quadrature detection

in nuclear magnetic resonance spectroscopy
https://doi.org/10.1351/goldbook.08399
Collection of time domain nuclear magnetic resonance spectroscopy data on both the \(x\) and \(y\) axes of the rotating frame of reference to allow discrimination of positive and negative frequencies.
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 701 (https://doi.org/10.1515/pac-2019-0203)