Band-to-Band transfer technique

To improve high frequency calibration, Allegro explores the B2B phase transfer methods using simultaneous dual frequency observation. Non-dispersive characteristics of the atmosphere in millimeter/sub-millimeter wave length enables the low frequency phase data to track the high frequency phase variation well with dependency only on the frequency ratio. Therefore simultaneous observation of the source using low- and high-frequency receiver provides a reliable solution for the high frequency phase variation based on the well calibrated low frequency data. Although currently ALMA provides B2B phase transfer calibration methods using interleaved observing scans in low- and high-frequency, it is not based on simultaneous observation and the performance is still not optimal.

Allegro is building expertise on the analysis methods for B2B phase transfer using dual frequency observation, which can be one of the directions of the future improvement of ALMA in high frequency observation including capability of using dual frequency receiver.