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).

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.

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: The Multi Mode Radar (MMR) jointly developed by LRDE and HAL Hyderabad will be fitted in the nose after redistributing the FTI carried in the first three aircraft. The MMR features LPRF, MPRF and HPRF modes, platform motion compensation, MTI and Doppler filtering, CFAR detection, range-Doppler ambiguity resolution, scan conversion, display of target and ground map data on MFDs and on line diagnostics to identify faulty processor modules.

The aircraft has the ADA developed Stores Management System (SMS) which will provide fully integrated control of weapon systems, external stores and fuel tanks. The SMS is based on a 32 bit, single chip micro controller with dual redundant architecture. Its main components include the single Stores Interface Box (SIB) and multiple pylon interface boxes (PIB) for each hard point.

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

Note : there has been unconfirmed reports in indian media that due to delays in MMR Radar ,Tejas has been intergrated with EL/M-2032  model from the ELTA Electronics Division of Israel Aircraft Industries (IAI), but no offical confirmation has come out yet

Prototypes Versions