Joint Tactical Radio System: Software Communications Architecture (SCA)
The functionality and expandability of the Joint Tactical Radio System (JTRS) was built upon the Software Communications Architecture (SCA). The SCA was an open architecture framework that told designers how elements of hardware and software were to operate in harmony within the JTRS. It governed the structure and operation of the JTRS, enabling programmable radios to load waveforms, run applications, and be networked into an integrated system. Design engineers used the SCA definition document just as an architect or planner uses a local building code to design and build homes.
The SCA did not tell designers how to design their equipment and programs. Thus, JTRS compliant radios and networked systems, when designed in compliance with the SCA, would meet JTRS standards for interoperability, just as properly designed plumbing or electrical systems would meet local codes for construction and safety.
The software application waveforms, including the Wideband Networking Waveform (WNW), network services, and the programmable radio set (i.e., the traditional radio box) form the JTR set. The JTR sets, when networked with other JTR sets, becomes the JTRS. The SCA Hardware (HW) Framework provided the designer with minimum design specifications that had to be be met by hardware devices. These specifications assure software written to the SCA guidance would run on SCA compliant hardware. Similar Software specifications were provided for software applications. The core framework provided an abstraction layer between the waveform application and JTR sets, enabling application porting to multiple vendor JTR sets.
The SCA thus provided a development rule set focused on the detailed radio set, waveform and software development standards and specifications that described what to build to make the system interoperable and to have interchangeable equipment, software and other network components. The JTRS was composed of loadable waveforms, radio sets, and network management software. Radio sets were tied together into a system using network management procedures and waveforms forming the JTRS. All components of the JTRS (i.e., waveforms, hardware, network management software and networking hardware) would be SCA compliant.
The Software Communications Architecture (SCA) defines standard interfaces that allow waveform applications to run on multiple hardware sets. The SCA defines a Core Framework (providing a standard operating environment) that must be implemented on every JTR set. Interoperability among radio sets was enhanced because the same waveform software could be easily ported to all JTR sets.
Standardization was the key and two activities were on-going to assure that the SCA was widely accepted as the programmable radio system definition standard. First, the JPO had been working closely with the Software Defined Radio Forum (SDRF) to involve their expertise in the development of the SCA. The SDRF was not a standards body itself. However, the group adopted the SCA as a body of work mature enough to move out to a formal standards body, in this case the Object Management Group (OMG). This occurred FY00 when the SCA was at v1.0. Since then the SDRF and the OMG developed a formal liaison relationship to help further the standardization of the SCA.
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