Custom Tracking Intervals

The CustomTrackingIntervals option lets you define inclusion and exclusion periods and increased time steps for all or selected satellites and/or facilities.

Click the Schedule property to display a List window in which you can add, edit and remove custom tracking intervals. When you click the Add button, a line appears in the list, in which the time step and inclusion/exclusion intervals can be added for selected satellites and trackers. To edit this line, click in each field and select or enter the appropriate information:

Tracking Interval Definition
Field Description
Enabled Set to true to apply the selected intervals to the selected assets.
Satellites Select among:
  • All Satellites - apply the intervals to all satellites in the scenario
  • GPS Constellation - apply the intervals to the satellites in the GPS constellation
  • Selected Satellite - apply the intervals to a single, selected satellite (see below)

See the special note below regarding the simulation of ground based tracking data to GNSS satellites whose orbits are not being estimated.

SelectedSatellite If appropriate (see above), select the satellite to which the intervals are 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 custom tracking intervals would apply.
SelectedTrackingStrand Select the tracking strand to which the intervals are to be applied.
TimeStep Enter the time step in the desired unit. Defaults to the simulator TimeStep.
InclusionIntervals The List dialog that appears will contain a line for the definition of the inclusion interval. Click the Add button to insert additional sub-intervals. On each line, set the Enabled value to true if the sub-interval is to apply; otherwise set it to false. Edit the Start and Stop times as desired. The first interval added has a default span based on the scenario's DefaultTimes.Intervals.TimeSpan attribute. To delete a line, select it and click the Remove button. To clear the list, click Remove All.
ExclusionIntervals Exclusion intervals are set in the same way as inclusion intervals (above).

To delete an interval, select it and click the Remove button. To clear the list, click Remove All. To re-order intervals, select one in the list and click the Up or Down button.

There are two alternative methods to define custom tracking intervals:

  1. You can define custom tracking intervals by using a link to an Interval File in an external (*.int) file and link to it. Click where indicated next to the IntervalFileLinks attribute. In the List dialog that appears, add lines and manage them as described above for the Schedule attribute. Here, instead of defining an interval manually, you specify the path and file name of the file where the interval is defined. The LinkedSchedule attribute displays a read-only list of the schedule defined via the IntervalFileLinks mechanism.
  2. You can also define custom tracking intervals by reading in the measurement information from the Scenario.Measurements.Files. This option is controlled by the "ImportMeasFileSchedule" property. When set to true a Tracking Interval definition is created for each enabled {Satellite, Tracker} present in the measurement files. An InclusionInterval will be added for each measurement time. Note that one can display the read-only measurement file schedule by clicking on the ImportedSchedule property. Be aware however that the displayed schedule only "data limits" the custom tracking intervals by the objects that are contained within the scenario, whereas the resulting simulated measurements are "data limited" by the Simulator SatelliteList, EmitterList, TrackingStrandList, and MeasurementTypes list.

NOTE: The simulator's TimeStep property sets the limit on the degree of fineness of measurements taken during the simulation. Setting the TimeStep field in the List window to a smaller time span than the TimeStep you defined for the simulator has no effect. If the TimeStep for the interval is set to an time span larger than the simulator's TimeStep but is not a multiple of the latter, the actual time span applied will be the next-higher multiple of the simulator's TimeStep. For example, if you set the simulator's TimeStep to 15 min and set the TimeStep in the custom interval to 20 min, measurements during the interval in question will be taken at times 0 min, 30 min, 60 min, etc.

NOTE: If GNSS satellites are defined to estimate the orbits of the satellites, they can be used in tracking data simulation in the same manner as normal satellites. If the GNSS satellites are defined to obtain their ephemeris information from a GNSS reference file, then ground based tracking data to the GNSS satellites will only be generated if the GNSS satellites of interest are included individually in custom tracking intervals. For example, to generate ground based tracking data to PRN01 when PRN01 is defined to obtain its ephemeris information from an SP3 file, then an entry must be added to the custom tracking schedule which specifies the Satellites option as GNSS Constellation and the SelectedSatellite option as PRN01. GNSS constellations which do not have populated GNSS satellites under them cannot be used to generated ground based tracking data.

ODTK 6.5