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Radio Astronomy Centre

Radio Centro Astronomy

Tata Institute of Fundamental Research

Ooty

CONTENTS

• Introduction
• Construction
• Electronic systems
• Electrical systems
• Protection Systems
• Data Acquisition System

INTRODUCTION

The Radio Astronomy

Radio astronomy is the study of the universe with the help of radio waves emitted by celestial objects. Radio waves are mostly from the high-energy charged particles moving with speeds close to that of light in the presence of fields magnetic with the help of the directional antenna or telescope intensity of radio waves received from different directions in the sky and can determine a map of the signals radius from the sky can be done.

Ooty Radio Astronomy Center

Radio astronomy is one of the research institutes under the Tata Institute of Fundamental Research (TIFR) proposed rain tool of radio astronomy. A telescope radio high structure was designed in July 1963. A suitable place was

Selected in the Nilgiri Hills. The work that began in 1965 was completed in 1969. coordinate latitude: 11 22 "and longitude coordinate: -76 40 '.

Ooty Radio Telescope (ORT)

ORT is situated on the slopes near the village muthorai in Ooty. The unique feature of the telescope is just entering the north direction south by a natural hill slope of about 11 ideal equal to the latitude of the observatory. This provision ensures that the axis of the telescope is parallel to the axis of the earth. This allows that oral rehydration therapy to track celestial objects for about 9.5 hours for a simple mechanical rotation of the telescope east to west.

CONSTRUCTION

The following are the basic components of the TRO:

• Reflector
• Dipole feed
• Receiver

Reflector

The antenna reflector of ORT is a parabolic surface formed by stainless steel wires 1100. Each stainless steel fine wire 0.38 mm in diameter. These stainless steel wires are stretched along the cylinder.

Dipole Feed

The power half-wave dipole consists of 1056 dipoles hacked by a corner reflector and placed in the focal line on the track power. The physical opening antenna is 530 m long by 30 wide.

Receiver

The oscillator signal 296.5 Mhz locally generated in the receiver room is near by the antenna. The signal is carried in the transmission line to a central part where branches are in two parts. A branch of the modules is part of the north and the other for the southern element modules. The RF amplifier is followed by a mixer setting converts the RF band of an intermediate frequency (IF) band centered at 30 Mhz. IF signal of each module is transmitted to the receiver room via a coaxial cable separately.

ELECTRONIC SYSTEMS

Low Noise Amplifier (LNA)

The LNA, which comes immediately after the dipole, plays important role in determining the temperature system, and therefore the overall sensitivity of the telescope. You must have a lower noise figure in the operating frequency with a noise figure of 0.06 dB at 2 GHz was chosen to LNA.

GaAs FET devices are generally used at microwave frequencies for optimum performance benefits and low noise using high gain Gas FET high frequency VHF and UHF, however, have special problems.

A simple charging broadband FET drainage technique was used to ensure the stability of broadband.

phase shifters

Scanning beam a radio telescope consists of an array antenna electronically switchable phase shifters using PIN diodes are commonly used.

Types of phase shifters:

• Phase-lag type
• Micro strip line type

The second type is used in oral rehydration therapy. The characteristic impedance is 50 ohms. Here the additional loss of 0.1 dB and 0.05 are presented in the direct path.

Image rejection filters

It's basically a band reject filter. The O / P of 326.5 Mhz Amplifier RF is fed to this filter. The O / P is obtained in the region is the band of 15 Mhz.

Mixer

The mixer is usually an adder or subtracter circuit. The O / P of the IRF and phase shifter local oscillator to produce the sum or difference and / p of the two frequencies.

Intermediate Frequency Amplifier

This is a tuned amplifier tuned 30 Mhz and a bandwidth is limited to 4 MHz to prevent unwanted signals. Receiver gain about 100 db. The receiving system is known as Super-heterodyne receiver.

ELECTRICAL SYSTEMS

The main functional units are:

1. Power Supply
2. Rotation
3. Protection

Power supply

power of 22 KVA RAC sandynalla is from the substation. There are two lines that are provided in case of failure of any of the lines. A source of care power transformer and circuit protection. From this, he resigned from the measuring device. As the three-phase power lines have to travel a great distance before reaching the center. From 220 KV down to 440V supply. The transformer coolant oil containing silica gel to observe the moisture. The 440V is taken to board distribution and is given to the various loads. If there is no need for heavy loads, a small generator of 40 KVA is used.

ROTATION

The telescope can rotate in an east-west.

Before Rotation

After rotation

There are two modes of rotation

1. Slew circuit
2. Track circuits

Pile circuit

• It employs 12.5 hp induction motor to 1440 rpm located at 4 frames (N4, S4, N10, S10)
• Induction Motor Speed Torque becomes 75 rpm with hiking gear.

Track circuits

• Used to perform track the object continuously.
• It employs 3-phase 5 hp engine that turns the axis of three revolutions per minute with the help of the gear paths.

Usually, the engines led to a stop, the strip telescope further from the desired position due to momentum. This is a position error.

PROTECTION SYSTEMS

Speeding tacho circuit (need)

Telescope (ORT) is rotated at a speed of 75 rpm. Because of fault conditions such as shaft breakage or failure of the engine, the telescope is subject to excessive speed. If the telescope is subject to excessive speed then the whole system would fail and damage the telescope, so to prevent damage, speeding circuit cue is used. When speeding is produced, identified by speeding Tacho circuit that activates a relay.

The misalignment loop:

If any frames are not rotated or twisted misalignment can be performed. To avoid this circuit are the rings in the alternate trusses and a cable connected between them with a supply of 30 V DC. When any misalignment occur to the wires touch the ring, which then alternates the relay to switch the supply off.

Differential synchronized

The system is used to detect the misalignment in the main axis of oral rehydration therapy.

The synchronization engine is fixed at the ends of the axle and the differential error W is fed to an electronic circuit, which operates a relay. The relay is set to fire the grid when the misalignment is beyond 150 in both directions.

Braking

After a track or drawing operation, the brakes are used to position the antenna in the desired position without fail. The braking is in nature and when given a DC source pushes the brake and stop rotation axis.

Data Acquisition System For Eas-III In Grapes

Introduction

Cosmic Ray Laboratory (CRL) is a few meters above the RAC jus. The CRL built more than 700 detectors arranged in a hexagonal, to detect cosmic showers of heaven, giving very high voltage to the squares of plastic scintillation.

Description

The very high voltages in the range of 2450-V provides the detectors,

then the output signal given to the control section.

In this section, the total signal is processed in the form of,

• TDC
• ADC

Possible Radio interference

• spurious effects due to the sun that appears through the distant sidelobes of the telescope.
• The interference radio failure is generated when TV booster amplifiers are in the function.
• They also spray insecticides used by farmers potatoes, can cause radio interference.
• Therefore to avoid such comments are temporarily suspended.

CONCLUSION

The IPT we suffered a great experience gave us new to RAC, Ooty. This training program will certainly help us in our future. We would like to thank everyone at RAC, Ooty for their support and encouragement throughout the training period.

About the Author

here i jus gave my experience which i got through an inplant training at RAC,ooty. i got permission through Mr.K.KALYANASUNDARAM, who is working there. It is useful for those who are interested in space science and astronomy science.