An approximate characterization of the distortion of narrowband signals by linear time-invariant systems

The increased demand for data communication at high rates has made it important to transmit this information as accurately as possible, and to characterize its distortion when passed through a communication link. Ultrawideband (UWB) links have applications in radar, location, tracking and sensor applications. Although some parts of such links (amplifiers, for instance) are nonlinear and/or time-varying, much of the signal path (including the antennas) can typically be characterized as a linear, time-invariant (LTI) system. In this paper, we will review a widely-used measure of distortion called the fidelity factor, and provide a simple analytical approximation for it that can be used to quickly assess the extent to which pulsed signals are degraded when passed through an LTI system.