RECEIVER SETUP
Section 6, Page 33 May 2002
OPTION 1 – FULLY AUTOMATIC GAIN-SETTING
In the fully automatic gain-setting mode, the receiver automatically reviews all parameters and
sets gains more efficiently and effectively than any other method. Always use this option for
normal field surveys.
Features
Adjusts SP and sets Gains automatically, without specific instructions, each time
frequency, transmitter current, Rx, Tx, N, station number, powerline notch filter or delay
(for TEM) are changed and data collection is started. Gains are also saved and reset after
checking contact resistance.
Can be either disabled or overridden on a case-by-case basis. The program first checks
the input signals and puts the attenuator IN for signals over ±3.5 volts, zeroes SP, and
adjusts the gains for a signal-plus-noise voltage of ±1.0 volts maximum for “NOISY”
gains or ±2.25 volts for “STANDARD” gains. The receiver adjusts gain stage G0 first, if
enabled, and then Gain stages G1 and G2 if necessary.
Operational Procedures
1. Connect field wires and turn on the transmitter.
2. Set the Frequency on both the controller and the receiver.
3. Ensure that fully automatic mode is enabled by pressing
. The fully automatic
mode is the default mode. Option 1 will say “turn off full automatic mode” indicating the
automatic gain option is selected.
4. Gains are displayed as they are set. Ensure that these values are reasonable.
NOTE: The process of automatic gain setting is longer for low frequencies than for high.
For example, at 0.125 Hz the process takes about 20 seconds, and only 7 seconds at 1.0 Hz.
NOTE: The fully automatic mode gains can be modified from the gain-setting mode. Select
the manual option (explained below.) This overrides the settings made by the fully automatic
mode, but does not disable the fully automatic mode. The receiver returns to the fully
automatic mode once a survey parameter is changed that affects the signal level (e.g.
frequency, transmitter current, notch filter, etc.)
Things to Consider
1. Avoid setting gains during anomalous bursts of noise.
2. See Section 0 above to determine if a powerline notch filter is necessary
Disabling Fully Automatic Mode
When the receiver is turned on, it defaults to Fully Automatic Gain Mode. It remains in this
mode until disabled.
To DISABLE the automatic gain mode:
Press
to view the gain setting menu.
Since the receiver is in fully automatic gain mode, Option 1 reads:
1) Turn off full automatic mode
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