Instruction Manual

Table Of Contents
7.4
Illegal Carrier Determination Feature (Trunked)
The Illegal Carrier Determination feature allows the device channels to continue operating with system-
configurable levels of channel interference.
In an ASTRO
®
25 system, the device uses Received Signal Strength Indicator (RSSI), an RF
Threshold Value, and the Malfunction Timer Value to implement this feature.
Table 48: Illegal Carrier Determination
If the channel receives a... and is assigned: and is not assigned:
Valid Network Access Code (NAC) The device does not change since
the carrier is considered valid.
If the RF Threshold Value is ex-
ceeded, the device enters the Ille-
gal Carrier state and generates an
Illegal Carrier message to Unified
Event Manager (UEM).
Invalid Network Access Code
(NAC) OR Carrier activity without
NAC
If the RF Threshold Value level is exceeded, the Malfunction Timer is acti-
vated. After the timer expires, the base radio enters the Illegal Carrier
state and generates an Illegal Carrier message to UEM. While in the ille-
gal carrier state, calls are not assigned to this channel. If the illegal carrier
disappears or drops below the RF Threshold Value for 12.5% of the time
period defined by the Malfunction Timer Value (or 10 seconds, whichever
is greater), an event is sent to UEM clearing the illegal carrier state, the
base radio exits the illegal carrier state and the channel is again included
in the available channel resource pool for call assignment
If the illegal carrier disappears or drops below the RF Threshold Value for
12.5%, but not less than 10 seconds of the time period defined by the
Malfunction Timer Value, an event is sent to UEM.
7.5
RF Channel Interference Determination Feature (Conventional)
The RF Channel Interference Determination Feature allows radio channels to detect RF interference
and log it to the station log. RF Channel Interference is declared when the Carrier Squelch level is
exceeded and none of the receive qualifiers are met. Receive qualifiers are the programmed Private
Line (PL), Digital Private Line (DPL), or receive Network Access Code (NAC) for the currently active
channel.
MN003286A01-H
Chapter 7: GTR 8000 Base Radio Operation
212