September-06-00 / jn
The following main updates have been improved the behaviour of the 8192
channel correlator:
-
Installation of an external
filter unit controlled by the computer with bandwidthes of
5,
2.5 and 1.25 MHz for 4 channels (if-units 1 3 5 and 7)
The OBSe command to set is:
SET NBAND < bw bw ....
>
bw = 5, 2.5 or 1.25
- Update of the
ac-internal synthesizers
Formerly the ac-internal synthesizer had a resolution of
only 2
MHz. They now have been updated to a resolution of 200
KHz giving the possibility of an easy use of the small
bandwidthes
of the external filter unit.
- Installation
of a precision
time source board connected (using IRIG B code) to the GPS station clock
With this board the exact time of the production of the
data can
be derived and compared to the internal clock controller of the VAX
control
system. That is of special importance for fast line observation "on the
fly".
- Suppression
of correlator generated
interferences by mounting in a new sheltered rack
That means, that it does not anymore produce
detectable interferences
in the 21cm band !
