3.3.1. Survey Index FileΒΆ

This file is input when forward modeling data. Using 4 columns, the observation file indexes the transmitters, receivers and time channels used for each measurement. Each row defines a unique field measurement. The general format is as follows:

tx_ind \(\;\) rx_ind \(\;\) t_ind \(\;\) data_opt
tx_ind \(\;\) rx_ind \(\;\) t_ind \(\;\) data_opt
tx_ind \(\;\) rx_ind \(\;\) t_ind \(\;\) data_opt
\(\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\; \vdots\)
tx_ind \(\;\) rx_ind \(\;\) t_ind \(\;\) data_opt



Click here to see an example file for an airborne TEM survey.

Important

Due to the way the forward problem is solved, it is imperative that the user sort the observations:

  • First by transmitter

  • Then by receiver

  • Then by time channel

Parameter Descriptions

  • tx_ind: The index corresponding to the desired transmitter within the transmitter file.

  • rx_ind: The index corresponding to the desired receiver within the receiver file.

  • data_opt:

    • A flag value of 2 is entered if the datum is the magnetic field H in units A/m

    • A flag value of 1 is entered if the datum is the time-derivative dB/dt in units T/s