NATURAL SOURCE MAGNETOTELLURICS
May 2002 Section 13, Page 12
Sta/Ant. The Sta(tion) field (station numbers for individual E-fields) can be changed in
Menu 4, but the Ant(enna) numbers are accessible only in Menu 3. In Menu 4, the cursor
will skip over any channels labeled with an H-field designator.
NOTE: Our standard data processing programs sort first on station number, second on
Rx and third on Tx. To ensure proper sorting in data processing the operator must make
sure the station numbers are entered properly.
G0, G1, G2. Gain stages 0, 1 and 2. In this example, all gain stages are set to unity
gain by default. Upon pressing
Enter
, the program will automatically set the gains and SP
buckout if the auto-gain mode is selected as denoted by the message at the bottom of the
screen: CONT- Set gains, ESCAPE-Prev menu. (This is the default mode).
Atn. The attenuator is bypassed (set to OUT). The other option is IN. The attenuator
should not normally be used for natural source methods.
SP. Self Potential or offset in millivolts. Initially set to 0.00. Will be set to the actual
value upon pressing
Enter
.
GGGA. Gain settings for stages 0, 1 and 2 (in powers of 2). The attenuator setting is A, I
for IN, O for OUT.
CAUTION: Some values are not registered in the computer memory until you exit the
parameter field by pressing
Pg Up
PREV FIELD
,
Pg Dn
NEXT FIELD
, or
Enter
. The exceptions to this rule are the
frequency band and the powerline notch filters. Frequency band is used as the sample rate
selection. Whenever you change the frequency the sample rate is automatically changed through
the timing card. However, the anti-alias filter is not changed until just prior to data acquisition.
Upon pressing
Enter
to gather data or set gains, the receiver will automatically set the anti-
alias filter as defined by internal look-up tables.
Notice also that the battery voltage (12.3) has now been inserted between the program version
number and the date.
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