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: http://www.naic.edu/~astro/spectral_line/handbook_old/blanker.html
Дата изменения: Fri Nov 9 12:38:58 2001 Дата индексирования: Sat Dec 22 22:53:06 2007 Кодировка: |
The radar blanker serves to "blank" data acquisition by the correlator during pulse emission by the FAA radars at 1330 and 1350 MHz situated on Pico del Este, PR. The blanking can be extended for a duration longer than the basic radar pulse in order to also eliminate delayed reflections of the pulse from aircraft, etc.
The blanker itself is situated in the "receiver room" (the room next to the Control Room itself), and is to be found in Rack 3, Box 1-10; i.e. just below the spectrum analyzer. The device should be permanently locked to the FAA radar pulses; to confirm this check the blanker box, where the "out of lock" light should not be lit, and the "FAA Radar On" light should be glowing green. If this is not the case, please report it immediately via a GUI comment, the telescope operator or, for immediate action if during working hours, to Edgar Castro, Jon Hagen or Bill Sisk of the Electronics Department. The blanker box also has a knob which is used to set the blanking duration. This has settings between 100 and 750 microsec; the typical value used is 400 microsec. Note that the switch found beneath the meter on the left of the box should be in the "acquired signal level" position. A "black belt" user can display the signals from the "detected output" and "blanking pulse" connectors to the right of the box on the digital scope to check the alignment of the blanking pulse with the FAA radar signal. (Alternatively, you can ask the operator if he/she can connect the oscilliscope for you.)
In the GUI, the button to switch ON or OFF the radar blanker is found at the bottom left of the "spectral line observer's widget" (see Fig. 9). When you click this ON, an information box will query you as to what is happening. The blanker will remain selected and operating until you switch it off by clicking on the same button. The equivalent instructions that could be entered directly into the vx-works line of the main AO_Control GUI window are "corblank on" and "corblank off"; note that if you use these vx-works commands directly in this way, the status displayed of the GUI blanker button of the "spectral line observer's widget" will change accordingly. (But why bother with direct vxworks commands when a click on the GUI will do the same for you!)