abem Terraloc Pro 2, Руководство пользователя

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ABEM Terraloc Pro 2
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the filter may also deteriorate original signals. The higher the cut-off frequency and
filter damping, the worse possible distortions become. Using an analog filter is always
a compromise.
If the noise level is high, record it. Use the frequency view to analyze it, and to see the
actual noise frequency. Thereafter select and use an appropriate analog filter.
If the noise level is not high, do not use the analog filters.
Analog filters affect all channels.
Note! Note that you will not be able to recover any
incoming signals that are filtered out. Use analog
filters only to remove low frequency ground roll.
Generally be cautious about using these filters, as
there is always a risk that they may eliminate valuable
signal information
Setting Description
Notch filter - Turns the notch filter on or off. The notch filter is calibrated at
factory for either 50 or 60 Hz. Use this when working in vicinity
of power lines otherwise leave it off. A spectrum analysis of a
noise recording may often show if power line noise is present
Lowcut filter
Status - Turns the analog low-cut filter on or off
Lowcut filter
Slope - Select the slope of the filter. Available choices are 12 dB/octave
and 24 dB/octave
Lowcut filter
Cutoff freq. - Selects the low cutoff (3 dB rejection) frequency in Hz. The
possible frequency choice depends on the selected slope. You
have 16 different cut-off frequencies for each filter slope to
choose from, see the table below.
When choosing filter slope, remember that generally 24
dB/octave filters distort more than 12 dB/octave, but will also
damp noise more effectively. Use as low a cut off frequency as
possible generally twice the maximum noise frequency. A good
rule is to start with the 12-dB/octave filter. If the recorded signal
is acceptable then keep the filter, otherwise try again with the 24-
dB/octave filter.
12 dB/octave 24 dB/octave
12 15
24 30
36 45
48 60
60 75
72 90
84 105
96 120
108 135