)
  • Current Space Weather: Solar Wind, Magnetogram, X-Rays, Protons
• QTH Locator - find coordinates and Maidenhead locators on Google Maps
• Elevation-Angle Analyzer - generate statistical elevation-angle data for HFTA
  • Statistical elevation-angle distribution - a case study
• Graphical User Interface for VOACAP for Linux
• Rockwell Collins offers VOACAP User's Guide on CD-ROM for free (shipping charges apply)
• World Radio Broadcasting Stations - explore various BC transmitting sites on Google Maps
• My blog in Finnish: VOACAP ja optimaalinen antennikorkeus
• Sunrise and sunset times around the world
  • 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

1. Downloading VOACAP

• Download from Greg Hand's site, all new updates of the ITSHFBC package are available here
• Alternative direct download, 8 Dec 2009 version (3.1 MB)
• Download from the home of VOACAP, NTIA/ITS, this ITSHFBC page has not been updated for long
  • The 8 Dec 2009 version
  • The 26 Mar 2009 version
• Download the Fortran source codes of the VOACAP Propagation Prediction Engine, in a special directory as ZIP files.
• VOACAP for Linux by J.A.Watson (M0DNS), an exciting project to make VOACAP available for Linux users. Please contribute!
  • Release 3 is out! Download the new VOACAP Linux GUI, Release 3! (1.5 MB gzipped file). Now supports Area Coverage Maps with Jim Watson's VoaAreaPlot! 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.
  • VOACAP for Linux Software
    • The voacapl application: voacapl-0.5.7.tar.gz
    • The itshfbc directory: itshfbcFiles18Apr08.tar.gz
    • The python scripts to display the output

2. 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

3. 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

4. VOACAP - Case Studies

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

5. VOACAP-related Papers

• Using Propagation Predictions for HF DXing [2010] Visalia 2010 presentation by Dean Straw, N6BV.
• Contest Antennas. DX or Domestic, What’s Your Pleasure? [2009] Visalia 2009 presentation by Dean Straw, N6BV.
• What’s the Deal About “NVIS”?, [2005] article courtesy by Dean Straw, N6BV
• 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

6. 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

7. HamCAP User's Guide

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

8. 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]

9. 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)
• World Radio Broadcasting Stations on Google Maps! new
• QTH Locator (Google Maps), updated!

Downloadables

Software

• Elevation-Angle Analyzer for VOACAP, v0.6
• 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 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

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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.

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© 2003-2010 Jari Perkiömäki OH6BG/OG6G. Last update: 19 June 2010.