Spectrum Analysis

Abstract

Translate Article

Most modern communication systems can be roughly divided into two general classifications: constant envelope and quadrature amplitude modulated. Constant envelope systems typically employ FM modulation or phase modulation. As such, these systems are quite immune to noise and distortion in the form of gain compression. Modern vector network analyzers consist multiple, synchronized down-converters with fully digital IF processing and as such can be reconfigured to be used as different instrument types including tuned receivers, noise figure receivers, and spectrum analyzers. The distortion measurement of two-tone intermodulation distortion (IMD) provides a means to characterize the linearity of an amplifier or mixer, but the response to complex signals may be difficult to predict from the two-tone IMD, and further the distortion caused by the in-channel part of the signal may produce products outside the signal band interfering with the operation of adjacent channel services.