Identification Friend or Foe

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Identification Friend or Foe
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Content
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Introduction

• The deployment of modern, high precision weapon
  systems and their effectiveness depend to a large
  degree on a timely and accurate identification of
  all targets both friendly and hostile. This
  presentation introduces the basic concepts and
  operations of the Identification Friend or Foe
  (IFF) systems currently deployed in major US and
  NATO combatants. The directly related commercial
  aircraft identification equipment is the Air
  Traffic Control Radar Beacon System (ATCRBS) or
  the Secondary Surveillance Radar (SSR). These two
  systems share the same operating philosophy,
  waveforms, and frequencies.

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Historical view

• 1937, radio recognition identification
  friend-or-foe (IFF) system, the Model XAE, which
  met an urgent operational requirement to allow
  discrimination of friendly units from enemy
  units.
• 1958, the FAA had established the Air Traffic
  Control Radar Beacon System (ATCRBS), which is
  essentially the civilian version of the Mark X.
  The International Civil Air Organization later
  adopted the ATCRBS, making the Mark X the basis
  of the world's air traffic control system.
• 1960, It was the first IFF system to use
  cryptographic techniques to prevent deception
  where an enemy appears as a friend by using a
  captured transponder.

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What is IFF?

• Identification, Friend or Foe (IFF)
• is a cryptographic identification system
  designed for command and control, that enables
  military, and national interrogation systems to
  distinguish friendly aircrafts, vehicles or
  forces, and to determine their bearing and range
  from the interrogator.

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Modern IFF systems

• Modern IFF systems are basically Question/Answer
  systems.
• An interrogator system sends out a coded radio
  signal that asks any number of queries,
  including Who are you?
• The interrogator system is frequently associated
  with a primary radar installation, but it may
  also be installed aboard a ship or another
  airplane.
• The interrogation code or challenge is received
  by an electronic system known as a transponder
  that is aboard the target aircraft.
• If the transponder receives the proper electronic
  code from an interrogator, it automatically
  transmits the requested identification back to
  the interrogating radar.
• The IFF system is also known as secondary radar
  Because it was developed and used as an adjunct
  to the primary echo-type detection radar.

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How does IFF work?

• Each vehicle is provided with
• a radiation transmitter
• a receiver with a detector to detect radiation
  transmitted by other vehicles.
• Steps
• Each transmitter can transmit a first coded
  signal which can be detected by the receivers in
  other vehicles.
• The receivers provide an unblocking signal after
  the first coded signal is correctly identified.
• The unblocking signal clears a radiation
  transmission path in the vehicle.
• This path containing a reflector which reflects
  the received signal back to the source of the
  transmission.
• The reflector adds a further predetermined code
  to the signal reflected from the reflector with
  each vehicle having another detector for
  detecting a reflected signal and a device to
  identify the further predetermined code.

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This is a typical example of an air traffic
control IFF response.The aircraft was told to
squawk a four digit number such as "4732". The
altitude encoded transponder provides the
aircraft altitude readout to the ground
controllers display along with the coded response
identifying that particular aircraft.
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Modes of operation
IIF can be classified into 5 modes of
operation Mode 1 which has 64 reply codes, is
used in military air traffic control to
determine what type of aircraft is answering or
what type of mission it is on. Mode 2 also
only for military use, requests the "tail number"
that identifies a particular aircraft. There are
4096 possible reply codes in this mode.
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Mode 3/A is the standard air traffic control
mode. It is used internationally, in conjunction
with the automatic altitude reporting mode
Mode C to provide positive control of all
aircraft flying under instrument flight
rules. Mode 4 provides a 3-pulse reply
(dependent upon a valid 32-bit crypto coded
challenge), military only.
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References
http//www.globalsecurity.org
http//www.dean-boys.com/extras/iff
http//www.tscm.com
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Questions ?