14-01-2011, 12:54 PM
training Project Transmitter (CAR).docx (Size: 167.5 KB / Downloads: 259)
SUBMITTED BY: JIUT CHAURASIYA
INSTITUTE OF INGINEERING & TECHNOLOGY
Dr. R.M.L. AVADH UNIVERSITY FAIZABAD -224001
BHARAT ELECTRONICS LIMITED
INDUSTRY
Bharat Electronics Limited (BEL) was established in 1954 as a Public Sector Enterprise under the administrative control of Ministry of Defence as the fountain head to manufacture and supply electronics components and equipment. BEL, with a noteworthy history of pioneering achievements, has met the requirement of state-of-art professional electronic equipment for Defence, broadcasting, civil Defence and telecommunications as well as the component requirement of entertainment and medical X-ray industry. Over the years, BEL has grown to a multi-product, multi-unit, and technology driven company with track record of a profit earning PSU.
started with a HF receiver in collaboration with T-CSF of France, the company's equipment designs have had a long voyage through the hybrid, solid state discrete component to the state of art integrated circuit technology. In the component arena also, the company established its own electron valve manufacturing facility. It moved on to semiconductors with the manufacture of germanium and silicon devices and then to the manufacture of Integrated circuits. To keep in pace with the component and equipment technology, its manufacturing and product assurance facilities have also undergone sea change. The design groups have CADDs facility, the manufacturing has CNC machines and a Mass Manufacture Facility, and Quality Control (QC) checks are preformed with multi-dimensional profile measurement machines, Automatic testing machines, environmental labs to check extreme weather and other operational conditions.
Today BEL's infrastructure is spread over nine locations with 29 production divisions having ISO-9001/9002 accreditation. Product mix of the company is spread over the entire Electro-magnetic (EM) spectrum ranging from tiny audio frequency semiconductor to huge radar systems and X-ray tubes on the upper edge of the spectrum. Its manufacturing units have special focus towards the product ranges like Defence Communication, Radar's, Optical & Opto-electronics, Telecommunications, Sound and Vision Broadcasting, Electronic Components, etc.
INTRODUCTION
The two most basic functions of radar are inherent in the word, whose letters stand for RAdio Detection And Ranging. Measurement of target angles has been included as a basic function of most radar, and Doppler velocity is often measured directly as a fourth basic quantity. Discrimination of the desired target from background noise and clutter is a prerequisite to detection and measurement, and resolution of surface features is essential to mapping or imaging radar. The block diagram of typical pulsed radar is shown in Figure. The equipment has been divided arbitrarily into seven subsystems, corresponding to the usual design specialties within the radar engineering field. The radar operation in more complex systems is controlled by a computer with specific actions initiated by a synchronizer, which in turn controls the time sequence of transmissions, receiver gates and gain settings, signal processing, and display. When called for by the synchronizer, the modulator applies a pulse of high voltage to the radio frequency (RF) amplifier, simultaneously with an RF drive signal from the exciter. The resulting high-power RF pulse is passed through transmission line or waveguide to the duplexer, which connects it to the antenna for radiation into space. The antenna shown is of the reflector type, steered mechanically by a servo-driven pedestal. A stationary array may also be used, with electrical steering of the radiated beam. After reflection from a target, the echo signal reenters the antenna, which is connected to the receiver preamplifier or mixer by the duplexer.
Evolution of Radar Signal Processing
The term radar signal processing encompasses the choice of transmit waveforms for various radars, detection theory, performance evaluation, and the circuitry between the antenna and the displays or data processing computers. The relationship of signal processing to radar design is analogous to modulation theory in communication systems. Both fields continually emphasize communicating a maximum of information in a specified bandwidth and minimizing the effects of interference. The somewhat slow evolution of signal processing as a subject can be related to the time lags between the telegraph, voice communication, and color television. Although Theory with Applications to Radar in 1953 laid the basic ground rules; the term radar signal processing was not used until the late 1950s. During World War I1 there were numerous studies on how to design radar receivers in order to optimize the signal-to-noise ratio for pulse and continuous wave (CW) transmissions. These transmitted signals were basically simple, and most of the effort was to relate performance to the limitations of the components available at the time. For about 10 years after 1945, most of the effort was on larger-power transmitters and antennas and receiver-mixers with lower noise figures. When the practical peak transmitted power was well into the megawatts, the merit of further increases became questionable, from the financial aspect if not from technical limitations. The pulse length of these high powered radars was being constantly increased because of the ever present desire for longer detection and tracking ranges. The coarseness of the resulting range measurement led to the requirement for what is now commonly referred to as pulse compression. The development of the power amplifier chain (klystron amplifiers, etc.) gave the radar designer the opportunity to transmit complex waveforms at microwave frequencies. This led to the development of the “chirp” system and to some similar efforts in coding of the transmissions by phase reversal, whereby better resolution and measurements of range could be obtained without significant change in the detection range of the radar.
At about the same time, diode mixers gave way to the parametric amplifier and in some cases the traveling wave tube. The promise of vastly increased sensitivity seemed to open the way for truly long range systems. Unfortunately, the displays of these sensitive, high powered radars became cluttered by rain, land objects, sea reflections, clouds, birds, etc. The increased sensitivity also made it possible for an enemy to jam the radars with low-power wideband noise or pulses at approximately the transmit frequency. These problems led to experiments and theoretical studies on radar reflections from various environmental reflectors. It was soon realized that the reflectivity of natural objects varied by a factor of over 10 to power 8 with frequency, incidence angle, polarization, etc. This made any single set of measurements of little general value. At the same time that moving target indicator (MTI) systems were being expanded to include multiple cancellation techniques, pulse Doppler systems appeared to take advantage of the resolution of pulse radars.
CENTRAL ACQUISITION RADAR
INTRODUCTION
The designed Radar would be a stand-alone all weather 3D surveillance radar. The radar operates in S-band and is capable of Track-While-Scan [TWS] of airborne targets up to 130 Kms, subject to line-of-sight clearance and radar horizon. The radar employs Multibeam coverage in the receive mode to provide for necessary discrimination in elevation data. It employs 8 beams to achieve elevation coverage of prescribed margin and a height ceiling of prescribed margin. The antenna is mechanically rotated in azimuth to provide 360 coverage. To get an optimum detection performance against various class of targets, different Antenna Rotation Rate [ARR] RPM modes are implemented and these can be selected by the operator.
The unique feature of the radar is, its operation is fully automated and controlled from a Radar Console with sufficient menus, keys and Hot keys. The designed Radar is an offshoot of the fully and successfully developed and demonstrated radar called as 3D Central Acquisition Radar (3D-CAR).
3D-CAR is designed to play the role of medium range surveillance radar mounted on a mobile platform. The radar carries out detection, tracking and interception of targets with an RCS of 2m2 upto 130 Kms in range.
The antenna can be manually positioned at different look angles in steps. In the receive mode the eight beams cater for a height coverage of required margin. The IFF antenna is placed atop the main antenna and it integrates the IFF for including of IFF data with the Primary Radar Data.
The RDP (Radar Data Processor) is implemented on a SBC and is fully software-based system with adequate memory and external interfaces to handle upto 150 target tracks. Robust algorithms for filtering are used to lock on to maneuvering target upto 6g without loss of tracking.
LAN interfaces are used to communicate with external systems. High-speed data transfer of target parameters can be done. This helps in data remoting upto a distance of 500 mtrs that can be extended with suitable repeaters. Facility for manual track indication for low speed targets and targets in heavy clutter zones are available to the console operator.
The color display has features for monitoring of radar performance, the radar output selection for radar modes of operation. Interfaces to radar control signals are built-in. The Radar generates different videos viz., Analog and Digital videos at the Receiver and Signal Processor. These are interfaced to the display over dedicated lines and displayed In addition to providing real time data on screen for viewing, the consoles will provide facility for training controllers/operators/ technical crew. The system is capable of creating targets and assigns values for range, azimuth, height and speed as defined by operator. It will enable the operator to control the motion of these targets for gaining/ loosing height, turning left/right, cruising, and rolling out. The software running on console will provide an online handy aid, for target interception. The training part of the software will be active as an offline facility or with tracked targets in real time. The offline mode will be capable of using recorded data.