EFA-200/-300 Annex A: Glossary
A-5
Figure A-3 Typical response of BANDSTOP filter for filter frequency f
m
= 100 Hz
For other filter frequencies, multiply the frequency axis by f
m
/ 100 Hz.
The selective filters from 16.7 Hz through to 50 Hz and 60 Hz (AC line
frequencies) up to 180
Hz are suitable for determining the fundamental and
harmonic fields caused by public power supply utilities.
The filters from 400 Hz up to 1200 Hz are suitable for determining the
fundamental and harmonic fields due to on-board (ship / aircraft) power
supplies.
Scaled measured value axis (dB scale)
In the Spectrum FFT and Harmonic Analysis modes, a very large
measurement range with a wide dynamic range is available. To be able to
clearly display both large and small measured values, the measured values
are normalized with respect to a reference value (see display field F1) and
plotted on a logarithmic axis (Y axis). The unit is known as the decibel (dB).
The field strength measured value can be directly read off with the marker.
However, it can also be computed as follows:
MeasuredValue ReferenceValue
DisplayValue dB[]()
20
-------------------------------------------------------
× 10=
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