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This is a
simplified block diagram of a single channel.
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The DSOS is an
open loop system - send out a command and let it go to where it has to go.
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It is one of
the only systems that adjusts the primary during observations. Most radio telescopes are
mechanically tuned to one zenith angle only.
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Starting on the
left is the standoff assembly which consists of a mounting bracket, embedded
thermistor, thermal electric cooler (TEC), and heat exchanger.
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DSOS computer
gets the present ZA from the antenna computer, then gets the offset values
for all 99 standoffs for the given ZA.
The D/As send out the desired voltage to the driver amps that drive
the thermal electric coolers mounted to the standoffs. The A/Ds monitor what the
temperature is, in Volts. As
the difference between the desired setting and thermistor reading decreases,
so does the drive level to the thermal electric coolers. When the offset is close to 0 Volts,
the standoff has acquired it's desired length change.
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~Melanie Leong~
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