Home

GPS receivers will be integral parts of software-defined radios.

A continuing development effort focuses on implementation of a Global Positioning System (GPS) waveform under the Software Communications Architecture (SCA). [As used within the special technological discipline of the SCA, "waveform" signifies not only a waveform in the commonly understood sense of the word, but also subsystems and components for receiving and transmitting the waveform; subsystems for processing the information conveyed by the waveform; subsystems that perform ancillary communication and control services relevant to the role of the affected software-defined radio (a transmitter, receiver, or transceiver) as a node in a data-communication network; and any or all of the aforesaid information and services.] The intent is to optimize GPS services by providing position and time information as an embedded waveform within a software-defined radio (SDR), rather than using additional GPS chip sets to provide the information. It is further intended that the GPS waveform first will be used to provide position and time information in Joint Tactical Radio System (JTRS) radios. [The JTRS is a family of military SDRs, waveforms, and cryptographic algorithms designed under the SCA.] The JTRS radios are reprogrammable to run a family of special waveforms that utilize carrier frequencies from 2 MHz to 2 GHz — a frequency range that includes the 1.2- and 1.5-GHz GPS frequencies.

This GPS Waveform (essentially, a software-defined GPS receiver) is initiated as a single aggregate device within an SDR.
An inherent aspect of SDR is the ability to redefine radio functionality by interchanging waveform software on one set of radio hardware. This ability supports interoperability of different radio-communication systems (e.g., systems used by allied military forces of different countries or different military and civilian government agencies of the same country). An industry demand for a clearly defined hardware, software, and network architecture to provide a standardized environment for the deployment of interoperable waveforms has been the driving force for formulation of the SCA, which is an open-architecture standard that tells designers how elements of hardware and software are to operate in harmony within an SDR. The SCA governs the structures and operations of SDRs, enabling programmable radios to load waveform software, run application programs, and become nodes in a network that constitutes or is part of an integrated data-handling system. Through adherence to standards detailed in the SCA definition document, both hardware and software designers know what equipment and programs to design. These specifications ensure that software written according to SCA guidance will run on SCA-compliant hardware. The core conceptual framework of the SCA provides an abstraction layer between the waveform application software and an SDR, enabling porting of application software to SDR products of multiple vendors.