Variable Area (*.dat) File Format
The Variable Area (*.dat) file is an ASCII formatted file with a header section. The file specified tabulated values of an identified parameter as a function of the indicated independent variable. Currently, the use of this file format is restricted to the specification of drag or solar pressure area as a function of time or argument of latitude. The file consists of a header section which contains information describing the content of the subsequent data section.
Header information inside the (*.dat) file is presented in terms of keyword-value pairs where the keywords and values are separated by an equals sign. Anywhere in the file, a # symbol in the first column of a line indicates a comment.
Header Information | |
---|---|
Keyword | Value Description |
Version | Version of file format (1.0) |
ParameterName |
Specifies the name of the parameter for which tabulated values will be provided. Valid choice is: Area - area specified in m2 |
IndependentVariable |
Specifies the independent variable according to which values of the indicated parameter will be tabulated. Valid choices are:
|
TimeScale (Added in Version 2.0) |
Specifies the time scale which will be used in the specification of times in the Data sections of the file. Valid choices are: UTC. UTC is the default value. Applies when IndependentVariable is specified as Time. |
TimeFormat (Added in Version 2.0) |
Specifies time formatting which will be used in the specification of times in the Data sections of the file. Valid choices are: ISO - YMD - (ex: 2012-10-15T00:00:00.000) ISO-YD - (Ex: 2012-232T00:00:00.000) EpSec – Continuous seconds past the specified ReferenceEpoch (Ex: 86400.0). EpSec is the default. Applies when IndependentVariable is specified as Time. |
ReferenceEpoch |
Reference epoch used when TimeFormat is specified as EpSec. Must be specified in Gregorian format (Ex: 12 Jun 2020 12:00:00.00) and interpreted as being in the UTC time scale. Applies when IndependentVariable is specified as Time. |
CycleRepeats |
Valid choices are: Yes, No. If set to Yes, the pattern indicated in tabulated data will repeat for times outside of the specified time span. Since the pattern will repeat, it is recommended that the parameter values at the start and end times of the tabulated data match. If set to No, or not specified, the appropriate end value from the data table will be held as a constant for times outside of the specified span of values. Applies when IndependentVariable is specified as Time. |
InterpolationOrder |
The order of Lagrange interpolation to be used in determining parameter values for independent variable values between nodes. Default value is 1. |
Example File 1
#This is an example DAT file using Argument of Latitude as the independent variable. Version = 1.0 ParameterName = Area IndependentVariable = ArgumentOfLatitude InterpolationOrder = 1 Begin Data 000 30 010 30 020 30 030 26 060 14 … 320 26 330 30 340 30 350 30 360 30 End Data
Example File 2
#This is an example DAT file using Time as the independent variable #With CycleRepeats set to Yes, the pattern will repeat for times outside of the data span #Setting CycleRepeats to No would result in the value of 30 being used for times # outside of the data span Version = 1.0 ParameterName = Area IndependentVariable = Time TimeScale = UTC TimeFormat = EpSec ReferenceEpoch = 12 Jun 2020 12:00:00.00 CycleRepeats = Yes InterpolationOrder = 1 Begin Data 00000 30 00060 30 00120 25 00180 25 00240 22 … 05580 22 05640 25 05700 25 05760 30 05820 30 End Data