Embraer EMB145 Operation Manual page 2605

NAVIGATION AND
AIRPLANE
COMMUNICATION
OPERATIONS
MANUAL
IDENTIFICATION FRIEND OR FOE SYSTEM (IFF)
The Mode-S/IFF Transponder System integrates military IFF functions
and civilian Mode-S/ATCRBS surveillance functions into a single
system.
The IFF system is a cooperative surveillance system designed to
classify airborne targets as friendly or hostile. It employs ground-based
and airborne interrogations and transponders.
A key feature of the Mode-S system that distinguishes it from ATCRBS
is that each airplane is assigned a unique address code. Using this
unique code, interrogations can be directed to a particular airplane and
replies can be positively identified. Channel interference is minimized
because a sensor can limit its interrogations to targets of interests. By
proper timing of interrogations, replies from closely spaced airplane
can be received without mutual interference.
The Mode-S/IFF Transponder System consists of the following major
components: one Mode-S transponder, one Mode-S/IFF transponder,
Mode-S/IFF control panel, one selector panel and top and bottom
antennas.
The transponder is capable of receiving/transmitting signals through
any one antenna, thus inhibiting the shadow effect caused by the
airplane structure while maneuvering. The reply signal provides an
identity, an altitude, an identification position, or an emergency
message. The Mode-S/IFF transponder operates in Mode 1, 2, 3/A, C
and S, the system receiving interrogations on 1030 MHz and
transmitting on 1090 MHz.
Avionics Master DC Bus 2A powers the Mode S/IFF transponder and
there is a 7.5 A circuit breaker for power wiring protection. The Mode-
S/IFF Transponder System will not operate in the event of either a
failure in the control panel or in the event of an electrical/generator
failure.
The transponder reply-transmit capability is disabled when the system
is in STANDBY mode. The Weight-On-Wheels (WOW) circuitry
disables the ATCRBS' transponder reply capability while the airplane
is on the ground. However, the air/ground switch does not disable
Mode-S transponder replies and airplane status is included in the
Mode-S/IFF transponder reply data.
For airplanes Post-Mod. SB 145-34-0089 or SB 145BAF-34-0006 or
equipped with an equivalent modification factory incorporated, the
Mode S Elementary Surveillance Transponder transmits the following
parameters:
Page Code
2-18-80 1 01
REVISION 38