Halytech
hydroSpider2 User’s Manual v1.23
Page 32
5.5.3.2
Ax + By + C
This type of super channel performs the calculation
𝑣𝑎𝑙𝑢𝑒
𝑐𝑎𝑙𝑐𝑢𝑙𝑎𝑡𝑒𝑑
= (𝐴 × 𝑣𝑎𝑙𝑢𝑒
𝑖𝑛𝑝𝑢𝑡 𝑥
) + (𝐵 × 𝑣𝑎𝑙𝑢𝑒
𝑖𝑛𝑝𝑢𝑡 𝑦
) + 𝐶
where A and B are scaling factors (which can be negative), x and y are the inputs to the calculation,
and C is a fixed offset which can be added to or subtracted from the result.
When “Ax + By + C” is selected as the source for a super channel the inputs to the calculation can
then be chosen via the advanced input options dialog (the ‘cog’):
For example, to accurately determine water depth from a pressure measurement, the atmospheric
pressure should be subtracted from the pressure at depth. This can be done by setting A = 1 and B =
-1, as shown.
If you also wanted to convert pressure (e.g. bars) to metres in the same calculation, you would enter
the appropriate scaling factor, e.g. A = 10.19 and B = -10.19.
