Specifications

The CNI GETC also performs data error detection and
correction, general control of timer and I/O functions (DIP
switch, LED’s, UART’s, etc.), receive and transmit buffer
management, message scheduling, and Turbo Board
interfacing.
When the CNI GETC receives a Group Channel
Request Message from the CEC/IMC’s Uplink, the CNI
GETC compares the Group ID with configuration data in
the CNI GETC’s Personality. If the Group ID is valid, the
CNI GETC sends a secondary assignment to the
CEC/IMC’s Uplink and simultaneously keys the base
station using the appropriate Channel Guard information.
CONSOLE PREEMPT
Since the CNI GETC operates as a one channel site,
only one conversation may occur at any time. The CNI
GETC ignores additional conventional transmissions with
the same Channel Guard information and Multisite Group
Call Requests. However, when the Console preempts the
current call, the CNI GETC will route audio from the
Console to the receiving conventional radio. The original
radio’s unkey does not drop the call as long as the console is
still keyed. The Console’s unkey will drop the call
regardless of the original radio’s status.
A different situation occurs when the CNI GETC is
processing one conventional transmission and is interrupted
with another conventional transmission with different
Channel Guard tone information. The additional call will
most likely interfere with the current call.
CHANNEL GUARD MAPPING
The CNI GETC performs conversions between Channel
Guard tones and EDACS IDs based on mapping
information within the CNI GETC’s Personality.
Personality refers to the GETC’s region of memory that
stores configuration data.
The personality data in Figure 13 shows an example of
the mapping information used to convert between the
Channel Guard tones and EDACS Group ID’s. The bottom
two lines of Figure 13 show a 67.0 Hz Channel Guard tone
maps to a Network Group ID of 271. Mapping provides a
maximum of four EDACS Network Groups for each CNI
GETC.
MAPPING WITHOUT CHANNEL GUARD
In addition to standard mapping, it is also possible to
map one EDACS group to a conventional transmission
without any Channel Guard tone information using the CAS
signal. This flexibility permits conventional radios, without
Channel Guard, access to the advanced trunking features of
EDACS. In this case, mapping provides one EDACS
Network Group per CNI GETC.
INSTALLATION
The installation process involves the following steps and
should be completed in the order presented:
1. Hardware Installation - This procedure provides
instructions for converting a standard GETC to a
CNI GETC in the field. The instructions include
hardware installation, instructions for modifying
existing cables, and installation of GETC jumpers.
2. GETC Firmware Installation - This procedure
provides instructions for installing the GETC
operating firmware.
3. Turbo Software Installation - This procedure
provides instructions for installing the Turbo Board
software.
Figure 2 - Data Communication
To prevent overlapping conventional transmissions, all
of the conventional radios should be programmed with
the Transmit Busy Lockout feature.
NOTE
CNI GETC’S ordered from the factory have already
been modified and set up for CNI operation using the
latest software. Use these installation procedures for
field conversion of a standard GETC to a CNI GETC
or to upgrade firmware or software.
NOTE
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