Why Are Video Bandwidth and Rise Time Important?

ABSTRACT: Among all the parameters to consider in RF design, power measurements remain one of the most important metrics for designers and operators, especially considering today’s complex modulation schemes, pulsed communication modes, and increased popularity of wireless devices. To accurately characterize modulated or pulsed signals, an important factor to keep in mind is the video bandwidth (VBW) of the RF power measurement test equipment. VBW describes a sensor’s ability to track signal variations of envelope power measurements; envelope power is the amplitude change due to modulation or distortion as a function of time averaged over one or a few cycles of the RF carrier signal – sometimes referred to as peak power. As a result, detecting pulse and peak power measurements correctly relies on the modulating signal’s rate of change in amplitude to be less than the sensor’s VBW.