3 – Operating software
DPN 402197 Issue 7.1
© Teledyne Limited
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3.2.3.2 Tone frequency reminder interval
To avoid potential deterioration in quality or loss of survey data you should perform a regular check on
the received tone signal and on the level of background noise.
DeepView provides three facilities that you may use to check on the quality of received signals:
❐
The Run Window and the Forward Search Window both include a display of the signal volt-
ages received on each channel.
❐
The Spectrum Analyser Window shows a clear representation of the received tone signal and
the level of noise frequencies across the received band.
❐
The Scope Window shows the actual received signal after amplification but before signal pro-
cessing. You may use this display to check for the effects of coil saturation.
At a pre-set interval, the system will remind you to check the tone frequency. Set a suitable value for
the reminder interval, up to a possible 360 minutes. The default setting is 30 minutes. A setting of zero
switches off the reminder facility.
3.2.3.3 Threshold
Threshold is an absolute value in microvolts. The 350 system considers targets to be out of range if
signals from them are below the threshold setting.
You should determine the correct setting for the threshold empirically, considering the level of noise
present in the survey environment. Low values for threshold will yield an improvement in the operating
range, but will make the system more susceptible to noise. The default setting of 100µV has proved to
be suitable for the majority of survey operations.
Figure 3-3: Threshold does not apply to vertical coils
Note that the setting for the threshold applies
only
to the signals from the lateral coils (in Run mode).
This is because the null-response form the vertical coils extends vertically downwards from the centre
of each coil triad. Any target close to this null-response line will not produce an output from the vertical
coil even when located very close to it. For the same reason, the threshold applies only to the fore-aft
coils in the Forward Search mode.
