GAI-Tronics MRTI 2000 (No. PL1877A) Microprocessor Radio Telephone Interconnect Installation & Service Manual - Manual (Page 92)

Parameter Modification PL1877A Microprocessor Radio Telephone Interconnect
12/10 86
General Purpose Inputs
Parameter Function
66 GPI-1 input is active low = 0
GPI-1 input is active high = 1
Default = 0
67 GPI-2 input is active low = 0
GPI-2 input is active high = 1
Default = 0
124 Function of programmable input GPI-1 (pin P1–14)
0 = GPI-1 unused
1 = Auxiliary carrier detect input
125 Function of programmable input GPI-2 (pin P1–16)
0 = GPI-2 unused
1 = Auxiliary carrier detect input
N OTE : If both GPI-1 and GPI-2 are programmed for auxiliary carrier detect, GPI-2 is
unused. In that event, only GPI-1 functions as the auxiliary carrier detect input.
The auxiliary carrier detect function is used in applications where two repeaters may be
sharing the same channel. In this situation, the auxiliary carrier detect input is connected
to the logic carrier detect output of an auxiliary receiver that monitors the repeater
transmit frequency. The auxiliary carrier detect function is used only to establish that
the channel is idle prior to generating mobile signaling (ring, paging, SID, etc.).