Sigma Editing

The filter enables residual editing options that include the specification of a nominal sigma, several dynamic editing options, and a custom sigma editing schedule to enable different sigmas and dynamic editing for any combination of objects and measurement types.

Defaults

ODTK applies the defaults to all the possible combinations of objects and measurement types unless overridden by the custom sigma editing schedule.

NominalSigma field

If the absolute value of the result of dividing the residual by the measurement sigma exceeds the value specified in the NominalSigma field, ODTK rejects that measurement. Enter a real number here to define that threshold.

Dynamic Thresholds Parameters
Parameter Description
Enabled Set to true to use dynamic editing; otherwise set to false.
HighSigma A large sigma used when the number of rejections in a row (errors falling outside the nominal sigma) exceeds a certain threshold. Enter a real number, e.g., enter 10 to indicate 10 sigmas.
NumRejectToStart Specify the number of rejections — errors falling outside the specified nominal sigma — in a row that will trigger application of the high sigma.
NumAcceptToStop Specify the number of acceptances in the nominal sigma range that will trigger reversion to the nominal mode.
InitialHighSigmaDuration Set tnitial time period during which the sigma range is held at its higher value, irrespective of the number of acceptances that occur. ODTK only applies the dynamic editing InitialHighSigmaDuration value during filter runs when in Initial mode During restart runs, ODTK does not use the InitialHighSigmaDuration value and also resets all dynamic editing statistics to zero, equal to the number of residuals accepted and rejected.

The dynamic editor operates independently on each combination of object and measurement type. This means, for example, that you can open up the acceptance criteria for Satellite2-Facility4-Range while remaining at nominal settings for Satellite2-Facility4-Doppler.

Custom Sigmas

The custom sigma schedule eanbles you define specific residual sigmas and dynamic editing for any combination of objects and measurement types.

Custom Sigma Editing
Parameter Description
Enabled Use this to urn on or off the entire sigma editing schedule.
Schedule Specify a list of sigma edit entries, described below.

Click the Schedule property to display a List dialog box in which you can add, edit, and remove custom sigma editing entries. When you click Add , a line appears in the list in which you can define editing for selected objects and trackers and selected measurement types. To edit this line, click in each field and select or enter the appropriate information.

Sigma Editing Schedule Definition
Field Description
Enabled Set this to true to apply the selected sigma editing criteria to the measurements being processed.
PrimaryObjects

Select from the following options:

  • All Emitters - Apply the intervals to all emitters in the scenario.
  • All Satellites - Apply the intervals to all satellites in the scenario.
  • All SurfaceVehicles - Apply the intervals to all surface vehicles in the scenario.
  • GNSS Satellites - Apply the intervals to the satellites in the GNSS constellation.
  • Specific Emitter - Apply the intervals to a single, selected emitter.
  • Specific Satellite - Apply the intervals to a single, selected satellite.
  • Specific SurfaceVehicle - Apply the intervals to a single, selected surface vehicle.
SelectedObject If you set PrimaryObjects to Specific Satellite, Specific SurfaceVehicle, or Specific Emitter, then select the object to which ODTK applies the intervals.
Trackers Select between All Trackers and Specific Tracker. Because each tracking strand contains specific tracking elements, Specific Tracker is an activator for the SelectedTrackingStrand option. After opting for Specific Tracker, you can make the tracking strand listing visible by clicking below the SelectedTrackingStrand header. Then, from the list of relevant tracking strands, you can select the strand containing the specific tracking elements to which the editing would apply.
SelectedTrackingStrand Select the tracking strand to which ODTK applies the editing.
MeasType Select between All and Specific. Selecting All means ODTK may apply edit criteria to all measurements. Selecting Specific will activate the MeasTypes list, and you may click MeasTypes to enter the measurement types for which the editing would apply.
MeasTypes Select each measurement type to which the editing would apply.
Sigma This is the same as definition for NominalSigma above.
DynamicEditing Click this to see attributes that are same as defined above.