NASA Technical Memorandum 109071 /H-oy • Q Packet Radio Data Link Applications in the NASA Langley _Research Center Transport Systems _Search Vehicle Wesley C. Easley, and Donald Carter Langley Research Center, Hampton, Virginia David G. McLuer Lockheed Engineering & Sciences Company, Hampton, Virginia (NASA-TM-I09071) PACKET RADIO DATA N94-27423 LTNK APPLICATIONS IN THE NASA LANGLEY RESEARCH CENTER TRANSPORT Unclas SYSTEM5 RESEARCH VEHICLE (NASA) 30 p G3/04 0000320 January 1994 National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23681-0001 : ..... ¥ i ! TABLE OF CONTENTS Summary ................................................ iii List of Figures ........................................ iv Credits ................................................. v 1.0 Introduction ...................................... 1 2.0 List of Abbreviations ............................. 2 3.0 Baseline Packet Link Configuration .... ............ 4 3.1 Baseline Packet Ground Station ............. 4 3.1.1 Terminal Node Controller (TNC) ........ 4 3.1.2 Ground VHF Transceiver ................ 5 3.1.3 Packet Ground Station Monitor and Control .......................... 5 3.2 Baseline Packet Airborne Station ........... 6 3.2.1 Interface Switching ................... 7 3.2.2 Packet Airborne Station Monitor and Control .......................... 7 4.0 Flight Research Programs Using the Packet Data Link ................................. 8 4.1 Air Traffic Control and Weather Data Link Experiments ..................... 8 4.1.1 Ground Packet Configuration ........... 8 4.1.2 Airborne Packet Configuration ......... 8 4.1.3 Remarks and Conclusions ............... 9 4.2 Differential Global Positioning System Flight Tests ....................... 10 4.2.1 DGPS Ground Packet Configuration ........................ 10 4.2.2 DGPS Airborne Packet Configuration ........................ 10 4.2.3 Remarks and Conclusions ............... 10 4.3 Windshear Applications of the Packet Data Link .......................... ii 4.3.1 Windshear Ground Packet Station Configuration ................ ii 4.3.2 Ground Computations and Display ....... ii 4.3.3 Windshear Airborne Packet Station Configuration ................ 12 4.3.4 Remarks and Conclusions ............... 12 5.0 Data Packet Configuration ......................... 13 6.0 Concluding Remarks ................................ 14 References ............................................. 16 ii SUMMARY An amateur packet radio system has been used to support bidirectional air/ground data link requirements for a number of Transport Systems Research Vehicle (TSRV) flight test programs at the National Aeronautics and Space Administration (NASA) Langley Research Center. Data transfer between ground-based and airborne packet radio stations was accomplished via audio modulation of a Radio Frequency (RF) carrier. For TSRV use, the baseline configuration of each station consisted of a Very High Frequency (VHF) transceiver, a packet Terminal Node Controller (TNC), an antenna, and a computer terminal for monitoring and control. User system interfaces for both ground and airborne baseline stations were configured to meet the specific requirements of each test conducted. Within each station, audio and RS-232 digital data connections are present for the packet TNC. The audio connection is to the VHF transceiver which serves as the air/ground data transfer medium. For transmission, the TNC passes audio signals to the transceiver for VHF carrier modulation. For reception, the TNC receives, via the audio interface, signals representing digital data transmitted by another station. The received and transmitted audio signals are converted respectively to and from RS-232 data by the TNC. The RS-232 data stream is the interface medium for two-way communication between the TNC and a user system. Descriptions of the varied packet link configurations employed to support the TSRV efforts are contained in this document. iii LIST OF FIGURES Title Page Configuration of TSRV Baseline Ground 18 Packet Data Link System .......................... Configuration of TSRV Baseline Airborne , Packet Data Link System .......................... 19 Ground and Airborne Configurations for , Air Traffic Control and Weather Information Data Link Experiments ................. 20 Ground and Airborne Configurations for . Differential GPS Data Link Application ........... 21 Ground and Airborne Configurations for , Data Link Support of Windshear 22 Flight Tests ..................................... Illustration of Ground and Airborne Map , 23 Displays for TDWR Packet Data Link ............... Windshear Downlink Messages Illustrating , Data Packet Configuration ........................ 24 iv CREDITS Borland C++ compiler package version 3.1, S/N DA973AI0058087 was used to support the tasks described in this document. This is a copyrighted product of Borland International, Inc., Scotts Valley, California. MS-DOS and Microsoft C were also used in support of the tasks described herein. They are copyrighted products of Microsoft Corporation, Redmond, Washington. The ground map illustrated in figure 6 was written by Richard W. Dickson of Computer Sciences Corporation. All airborne display software was written by Chris Slominski and Valerie Plyler of Computer Sciences Corporation. The packet Radio Terminal Node Controllers (TNC's) described in this document are products of MFJ Enterprises, Starkville, Mississippi. Personnel from MFJ Enterprises also have provided technical support. The radios used with the MFJ packet TNC's are products of Motorola Corporation. All other tasks described in this document were performed by the authors. v