MIL-STD-1773

Mohamed Sameer T K

Dept. of Aeronautical

JCET

MODULE 2

MIL-STD-1773

Fiber-optic version of 1553B

It also operates at the rate of 1Mbps

It also have the same 20 bit word and threewords, command word, status word and dataword

WHY OPTICAL FIBER?

Though 1553B is used in various modern aircraft,it is recognized that buses operate in extremelysevere environment like

EMI from intersystem and intra system

Lightning

Electrostatic discharge

High Altitude Electromagnetic pulse

AFDX

AFDX

Avionics Full DupleX Switched Ethernet (AFDX) is

a standard that defines the electrical and protocol

specifications (IEEE 802.3 and ARINC 664, Part 7)

for the exchange of data between Avionics

Subsystems.

One thousand times faster than its predecessor,

ARINC 429, it builds upon the original AFDX

concepts introduced by Airbus.

One of the reasons that AFDX is such an attractive

technology is that it is based upon Ethernet, a mature

technology that has been continually enhanced

Increase flexibility in Avionics design

Reduce aircraft wire counts, thus lowering aircraft

weight and cost

Its first major use in A3xx

Faults can be isolated and analyzed without impacting the

system as a whole

ARINC 429 data bus may still be used but the main

Avionics data pipe will be Ethernet (AFDX) of 100 Mbps

AFDX

AFDX Network

AFDX system comprises the following components:

1. Avionics Subsystem: The traditional Avionics

Subsystems on board an aircraft, such as the flight

control computer, global positioning system, tire

pressure monitoring system, etc.

An Avionics Computer System provides a

computational environment for the Avionics Subsystems.

Each Avionics Computer System contains an embedded

End System that connects the Avionics Subsystems to

an AFDX Interconnect.

AFDX Network

2. AFDX End System (End System): Provides an

"interface" between the Avionics Subsystems and

the AFDX Interconnect. Each Avionics Subsystem

the End System interface to guarantee a secure and

reliable data interchange with other Avionics

Subsystems.

3. AFDX Interconnect: A full-duplex, switched Ethernet

interconnect. It generally consists of a network of

switches that forward Ethernet frames to their

appropriate destinations

AFDX Network

HSDB

HSDB

• Used in F-22 Advanced tactical fighter

• Generic version SAE Aerospace Standard 4074.1

• 50 Mbps- linear bus

• For optical medium implementation – star

topology

• HSDB uses distributed control in which each

terminal is permitted to transmit only when it

receives the token frame.

SCI

SCI

IEEE –STD-1596-1992

SCI is an interconnect system for both backplane and LAN

usage.

Operates at 1 Gbps

Electrical links upto 30m and optical links upto several

kms.

Same Bandwidth as today’s 155Mbits/sec ATM links , 32

times that of today’s fiber optic channel and 800 times that

of Ethernet.

To meet the Demands of Avionics requirements

for Highly Sophisticated fighter aircraft

Data Rate

Message Length

Max No. of Stations

Transmission Technique

Access Protocol

1 Mbps (LS), 20Mbps (HS)

Word Length 16 Bits

32 Word(LS), 4096 Word (HS)

32

Half - Duplex

Command /Response