VOACAP & VOAAREA contours
There are three files, located in the default installation at C:\itshfbc\database\, where the contour values are defined for output parameters, to be used in VOACAP graphs & VOAAREA coverage maps:VOACAP GPH VOACAP Point-to-Point parameter auto scaling info VOAPLT GPH VOACAP auto scaling data used by AREAPLTW.EXE
Syntaxxfact, icode, num, [ con(num) ]
Where:xfact = multiplying factor Usually either 1. or 100. (100 for percents) icode = calculating code 0 = user-defined values given in CON (max of 6 allowed **) 1 = MAX down in CON(1) increments, Min allowed CON(2) 2 = MIN to MAX in 6 program-defined steps 3 = MIN up in CON(1) increments, Max allowed CON(2) num = number of numeric arguments to follow. con(num) = numeric arguments, up to num If num = 2, then two arguments have to follow. They become CON(1) and CON(2). When num = 0, there are no numeric arguments (icode = 2). The max value of num = 6 can only be used in the case of icode = 0.
** in reality, VOACAPW.EXE accepts 10 user-defined values. These need to be defined in the data input card.
Contour colorsThe default values will be read from C:\itshfbc\database\colors.gph (for graphs) and C:\itshfbc\database\colors.con (for coverage maps). See http://www.uwasa.fi/~jpe/voacap/colors.html
1. USER DEFINED CONTOUR VALUES (ICODE = 0)MUFday= % of days/month sky-wave propagation expected at MUF mode MUF days expected [%] 100. 0 6 1. 10. 50. 90. 99. 110.
- Multiply values in datafile by 100.
- Use 6 values given.
2. PROGRAM DEFINED MAX TO USER DEFINED MIN + INCREMENT (ICODE = 1)DBU = Median field strength at receive location (dBu) Field Strength Median [dBu] 1. 1 2 5. 0.
- Find MAX in datafile (e.g. say it was 69)
- Round up to the next multiple of CON(1) (70 in this case).
- Contours start at 70 (but you will not see this one) and go down in steps of 5 [= CON(1)] for 6 contours. The lower limit will be 0 [= CON(2)]. Thus, if max was 14, contours would be >10, 5, <0.
3. PROGRAM DEFINED MAX, MIN AND INCREMENT (ICODE = 2)TANGLE= Radiation angle (degrees) Radiation Angle Transmit [degrees] 1. 2 0
The steps are based on a complicated algorithm, but it essentially finds 6 contours within the min and max. In this case it would find <6,12,18,24,30,>30.
- Find MIN and MAX in datafile (e.g. 4.6, 32.3)
4. PROGRAM DEFINED MIN TO USER DEFINED MAX AND INCREMENT (ICODE = 3)RPWRG = Required power & antenna gain to achieve reliab (dB) Required Power & Antenna Gain [dB] 1. 3 2 10. 200.
icode=3 is opposite of icode=1, and is used for values that are really negative, but are calculated as positive values (such as LOSS & RPWRG).
- Find MIN in datafile
- Round down to the next multiple of CON(1)
- Contours start at this value and go up in steps of 10 [= CON(1)] for 6 contours. The upper limit is 200 [= CON(2)].
Thank-youThis article would have not been possible without the help of Greg Hand who explained the syntax and provided the examples. Any errors in this article are therefore due to my own misinterpretation :)