Radiometer Data Acquisition (J.Quick)

Our simplest data acquisition task takes the form of monitoring the radiometric output of various receivers as a function of telescope orientation and of time. Such fast data aquisition is currently done using the Fluke 8840 digital voltmeters. Position and time stamping are handled in software, relying on the real time nature of the HP1000 operating system for accuracy. The NCCS plans to replace the Flukes which are on their last legs with high resolution V/F converters connected to custom counter cards built into the new PC-STEER hardware interface. Synchronous acquisition of counter readings, NASA timecode and telescope position encoder readouts is handled by means of a common hardware strobe. All radiometers will be equipped with dedicated V/Fs with each counter card being switched between up to eight different V/F outputs under computer control. Several binary divider outputs based on the hardware strobe are available for the switching of Dicke Switches and Noise Adding Diodes to facilitate future synchronous digital radiometer modes.

Tasks completed :

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SELECT A V/F CHIP AND DESIGN AND BUILD SUITABLE CONVERTERS,

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DESIGN AND BUILD COUNTER CARDS FOR PC-STEER HARDWARE INTERFACE,

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ADD SYNCHRONOUS ACQUISTION OF COUNTER READINGS INTO PC-STEER.

Tasks still to be done :

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QUALIFY V/F CONVERTERS FOR USE ON EXISTING RADIOMETERS,

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INTEGRATE A SUITABLE RADIOMETER DEVICE SERVER INTO PC-STEER.