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!