抄録
We have been observing the spectral line of the carbon monoxide which is emited from the molecular clouds in our Galaxy. For such observations in radio astronomy, stable and precise local osillators are indispensable. Frequency synthesizers commercially available generlly have high level of spurious noise, which cannot be ignored from the observational point of view. We have made an improved PLL (Phase Locked Loop) frequency synthesizer which have very low spurious noise and high frequency stbility. Frequency is controlled both manually and in program mode.
