Vector analyzer with display markers and linear transform capability

Abstract

A vector analyzer incorporates a set of five types of markers for the display, which facilitate the visual analysis of the magnitude, phase and time relationships of the I and Q components of the modulation states displayed. The five markers are: an I marker, a Q marker, a magnitude marker, a phase marker and a time marker. The I and Q markers indicate amplitude in the I and Q coordinates displayed on the X-Y displays. The magnitude marker indicates amplitude on the radial coordinate of the X-Y displays. The phase marker indicates relative phase on the angular coordinate of the X-Y displays. The time marker indicates the time coordinate on the displays, and controls the time instant displayed. The analyzer also incorporates a circuit for performing linear transforms on the I, Q, and time data which allows real time adjustment of the sampled signals and enables the signals to be displayed in a three dimensional projection mode. The linear transform can be used to correct the display for three common sources of error in vector modulated signals: amplitude imbalance, phase errors, and quadrature errors. After the display has been corrected, the correction factors are a measure of the errors in the input signal, or in the device demodulating the input signal.