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This guide describes the basic installation and operation of the voacapl application. As voacapl is port of VOACAP, much of the information here is applicable to VOACAP as well.
voacapl requires access to a number of data files containing input parameters, ionospheric coefficient, antenna characteristics etc. These are stored in a defined hiearchy under a nominated directory name, usually itshfbc. This may be created in your home directory by running the command makeitshfbc.
When running voacapl, the location of the itshfbc directory must be specified, i.e.;
$ voacapl ~/itshfbc
The above command will run voacapl, reading input parameters from the default location (itshfbc/run/voacapx.dat) and writing results to the default output file location (itshfbc/run/voacapx.dat). Input and output files may be specified at the command line i.e.
$ voacapl ~/itshfbc my_input.dat
$ voacapl ~/itshfbc my_input.dat my_output.out
By convention, input and output files use the suffixes .dat and .out respectively.
Current sun spot predictions may be found at the proppy website.
Voacapl supports both the standard and older IONCAP absorption models. In addition, modified forms are available for each of these (refer to the news on Greg Hand's website for further details. The alternative models may be selected by modifying the contents of the file itshfbc/database/version.w32;
- Version 16.1207W = normal code
- Version 16.1207I = use old IONCAP absorption model
- Version 16.1207A = use Alex's changes with normal absorption
- Version 16.1207a = use Alex's changes with IONCAP absorption
In the interests of compatibility with the original Windows based application, the default value is 'W'. A comparison between the models indicates that the modified IONCAP model ('a') is the most accurate when compared to the ITU's D1 Databank of HF field strength data.
The absorption model is global and affects both point-to-point and area predictions.
Input files are text based and made up of rows of data, or cards. The collection of cards is soemtimes referred to as the 'deck', harking back to the card based I/O of early computer systems.
The formatting of the input deck is critical to the operation of voacap and many 'bugs' can be traced to a malformed deck. This section defines the formatting of the individual input cards.
This card is used to define the characteristics of the transmit and receive antennas and is formatted as follows;
ANTENNA 1 1 2 30 0.000[harris/[email protected] ] 0.0 0.4000
ANTENNA 2 2 2 30 0.000[harris/1950BD10.anw ] 23.2 0.0000
This is read by voacapl with the following;
1510 FORMAT(10X,4I5,f10.3,1x,a21,1x,f5.1,f10.4)
READ(INPUT,1510) IAT,iantr,minfreq,maxfreq,designfreq(iantr),antfile(iantr),beammain(iantr),pwrkw(iantr)
| Columns | Name | Format | Description |
|---|---|---|---|
| 1-10 | Label | 10X | ANTENNA Label |
| 11-15 | IAT | I5 | Antenna Type (1 = Transmit, 2 = Receive) |
| 16-20 | iantr | I5 | integer value to identify antenna |
| 21-25 | minfreq | I5 | Minimum frequency of operation |
| 26-30 | maxfreq | I5 | maximum frequency of operation |
| 31-40 | designfreq | F10.3 | Antenna design frequency |
| 41-61 | antfile | A21 | Filepath to the relevant antenna file (relative to the itshfbc directory) |
| 62-66 | beammain | f5.1 | Antenna bearing (degrees) |
| 67-76 | pwerkw | f10.4 | Power (kW) |
COEFFS card allows either CCIR or URSI88 foF2 coefficients. It is recommended that this is set to 'CCIR'
| Columns | Name | Format | Description |
|---|---|---|---|
| 1-10 | Label | 10X | COEFFS Label |
| 11-14 | coeffs | A4 | 'URSI' or 'CCIR' |
The COMMENT command line permits the user to place comments anywhere in the user-defined input file. This may benefit the user in specifying the system configuration in terms of descriptive text, and any number of comment lines may be used. During program execution, the comment lines are listed along with the other command lines, but otherwise they have no effect on execution of the program.
| Columns | Name | Format | Description |
|---|---|---|---|
| 1-10 | Label | 10X | COMMENT Label |
| 11-90 | comment | A80 | Comment text |
The MONTH command indicates the year and month/days for which the analysis and prediction are to be performed. The year is used for identification purposes only and has no effect on the program calculations. June and December are typical of seasonal extremes for long-range planning. Up to thirteen month/days may be specified in a single MONTH card.
Each MONTH is a variable in the form mm.dd (month.day), e.g. 4.20 represents 20th April. Note: Specifying a day will force the use of URSI units. CCIR units are only possible when the days values is '00', eg. '4.00'.
The program analysis and predictions are performed for each of the months the user specifies. The desired months can be specified in any order. This, for example, allows the user to perform the analysis and predictions for December before January if so required.
MONTH 1994 6.00
| Columns | Name | Format | Description |
|---|---|---|---|
| 1-10 | Label | 10X | MONTH Label |
| 11-14 | NYEAR | A5 | A character string representing the year. NOTE: This value has no effect on the program's calculations. |
| 15-20 | MONTH(1) | f5.2 | Month 1 in mm.dd format |
| 21-25 | MONTH(2) | F5.2 | Month 2 in mm.dd format |
| 26-30 | MONTH(2) | F5.2 | Month 2 in mm.dd format |
| --- | --- | --- | --- |
| 61-65 | MONTH(13) | F5.2 | Month 13 in mm.dd format |
Time may now run around midnight (e.g. 22 to 04)
| Columns | Name | Format | Description |
|---|---|---|---|
| 1-10 | Label | 10X | TIME Label |
| 11-14 | IHRO | I5 | Start time, hours |
| 11-14 | IHRE | I5 | Stop time, hours |
| 11-14 | IHRS | I5 | Hour increment, hours |
| 11-14 | ITIM | I5 | If negative LMT at transmitter, otherwise UT |