June-14-00 / jn
The new 1,3 cm primary focus receiver (the successor
of the
MASER-RX)
has a rotating feed with two fixed positions
in azimuth, if used in the normal configuration with an OPOS of 90 D *.
These two positions are interchanged using dynamic
switch
2 of the frontend control. In this way it can be used like
a
receiver with two beams ( ~ 120 " distance ) switching switch 2 during
the observations. The dynamical properties of this contruction allows a
minimum blanking time of ~ 125 msec only, if switching is
used. As the frontend control units are not able to switch such a long
blanking time, the phase- and blanking times given by the control
computer are doubled in hardware afterwards. Without
switching
dynamic
switch 2 one can use the receiver in normal line (PSWITCH,FSWITCH) or
continuum
modes (Total Power). But taking advantage of the beamswitch one has to
use in linemode the procedure LDSWITCH and in continuum mode
Loadswitch.
These modes automatically set the adapted phase- and blank-times and
the
phase-matrix and the right parameters for the online display.
The default parameters in OBSe for
continuum
observations
are LOAD, i.e. switching switch 2 and reducing in loadswitch-mode
(difference
between phases with beam1-position and beam2-position). For example,
typing
POINTING means POINTING LOAD. If for example the weather
conditions
are good, one can use POINTING TOTAL without switching dynamic switch
2.
On the other hand one can use the 8192-correlator
in continuum
for 
doing
pointing
with lines:
FRQRX
<linefrequency
[GHz]>
for the frequency of the line
SET NBAND < bw bw bw bw
>
bw = 20,10,5,2.5 or 1.25 for the bandwidth
POINTING
D(o_line)
Starting the Pointing
Using the rotating beams for line observations a
newly updated
version
of LDSWITCH
is available for this receiver.
