Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.atnf.csiro.au/vlbi/dokuwiki/doku.php/lbaops/tidnotes/antennastartup
Дата изменения: Unknown Дата индексирования: Tue Apr 12 02:23:57 2016 Кодировка: ISO8859-5 Поисковые слова: о п п |
The antenna pointing models, subreflector rotation, first source coordinates etc are different depending on the observation. Below is an example.
Manual boresighting is probably the quickest method. You will need to enter offset commands at the NMC and observe the effect with xplot or the squarelaw sampler plot. The idea is to move the antenna to approx the positive half-power point in cross-El, observe the amplitude, then move to the negative half-power point and observe the level again. If the levels are not the same, move closer or further away until they ballance. The offset position is then the average of the two values. This is then repeated for the Elevation offsets. The NMC command for moving to an offset is:
ap po <axis> <offset>
where <axis>
is xel
or el
for cross-el and El respectively, <offset>
is the offset in milli-degrees.
Once the receivers are configured correctly, check the levels of the PCFS (with vread
) and on the DAS. If necessary, adjust the attenuation to bring them within range.