Quadrature detection

{
  "id": "MLC-T-CHM-009719",
  "term": "Quadrature detection",
  "field": "Chemistry",
  "definition": "A scheme for detecting NMR signals with a pair of phase-sensitive detectors whose reference phases are set 90 degrees apart, so the signal is recorded along both the x and y directions of the rotating frame. The two outputs together form a single complex signal, one channel supplying the real part and the other the imaginary part, which makes frequencies above and below the carrier distinguishable. Its signal-to-noise ratio exceeds that of single-channel detection by a factor close to the square root of two.",
  "subject": "Analytical Chemistry",
  "see_also": [
    "nuclear magnetic resonance spectroscopy"
  ],
  "references": [
    "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)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/quadrature-detection/"
}