Direct Digital Synthesizers: Possibilities and Limitations for Microwave Spectroscopy

Abstract

Based on the analysis of transients in the phaselocked loop, it is shown that a wide-range spectrometer with fast frequency scan may be constructed using direct digital synthesizers. Speed of record of molecular spectra in this case may be comparable with that of the FASSST spectrometer. Shape and duration of transients allow to provide highaccuracy frequency modulation that leads to minimal distortion of line shape and hence to minimal frequency determination errors. At the same time, application of the direct digital synthesizer does not give any advantage for spectroscopy of coherent spontaneous emission.