VOACAP Quick Guide: Y-axis scaling for VOACAP Time & Distance graphs

Y-axis scaling for VOACAP Time & Distance graphs

VOACAP Quick Guide: Home

The VOACAP Time and Distance Plots (Run > Time and Run > Distance) are very informative graphs that let you compare the output parameter values for user-specified frequencies. The Time Plot lets you view the output parameters on a 24-hour scale, e.g. if you want to see which of the specified frequencies is best at the given time of day.
The Distance Plot calculates the variation of output parameter values with regards to distance at the user-specified hour.
By default, most of the output parameter values are automatically scaled. There are, however, some parameters which could benefit from a fixed Y-scale. The Y-axis scaling info is found in C:\itshfbc\database\voadist.gph.
VOADIST  GPH	VOACAP Point-to-Point parameter Y-scale info
Syntax
The variable names are:

  xfact,icode,zmin,zmax,zlab,zinc

  xfact = The multiplier factor, usually 1 or 100 [for percentages]
  icode = 0 = zmin & zmax are fixed.
        = 1 = zmin & zmax are calculated from data.
  zmin  = minimum Y value on axis
  zmax  = maximun Y value on axis
  zlab  = number label at every ZLAB increment
  zinc  = tick mark at every ZINC increment
Example 1
SDBW  = Median signal power at receiver (dBW)
        Signal Power at Receiver (dBW)
        1. 0  -160. -50. 10.  2.
Explanation:

Set the minimum value to -160 (corresponds to [median] S0 on the S-meter)
Set the maximum value to -50 (corresponds to [median] > S9 + 40 dB)
Set the number label at every 10th increment
Set the Y-axis tick mark at every 2nd increment

Example 2
SNR   = Median signal-to-noise ratio (dB)
        Signal-to-Noise (Median) (dB)
        1. 0  0. 100. 10.  2.
Explanation:

Set the minimum value to 0. This is, in fact, too low. A minimum value of 20 would do.
Set the maximum value to 100. For big BC stations, this can be too low a max value...
Set the number label at every 10th increment
Set the Y-axis tick mark at every 2nd increment

Example 3
SNRxx = Signal-to-Noise ratio (dB) at Req. Rel.
        Signal-to-Noise at Req. Rel. (dB)
        1. 0  0. 100. 10.  2
Explanation:

Set the minimum value to 0. This is, in fact, too low. A minimum value of 20 would do.
Set the maximum value to 100. Now, this can be too high a value. However, now at least, the SNR and SNRxx scales are the same.
Set the number label at every 10th increment
Set the Y-axis tick mark at every 2nd increment

Thank-you

A big thank-you to Greg Hand who explained the syntax.