HamCAP User's Guide

 

By Jari Perkiömäki OH6BG (with kind assistance of the HamCAP author, Alex Shovkoplyas VE3NEA)

HamCAP by Alex VE3NEA is a compact freeware interface program to VOACAP, incorporating both graphical Point-to-Point and Area Coverage predictions. The program is pretty much self-contained; the only thing you probably need to get from the Internet is the smoothed International Sunspot Number from Royal Observatory of Belgium.

Getting started quickly

Overview

Please note that the Windows version of VOACAP has to be installed before you can use HamCAP. For a more detailed HamCAP discussion, please read on.

In HamCAP, there are five screens (= tabs) that can be accessed at the bottom of the program window. The screens are:

• Params (input parameters for running the prediction, default tab)
• Chart (Point-to-Point prediction window)
• Map (Area Coverage Map window)
• Settings (settings for displaying P-to-P and Coverage Maps, and coordinates for your home QTH)
• Ant (TX/RX antenna selections for running the prediction)

The minimum system requirements are:

• 600 MHz Pentium II CPU;
• 64 Mb RAM;
• 16-bit or 32-bit color video card;
• MS Windows 95/98/ME/NT4/2000/XP;
• VOACAP v.3.827 or above.

Params tab

This is the opening screen as you launch the program. Here you will need to define the basic input parameters for the prediction:

• the coordinates or the callsign of the DX station. Entering the callsign is typically the most convenient way of getting the coordinates.
• the month and year of prediction. The default value is the current month and year.
• the great cirle path to the DX station. Choose between Short (default) or Long path.
• the smoothed International Sunspot Number. The program suggests a default value from its built-in database which most probably needs to be adjusted. Click the "Sun" button to the left of the SSN input box to get the current value from the local SSN file that HamCAP uses. The file is located at "C:.....\AppData\Roaming\Afreet\Reference\SSN.dat". See below for the suggested SSN values in 2023 and 2024.
• Kp value (unused by default). This is not actually needed in VOACAP calculations. If you wish, you can leave it alone. If you want to experiment with it, check the "Use Kp" box. Choose the Kp value by clicking the button to the left of Kp input box; the web page https://services.swpc.noaa.gov/text/daily-geomagnetic-indices.txt will be opened.
• Power. This is the power at the antenna feedpoint in Watts. Calculate this as 0.8 x the transmitter power.

To get easily to the HamCAP home page, just click on the "Ham CAP 1.x" text box.

You can use the following (heavily guesstimated) values for the local SSN file:

Jan 2023=109
Feb 2023=112
Mar 2023=115
Apr 2023=123
May 2023=129
Jun 2023=126
Jul 2023=128
Aug 2023=131
Sep 2023=133
Oct 2023=135
Nov 2023=136
Dec 2023=139
Jan 2024=141
Feb 2024=143
Mar 2024=143
Apr 2024=143
May 2024=142
Jun 2024=143
Jul 2024=142
Aug 2024=141
Sep 2024=140
Oct 2024=140
Nov 2024=138
Dec 2024=139

Chart tab (point-to-point)

The Chart screen is the output window for the Point-to-Point prediction from your home QTH to the DX QTH. The prediction shows the median SNR values vs. the UTC time and frequencies from 2 to 30 MHz. The ham bands are shown as green horizontal dotted lines. The whiter the tile, the better the propagation. The white vertical hair line indicates the current hour.

The red curve shows the statistical median MUF (50% Maximum Usable Frequency). The MUF is defined here as the median maximum usable frequency for a given ionospheric path, month, SSN and hour. On each day of the month at this hour, there is a Maximum Observed Frequency (MOF) for a mode. The median of this distribution is called the MUF. Therefore, the red curve does not show the maximum usable frequency in terms of communications.

In other words, the median MUF is the frequency for which ionospheric support is predicted on 50% of the days of the month, ie. 15 days out of 30 days. So on a given day communications may or may not succeed on the frequency marked as the MUF. Read more about the MUF and SNR.

Mark the best hour. The program finds the highest SNR value along each green horizontal dotted line, and plots a yellow box at the peak, one box per one ham band.

Move your mouse cursor over the chart and read the predicted parameters under the cursor point on the status bar. The predicted parameters are (see picture below):

• the time in UTC
• frequency in MHz
• SNR in dB*Hz
• elevation angle in degrees
• propagation mode via the ionosphere, and
• the MUF (in MHz) at the given hour.

To save the prediction screen onto the hard disk, right-click on the screen and choose "Save image". By right-clicking on the screen you can also toggle the visibility of the MUF plot and the best hours (yellow boxes).

Please note that in calculation of the Point-to-Point prediction, the following input parameter values are used by default, and they are not user-modifiable:

• Man-made noise: -145 dBW/Hz (residential)
• Minimum takeoff angle: 3 degrees
• Method: 23 (user-selectable output)
• Coefficients: CCIR
• FPROB multipliers: 1.00*foE, 1.00*foF1, 1.00*foF2 and 0.00*foEs

Please note that the calculation method (Method 23) is different from the Method 30 used in Area Coverage calculations. You can see some differences in prediction at distances over 7000 km.

(Coverage Area) Map tab

The Map Tab displays the area coverage map for the entire globe. When you enter the Map screen, HamCAP calculates the prediction for 14 MHz by default. The calculations take a while, even on a fast computer. Click on the band buttons to calculate the prediction for the given band. There is a separate box for choosing the UTC time on the left of the screen.

The map color can be changed under the Settings Tab. The color can be Color, Gray or Pseudo-color. The Pseudo-color is most distinctive of the choices. If you use the Color option, the lighter the area, the better the propagation.

The map resolution can also be changed under the Settings Tab. The choices are: High, Medium and Low. The higher the resolution, the more accurate the coverage map. The accuracy means also more CPU processing time as the area coverage map is actually a matrix of thousands of point-to-point calculations.

The DX (receive) QTH can be changed in this screen very easily. Just left-click on the map at the desired location and the DX QTH moves to that position. Then go to the Chart Tab to calculate the Point-to-Point prediction to that QTH.

The TX (transmit) QTH can also be changed in a similar way. Just CONTROL-left-click on the map at the desired location and the transmit QTH moves to that position. Then go to the Chart Tab to calculate the Point-to-Point prediction anew.

To save the area coverage map onto the hard disk, right-click on the screen and choose "Save image". By right-clicking on the screen you can also pre-compute coverage maps for all hours and ham bands in one go. Please note that this is an extremely processor-intensive task and can take more than a while. The pre-computed maps will be valid until you change any of the prediction parameters. This is a useful feature e.g. in contests. See picture below.

Finally, the position of the sun and the DX QTH location can be toggled on and off under the Settings Tab, or by right-clicking the screen.

Move your mouse cursor over the map to read the predicted parameters under the cursor point on the status bar. The predicted parameters are the coordinates, SNR in dB*Hz, elevation angle in degrees, propagation mode via the ionosphere, and the MUF (in MHz) at the given hour.

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Hidden Functions of HamCAP

Since the very first version of HamCAP, there have been some hidden features which are particularly useful in contest operations or during DXpeditions. The enhancements are available by keeping the Ctrl button down and right-clicking on the map screen. Take a look at the map screen:

There are four new menu options:

• Maximum Over Hours
• Maximum Over Bands
• Maximum Maximorum
• Generate GIFs

Maximum Over Hours

This choice plots a map of maximum SNR (monthly median) values from the 24-hour period on the given band. Extremely handy e.g. in a single-band contest operation as you can get an overview of propagation to all geographical areas during the 24-hour time period. When an opening is happening to a specific geographical area has to be checked in the individual hourly propagation maps. This function requires that the user has pre-computed all hourly maps (Pre-compute Maps: All Hours).

Maximum Over Bands

This choice plots a map of maximum SNR (monthly median) values at the given hour on all given amateur bands. Again, useful for instance in a multi-band contest operation as you can see to which parts of the world you can expect to have openings at the given hour. The band-specific maps of the given hour will show the propagation details. This function requires that the user has pre-computed all hourly maps on all bands (Pre-compute Maps: All Bands + All Hours).

Maximum Maximorum

This choice plots a map of maximum SNR (monthly median) values at all 24 hours on all given bands. This is a broad overall picture of propagation characteristics in the given month. All more specific propagation details have to be consulted in the hourly maps for each band. This function requires that the user has pre-computed all hourly maps on all bands (Pre-compute Maps: All Bands + All Hours).

Generate GIFs

This choice saves the coverage maps from all hours and all bands in GIF format into a folder named "Gifs" under the HamCAP installation directory. One map takes approximately 10 kB in size. This is extremely handy function to generate individual propagation maps for a DXpedition or for making propagation animations, etc. This function requires that the user has pre-computed all hourly maps on all bands (Pre-compute Maps: All Bands + All Hours).

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A note on the E-layer absorption model in VOACAP

The settings you define in VOACAP has an effect on your HamCAP predictions. To use the recently implemented "System" parameter that allows you to choose the E-layer absorption model called "IONC a", do as follows:

• Open VOACAP
• Locate and click on the "System" button
• Set Man-Made Noise level at 3 MHz to "164" if you have a noise-free QTH
• Choose "IONC a" (=IONCAP absorption model + Alex changes) as the Absorption Model
• Click on the "Accept" button
• Exit VOACAP

You are all set to use HamCAP with the IONCAP model that produces more optimistic predictions on lower frequencies up to 14 MHz! Be sure to use the latest version of Windows VOACAP.

Please note that in calculation of the Area Coverage Maps, the following input parameter values are used by default, and they are not user-modifiable

• Man-made noise: -145 dBW/Hz (residential), effective at every location in the world
• Minimum takeoff angle: 3 degrees
• Method: 30 (Short/long method smoothing)
• Coefficients: CCIR
• FPROB multipliers: 1.00*foE, 1.00*foF1, 1.00*foF2 and 0.00*foEs

Settings tab

This is the place where the coordinates of your home QTH are entered. Furthermore, the settings used in the Chart screen and in the Area Coverage Maps are defined here.

There are also two buttons that integrates HamCAP with DX Atlas and IonoProbe. If you have DX Atlas, the area prediction data will be superimposed over the DX Atlas map, and you will be able to magnify and scroll the map, and view it in the Azimuthal and 3D projections.

IonoProbe -- Alex' space weather monitor -- will provide real-time ionospheric indices to HamCAP, and the prediction will be automatically updated when the indices change.

Ant (Antenna) tab

On the Ant screen, you will have to define the transmit antenna (TX Antenna) for yourself and the receive antenna (RX Antenna) for the DX station. You may select a different TX and RX antenna for each ham band.

HamCAP comes with a variety of antenna models for Yagis, dipoles and verticals.

Click on the button to the left of an antenna selection combobox to view the antenna pattern and gain information.

If you create or download models for other antennas, put them in the HamCAP\AntBkup\ folder so that HamCAP can pick them up. Use model type 14 for omni-directional and rotated directional antennas, and type 13 for fixed directional antennas (or Type 0, Isotropic).

• How to create Type 13 and Type 14 antenna models of your own? (by Alex Shovkoplyas VE3NEA)

Also Type 11 (and other) antennas will work, such as these artificial antennas ; however, you cannot view their antenna pattern or gain information. For the description of the antenna model types, please see the VOACAP documentation.