3.3.2. Observations FileΒΆ

This file is input when forward modeling or inverting field-collected data. Using 6 columns, the observation file indexes transmitters, receivers and times used for each measurement as well as the field observations and data uncertainties. Each row defines a unique field measurement. The general format is as follows:

Note

  • Blue hyperlinked entries are values specified by the user

  • To omit a particular datum in the inversion, used the flag -99 on its corresponding uncertainty.

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



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

Below is an example of an observations file.

../../_images/dobs.png

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.

  • t_ind: The index corresponding to the desired time channel within the time channels 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

  • data: The data observation (H or dB/dt).

  • uncertainty: The uncertainty for the datum.