Identify Reversed Polarity
Use the Quality Control > Identify Reversed Polarity option, (geogxnet.dll(Geosoft.GX.IP.IdentifyReversedPolarity;Run)*), to determine if the polarity of the potential difference channel values is reversed.
Identify Reversed Polarity dialog options
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Line selection
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Select the lines to test. The options are: the selected lines (the default option), the currently displayed line, and all the lines.
Script Parameter:
IDENTIFY_REVERSED_POLARITY.LINES [S – Selected lines (default), A – All lines, D – Displayed line]
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Transmitter 1 & 2
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Define the coordinate channels of the 1st transmitter (Transmitter 1 tab). This is required for all IP configurations. If the configuration includes a 2nd transmitter, proceed to enter its coordinates under the Transmitter 2 tab.
After entering the first channel name, intelligent defaults are computed for all other existing electrode coordinates.
Script Parameters:
IDENTIFY_REVERSED_POLARITY.Tx1X, Tx1Y, Tx1Z
IDENTIFY_REVERSED_POLARITY.Tx2X, Tx2Y, Tx2Z
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Receiver 1 & 2
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Define the coordinate channels of the 1st receiver (Receiverer 1 tab). This is required for all IP configurations. If the configuration includes a 2nd receiver, proceed to enter its coordinates under the Receiver 2 tab.
Script Parameters:
IDENTIFY_REVERSED_POLARITY.Rx1X, Rx1Y, Rx1Z
IDENTIFY_REVERSED_POLARITY.Rx2X, Rx2Y, Rx2Z
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Voltage channel
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Select the channel containing the potential difference between the potential electrodes. This content will be checked for potential polarity reversal.
Script Parameter: IDENTIFY_REVERSED_POLARITY.VOLTAGE_CHANNEL
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Current channel
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Select the channel containing the current. If the Voltage channel has already been normalized to the current, you can leave this entry blank. The current is sometimes negative due to the reversal of the connection terminals.
Script Parameter: IDENTIFY_REVERSED_POLARITY.CURRENT_CHANNEL
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Correct polarity
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Select the correct polarity as Change data sign, where the sign of the voltage difference channel is corrected, or Swap R1 and R2, where the coordinates of the two receivers are swapped, which is analogous to swapping the sign of the geometric factor.
Script Parameter: IDENTIFY_REVERSED_POLARITY.ACTION [0 – Change data sign (default), 1 – Swap R1 and R2]
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Output flag channel
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This channel will be populated on output with "1" if the polarity of the potential difference is reversed and with dummies if it is correct. This calculation is made assuming an electrically homogeneous half space.
Script Parameter: IDENTIFY_REVERSED_POLARITY.OUTPUT_SIGN_CHANNEL
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Adjusted voltage channel
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This entry only appears if you have chosen to reverse data polarity – the Change data sign option is selected. If, in addition to the polarity flag, you would like to produce a corrected voltage difference channel, enter a channel name.
Script Parameter: IDENTIFY_REVERSED_POLARITY.ADJUSTED_VOLTAGE_CHANNEL
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Application Notes
The homogeneous half space resistivity equation for a 4-electrode array with current electrodes A & B and potential electrodes M & N is given as:
Where the geometric factor is defined as:
The Rij values are calculated using the georeferenced X, Y, Z coordinates of the electrodes.
Given that the resistivities ( ρ ) should be positive, the sign of the potential difference over the current 
and the geometric factor K should be the same.
In order to identify polarity reversal, this dialog calculates the geometric factor K and compares its sign with that of 
. For the identified readings, one of the following two approaches can be taken:
Reversal Data Polarity
Output a new potential difference channel with the appropriate sign.
Swap R1 & R2
Swap the Receiver 1 and 2 coordinates (and Z too if they exist).
