Improving Testing Capability of Interoperability for Link-11 by building a Gateway for a TCP/IP Network

Link-11 is a tactical digital communication network standard deployed in military platforms now for several decades. The standard employs the digital modulation technique Differential Quadrature Phase Shift Keying (DQPSK) to encode formatted binary messages (M-series messages) onto an audio channel, which are then modulated and transmitted over a radio communications network. Testing of the various systems that use this communications network requires either a fully operational RF network or exchange of the audio-encoded data over a voice channel. An alternative is to send and receive over an IP network, by encoding and decoding the audio from a Data Terminal Set (DTS) that is part of the normal operational equipment. This allows the test community to interconnect distant test sites over IP networks using this robust connectivity for message exchanges. This facilitates interoperability testing at the data and applications level where RF and audio connectivity is not available or is unreliable. We explore this approach to interoperability testing of Link-11 by implementing a gateway between the Link-11 network and a TCP/IP network. Such a gateway has been built and tested at the Joint Interoperability Test Command (JITC) by a team of contractors and government. A review of the engineering and implementation is provided, along with a proposed future expansion of the prototype within a given experimental frame in the Discrete Event System Specification (DEVS) framework.