25
beginning. You can set any gain function as a polyline connecting up to 10 points
while each of them can be adjusted within 0-84 dB. It is
important to
remember
, that
the signal itself is digitized and saved on the disk
without any gain
. Gain is used only
while displaying the data in the form of radar profile on your computer. When entering
the
Gain
option under the signal window
Digital gain function setup
window will
appear there will be movable points, the amount of which is set by pressing keys 2 to
9. To set 10 points press key 0. Point selection is performed with the arrow keys
and
, to adjust the gain levels use arrow keys
and
. For most cases it is sufficient
to set only two points with values 0 dB at the beginning and 48 dB at the end. If these
settings are not optimal, you can always set other ones when displaying and processing
data in the main menu (see Section 10).
High-pass filter
– high-pass filter’s cutoff frequency selection for received signal to
attenuate low-frequency noises, which arises while antenna is crossing the rough
terrain. Pay attention to the recommendations in the information window.
Customized
filter is a digital real-time bandpass filter. This option will disable hardware high-pass
filter. Frequency band of customized filter is modified in appeared filter setup window
that is visualizing signal’s spectrum in accordance to the frequency response.
Frequency band is characterized by its vertexes (each vertex corresponds to filter
cutoff frequency). To navigate through filter’s vertexes use < and >, or tab keys.
Changing vertexes’ position (filter cutoff frequency) could be done by
and
keys.
Warning: signal itself is recorded in original shape (not filtered). Filtering (the
same as a Gain function) is just a software tool and is used for data visualization.
We recommend using Customized High-Pass Filter, only if you are familiar with the
spectrum analysis and the digital signal processing. Otherwise we recommend using
Weak, Strong and Super Strong filters, by following recommendations.
Real-time filter
– real-time filter selection to remove background noises, which can
arises because of external electronic noises, cables, constant distortions, etc. Such
constant background signals could be seen on the profile as a horizontal lines that do
not change their intensity and time position and may mask the real reflected signals.
To read more detailed information about “background removal” see 11.
Warning: Real-time filtering rebuilds the original shape of the signal and records
already filtered data! To prevent unexpected data lose a semi-transparent red
warning message appears in the signal oscillation and profile receiving windows.
Pulse delay –
this option is changing sounding signal’s position within the sounding
time range. Default delay values in most cases are not optimal. It is important to make
an appropriate setup at the first start of Georadar with a given antenna and for the
given Range value. Relevant adjustment may be performed in the automatic or manual
mode. When key
‘а’
or
‘A’
is pressed (automatic mode), a sounding signal shall be
automatically positioned to the beginning of the sounding time range. When in the
manual mode, set the sounding signal to the desirable position in the sounding time
range using
and
(fine tuning) and keys
Page up
и
Page down
(rough
adjustment). Optimal sounding pulse position in the sounding time range is position,
where the first lobe is spaced from the time axis beginning by about 1/20 of its length
(see Fig. 8.1). After any adjustment, the
Pulse delay
values will be saved for each
