A RANDOM WAVE METHOD FOR DETECTING PHASE IMBALANCE IN A COHERENT RADAR RECEIVER

The question of monitoring the angle between the in-phase (I) and quadrature (Q) channels of a coherent radar receiver is considered in this paper. Random interference-type scattering (e.g., rain echo) is assumed so that the received signal is a random phasor sum. It is also assumed that I and Q voltages have a (90 + phi0) phase difference. The effects of nonzero phase imbalance phi0 on the I and Q statistics are examined. Joint I and Q as well as amplitude and phase probability distributions are derived. It is shown that the cross-correlation coefficient at zero lag between I and Q time series is proportional to phi0, which provides a simple algorithm to detect the phase imbalance. This is verified by Monte Carlo simulations.