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Implementing a GPS Waveform Under the Software Communication Architecture

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SCA governs the structure and operation of software defined radios, enabling programmable radios to load waveforms, run applications, and network into an integrated system. Adherence to standards detailed in the SCA definition document allows hardware and software designers to know what equipment and programs to design. The SCA Hardware HW Framework tells the designer what minimum design specifications must be met by hardware devices. These specifications assure software written to the SCA guidance will run on SCA compliant hardware. Similar software specifications are provided for software applications. The core framework provides an abstraction layer between the waveform application and the software defined radio, enabling application porting to multiple vendors SDR products. NAVSYS is engaged in creating an SCA compliant prototype for an embedded Global Positioning System GPS waveform in a software defined radio. The intent is to optimize GPS services by providing position and time as an embedded waveform within a Software Defined Radio rather than requiring additional GPS chip sets. This paper will cover the design of the GPS devices and prototype software defined radio PowerPC processor and Xilinx FPGAs used to implement and test the GPS waveform under the SCA. This application necessitates the ability to switch tasking and adjust to various mission types within the radio framework. Test results are included showing the ability to run the GPS waveform under the SCA and demonstrating the GPS waveform with performance in tracking the GPS satellites. A discussion is also included on how the waveform could be ported to different SDRs running the SCA with different host processors and FPGAs. The flexibility of the design will allow SDR-enabled devices to be programmed to include GPS functionality running within the same radio that is supporting communications functions.

Subject Categories:

  • Computer Programming and Software
  • Navigation and Guidance
  • Radiofrequency Wave Propagation

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