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Switching Modes

In the NCS we distinguish the following 4 ``Switching Modes'':

TOTAL POWER

BEAM SWITCHING

WOBBLER SWITCHING

FREQUENCY SWITCHING (only with heterodyne receivers)

The corresponding commands are:

SWTOTAL
SWBEAM
SWWOBBLER
SWFREQUENCY

BEAM SWITCHING, WOBBLER SWITCHING, and FREQUENCY SWITCHING are realized by a system with hardware synchronization signals that allow a precise and fast switching within subscans.

TOTAL POWER simply means that none of the other 3 switching modes is active.

The system switches through a regular cycle with several (1, 2, or 4) switching phases.

The 4 switching modes are mutually exclusive, i.e., at any time the system uses only one of them.

During the transitions between phases, e.g., while the Wobbler is moving between its positions, no data are taken during the short ``blanking'' time.

The switching mode and its parameters should normally be set before choosing an observing mode, because for some observing modes details of the setup depend on the switching mode.

!
!  Id: demo-switching.pako,v 1.1.1 2009-05-05 Hans Ungerechts
!
SWTOTAL                       /tphase 0.2     !  Total Power
PAUSE
!
SWBEAM                                        !  Beam Switching
PAUSE
!
SWFREQUENCY                   /default        !  Frequency Switching
PAUSE
!
SWFREQUENCY   -3.3     3.3                    !  for all RXs
PAUSE
!
SWFREQUENCY   -3.9     3.9  /receiver E090    !  select frequency switching
SWFREQUENCY  -11.7    11.7  /receiver E230    !  for EMIR band E230
SWFREQUENCY                 /tphase   0.20    !  same for all receivers
PAUSE
!
SWWOBBLER   -22  +22          /tphase 0.25    !  Wobbler Switching
PAUSE
!
!! NOTE:
!! after changing the switching modes, always (re-)execute a command
!! for an observing mode, because internal parameters and error checks
!! of the observing modes depend on the switching mode!



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