Sib Geofiz Pribor Ltd
Repeated pressing the “START-STOP” button terminates testing. It should be noted
that every test is performed during a certain time interval (up to several seconds), so,
response to pressing of button may be not instantaneous. If pressing the button causes
an audible signal to sound, continuous testing will be terminated after the current test. If
no signal sounded upon pressing the “START-STOP” button, press the button once
again.
4.4.3.1. Polarity
This parameter can take values 0 (Off) and from 1 to 1000 mV. The parameter value
can be changed both by the use of LEFT and RIGHT arrows and by entering a number.
On entering 0, the parameter takes the “Off” value. The number specifies the response
level in millivolts. The response level should be specified depending on the sensitivity of
geophones and the noise level at their location. Generally, the 100mV level is
acceptable.
Testing is performed in semi-automatic mode: it is necessary to strike a gentle blow
from top downward (in horizontal direction for horizontal geophones) against each
geophone in an string. The Tester performs continuous recording of the string signal.
When the signal level exceeds the selected operating threshold, the Tester detects
geophone polarity based on to the signal peak polarity.
Polarity deems to be positive (corresponding to the SEG standard) if the peak polarity is
positive when striking from top downward.
Figure 9
Pressing the START-STOP button can start continuous performance of the polarity test
without writing results into memory. Once a blow on the geophone is detected, the
Tester displays 240 signal samples with 1 ms quantization (see Fig. 9). The point of
signal detection corresponds to 40 ms. The positive and negative thresholds are shown
by dashed lines. The screen image is updated after each blow. To terminate the test,
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