The Effects of Quadrature Sampling Imbalances on a Phase Difference Analysis Technique

This paper studies the effects of amplitude and phase imbalances between the in-phase I and quadrature Q channels of a Digital Radio Frequency RF receiver on a phase analysis processing technique. Particular attention will be given to the effect that these errors have on the detection and accurate frequency resolution of simultaneous signals. Phase analysis processing of digitized time domain data to extract a radars carrier frequency can be very reliable if the quadrature phase and 11 amplitude relationship can be maintained between the I and Q channels across the frequency band of interest. In practice it is very difficult to closely match the channels with respect to these parameters over wide bandwidths. The literature to present 2,3 has shown these imbalances to be the main sources of error in quadrature detectors. This paper will illustrate both through simulation and from data collected from a 250 MHz, 8 bit, digital receiver, how these errors along with other anomalies affect the performance of phase analysis processing and specifically how they affect detection and determination of simultaneous signals.