Diurnal Variations (Batch QC Parameters)

Use the Diurnal Variations tab (QCDIURNL GX) to apply quality control on magnetic diurnal variations during a survey.

Diurnal Variations tab options

Diurnal channel	Select the diurnal channel. This is a required field. Script Parameter: QCDIURNL.DCHAN
Time channel	Select the time channel. Time must be in decimal hours. This is a required field. Script Parameter: QCDIURNL.TCHAN
Diurnal deviation	Specify the diurnal deviation, in nT. This is a required field. Script Parameter: QCDIURNL.ALLDEV
Over a time chord of	Specify the "over a time chord of" parameter such that, if the Diurnal deviation value (see above) is exceeded for this specified time chord then the line will be flagged as out of survey specification. This is a required field. Script Parameter: QCDIURNL.TIME

Application Notes

Current database

This dialog assumes that the current database contains magnetic survey data with a diurnal channel representing the magnetic data recorded at a synchronized magnetic base station and a time channel.

Quality Control Specification and Indicators

This dialog checks magnetic diurnal variations against a moving straight line. The length of this line, representing a time chord specified in minutes, is defined as the average number of data points in the time period specified. This average is calculated independently for each line of data.

The time period specified is most often equal to the length of time required for an aircraft to fly between a pair of adjacent tie lines.

The dialog creates a Flag_diurnal channel. This channel contains a value of 0 or 1. 0 indicates points within the specification and 1 represents points which fail the test.

The dialog also create a Diurnal_Dev channel which contains the maximum diurnal deviation at each point. This can be compared directly with the Flag_diurnal channel, as all values greater than the input maximum will have a flag value set to 1.0.