Sigma Editing

The filter allows residual editing options which include the specification of a nominal sigma, several dynamic editing options, and a custom sigma editing schedule to allow different sigmas and dynamic editing for any combination of objects and measurement types

Defaults

The defaults are applied to all the possible combinations of objects and measurement types unless overridden by the custom sigma editing schedule.

NominalSigma

If the absolute value of the result of dividing the residual by the measurement sigma exceeds the value specified in the NominalSigma field, the given measurement is to be rejected. 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 The number of rejections (errors falling outside the specified nominal sigma) in a row that will trigger application of the high sigma.
NumAcceptToStop The number of acceptances in the nominal sigma range that will trigger reversion to the nominal mode.
InitialHighSigmaDuration Initial time period during which the sigma range is held at its higher value, irrespective of the number of acceptances that occur. The dynamic editing InitialHighSigmaDuration value is only applied during filter runs when in Initial mode; during restart runs the InitialHighSigmaDuration value is not used, and all dynamic editing statistics are reset to zero (number of residuals accepted and rejected).

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

Custom Sigmas

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

Custom Sigma Editing
Parameter Description
Enabled Turn on or off the entire sigma editing schedule.
Schedule A list of sigma edit entries, described below.

Click the Schedule property to display a List window in which you can add, edit and remove custom sigma editing entries. When you click the Add button, a line appears in the list, in which editing can be defined 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 to true to apply the selected sigma editing criteria to the measurements being processed.
PrimaryObjects

Select among:

  • All Emitters - applies to all emitters in the scenario


  • All Satellites - applies to all satellites in the scenario


  • GNSS Constellation - applies to the satellites in the GNSS constellation OR a single, specific GNSS satellite if one exists as a GNSSSatellite object in ODTK.


  • Selected Emitter - applies to a single, selected emitter


  • Selected Satellite - applies to a single, selected satellite
SelectedObject If appropriate (see above), select the emitter, satellite or GNSS satellite to which the editing is to be applied.
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 the editing is to be applied.
MeasType Select between All and Specific. Selecting All means edit criteria may be applied 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 Same as definition for NominalSigma above.
DynamicEditing Click to see attributes, which are same as defined above.

ODTK 6.5