Interfacing with External Resources Samples

These sample Mission Plans cover various aspects of FreeFlyer's ability to interface with other programs and data sources. After exploring the Mission Plans below, continue to the Interfacing with External Resources Guide to learn more.

Note: For Mission Plans that generate a batch file, you do not need to use a Mission Plan to create that batch file. This approach was used for these examples so that the batch files would reflect each user's FreeFlyer installation directory. You can create a batch file manually by following the instructions in the Creating a Batch File article.

Mission Plan	Engineer	Mission
Client Socket	•	•
Create Auto User Info Batch Files	•	•
oAuto Pass User Info	•	•
Create List Batch Files	•	•
Create Movie-Generation Batch Files	•	•
oMovie Views	•	•
Create Namelist Batch Files	•	•
Download TLEs	•	•
Excel File Interface	•	•
FileInterface - ASCII	•	•
FileInterface - Binary	•	•
MatlabInterface - Cubic Spline	•	•
MatlabInterface - Force Model Example	•	•
MatlabInterface - Simple Calculation	•	•
MatlabInterface - Socket Connection	•	•
MatlabInterface - User Function	•	•
Run Command		•
Server Socket	•	•
UserInterface - Navigation Type	•	•
UserInterface - Script Example	•	•
UserInterface - Spacecraft Orbit	•	•
UserInterface - String Input	•	•
Using Externals	•	•
Using Globals	•	•

Client Socket

This Mission Plan demonstrates the use of FreeFlyer to send and receive data through a Socket Interface. There are two Mission Plans associated with this example, a Server and a Client. This Mission Plan is the Client, and has a Socket called ClientSocket that will be used to send and receive data from the Server.

The Mission Plan propagates a Spacecraft, and sends the SMA, Eccentricity, and Inclination to the Server through the Socket. It then waits to receive manipulated data from the Server through the Socket. Once this Mission Plan receives the manipulated data from the Server, it reports the data to the screen and steps the Spacecraft to the next propagation step.

To learn more about topics related to this sample Mission Plan, see the Sockets guide.

Create Auto Pass User Info Batch Files

This Mission Plan creates two batch files that execute a FreeFlyer Mission Plan. The first batch file, 'BatchFile_FF_NoGUI.bat', will call FF.exe, the no-GUI mode that runs only in the command line. The second batch file, 'BatchFile_FreeFlyer_GUI.bat', will call FreeFlyer.exe, the GUI mode of FreeFlyer. Both batch files will run the Auto Pass User Info Sample Mission Plan.

After running this Mission Plan, open the _Output_Files directory in an explorer window and launch each batch file.

Auto Pass User Info

This Mission Plan is supposed to be kicked off by a batch file that passes information via the '-ui' command. The batch file is created by the CreateAutoPassUserInfoBatchFiles Sample Mission Plan in the Interfacing with External Resources folder. This Mission Plan propagates a Spacecraft, given the parameters that were sent to FreeFlyer via the '-ui' command. While propagating, the Mission Plan generates a report of the contact times between the Spacecraft and the Groundstation. This Mission Plan is located in the _Support_Files/MissionPlans directory.

Note: If this Mission Plan is run without the batch file, an error message will be displayed.

Create List/Loop Batch Files

This Mission Plan creates two batch files that executes a list or a looping list of FreeFlyer Mission Plans. The first batch file, 'BatchFile_FreeFlyer_GUI.bat', will call FreeFlyer.exe, the GUI mode of FreeFlyer. The second batch file, 'BatchFile_FF_NoGUI.bat', will call FF.exe, the no-GUI mode that runs only at the command line.

After running this Mission Plan, open the _Output_Files directory in an explorer window and launch each batch file.

Create Movie Generation Batch Files

This Mission Plan creates five batch files that each generate one or more movies using the FreeFlyer Mission Plan MovieViews found in the _Support_Files/MissionPlans directory.

After running this Mission Plan, open the _Output_Files directory in an explorer window and launch each batch file. Then, run each of the movies that have been created.

Movie Views

This Mission Plan propagates a Spacecraft and displays two ViewWindows with the titles "Spacecraft View" and "MissionView 1". These ViewWindows are accessed by the batch files created by the CreateMovieGeneratingBatchFiles Mission Plan so that various movies can be created, exercising the available command line options. This Mission Plan is located in the _Support_Files/MissionPlans directory.

Create Namelist Batch Files

This Mission Plan creates two batch files that execute the Walker Constellation Sample Mission Plan. The first batch file, 'BatchFile_Create_Namelist.bat', calls the Mission Plan and creates a output file of your UserInterface selections. The second batch file, 'BatchFile_Import_Namelist.bat', calls the Mission Plan and uses a namelist input file provided in the _Support_Files directory to override the UserInterface.

After running this Mission Plan, open the _Output_Files directory in an explorer window and launch each batch file.

Download TLEs

This Mission Plan demonstrates the Socket object as an interface to a website. The socket connects to www.celestrak.com.First the socket is used to download the source from the websites homepage. The source is used to build a list of all the TLE sets available on CelesTrak. This list is then presented through a UserInterface object allowing the user to select which TLEs to download. Once a TLE set is selected FreeFlyer sends a "Get" command to the Celestrak website, and receives a string of TLE data which is parsed into a StringArray object. The TLE file is saved, and then loaded into a formation object to be visualized in a 3D Mission View.

To learn more about topics related to this sample Mission Plan, see the Sockets and Lists and Formations guides.

Excel File Interface

This Mission Plan demonstrates the use of FreeFlyer to read a randomly-formatted external file. In this case, the pre-generated external file contains ephemeris data (epoch, position, and velocity) for a Moon-orbiting Spacecraft.

The data in the external file is comma-separated (CSV). A FileInterface object is used to read the file and assign each state to a Spacecraft. The Spacecraft is propagated until the end of the CSV file is reached. A new FreeFlyer-formatted ephemeris file is generated at the end of the Mission Plan.

FileInterface - ASCII

This Mission Plan retrieves unmodeled acceleration data from a randomly formatted external file. The data shown in the WatchWindow matches the acceleration values read from the external file 'UnmodAccel.txt'. This shows that those values are now associated with the Force Model's Unmodeled Accelerations.

FileInterface - Binary

This Mission Plan demonstrates the use of the FreeFlyer FileInterface object to read in data from a binary data file. In this example, selected integer and double data is extracted from the binary data and displayed. The data file used is a TDRSS Universal Tracking Data Format (UTDF) file. A UTDF file is the standard file format used by the Space Network (TDRSS) to communicate TDRS tracking data to its customers.

As a general rule, the extraction of binary data requires a priori knowledge of the file format. For this example, the UTDF file format is detailed in the Space Network - Flight Dynamics Facility Interface Control Document. For the purposes of this Mission Plan, the locations of the data elements extracted from the UTDF file are detailed in the "Relevant UTDF Format Description" window. After execution of this Mission Plan is complete, this window can be found minimized at the bottom of the output screen.

MatlabInterface - Cubic Spline

This Mission Plan demonstrates the use of FreeFlyer to interface with Matlab and use Matlab's cubic spline interpolation to calculate and plot a set of data. The exact value of the measured Y-data will be returned if a corresponding X-value is input.

The script in this example can be used as a template for interfacing with other Matlab functions. The Matlab m-file is very simple as well, requiring only two lines:

To learn more about topics related to this sample Mission Plan, see the Matlab Interface guide.

MatlabInterface - Force Model Example

This Mission Plan demonstrates the different Atmospheric Model representations available in FreeFlyer. Four spacecraft are created with different Atmospheric Force Models. The Analytic Spacecraft uses the Analytic Force Model, HP75 uses Harris-Priester 75 model, Jacchia uses Jacchia-Roberts model, and the CustomFM uses a custom Force Model calculated in Matlab. The custom Force Model is enabled using the ForceModel.OtherAcceleration property, and is defined through FreeForm.

In order to calculate the custom accelerations, 7 properties of CustomFM spacecraft are sent to Matlab, using a Matlab Interface called MatlabInterface1. These seven properties are Cd, DragArea, SRPArea, VX, VY, VZ, and NewMass of the CustomFM spacecraft. NewMass is calculated as a 0.3% loss of fuel. Matlab takes this data and calculates the UX, UY, and UZ components of the unmodeled acceleration, and sends the output back to FreeFlyer through the CustomDragAccelerations array. FreeFlyer takes these array elements and applies them to the UX, UY, and UZ components of the Force Model of the CustomFM spacecraft.

The 3D View shows the orbit of each spacecraft with respect to the Analytic Spacecraft. The Plots show Range for each spacecraft from the Analytic Spacecraft.

To learn more about topics related to this sample Mission Plan, see the Matlab Interface guide and the Force Modeling reference.

MatlabInterface - Simple Calculation

This Mission Plan calls a Matlab .m file which performs a simple calculation on an Array, a Matrix, a String, a StringArray, and a Variable. The Mission Plan demonstrates how to interact with Matlab through FreeFlyer's object and commands editors as well as FreeForm script editors.

To learn more about topics related to this sample Mission Plan, see the Matlab Interface guide.

MatlabInterface - Socket Connection

This Mission Plan demonstrates how a user could use the Socket Object in FreeFlyer to communicate with Matlab over a socket interface. This code represents the CLIENT socket. It receives data from Matlab, does 'something' with that data, and then returns the results back to Matlab. This Mission Plan is meant to be called from Matlab. To see the full example, run the SimpleSocket.m script in Matlab. Be sure to set the FreeFlyer install path as well as the Mission Plan location in the Matlab script.

To learn more about topics related to this sample Mission Plan, see the Matlab Interface guide and the Socket guide.

MatlabInterface - User Function

This Mission Plan demonstrates how to request and plot a custom function calculated in Matlab. The user inputs a one-variable function as a string in Matlab format with a desired range and the number of data points. The (x,y) data will be output to arrays and plotted.

This allows users to quickly set up arrays containing the desired output and provides access to Matlab math functions that are not built in to FreeFlyer. The Matlab m-file used by this example is very simple, requiring only five lines:

To learn more about topics related to this sample Mission Plan, see the Matlab Interface guide.

Run Command

This Mission Plan demonstrates the use of the FreeFlyer Run command. The Spacecraft is propagated for one day when this Mission Plan is run from the GUI, generating an ephemeris file. This Mission Plan then kicks off an instance of command line FreeFlyer which analyzes the Ephemeris and reports some diagnostic information about it to standard output.

Server Socket

This Mission Plan demonstrates the use of FreeFlyer to send and receive data through a Socket Interface. There are two Mission Plans associated with this example, a Server and a Client. This Mission Plan is the Server, and has a Socket called ServerSocket that is awaiting data from the Client.

Once this Mission Plan receives the data, it edits the data and sends it back to the Client.

To learn more about topics related to this sample Mission Plan, see the Sockets guide.

UserInterface - Navigation Type

This Mission Plan demonstrates the User Interface property "NavigationType", which controls how the user accesses the pages of a UserInterface. NavigationType has two valid values: "Ordered Access" and "Random Access". The default is "Ordered Access", in which the pages are shown sequentially with "Next Page" and "Previous Page" buttons. With "Random Access", the user navigates the pages using a list of available pages shown in a panel on the left side of the UI.

In this example, two Spacecraft Objects are modified through two separate UserInterfaces. The UserInterface "OrderedUI" is created through FreeForm script, and it displays three pages in Ordered Access. The UserInterface "RandomUI" is created through the Object Browser, and it displays the same input options using Random Access.

To learn more about topics related to this sample Mission Plan, see the User Interfaces guide.

UserInterface - Script Example

This Mission Plan demonstrates how to create a UserInterface in script. The User Interface allows the user to configure a Ground Station created in FreeForm Script. The User Interface has three pages. The first page allows the user to edit the location and name of the Ground Station, the second page allows the user to control the visualization properties of the Ground Station and the third page allows the user to set some of the Ground Station Orbit Determination properties.

UserInterface - Spacecraft Orbit

This Mission Plan demonstrates the use of a UserInterface. The UI is a custom-designed panel or series of panels allowing the user to input key data for that specific Mission Plan. A User Interface provides a simple, focused input mechanism for a limited scope of input data. This device can be especially helpful to users with limited experience or where the same procedure is to be run many times. Data entered in the UI overrides corresponding data in the Mission Plan.

To learn more about topics related to this sample Mission Plan, see the User Interfaces guide.

UserInterface - String Input

This Mission Plan demonstrates how to receive string-based data from a UserInterface and assign the input to FreeFlyer String objects. The results of the User Interface are reported out to the Console.

To learn more about topics related to this sample Mission Plan, see the User Interfaces guide.

Using Externals

This Mission Plan uses external script files, known as Procedures, to execute generalized sections of FreeFlyer script. The Call command is used to execute the desired Procedure or Macro.

The orientSC Procedure sets a Spacecraft's attitude so that it is pointing toward the sun if in sunlight and aligned with the LVLH frame if in shadow. This Procedure calls a second Procedure, sunpoint, to calculate the normalized vector pointing from the Spacecraft to the Sun in the Spacecraft LVLH frame. A Macro called StepMacro is used to step the Spacecraft forward in time.

To learn more about topics related to this sample Mission Plan, see the Using Procedures reference.

Using Globals

This Mission Plan demonstrates the use of the Externals Browser to include a file with a Global Variable 'GlobalNumber'. 'GlobalNumber' is available to the Mission Plan as well as to the Example.FFProcedure (also in the Externals browser) without having to be passed as an argument to the Procedure.

'GlobalNumber' and another variable in the Mission Plan, 'Number', are displayed, then sent to the Procedure, which sums them, and then are displayed again.