Millimeter-wave channel sounders are much more sensitive to phase drift than their microwave counterparts by virtue of shorter wavelength. This matters when coherently phasing (electronic or mechanical) antenna scans collected over seconds, minutes, or even hours in order to obtain directional channel data. To eliminate phase drift, a synchronization cable between the transmitter and receiver is required, limiting deployment range and flexibility indoors, and in most scenarios precluding outdoor operation. Instead, we propose a blind technique to correct for phase drift by post-processing the channel data collected; the technique is referred to as blind because it obviates the need for a known reference signal and, as such, works even in non-line-of-sight conditions when the (known) direct path is undetectable. To substantiate the technique, it was tested on both simulated and real measurement data collected with our 60-GHz virtual-array channel sounder. The technique was demonstrated robust enough to deal with the most severe case of phase drift (uniformly distributed phase) over a 60-minute scan duration in non-line-of-sight and in low signal-to-noise conditions.
IEEE Access Journal
mmWave, clock drift, calibration, phased-array antennas, phase coherence, beamforming