http://www.lca-tejas.org/avionics.html
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AVIONICS.
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AVIONICS
The avionics system enhances the
role of Light Combat Aircraft as
an effective weapons platform.
The glass cockpit and hands on
throttle and stick (HOTAS)
controls reduce pilot workload.
Accurate navigation and weapon
aiming information on the head
up display helps the pilot achieve
his mission effectively. The multi-
function displays provide
information on engine,
hydraulics, electrical, flight
control and environmental
control system on a need-to-
know basis along with basic flight
and tactical information. Dual
redundant display processors
(DP) generate computer-
generated imagery on these
displays. The pilot interacts with
the complex avionics systems
through a simple multifunction
keyboard, and function and
sensor selection panels.
A state-of-the-art multi-mode
radar (MMR), laser designator
pod (LDP), forward looking infra-
red (FLIR) and other opto-
electronic sensors provide
accurate target information to
enhance kill probabilities. A ring
laser gyro (RLG)-based inertial
navigation system (INS), provides
accurate navigation guidance to
the pilot. An advanced electronic
warfare (EW) suite enhances the
aircraft survivability during deep
penetration and combat. Secure
and jam-resistant communication
systems, such as IFF, VHF/UHF
and air-to-air/air-to-ground data
link are provided as a part of the
avionics suite. All these systems
are integrated on three 1553B
buses by a centralised 32-bit
mission computer (MC) with high
throughput which performs
weapon computations and flight
management, and
reconfiguration/redundancy
management. Reversionary
mission functions are provided
by a control and coding unit
(CCU).
Most of these subsystems
have been developed
indigenously.
The digital FBW system of the
Tejas is built around a
quadruplex redundant
architecture to give it a fail op-
fail op-fail safe capability. It
employs a powerful digital flight
control computer (DFCC)
comprising four computing
channels, each powered by an
independent power supply and
all housed in a single line
replaceable unit (LRU). The
system is designed to meet a
probability of loss of control of
better than 1×10-7 per flight
hour. The DFCC channels are
built around 32-bit
microprocessors and use a safe
subset of Ada language for the
implementation of software. The
DFCC receives signals from quad
rate, acceleration sensors, pilot
control stick, rudder pedal,
triplex air data system, dual air
flow angle sensors, etc. The
DFCC channels excite and
control the elevon, rudder and
leading edge slat hydraulic
actuators. The computer
interfaces with pilot display
elements like multi-function
displays through MIL-STD-1553B
avionics bus and RS 422 serial
link.
Multi-mode radar (MMR), the
primary mission sensor of the
Tejas in its air defence role, will
be a key determinant of the
operational effectiveness of the
fighter. This is an X-band, pulse
Doppler radar with air-to-air, air-
to-ground and air-to-sea modes.
Its track-while-scan capability
caters to radar functions under
multiple target environment. The
antenna is a light weight (<5 kg),
low profile slotted waveguide
array with a multilayer feed
network for broadband
operation. The salient technical
features are: two plane
monopulse signals, low side lobe
levels and integrated IFF, and
GUARD and BITE channels. The
heart of MMR is the signal
processor, which is built around
VLSI-ASICs and i960 processors
to meet the functional needs of
MMR in different modes of its
operation. Its role is to process
the radar receiver output, detect
and locate targets, create
ground map, and provide
contour map when selected.
Post-detection processor resolves
range and Doppler ambiguities
and forms plots for subsequent
data processor. The special
feature of signal processor is its
real-time configurability to adapt
to requirements depending on
selected mode of operation.
Following are the important
avionics components:
Mission Computer (MC): MC
performs the central processing
functions apart from performing
as Bus Controller and is the
central core of the Avionics
system. The hardware
architecture is based on a dual
80386 based computer with dual
port RAM for interprocessor
communication. There are three
dual redundant communication
channels meeting with MIL-
STD-1553B data bus
specifications. The hardware unit
development was done by
ASIEO, Bangalore and software
design & development by ADA.
HUD: The Head-up-Display of
the LCA is a unit developed by
the state-owned CSIO,
Chandigarh. The HUD is claimed
to be superior to similar systems
in the international market.
According to Mr. CV M L
Narasimham, head of CSIO's
Applied Optics division,
compared to Israel's HUD, the
CSIO equipment is noiseless,
silent, and offers a better field of
view. It is compact, reliable, non-
reflective and designed for high-
performance aircraft. It was first
put on the PV-2 version of the
LCA.
Control & Coding Unit (CCU):
In the normal mode, CCU
provides real time I/O access
which are essentially pilot's
controls and power on controls
for certain equipment. In the
reversionary mode, when MC
fails, CCU performs the central
processing functions of MC. The
CCU also generates voice
warning signals. The main
processor is Intel 80386
microprocessor. The hardware is
developed by RCI, Hyderabad
and software by ADA
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Display Processors (DP): DP is
one of the mission critical
software intensive LRUs of LCA.
The DP drives two types of
display surfaces viz. a
monochrome Head Up display
(HUD) and two colour
multifunction displays (MFDs).
The equipment is based on four
Intel 80960 microprocessors.
There are two DPs provided (one
normal and one backup) in LCA.
These units are developed by
ADE, Bangalore.
Mission Preparation & Data
Retrieval Unit (MPRU): MPRU is
a data entry and retrieval unit of
LCA Avionics architecture. The
unit performs mission
preparation and data retrieval
functions. In the preparation
mode, it transfers mission data
prepared on Data Preparation
Cartridge (DPC) with the help of
ground compliment, to various
Avionics equipment. In the
second function, the MPRU
receives data from various
equipment during the
Operational Flight Program
(OFP) and stores data on
Resident Cartridge Card (RCC).
This unit is developed by LRDE,
Bangalore.
USMS Electronic Units: The
following processor based digital
Electronics Units (EU) are used
for control and monitoring, data
logging for fault diagnosis and
maintenance: Environment
Control System Controller
(ECSC), Engine and Electrical
Monitoring System Electronics
Unit (EEMS-EU), Digital Fuel
Monitoring System Electronics
Unit (DFM-EU) and Digital
Hydraulics and Brake
Management System Electronics
Unit (DH-EU)
Changes in PV-2: The production
standard cockpit has no electro
mechanical standby instruments.
The cockpit is dominated by
three 5"x 5" AMLCD MFD's, two
Smart Standby Display Units
(SSDU) and the indigenous HUD.
The HUD has an Up Front
Control Panel (UFCP) which is a
significant man machine interface
(MMI) enhancement which
allows the pilot to program,
initialize the avionics and enter
mission and system critical data
through an interactive soft touch
keyboard. Although the FOV of
this HUD is slightly less than that
of contemporary units on other
aircraft of this generation it is not
considered significant because
the ELBIT, Israel furnished DASH
helmet mounted display and
sight (HMDS) will form an
integral part of the avionics suite.
The four utilities system
monitoring LRUs have been
reduced to two dual redundant
units. These units perform the
control, monitoring, data logging
for fault diagnosis and
maintenance functions.
A HAL Korwa developed Flight
data recorder will be fitted after
the initial flights.
The PV2 is a much lighter aircraft
and possesses advanced software
technology, unlike the Test
Demonstrator I, II and PV1.
There is an advancement in the
build standard of PV2, which is a
software intensive fourth
generation combat aircraft built
to production standard. Besides
having a high percentage of
composite materials in its
airframe structure, it
incorporates a state-of-the-art,
integrated, modular avionics
system with open architecture
concepts to facilitate easy
hardware and software upgrades
and re-usability.
MMR HYBRID : Another critical
technology area tackled for
indigenous development by the
ADA team is the Tejas' Multi-
Mode Radar (MMR). It was
initially planned for the LCA to
use the Ericsson Microwave
Systems PS-05/A I/J-band multi-
function radar, which was
developed by Ericsson and
Ferranti Defence Systems
Integration for the Saab JAS-39
Gripen. However, after examining
other radars in the early 1990s,
the DRDO became confident
that indigenous development
was possible. HAL's Hyderabad
division and the LRDE were
selected to jointly lead the MMR
program; it is unclear exactly
when the design work was
initiated, but the radar
development effort began in
1997.
The DRDO's Centre for Airborne
Studies (CABS) is responsible for
running the test programme for
the MMR. Between 1996 and
1997, CABS converted the
surviving HAL/HS-748M Airborne
Surveillance Post (ASP) testbed
into a testbed for the avionics
and radar of the LCA. Known as
the 'Hack', the only major
structural modification besides
the removal of the rotodome
assembly was the addition of the
LCA's nose cone in order to
accommodate the MMR.
By mid-2002, development of the
MMR was reported to be
experiencing major delays and
cost escalations. By early 2005
only the air-to-air look-up and
look-down modes two very basic
modes were confirmed to have
been successfully tested. In May
2006 it was revealed that the
performance of several modes
being tested still "fell short of
expectations." As a result, the
ADA was reduced to running
weaponisation tests with a
weapon delivery pod, which is
not a primary sensor, leaving
critical tests on hold. Due to
delay in development of MMR,
government have come out with
the collaboration with IAI for
development of Radar the
sensor for the new radar is
supposed to be EL/M-2052 AESA
from Elta and the remaining item
and software will be combination
of MMR and IAI developed
products. Varadarajan, (Director
- LRDE) has said that LRDE has
initiated development of active
electronically scanning array
radar for airborne applications.
And that these radars will be
integrated with Tejas light
combat aircraft-Mark II by
2012-13.
EW suite:. Primary responsibility
for development of the EW suite
is that of the Defence Avionics
Research Establishment (DARE),
Bangalore.but recently (DARE)
has entered a joint venture with
israeli aircraft industry (IAI) for
development of EW suite called "
Mayavi " an ancient sanskrit
word ,which (IAI) will intergrate it
with Jsf F-35 and (DARE) in lca-
tejas
