User Manual DEV 1953
42
Copyright DEV Systemtechnik GmbH 2015-2017
If Option 28 (automatic switch back) is installed and activated (as described in
chapter 5.5.7.3.2), the switching back from the secondary to the primary input port
is initiated by the RF level rising above the RF threshold level again (the digital
signal quality becoming "OK" again, respectively) on the failing primary input port.
This switching back is supported by an offset which is an adjustable hysteresis
(0 dB, 1 dB, 3 dB, or 5 dB) for sensing switch modules, or which is an adjustable
delay (0…10 seconds) for digital signal switch modules.
For the autonomous switching capability has to be considered in addition, whether
Individual switching mode or Simultaneous switching mode is activated
(chapter 5.1.4) and whether (and which) input ports are disabled (chapters 5.5.4.2
& 5.9.4.3.9.2), since this has an influence on the switching behavior. Therefore, the
following scenarios are to be examined for the autonomous switching functionality:
Switching from the primary input port to the secondary input port in
Individual switching mode:
- If both input ports of a sensing switch module (or of a digital signal switch
module) are enabled, the switching is performed as described above.
I.e. the device switches only if on the primary input port the RF level falls
below the RF threshold level (the digital signal quality becomes "Fail", re-
spectively) and if on the corresponding secondary input port the RF level is
above the RF threshold level (the digital signal quality is "OK", respectively).
- If the primary input port of a sensing switch module (digital signal switch
module) is disabled, the RF level information (the digital signal quality infor-
mation, respectively) of the port is ignored as a trigger; i.e. the device does
not switch to the secondary input port.
- If the secondary input port of a sensing switch module (digital signal switch
module) is disabled, the RF level check (the digital signal quality check, re-
spectively) of this port is omitted. Thus, if the sensing switch module (digi-
tal signal switch module) is switched to the (enabled) primary input port
and if on the primary input port the RF level drops below the RF threshold
level (the digital signal quality becomes "Fail", respectively), the device un-
conditionally switches this sensing switch module (digital signal switch
module) to the secondary input port.
Switching from the primary input port to the secondary input port in
Simultaneous switching mode:
- If all input ports of a group (chapter 5.1.4) are enabled, the autonomous
switching is performed for all members of the corresponding group from
the primary input ports to the secondary input ports.
The condition is that on the primary input port of one or more members of
the group the RF level drops below the RF threshold level (the digital signal
quality becomes "Fail", respectively) and that on all secondary input ports
of the group the RF level is above the RF threshold level (the digital signal
quality is "OK", respectively).
- If one (or more) of the primary input ports is disabled, this port is (these
ports are) not considered in the switching decision, i.e. the device switches
if on the enabled primary input port(s) the RF level drops below the
RF threshold level (the digital signal quality becomes "Fail", respectively).
There is no autonomous switching if all primary input ports of a group are
disabled.