Radome Environment and Telescope Thermal Control

The temperature stability of the antenna has a big impact on its performance. Accordingly, there are several devices under computer control in the radome which aid in the temperature control of the dish. These include: (1) a hatch at the top of the radome to release warm air trapped at the top of the radome to the outside; (2) two fans which circulate air to help maintain a uniform temperature in the radome; (3) two vents which permit the radome fans to pull in outside air; (4) the furnace which heats the radome; and (5) the radome dehumidifier, which keeps frost from forming on the inside surface of the radome.

The current status of the radome devices under computer control is listed on SCREEN 18. This produces a list of the current state of the radome devices. The ENV command with arguments "AUTO" or "OFF" will enable or disable the computer control of these devices by the tracking programs.

truein

Table 3.8

Environment Control Keywords

ENV OFF

radome equipment NOT under computer control

ENV AUTO

radome equipment is turned on and off, based on measured temperature info and an algorithm; commands entered by a user will be over-ridden

DEHUM (ON/OFF)

turn the dehumidifier on or off

(OPEN/CLOSE) VENT ID

controls vents ; ID=1,2
Note: vent positions cannot be changed while corresponding Fan is running.

(OPEN/CLOSE) HATCH

controls hatch

FURN (AUTO/OFF)

controls furnace

FAN ID (OFF/LOW/HIGH)

control radome fans

SCREEN 18

display state of environment controls.

TDOME (temp in F)

set desired radome temperature in Fahrenheit (yes! Fahrenheit). e.g., TDOME 30 . This value will be used by the computer during implementation of the control algorithm. Note that setting this quantity will have no effect if the environmental control software is not in the AUTO mode.

truein

Please note that the radome environmental control equipment reverts to MANUAL operation when the computer is off.