User's Manual
SYSTEM DESCRIPTION AND INSTALLATION MANUAL
TCAS 3000 Traffic Alert and Collision Avoidance System
34−43−23
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Page 1−17
15 Dec 2005
4. Component Descriptions
A. TCAS 3000 Computer Unit
The TCAS Computer Unit (CU) is the heart of the TCAS 3000 system. It contains the RF
transmitter and the receivers necessary to interrogate and receive replies from other
transponder equipped aircraft. Dual microprocessors are utilized to implement the
surveillance and collision avoidance algorithms. The algorithms determine whether an
intruder aircraft should be considered a threat and then determine the appropriate vertical
response to avoid a midair or near midair collision. In addition, output data is provided to
drive displays that inform the flight crew what action to take or avoid.
An interface is provided with an onboard Mode S transponder in order to communicate
with other TCAS ll equipped aircraft. The ACSS TCAS Computer Unit also provides past
and present LRU and system status through the front panel mounted TEST switch and
PASS/FAIL annunciators. Software updates can be incorporated into the computer by an
ARINC 615 data loader port through either the connector mounted on the front panel of
the computer or the port provided on the LRU rear connector or with a compact flash card
inserted into the slot on the front of the LRU.
Figure 1−7 shows a graphical view of the 6MCU TCAS Computer Unit and Figure 1−8
shows a graphical view of the 4MCU TCAS Computer Unit. Table 1−6 provides items and
specifications that are particular to the computer.
Figure 1−7. 6MCU TCAS Computer Unit