RPS - Background

Use the Specify Aircraft Background & Cosmic Stripping Values dialog (RPSLEVL1 GX) to create background-corrected airborne radiometric data.

Specify Aircraft Background & Cosmic Stripping Values dialog options

Aircraft Background Values (cps)	Select the aircraft background values (cps).
	Total Count
	Potassium
	Uranium
	Thorium
	Upward U
Cosmic Stripping Ratios (cps / cosmic cps)	Specify the cosmic stripping ratios (cps/cosmic cps)
	Total Count
	Potassium
	Uranium
	Thorium
	Upward U

Select Radon Background Leveling Method dialog options

Choose Radon Background method from list

Select the radon background method from the drop-down list (Upward, Backgnd_Table or Overwater).

Additional Script Parameters

Script Parameter: RPSLEVL.UFILT	Input U Channel Name
Script Parameter: RPSLEVL.KFILT	Input K Channel Name
Script Parameter: RPSLEVL.THFILT	Input TH Channel Name
Script Parameter: RPSLEVL.TCFILT	Input TC Channel Name
Script Parameter: RPSLEVL.COSFILT	Input COSmic Channel Name
Script Parameter: RPSLEVL.ULEVL	Output U Channel Name
Script Parameter: RPSLEVL.KLEVL	Output K Channel Name
Script Parameter: RPSLEVL.THLEVL	Output TH Channel Name
Script Parameter: RPSLEVL.TCLEVL	Output TC Channel Name
Script Parameter: RPSLEVL.UCOSSTRIP	Ratio for U
Script Parameter: RPSLEVL.KCOSSTRIP	Ratio for K
Script Parameter: RPSLEVL.THCOSSTRIP	Ratio for TH
Script Parameter: RPSLEVL.TCCOSSTRIP	Ratio for TC
Script Parameter: RPSLEVL.UUCOSSTRIP	Ratio for Upward Uranium
Script Parameter: RPSLEVL.UAIRBACK	Background for U
Script Parameter: RPSLEVL.KAIRBACK	Background for K
Script Parameter: RPSLEVL.THAIRBACK	Background for TH
Script Parameter: RPSLEVL.TCAIRBACK	Background for TC
Script Parameter: RPSLEVL.UUAIRBACK	Background for Upward Uranium
Radon levelling reference channels
Script Parameter: RPSLEVL.URADREF	Uranium radon reference channel name
Script Parameter: RPSLEVL.KRADREF	Potassium radon reference channel name
Script Parameter: RPSLEVL.THRADREF	Thorium radon reference channel name
Script Parameter: RPSLEVL.TCRADREF	Total Count radon reference channel name
Script Parameter: RPSLEVL.UPURADREF	UP Uranium radon reference channel name
User input parameters for Radon levelling	Upward-looking method
UPA1, UPA2, UPAU, UPAT, UPAK and UPAI	Alpha values
UPBU, UPBT, UPBK and UPBI	Beta values
Radon levelling	Parameters for Overwater 2 table-based levelling
Script Parameter: RPSLEVL.RADBACK	Background picks lookup table file name
Script Parameter: RPSLEVL.RADREF	Radon Reference dummy channel. This method works on a flight of selected data. The data can be broken up into survey lines, as the table based method will take its entries and interpolate across lines from the first index value to the last.
Water Background levelling	Parameters for WaterBack levelling
Script Parameter: RPSLEVL.RADREF	Radon Reference dummy channel
Script Parameter: RPSLEVL.WBSWAV	Low pass Filter short wavelength cut-off value

Application Notes

The RPS Background option first corrects data for cosmic and aircraft background radiation. It then corrects data for atmospheric radon background radiation using one of several methods (Upward-looking crystals, Overwater2, or WaterBack methods).

The dialog works on pre-processed channels (denoted by FILT) and creates background-removed channels (denoted by LEVL). Note that in the current implementation these channel names are hardcoded. This streamlines the data input process.

The Background dialog runs three processes -- aircraft corrections, cosmic corrections and radon background corrections. There are three methods for applying radon corrections, including a channel-based method (upward-looking uranium), a table-based method (Overwater2), and an interactive highlighting method (WaterBack).

To level your database, you must complete multiple dialogs. The first of these is for aircraft background and stripping corrections and the second is for selecting a radon levelling method. Depending on the method you select, the system displays either two more or one more dialog.

Aircraft background and stripping values are normally supplied by your survey contractor. When you see this screen, you can either enter new values or accept the defaults as displayed. Click OK.

Next choose a method, for example, Upward and click OK. You see another dialog containing instrument-dependent proportionality factors and experimental constants. Enter the values for your survey or enter zeros and press OK.

The next dialog requires that you enter a name corresponding to the channel configured for upward-looking uranium data. Click OK. When Processing is complete, compare the raw, filtered (FILT) and levelled (LEVL) channels in the profile window.

Additional Notes

You may have noticed that the dialog in which you entered the name of the upward-looking channel also provided fields for levelling interim channels (UTEMP, etc).

The default filtering settings are designed to eliminate any remaining high frequency noise in the interim channel so that data are levelled as smoothly as possible.

To evaluate how these filters will affect levelling of datasets in the real world, you may want to experiment by changing the low pass value. A 200 point filter (for 1 second data) is recommended as a starting point - the data should be stored as a single line for the entire flight in order to use these long filters.

This method works on a line of data - therefore, if you want to process your data by flight (recommended), then you must store your flights of data as single lines until all processing is done. You can then break up the flight into survey lines.