Successful Analysis of Modulated Signals
应用文章
The design and optimization of modern digital communications systems is a complex and multifaceted challenge. Because of this complexity, an organized approach is beneficial. This application note will outline one such approach that has proven to be effective in the development of a variety of systems.
When measuring and troubleshooting digitally-modulated signals, it is tempting to proceed directly to digital demodulation, specifically modulation quality analysis. However this approach is generally not the most productive one, as important clues to system problems may be missed. Modern systems and signals depend on many factors working together including frequency coordination and time alignments.
Even when demodulation is successful—not always the case—the results may not reflect the entire nature of system performance and the measurement of impairments may not point to their cause. In addition, initial efforts at demodulation are often problematic because even simple impairments such as symbol rate or frame timing errors can cause demodulation failure. Without successful demodulation the designer is left with little information to guide subsequent troubleshooting.