22 System Feature Overview
April 2011 68007024085
NOTE: It is very important to note that when a radio is utilizing impolite operation, it is possible that
it is transmitting on top of another user’s transmission. This causes RF contention at the
target. When RF contention occurs between digital transmissions, it is impossible to
predict which signal is usable. If one transmission is much stronger than the other, it is
received instead of the weaker signal. But in most cases, the two transmissions on the
same frequency and time slot results in both transmissions being unusable. Thus, it is
recommended that only disciplined users are granted the right to use impolite operation.
Further, those impolite users are encouraged to utilize the busy channel LED on their radio
to determine, if the channel is idle prior to transmitting.
When operating in IP Site Connect mode, it is important to understand that impolite channel
access only occurs at the local site. If a call is taking place on the IP Site Connect system, and the
original source of that call is at the same site as the interrupting “impolite” radio, RF contention will
occur and it is unclear which source will be successful. If the original source of the call is at a
different site from the interrupting radio, the original call continues at all other sites except where
the interrupting radio is located.
When operating in Capacity Plus mode, the impolite operation is supported only in Emergency
Calls.
2.2.3.2 Polite to All Operation (Admit Criteria of “Channel Free”)
When configured for Polite to All operation, the radio checks if channels are idle or busy, prior to
allowing a transmission. The radio is polite to all analog or digital transmissions, another system’s
transmission, or other traffic on your system. This option is often used, when there are neighboring
communications systems, to prevent radio users from disrupting each other’s transmissions.
However, when this option is used, any strong signal on the channel blocks other users from
transmitting.
2.2.3.3 Polite to Own Digital System Operation (Admit Criteria of “Color
Code Free”)
This criteria applies only to digital channels. When configured for Polite to Own Digital System
operation, the radio checks for an idle or busy channel, prior to allowing a transmission. This
operation is similar to the Polite to All operation with exception that the radio is not polite to analog
systems or other system’s transmissions. It is only polite to other traffic in its own system. This
option is often used when there are no neighboring communications systems, or when there is no
concern about interfering with radios in neighboring communication systems.
2.2.3.4 Polite to Other Analog System Operation (Admit Criteria of
“Correct PL”)
This criteria applies only to analog channels. When configured for Polite to Other Analog System
operation, the radio checks for an Idle or busy channel, prior to allowing a transmission. This
operation is similar to the Polite to All operation with exception that the radio is not polite to analog
systems with the same PL. It is polite to other system’s transmissions. The radio checks for a PL
match prior to allowing a transmission.
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