<title>Automated tuning of the Berkeley-Illinois-Maryland array receivers</title>

Abstract

The Berkeley Illinois Maryland Association (BIMA) array consists of 6 antennas, each 6 meters in diameter, operating at a wavelength of 3 mm. The telescope control is fully automated, allowing round-the-clock observing with little or no supervision. The array can also be controlled from a remote site.One of the major challenges of automated operation is the ability to tune multiple receivers to the desired operating frequency in a reliable manner. The large tuning range required at millimeter wavelengths (85 to 115 GHz) , the non linear response of the microwave cavities and oscillator phase lock problems have been stumbling blocks for remote receiver tuning.At BIMA, we have developed an automated system capable of tuning all the receivers to any observing frequency within a few minutes. The system uses a Sun workstation in conjunction with dedicated hardware to control the receivers. Large disparities between receiver characteristics are handled in an efficient manner through the use of lookup tables. We describe the system design in detail, and discuss the problems encountered along with appropriate solutions. The generation of lookup tables in the laboratory is also presented.