The vector signal analyzer (VSA) is a tool that is replacing the spectrum analyzer (SA) as the tool of choice for RF designers working on these systems. The VSA is a powerful tool that can perform many of the same measurement and characterization tasks that the SA can, but it can also perform many more useful digital demodulation functions. The SA and VSA operate in different manners. These operational differences can result in measurement errors if these differences aren't properly considered while making a measurement.