268 | Product Options
Aprisa SRx User Manual 1.3.0
Protected Ports
The protected ports are located on the protected station front panel. Switching occurs between the active
radio ports and the standby radio ports based on the switching criteria described below.
The protected ports include:
Antenna ports ANT/TX and RX (if dual antenna ports used)
Ethernet ports
Serial ports
Operation
In hot-standby normal operation, the active radio carries all RS-232 serial and Ethernet traffic over the
radio link and the standby radio transmit is on with its transmitter connected to an internal load. Both
radios are continually monitored for correct operation including the transmitter and receiver and alarms
are raised if an event occurs.
The active radio sends regular ‘keep alive’ messages to the standby radio to indicate it is operating
correctly. In the event of a failure on the active radio, the RF link and user interface traffic is
automatically switched to the standby radio.
The failed radio can then be replaced in the field without interrupting user traffic.
Switch Over
The switch-over to the standby radio can be initiated automatically, on fault detection, or manually via
the Hardware Manual Lock switch on the Protection Switch or the Software Manual Lock from SuperVisor.
Additionally, it is possible to switch-over the radios remotely without visiting the station site, via the
remote control connector on the front of the Protection Switch.
On detection of an alarm fault the switch-over time is less than 0.5 seconds. Some alarms may take up to
30 seconds to be detected depending on the configuration options selected.
The Protection Switch has a switch guard mechanism to prevent protection switch oscillation. If a switch-
over has occurred, subsequent switch-over triggers will be blocked if the guard time has not elapsed.
The guard time starts at 20 seconds and doubles each switch-over to a maximum of 320 seconds and
halves after a period of two times the last guard time with no protection switch-overs.
