User's Manual

Hot Standby Operation
RFI-148 & RFI-900 High Output Power Paging Transmitters User Manual Page 49 of 134
7. Check the current Hot Standby state: “ATM14”:
a. “0”: Hot standby is not configured
b. “1”: The unit is currently Active
c. “2”: The unit is currently in Standby
d. “3”: The RFI-PHSB was not detected at start-up. Check the RFI-PHSB connection.
7.3 Operation
The Primary RFI-148 250 has control of the RF switch position. The default switch position, when no Primary
unit exists or the RFI-PHSB is unpowered, is for the Secondary unit. Upon power up the Primary unit will
always favour itself for the RF switch position, but the power up default is to leave the switch in the Secondary
unit position.
The Primary unit will change the RF switch to itself when all three signals satisfy the conditions:
• “Can Go Active” is True
o For Hardware Standby Mode: Pin 17 is HIGH
o For Software Standby Mode: “Can Go Active (SW)” is set to “True” (Hayes command:
ATM12=1)”
• “TX Fault” is False (See section 7.4 below)
• “PTT” is Inactive
The Primary unit will change the RF switch to the Secondary unit if any two signals violate the conditions:
• “Can Go Active” is True
• “TX Fault” is False
Both the Primary and Second units know what position the switch is in. If the unit does not hold the switch
position, transmission is disabled using the “PTT Override” feature. In this case “PTT Override Status” will
read “DISABLED:In Standby”. Because of this behaviour, the Base Station Controllers providing encoded
paging data and PTT need not know of the RF switch position.
7.4 Switchover Faults
An additional option per fault is provided that is the source of the “TX Fault” signal. By default, any faults
that would usually cause paging messages to fail to transmit will assert the “TX Fault” signal. This is
configurable per-fault within the Faults menu as the “Go Standby” option.
Faults -> Fault Configuration -> Go Standby