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Combining Simulation and Test to Accelerate SDR Development Software-defined capabilities create versatile test platforms that enhance design and test Application Note The goal of software-defined radio In SDR design, development and This application note reviews the (SDR) technology is to provide a test, tracing an issue back to its root major attributes of SDRs then looks foundation for seamless interopera- cause can be a complex endeavor. at three key topics: the use of mul- tion between diverse communication This is often due to differences tiple waveforms during SDR design, systems. This level of interoperation between the baseband and radio the use of simulation to add flexibility is easy to envision but difficult to frequency (RF) sections of the design. to SDR testing, and the use of logic achieve. For example, the hardware The complexity is often compounded analyzers and digital oscilloscopes and software elements required to by three organizational factors: any to address baseband/RF testing chal- enable greater flexibility introduce separation between the baseband, RF lenges. These techniques can create major challenges that reach back and digital design teams; the diver- a common ground that helps mitigate to the earliest stages of the design gent skill sets of analog and digital the risks caused by literal and figura- process. Later, as prototypes or designers; and differences in the tive disconnects between baseband, end-user devices become available, design and test tools used by each RF and digital design teams and their interoperation introduces challenges type of engineer. Addressing these designs. and tradeoffs in testing methods and issues early in the design process will test systems. help ensure timely completion and introduction of the end-user device. Reviewing SDR characteristics and Their implications As context, let's define an SDR as follows: It's a radio in which the baseband processing--the physical or PHY layer--is implemented in re-configurable hardware and software. The PHY layer includes field-programmable gate arrays (FPGAs), as well as RF hardware such as mixers, filters, modulators, demodula- tors, and amplifiers. The software that emulates these devices may be a C pro- gram running in a digital signal processing (DSP) or general-purpose processor (GPP) chip, or could be VHDL code for an FPGA design To the outside world, the result is a receiver/transmitter that can handle multiple types of formats and modulation schemes. This has two key benefits: flexibility and portability. An SDR offers greater flexibility through inter