The objective of the LTAS Simulator application is to transmit one or more streams of simulated LTAS data frames in User Datagram Protocol (UDP) packets to the network. Each LTAS data frame is filled with simulated data values, with each data field determined using several methods: 1) constant value from the user’s input via a graphical user interface (GUI), 2) internal generated counter from a start value, 3) internally generated random value using uniform probability that is set by the user, and 4) internally generated modified value using uniform probability that is set by the user.

The Portable Object Simulator (POS) application, a prior art, has the capability to perform the objective, but the user interface is limited in regards to manipulating each data value in the LTAS frame while the simulation is running. This POS application requires the user to pre-generate a dataset and then feed it to the application during running. The pre-generated dataset generally is not ideal, especially when the dataset is repeated without allowing unpredictable data values like internally generated random values in the LTAS Simulator application.

The LTAS Simulator software is a standalone application running on Microsoft Windows 7.

This software was developed using the C/C++ programming language with Qt for the integrated development environment (IDE), Qt libraries, and Microsoft Visual Studio 2013 or MinGW for the compiler. The LTAS Simulator application is generally built using the model-controller-view design pattern by grouping the source code into two categories: logic and graphics. The logics portion is responsible for determining simulated data value for each data field in LTAS frame, generating the LTAS frame, and transmitting these to the network in UDP packets at a specified time interval. This portion also passes the transmitted packets to the graphics portion for displaying what is already transmitted. The graphics portion contains buttons, text fields, numerical spinners, and radio buttons for the user to enter simulated value and/or select generating options. A dialog of Earth map is included to allow the user to pinpoint on the map and determine Earth coordinates (in Latitude, Longitude, and Altitude), which is converted to ECEF X, Y, and Z to be inserted in each LTAS data frame.

In addition to these functions, this application records all outgoing LTAS data streams to files with time stamps in binary format. A configuration file, in XML (Extensible Markup Language) format, is used and loaded at the user’s request to describe the outgoing data streams and data value options. Network Countdown Time Protocol is used for time-synchronizing and displaying Earth and countdown times for informational purposes.

This work was done by Nathan Riolo of NASA Wallops Flight Facility for Goddard Space Flight Center. NASA is seeking partners to further develop this technology through joint cooperative research and development. For more information about this technology and to explore opportunities, please contact Scott Leonardi at This email address is being protected from spambots. You need JavaScript enabled to view it.. GSC-17406-1


NASA Tech Briefs Magazine

This article first appeared in the April, 2017 issue of NASA Tech Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.