Field Visit: Giant Meterwave Radio Telescope

#Meterwave #Radio #telescope #astro #physics #radio #astronomy

The Giant Metrewave Radio Telescope, located near Pune in India, is an array of thirty fully steerable
parabolic radio telescopes of 45 metre diameter, observing at metre wavelengths.
It is operated by the National Centre for Radio Astrophysics, a part of the Tata Institute of Fundamental
Research, Mumbai.
 At the time it was built, it was the world's largest  interferometric  array offering a baseline of up to 25
kilometres (16 mi).
GMRT is a very versatile instrument for investigating a variety of radio astrophysical problems ranging
from nearby Solar system to the edge of observable Universe.

• Date: 01 Mar 2019
• Time: 01:30 AM UTC to 02:30 PM UTC
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• GMRT Project,
• P. B. No. 6, Narayangoan,Tal - Junnar,
• Pune, Maharashtra
• India 410504

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• Starts 18 February 2019 03:30 AM UTC
• Ends 22 February 2019 10:30 AM UTC
• No Admission Charge

• 

On 1 st March 2019, 30 students of SIESGST went on a Industrial visit to GMRT (Giant
Metrewave Radio Telescope) Center, Khadad, Pune. The visit began with a brief introduction
about GMRT from a onsite guide. It is an array of thirty fully steerable parabolic radio telescopes of
45 metre diameter, observing at metre wavelengths. It is operated by the National Centre for Radio
Astrophysics (NCRA), a part of the Tata Institute of Fundamental Research (TIFR), Mumbai.The first
use of the telescope to take an astronomical image was in 1995. The parabolic receiver has a
operating frequency range of 50MHz to 1500MHz (wavelength range:: 6m to 0.2m).
Each year on National Science Day (28 th Feb.) the observatory invites the public and pupils from
schools and colleges in the surrounding area to visit the site where they can listen to explanations of
radio astronomy, receiver technology and astronomy from the engineers and astronomers who work
there. We observed the projects and presentations on display from various scientific fields.
There after we entered the tent where the different system parts of a Earth Station and Parabolic
receiving antennas were on display. For public and student understanding detailed poster of each
system with its working and operation were put up. Employee of GMRT also took an extensive effort
to make the visitors understand the exhibited models of system.
The practical models that were on display::
1. Feed position system
2. GMRT servo control system
3. EMU cabinet for Brushless drivers and control system
Subparts :: Motor filter and Server
4. DC servo motor 700W each
5. Different types of antennas::
(a) Monopole antenna - 500MHz and 850MHz
(b) Cross dipole - 900 - 1500MHz
(c) Micropatch antenna – 4 to 8GHz
(d) Log periodic dipole antenna
(e) Ultra wideband cone antenna
6. Front end receiver system consisting of::
(a) Low noise amplifier
(b) Band pass filter
(c) Notch filter
(d) Quadrature hybrid
(e) Solar attenuator
7. Broadband DC fiber optic cable system operating at 2000MHz consisting of::
(a) RF amplifier
(b) DWDM coupler to split incoming signals into 1930/2/4/6 THz signal

(c) MUX and DEMUX
(d) Optical receiver
8. AOR communication receiver
9. RFI shielding components
10. GSM/ CDMA rectifiers (Microstrip) and TV filter (Lumped)
11. Signal control system consisting of::
(a) RF filter
(b) Analog receiver
(c) Local oscillator
(d) Control and monitor
(e) Baseband filter
(f) Noise cancellation
12. Telemetry command and control system
The instructors explained about the signal flow mechanism of various systems installed within
the antenna tower and its receiver (stated above) and their correlation with the subjects and
topics in our curriculum. They also explained about the working of Giant Parabola antenna as
reflector and the Receiver located at its focal point (point of concentration of parabola).
The receiver consisted of 4 different feed antenna to operated at different frequency ranges::
(1) Dual Ring Feed antenna (120 – 240 MHz)
(2) Cone Dipole Feed antenna (Solid-Large diameter)(250 – 500 MHz)
(3) Cone Dipole Feed antenna (Solid- Smaller diameter) (550 – 900 MHz)
(4) Horn Feed antenna (1000 – 1400 MHz)
Further we learnt about Mr.Govind Swarup who  is a radio astronomer and one of the pioneers
of radio astronomy and has been the key scientist behind concept, design and installation of the
GMRT, Pune.
We also learnt about the life cycle of Sun, Moon, Stars and about their study and research.
There was a video explanation room wherein they showed how the Giant Radio Telescopes were
used to receive information about stars and other celestial bodies and used to communicate with
the satellite or for broadcasting. It also explained the travelling of signal from Receiving Antenna
Tower to Receiver room to Correlator room to the Control room and finally to the receiver client.