Patent ID: 11255948

Abstract:
Devices and methods are provided for determining frequency spectra, as well as the polarity of frequency, of energy in quadrature signals. In Doppler detection systems, found in sonar, radar, lidar, optical velocimeters using interferometers, and ultrasonics applications, for example, this information can be used to determine target speed and direction. Embodiments obtain a quadrature signal and determine a sine transform of a cross correlation between the I and Q components of the quadrature signal, and can provide an output comprising a signed frequency spectrum. A sign of a sample of the signed frequency spectrum can correspond to a polarity of frequency. The signed frequency spectrum can be rapidly determined over a unipolar frequency span that may be only approximately half the baseband sampling frequency. The signed frequency spectrum may be impervious to imaging under severe conditions of uncorrected quadrature amplitude imbalance.