Millimeter- And Submillimeter-Wave Spectrometers on the Basis of Direct Digital Frequency Synthesizers

Two new spectrometers based on the direct digital frequency synthesizers are presented. The instruments are characterized by a high rate (up to 100 GHz/hr) of molecular spectrum recording with a high accuracy of measuring transition frequencies (the measurement error for isolated spectral lines lies within ±0.002 MHz provided that the signal-to-noise ratio is 50 or greater). Frequency modulation of the radiation source is provided by direct digital frequency synthesizers that guarantees high stability and determinancy of frequency-modulated signal parameters and makes it possible to minimize the spectral lineshape distortions.