Digital RF technologies make wireless access available in more places, to more people, and for less money. Increasingly, this demand is being met by devices which are software defined, allowing for changes to be made via a simple update in firmware and a plug-in analog front end (RFIC). This, in turn, is driving the need for more development and testing to be done in the digital baseband realm. Consequently, interfaces are in transition from analog to digital. The signals being created by these innovative devices are increasingly complex and dynamic; there is a growing need to create signals which use complex modulation and multiplexing schemes which rapidly change frequency, amplitude, and phase.