The FREQUENCY card of VOACAPW
Introduction
The VOACAPW.EXE is the calculation engine in the VOACAP that accepts the VOACAPX.DAT as input. This data input file is composed of a number of "control cards", or labeled lines.
There are a few things you can do with the FREQUENCY card (line) that are not available when using the VOACAP GUI for creating the data input file.
Below is the normal structure of VOACAPX.DAT (as created by the VOACAP GUI) when I want to know about the path from Vaasa (Finland) to New York (USA) on 7.05, 10.12 and 14.05 MHz:
COMMENT Any VOACAP default cards may be placed in the file: VOACAP.DEF LINEMAX 55 number of lines-per-page COEFFS CCIR TIME 1 24 1 1 MONTH 2003 7.00 SUNSPOT 63. LABEL VAASA NEW YORK CIRCUIT 63.10N 21.60E 40.72N 74.00W S 0 SYSTEM 1. 155. 3.00 90. 24.0 3.00 0.10 FPROB 1.00 1.00 1.00 0.00 ANTENNA 1 1 2 30 0.000[default\CCIR.000 ] 0.0 0.1000 ANTENNA 2 2 2 30 0.000[default\SWWHIP.VOA ] 0.0 0.0000 FREQUENCY 7.0510.1214.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 METHOD 30 0 EXECUTE QUIT
First of all, it is important to note that the placement of decimal points for frequencies on the FREQUENCY line is crucial since they are in fixed positions. You can mess the frequencies up big time if you are not careful. This is probably one of the reasons that there is an interface program that takes care of things like this.
Typically, the FREQUENCY line accepts up to 11 user defined frequencies. However, there are other ways of using the FREQUENCY line.
Calculating from 2 to 30 MHz
If you want to calculate the prediction for the whole HF range on the given path from 2.0 MHz to 30.0 MHz in 1.0 MHz steps, you write as follows:
FREQUENCY -1
The start of the result pages would be as follows:
CCIR Coefficients ~METHOD 30 VOACAP 03.0724W PAGE 1
Jul 2003 SSN = 63. Minimum Angle= 3.000 degrees
VAASA NEW YORK AZIMUTHS N. MI. KM
63.10 N 21.60 E - 40.72 N 74.00 W 295.58 32.58 3406.9 6309.2
XMTR 2-30 + 0.0 dBi[default\CCIR.000 ] Az= 0.0 OFFaz=295.6 0.100kW
RCVR 2-30 2-D Table [default\SWWHIP.VOA ] Az= 0.0 OFFaz= 32.6
3 MHz NOISE = -155.0 dBW REQ. REL = 90% REQ. SNR = 24.0 dB
MULTIPATH POWER TOLERANCE = 3.0 dB MULTIPATH DELAY TOLERANCE = 0.100 ms
1.0 14.3 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 0.0 0.0 FREQ
2F2 4 E 4F2 3F2 3F2 3F2 3F2 3F2 3F2 2F2 - - MODE
7.7 3.0 21.5 13.8 11.0 10.3 10.0 10.1 10.4 3.1 - - TANGLE
22.5 21.3 23.9 22.8 22.4 22.3 22.2 22.2 22.3 21.8 - - DELAY
434 92 380 362 304 289 284 286 292 291 - - V HITE
0.50 1.00 1.00 1.00 1.00 1.00 1.00 0.99 0.94 0.99 - - MUFday
171 203 183 168 158 156 155 154 154 157 - - LOSS
-18 -61 -36 -22 -14 -7 -4 -6 -5 -1 - - DBU
-151 -181 -154 -141 -135 -133 -132 -132 -133 -132 - - S DBW
-171 -144 -149 -152 -154 -156 -158 -159 -161 -163 - - N DBW
20 -37 -5 11 19 23 26 27 28 30 - - SNR
30 81 48 32 24 19 17 17 17 16 - - RPWRG
0.42 0.00 0.00 0.08 0.27 0.46 0.55 0.58 0.60 0.64 - - REL
0.00 0.00 0.00 0.02 0.12 0.24 0.32 0.42 0.00 0.59 - - MPROB
0.20 0.00 0.04 0.11 0.17 0.21 0.24 0.27 0.28 0.27 - - S PRB
25.0 16.4 16.4 16.4 16.4 16.4 16.8 18.5 20.1 21.0 - - SIG LW
25.0 8.3 8.3 8.3 8.3 8.3 8.3 8.8 9.1 8.8 - - SIG UP
25.9 19.8 19.2 18.8 18.4 18.2 18.3 19.7 21.2 22.0 - - SNR LW
25.4 13.3 12.6 12.0 11.6 11.1 10.8 10.9 11.0 10.5 - - SNR UP
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 - - TGAIN
-2.0 -7.5 0.0 -0.5 -1.1 -1.2 -1.3 -1.3 -1.2 -7.4 - - RGAIN
-6 -57 -24 -8 0 5 7 7 7 8 - - SNRxx
The MUF is 14.3 MHz at 01 UTC, followed by frequencies starting from 2.0 MHz. The output file consists of many pages.
Calculating the FOT
If you want to calculate the frequencies of your interest as well as the FOT ("the frequency of optimum traffic", or frequency where MUFday = 0.90), you write as follows:
FREQUENCY 0.00 7.0510.1214.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00
As you can see, the first frequency on the line is zero. What that will do is the output for frequencies:
MUF FOT f1 f2 f3 ...
The start of the result pages would be as follows:
CCIR Coefficients ~METHOD 30 VOACAP 03.0724W PAGE 1
Jul 2003 SSN = 63. Minimum Angle= 3.000 degrees
VAASA NEW YORK AZIMUTHS N. MI. KM
63.10 N 21.60 E - 40.72 N 74.00 W 295.58 32.58 3406.9 6309.2
XMTR 2-30 + 0.0 dBi[default\CCIR.000 ] Az= 0.0 OFFaz=295.6 0.100kW
RCVR 2-30 2-D Table [default\SWWHIP.VOA ] Az= 0.0 OFFaz= 32.6
3 MHz NOISE = -155.0 dBW REQ. REL = 90% REQ. SNR = 24.0 dB
MULTIPATH POWER TOLERANCE = 3.0 dB MULTIPATH DELAY TOLERANCE = 0.100 ms
1.0 14.3 11.9 7.1 10.1 14.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 FREQ
2F2 2F2 3F2 2F2 2F2 - - - - - - - MODE
7.7 3.7 10.0 3.1 6.0 - - - - - - - TANGLE
22.5 21.9 22.2 21.8 22.2 - - - - - - - DELAY
434 310 284 291 379 - - - - - - - V HITE
0.50 0.90 1.00 0.99 0.56 - - - - - - - MUFday
171 156 155 157 164 - - - - - - - LOSS
-18 -1 -4 -1 -10 - - - - - - - DBU
-151 -136 -132 -132 -143 - - - - - - - S DBW
-171 -166 -158 -163 -170 - - - - - - - N DBW
20 30 26 30 27 - - - - - - - SNR
30 19 16 16 23 - - - - - - - RPWRG
0.42 0.62 0.55 0.65 0.56 - - - - - - - REL
0.00 0.00 0.33 0.59 0.00 - - - - - - - MPROB
0.20 0.29 0.24 0.28 0.26 - - - - - - - S PRB
25.0 24.1 16.8 21.1 25.0 - - - - - - - SIG LW
25.0 9.0 8.3 8.9 20.0 - - - - - - - SIG UP
25.9 24.9 18.3 22.0 25.9 - - - - - - - SNR LW
25.4 10.3 10.8 10.6 20.4 - - - - - - - SNR UP
0.0 0.0 0.0 0.0 0.0 - - - - - - - TGAIN
-2.0 -6.0 -1.3 -7.4 -3.2 - - - - - - - RGAIN
-6 5 8 8 1 - - - - - - - SNRxx
The MUF is 14.3 MHz, the FOT is 11.9 MHz and the rest of the frequencies are my 7.05, 10.12 and 14.05 MHz.
Calculating from 2 MHz to the HPF
Lastly, there is an option to calculate from 2.0 MHz to the HPF. The HPF is "the highest possible frequency", or the frequency where the value of MUFday reaches 0.10.
You would put:
FREQUENCY 0
or
FREQUENCY 0 -1
The start of the result pages would be as follows:
CCIR Coefficients ~METHOD 30 VOACAP 03.0724W PAGE 1
Jul 2003 SSN = 63. Minimum Angle= 3.000 degrees
VAASA NEW YORK AZIMUTHS N. MI. KM
63.10 N 21.60 E - 40.72 N 74.00 W 295.58 32.58 3406.9 6309.2
XMTR 2-30 + 0.0 dBi[default\CCIR.000 ] Az= 0.0 OFFaz=295.6 0.100kW
RCVR 2-30 2-D Table [default\SWWHIP.VOA ] Az= 0.0 OFFaz= 32.6
3 MHz NOISE = -155.0 dBW REQ. REL = 90% REQ. SNR = 24.0 dB
MULTIPATH POWER TOLERANCE = 3.0 dB MULTIPATH DELAY TOLERANCE = 0.100 ms
1.0 14.3 2.0 3.7 5.5 5.5 7.2 8.9 10.7 12.4 14.1 15.9 17.6 FREQ
2F2 4 E 3F2 3F2 3F2 3F2 3F2 2F2 2F2 2F2 2F2 2F2 MODE
7.7 3.0 15.2 10.6 10.5 10.0 10.4 3.2 4.0 6.5 7.7 7.7 TANGLE
22.5 21.3 23.1 22.3 22.3 22.2 22.3 21.8 21.9 22.3 22.5 22.5 DELAY
434 92 394 295 294 284 292 296 319 396 434 434 V HITE
0.50 1.00 1.00 1.00 1.00 1.00 0.95 0.97 0.84 0.54 0.27 0.10 MUFday
171 203 173 157 157 155 154 157 156 165 187 215 LOSS
-18 -61 -25 -11 -10 -7 -5 -1 -2 -12 -34 -61 DBU
-151 -181 -144 -134 -134 -132 -133 -133 -136 -144 -167 -195 S DBW
-171 -144 -151 -155 -155 -158 -161 -164 -167 -170 -174 -177 N DBW
20 -37 7 21 21 26 28 31 31 26 7 -18 SNR
30 81 36 22 21 17 17 16 19 24 44 68 RPWRG
0.42 0.00 0.04 0.35 0.37 0.54 0.60 0.65 0.63 0.54 0.19 0.02 REL
0.00 0.00 0.00 0.16 0.17 0.34 0.00 0.58 0.00 0.00 0.00 0.00 MPROB
0.20 0.00 0.09 0.19 0.20 0.25 0.28 0.28 0.29 0.24 0.11 0.03 S PRB
25.0 16.4 16.4 16.4 16.4 17.6 20.0 21.5 25.0 25.0 25.0 25.0 SIG LW
25.0 8.3 8.3 8.3 8.3 8.4 9.1 9.7 9.7 21.8 25.0 25.0 SIG UP
25.9 19.8 18.9 18.3 18.3 19.0 21.0 22.4 25.8 25.9 26.1 26.3 SNR LW
25.4 13.3 12.2 11.4 11.3 10.8 10.9 11.2 10.9 22.2 25.3 25.3 SNR UP
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TGAIN
-2.0 -7.5 -0.4 -1.2 -1.2 -1.3 -1.2 -7.1 -5.4 -2.8 -2.0 -2.0 RGAIN
-6 -57 -12 2 3 7 7 8 5 0 -20 -44 SNRxx
Here, the MUF is again 14.3 MHz, the first frequency to the right of the MUF is 2.0 MHz and the last is 17.6 MHz which is the HPF (MUFday = 0.10) at 01 UTC. The HPF is obviously different from hour to hour.
The remaining nine frequencies are "computed on a non-linear scale based on the E-MUF and F-MUF values". This comes from the original IONCAP and can be elaborated by those more knowledgeable in the IONCAP theory.
Thanks to Greg Hand for explaining the FREQUENCY parameters.