Applying Media Corrections to Tracking Data

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The DSNMediaCorrections Object can be used to apply media corrections to ground based DSN observations. This page discusses the following items:

 

•Media Corrections in FreeFlyer

•Apply DSN Media Corrections

•CalibrationCommands Table

 

 

Media Corrections in FreeFlyer

DSN transmission are susceptible to errors introduced by activity in the atmosphere. Errors from the effect of interactions with the ionosphere and troposphere can be modeled by applying biases to DSN observables. The DSN provides calibrations to evaluate these biases for specified time, ground station location, and elevation of the line-of-sight to the observed spacecraft.

 

FreeFlyer enables users to apply ionospheric and tropospheric media corrections to DSN tracking data files using the DSNMediaCorrections Object. These corrections can be imported from Trk 2-23 formatted files or configured manually using FreeFlyer script. Media corrections may be evaluated and applied to range, range-rate, or VLBI measurements.

 

Note: While VLBI is not natively supported in FreeFlyer, the correction model is agnostic to measurement type and can be adapted to users.

 

The DSNMediaCorrections Object provides an interface for applying calibrated corrections to DSN observables by calculating the associated media-induced biases. Typically, these calibrations are imported from a Trk 2-23 file, but calibration records can also be configured manually using the DSNMediaCorrectionCommand Object in script.

 

Apply DSN Media Corrections

The DSNMediaCorrections Object supports the import of correction data from Trk-2-23 formatted files and manual configuration.

 

Configuring the DSNMediaCorrections Object

 

Users can import correction data directly from a Trk-2-23 file using the syntax below:

 

 

Users can manually input calibration data with the DSNMediaCorrections.AddMediaCalibrationCommand() Method using the syntax below:

 

 

Apply Corrections to Observations

 

Users can apply media corrections to an observation with the DSNMediaCorrections.EvaluateMediaCorrection() Method using the syntax below:

 

 

CalibrationCommands Table

Users can add a DSNMediaCorrections.CalibrationCommands entry to the DSNMediaCorrections Object with the configuration settings provided in the Table below.

Note: Entries in the CalibrationCommands table directly correspond to definitions provided in the Trk 2-23 specification.

 

Command Name

Type

Access

Range/Set

Default Value

Description

Coefficients

Array

RW

N/A

{1.0}

The coefficients for the fit function

 

Computation Specifier

String Set

RW

{"NRMPOW", "TRIG", "CONST", "DNRMPOW", "DTRIG", "DCONST"}

"DCONST

The function type used for the calibrated correction. Note that while the prefix ‘D’ is allowed all evaluations will be performed in double precision.

DataType

String Set

RW

{"DOPRNG", "RANGE", "DOPPLER", "VLBI", "ALL"}

"DOPRNG"

Measurement type that is corrected.

 

Medium

String Set

RW

{"CHPART", "WET NUPART", "DRY NUPART"}

"DRY NUPART"

The transmission medium for which the correction is evaluated.

Source

Variable

RW

>=0

0

The spacecraft or quasar ID associated with the calibrated correction.

Station or Complex

String

RW

[C]?[0-9]{2}

"C20"

The station or complex for which the correction is evaluated. If this property starts with a n’C” then all stations with a station ID with the same starting digit of the value of this property are matched.

From

TimeSpan

RW

N/A

Default Epoch

The epoch at the start of the time span in which the correction calibration is evaluated,

To

TimeSpan

RW

N/A

Default Epoch

The epoch at the end of the time span in which the correction calibration is evaluated,

 

 

See Also

•DSN Observations Guide

•Simulate Tracking Data Guide

•Generate Tracking Data Files Guide