| Comment:
Frequency dependence of "Ship" man-made noise |
Problem:
The problem arises because the on-line "Help" information is
not clear on this topic.
The formula that is used in GWPS for the frequency dependence of
man-made noise is the same for all noise categories (Ship, Business, etc.),
namely:
N(f) = A - B log (f/3)
where "f" is the frequency in
MHz and the logarithm ("log") is to base 10. However, the
coefficients A and B are different for each category, as in the
following table:
Category : A : B
Ship: -130 : 13.5
Business: -140 : 27.7
Residential: -145 : 27.7
Rural: -150 : 27.7
Remote: -164 : 28.6
where the noise is measured in units of
dBW/Hz.
For a "User Defined" category, A is the entered value (which
is assumed to be the man-made noise at 3 MHz) and B is 28.0. This is the
only case specified in the on-line Help.
In summary, the predictions for all noise categories are calculated
correctly in GWPS, but the on-line help needs to be improved, as above.
This has been done in the latest version of GWPS (Version 3), which is
due for release in the second half of 2003.
GWPS V3 runs as a Microsoft Windows application. |