modernengineeringtrendsin astronomy-2019 · contents...

Modern Engineering Trends inAstronomy - 2019

Sunday 15 September 2019 - Tuesday 17 September 2019Banglore

Book of Abstracts

Contents

”Brush arrangement for dome of 3.6m Devasthal optical telescope at ARIES”- Tarun Bangia,ARIES, Vaibhav Sharma, Zakir Husain College of Engineering & Technology, AligarhMuslim University . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

”Conceptual design for TMT high resolution optical spectrograph”- Amirul Hasan, ProjectEngineer I, India-TMT Coordinate Center, IIA, Bengaluru . . . . . . . . . . . . . . . . 1

”Wide Field Optical Spectrograph for Thirty Meter Telescope – India’s contribution in thedesign and development”-Devika K Divakar, Project Scientific Associate, India-TMTCoordinate Center,IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

0 Breakfast at VBO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

21 cm Horn Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Accelerated Tile Processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Adaptive Optics Program at IIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Advanced technology used in LIGO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

An overview of Analog Receiver System for Detection of Global EoR Signal . . . . . . . 3

Antenna and RF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Brush arrangement for dome of 3.6m Devasthal optical telescope at ARIES . . . . . . . . 4

Challenges in Designing a Digital Spectrometer for Detection of Signals from CD/EoR,Girish B. S, RRI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Challenges in Designing a Digital Spectrometer for Detection of Signals from CD/EoR,Girish B. S, RRI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Characterisation of Upgraded Frequency Standard for the GMRT Observatory . . . . . . 5

Closed-loop control of Filter Wheel for 70 cm GROWTH telescope . . . . . . . . . . . . 5

Coffee/Tea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Coffee/Tea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Coffee/Tea Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Concept Design of retractable dome for the proposed 2m class National Large Solar Tele-scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

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Conceptual Design of Primary Mirror Cover for the proposed 2m class National Large SolarTelescope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Configuration Design for a Prototype Segmented Mirror Telescope . . . . . . . . . . . . 7

DESIGN OF DRIVE CIRCUIT FOR PIEZO WALKER FOR CONFIGURABLE SLIT UNIT . 7

Departure from VBO and arrival to IIA Bangalore, Conference closure . . . . . . . . . . 8

Design and Development of Telescope Cover Structure for 3.6m Telescope at ARIES . . . 8

Design and Development of stress relieving support system for TMT primary glass blanks 8

Design and development of mechanical systems of SUIT Payload onboard Aditya L1. . . 9

Development of tools and methods to characterize low noise power supplies for the purposeof Astronomical instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Developmental status of X-ray polarization sensitive mirrors. . . . . . . . . . . . . . . . 10

Dinner at ICNAPP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Dual polarized broadband dipole antenna feed with conical reflector for uGMRT . . . . . 11

Engineering challenges in realization of Visible Emission Line Coronagraph on-board AdityaL1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Evolution of GMRT Servo Computer with RTAI: Status and Updates . . . . . . . . . . . . 13

FE analysis for the mechanical structure of Prototype Segmented Mirror Telescope . . . 13

FPGA-based Focal Plane Array Beamformer Architectures for the Expanded GMRT . . . 14

Filter integrated Low Noise Amplifier to suppress out of band Radio Frequency Inference 14

GMRT back-end system monitoring system . . . . . . . . . . . . . . . . . . . . . . . . . 15

INSIST: A Proposed Wide-Field, UV-Optical, Imaging and Spectroscopic Space Telescope 15

INVESTIGATING SINGLE PHOTON INTERACTION PRODUCED BY TYPE II SPDC . . 16

Invited Talks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Low cost - 21cm observation on Sun from Kodaikanal Solar Observatory . . . . . . . . . 17

Low cost Characterisation of Sun and Nadir Sensors for Attitude Control of Nano Satellites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Lunch Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Lunch Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Lunch Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Mirror Segment Error Budget Development for 10 meter class Telescope; NLOT/MSE . . 18

Monopole antenna for detecting the signal during Cosmic Dawn to Epoch of Reionization– Current status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Non-spherical representation of optical surfaces - an advanced study . . . . . . . . . . . 19

Opto-mechanical design and analysis of Cubesat based NUV Spectrograph . . . . . . . . 20

Plenary Session, ”L&T’s contribution to Mega Science Projects”-Ravi Kataria, Head Busi-ness Development & Marketing, Missiles & Aerospace Business, Larsen & Toubro Lim-ited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Poster Presentation & Coffee/Tea Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20




Power and Heat Management of New Era Electronic Systems (GMRT) . . . . . . . . . . . 21

Prototype for raw voltage recording in the backend system of the upgraded GMRT . . . 21

RASCAL (Reflector Antenna Sensitivity Calculator) Software . . . . . . . . . . . . . . . . 22

RF over fibre optic backplane for phased array antennas . . . . . . . . . . . . . . . . . . 23

Radio Frequency Interference and its mitigation at upgraded GMRT . . . . . . . . . . . . 23

Radio telescope observation planning using machine learning techniques . . . . . . . . . 24

Recent and Future development of Far Infra-Red (FIR) Balloon borne experiment. . . . . 24

Reducing effects of cross talk in a Radio Telescope using Walsh modulation . . . . . . . 25

Registration opens and breakfast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Sky Watch Array Network (SWAN) : Wide-band Receiver Instrumentation developmentand Current Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Study of Alignment Sensitivity of TMT Primary Mirror Segments on Image Quality . . . 26

Study of performance of segment support assembly for NLOT/MSE primary mirror seg-ments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

TELESCOPE AUTOMATION AND CONTROL . . . . . . . . . . . . . . . . . . . . . . . . 27

Testing a Multi-element, Multi-beam, FPA Beamformer in Free-space Test Range . . . . 28

The 3.6 m DOT electronics: Maintenance and future upgradation strategies . . . . . . . . 28

The Infrared Astronomy Group (IR group) of TIFR, Milind Naik . . . . . . . . . . . . . . 29

Title: Reliability Study of GMRT Analog Backend Receiver System . . . . . . . . . . . . 29

Towards an Optimal Real-time Broadband RFI Filter for the Upgraded GMRT . . . . . . . 30

Ultra-Precision Engineering-Enabling human’s fundamental quest to decode the COSMOS- Sendhil Raja S. Ph.D., RRCAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Visit to JCBT,40” & 30” Telescopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Visit to VBO (Starting Point: IIA, Koramangala) . . . . . . . . . . . . . . . . . . . . . . . 30

Visit to VBT (90”) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Welcoming Remarks -Director, IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . 31

“Accelerated Tile Processor”- Prabu T, RRI . . . . . . . . . . . . . . . . . . . . . . . . . . 31

“Adaptive Optics Program at IIA”- Dr.Sridharan Rengaswamy,IIA, Bengaluru . . . . . . . 31

“An overview of Analog Receiver System for Detection of Global EoR Signal” - SomashekarR, RRI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

“Antenna and RF”-Abdipour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

“Conceptual Design of Primary Mirror Cover for the proposed 2m classNational Large SolarTelescope”- Mr. Govinda K.V. IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . 31

“Design and Development of Telescope Cover Structure for 3.6m Telescope at ARIES”–Dr.Tarun Bangia, ARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

“Design and Development of stress relieving support system for TMT primary glass blanks”-Mr. Alikhan Basheer, IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

“Design and development of mechanical systems of SUIT Payload onboard Aditya-L1”-Mr.Akshay Kulkarni, IUCAA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

“Design of Drive Circuit for piezo walker for configurable slit unit”- Mr Pankaj Madhwani,TIFR, Mumbai . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

“Developmental status of X-ray polarization sensitive mirrors”-Mr Panini Singam, IIA, Ben-galuru . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

“Dual polarized broadband dipole antenna feed with conical reflector for uGMRT”-Mr Hanu-manth Rao Bandari, TIFR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

“Engineering challenges in realization of Visible Emission Line Coronagraph on-boardAditya-L1”-Mr. Subramanya NagabhushanaIIA, Bengaluru . . . . . . . . . . . . . . . 32

“Evolution of GMRT Servo Computer with RTAI: Status and Updates”-Mr.ThiyagarajanBeeman, Mr.Shailendra Bagde, GMRT, TIFR. . . . . . . . . . . . . . . . . . . . . . . . 32

“FE analysis for the mechanical structure of Prototype Segmented Mirror Telescope”- Mr-Sandeep D.S.IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

“FE analysis for the mechanical structure of Prototype Segmented Mirror Telescope”- Mr-Sandeep D.S.IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

“INSIST: A Proposed Wide-Field, UV-Optical, Imaging and SpectroscopicSpace Telescope”-Mr.Sriram Sripadmanaban, IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . 33

“India and Square Kilometre Array”-Y. Gupta, Centre Director,NCRA . . . . . . . . . . . 33

“India’s contribution to TMT hardware”-N Viswanatha, Former GD, ISRO & ConsultantTMT Project, IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

“Low cost - 21cm observation on Sun from Kodaikanal Solar Observatory”-Mr. Manick-avasagam G (SBM college of Engg. and Technology, Dindigul) . . . . . . . . . . . . . 33

“Low cost Characterisation of Sun and Nadir Sensors for Attitude Control of Nano Satellites”-Mr. Asir Nesa Dass N, IIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

“Non-spherical representation of optical surfaces - an advanced study”- Mr Totan Chand,IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

“RASCAL (Reflector Antenna Sensitivity Calculator) Software”- Mr. Sougata Chatterjee,GMRT-NCRA-TIFR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

“RF over fibre optic backplane for phased array antennas”- Mr.Sanjeet Kumar Rai ,NCRATIFR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

“Radio Frequency Interference and its mitigation at upgraded GMRT”-Mr.Sureshkumar S. ,NCRA-TIFR Pune . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

“Single Antenna Receiver Design for Radio Astronomy” . . . . . . . . . . . . . . . . . . 34

“Sky Watch Array Network (SWAN): Wide-band Receiver Instrumentation developmentand Current Status”- Mr. Raghavendra Rao K.B, RRI . . . . . . . . . . . . . . . . . . . 35

“Software for the Thirty Meter Telescope”- Prof. Annapurni Subramaniyam, IIA, Bengaluru. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

“Telescope Control Software and Communication server for 30 inch Telescope, VBO - anOverview / Software aspects of 2.4 M mirror coating plant, VBO”- V Arumugam,Engineer-E,IIA, Bengaluru . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

“Testing a Multi-element, Multi-beam, FPA Beamformer in Freespace Test Range”- Ms BelaDixit, GMRT, NCRA-TIFR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

“The 3.6 m DOT electronics: Maintenance and future upgradation strategies”- Dr Kumar T.S. ARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

“VELC payload on ADITYA-L1” – Prof.B.R.Prasad, PI VELC ADITYA L1,IIA, Bengaluru . 35

“VELC payload on ADITYA-L1” – Prof.B.R.Prasad, PI VELC ADITYA L1,IIA, Bengaluru . 35

Modern Engineering Trends in Astronomy - 2019 / Book of Abstracts

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”Brush arrangement for dome of 3.6mDevasthal optical telescopeat ARIES”- Tarun Bangia, ARIES, Vaibhav Sharma, Zakir HusainCollege of Engineering & Technology, Aligarh Muslim Univer-sity

106

”Conceptual design forTMThigh resolution optical spectrograph”-Amirul Hasan, Project Engineer I, India-TMT Coordinate Center,IIA, Bengaluru

68

”Wide Field Optical Spectrograph for Thirty Meter Telescope –India’s contribution in the design and development”-Devika KDivakar, Project Scientific Associate, India-TMT Coordinate Cen-ter,IIA, Bengaluru

111

0 Breakfast at VBO

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21 cm Horn Receiver

Author(s): Arul Pandian1 ; Prabu T2

Co-author(s): L Ganesh ; Stephen Inbanathan 3

1 The American College2 Raman Research Institute3 American College

CorrespondingAuthor(s): [email protected], [email protected], [email protected]

We have developed a 21 cm receiver based on a horn antenna and RTL SDR, and successfully detectedthe 21 cm line emission from different directions. The design details and results will be presented inthis poster.

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53

Accelerated Tile ProcessorAuthor(s): Prabu T1

Co-author(s): Srivani K S 1 ; Girish B S 1 ; Somashekar R 1

1 Raman Research Institute

Corresponding Author(s): [email protected], [email protected], [email protected], [email protected]

Modern FPGAs are revolutionizing the digital system designs with built-in analog to digital convert-ers (RFSoC), floating point DSP processors and with high-level programming tools. We have plannedto build a versatile digital receiver, namely the accelerated tile processor, by exploiting these FPGAfeatures. We will present here the salients features of the digital processing architecture consideredand discuss the advantages arising from such a design for a multi element radio telescope applica-tion.

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Adaptive Optics Program at IIAAishwarya Selvaraj1 ; Ravinder Banyal1 ; Sreekanth vallapureddy1 ; Sridharan Rengaswamy1

1 IIA

Corresponding Author(s): [email protected], [email protected], [email protected]

Adaptive optics is an inevitable technology in any modern large ground-based telescope. It involvesuse of corrective optical elements within the telescope to compensate for the deleterious effects of theEarth’s atmospheric turbulence on the image quality. Indian Institute of Astrophysics is deliberatingon building a 2 m class large solar telescope (The National Large Solar Telescope) and a 10 m classstellar telescope (The National Large Optical Telescope). In view of this, an adaptive optics programhas been initiated at IIA to generate necessary expertise by demonstrating adaptive optics on existingsmall telescopes. In this talk, I will present the progress made in last two years in this initiative anddiscuss the future prospects.

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Advanced technology used in LIGORichal Abhang1

1 IUCAA

Corresponding Author(s): [email protected]

LIGO (Laser Interferometer for Gravitational-Wave Observatory) is one of the technological marvelinvolving world’s advanced technology. It has overcome many difficulties to achieve one of the finestscientific measurements ever taken precisely. Its extreme engineering can be divided into differentdomains including mechanical structures, optics, civil engineering, physics, geology, electronics,high performance computation,analysis, testing, etc. Some of the following are the advances inLIGO experiment:Vacuum tubes: The vacuum tubes are world’s third largest vacuum tubes having one trillionth ofpressure as that of the atmospheric pressure carried by very thin walls for 20 years now. Its a blindL shaped 4 km long tubes and it took 40 days to achieve this vacuum. Also it is second in the world

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for having Ultra-High vacuum in the tubes.Sensitivity: It is able to measure motion 10000 times smaller than the atomic nucleus. It has someof the best seismic isolation and dampening systems e.g. HAM AUX. Its accuracy of measuring thedistance of the nearest star (4.2 light years) is smaller than the human hair.Civil Construction: The length of the tubes is 4 Km long. While construction care had to be takento overcome the Earth’s curvature of about one meter by pouring concrete. Also CFD models weretaken into account while constructing the structure to cancel the wind load effect on the tubes givingrise to vibrations.Optics: LIGO’s main mirror absorb only one photon out of 3.3 million photos. The test masses eachweigh 40 Kg giving acting as large inertial masses to resist vibrations upto certain level. The testmasses are coated with many optical coatings and polished to a nanometer smoothness. There are280 reflections before reaching the photo detector.Laser: It uses electricity to generate 4 watt near-IR laser. It is 800 times more powerfull than off-the-shelf laser pointers. The control and use of this laser is a very complex game of optics andelectronics.

These are very few engineering marvels involved. It has many important and complex electron-ics and computers involved in its complete operation which can be studied and discussed in de-tail.

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An overview of Analog Receiver System for Detection of GlobalEoR SignalAuthor(s): Somashekar R1

Co-author(s): Jishnu Nambissan T 1 ; Ravi Subrahmanyan 1 ; Udaya Shankar N 1 ; Saurabh Singh 1



SARAS is an ongoing experiment aiming to detect the redshifted global 21-cm signal expected fromCosmic Dawn (CD) and the Epoch of Reionization (EoR). Standard cosmological models predict thesignal to be present in the redshift range z ~6-30 corresponding to a frequency range of 40-200 MHz,and as a spectral distortion of amplitude 20-200 mK to the cosmic microwave background. Designof a radiometer for detection of this weak signal is a challenging task, owing to the fact that thisfrequency range is dominated by astrophysical foregrounds of Galactic and Extragalactic origin, withseveral orders of magnitude greater brightness temperature and strong terrestrial Radio FrequencyInterference (RFI). It is critical that the instrumental systematics do not preclude the measurementof the weak 21-cm signal via additive or multiplicative confusing structures in the measured skyspectrum.

Here, we present the system design of the SARAS 3 version of the receiver, emphasising on the re-ceiver configuration and the signal flow from the antenna to the digital backend. We touch uponthe aspects on the system design and laboratory measurements. New features in the evolved de-sign include Dicke switching, double differencing and implementation of optical isolation and op-tical switching for improved accuracy in calibration and rejection of additive systematics leave noconfusing systematic structures at a level of a few mK. We review the design and engineering chal-lenges involved in the deployment of the system in field for sky observations with future plan ofaction.

mage Processing, Antennas and RF & Electrical System, Observatory Control System and Soft-ware / 3

Antenna and RF

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HedayatiNone ; MkNone ; AbdipourNone

Design considerations and challenges of integrating on-chip antennas in nanoscale CMOS technol-ogy at millimeter-wave (mm-wave) to achieve a compact front-end receiver for 5G communicationsystems. Solutions to overcome these challenges are offered and realized in digital 28-nm CMOS.A monolithic on-chip antenna is designed and optimized in the presence of rigorous metal densityrules and other back-end-of-the-line (BEoL) challenges of the nanoscale technology. The proposedantenna structure further exploits ground metallization on a PCB board acting as a reflector to in-crease its radiation efficiency and power gain by 37.3% and 9.8 dB, respectively, while decreasingthe silicon area up to 30% compared to previous works. The antenna is directly matched to a 2-stageLNA in a synergetic way as to give rise to an active integrated antenna (AIA) in order to avoid ad-ditional matching or interconnect losses. The LNA is followed by a double-balanced folded Gilbertcell mixer, which produces a lower intermediate frequency (IF) such that no probing is required formeasurements. The measured total gain of the AIA is 14 dBi. Its total core area is 0.83 mm² whilethe total chip area, including the pad frame, is 1.55×0.85 mm².

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Brush arrangement for dome of 3.6m Devasthal optical telescopeat ARIESBangia Tarun1 ; Bansal Tanmay2 ; Sharma Vaibhav3

1 ARIES2 KIET group of institution, Ghaziabad3 Zakir Husain College of Engineering & Technology, Aligarh Muslim University


ARIES 3.6 m optical telescope at Devasthal is enclosed in steel building with rotating dome. Domecomprises of upper rotating cylindrical steel structure and lower fixed dome support structure. Ro-tating dome being a fabricated structure of about 16.5m mean diameter involved lot of welding anda clearance of about 150 mm was kept between fixed dome structure outer wall and rotating domeouter plate. Flexible sheets were fixed between fixed and rotating structure to avoid entry of rainwater and dust etc. Requirement for better arrangement to solve the problems posed by rain water,dust, insects and fog etc. was felt at ARIES. Arrangement of brushes with polyethylene terephtha-late (PET) bristles has been prepared for the purpose of filling the gap between fixed and rotatingstructure. A sliding mechanism has been developed for changing of bristles during their wear andtear. Material for the bristles was selected using various economical, ecological, physical and chem-ical parameters. Certain necessary tests on prototype were also performed to check that bristlesmeet the required conditions. ARIES is planning to put the brush arrangement for dome of 3.6mDevasthal optical telescope.

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Challenges in Designing a Digital Spectrometer for Detection ofSignals from CD/EoR, Girish B. S, RRI

Challenges in Designing a Digital Spectrometer for Detection of Signals from CD/EoR, Girish B. S,RRI

82

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Challenges in Designing a Digital Spectrometer for Detection ofSignals from CD/EoR, Girish B. S, RRI

27

Characterisation of Upgraded Frequency Standard for the GMRTObservatoryNavnath Shinde1 ; Ajit kumar B.1

1 NCRA-TIFR

Corresponding Author(s): [email protected], [email protected]

An Active Hydrogen Maser (AHM) unit was recently installed and upgraded the frequency standardof the Giant Metrewave Radio Telescope (GMRT) observatory. The ultra-low phase noise and sta-bility characteristics of this AHM have facilitated the observatory to carry out Very Long BaselineInterferometry (VLBI) observations. The outputs from the AHM are used as a precision frequencyreference for the GMRT signal processing receiver chain particularly for synchronizing samplingclocks for the digitizers and as a reference to the computing cluster.

The AHM is housed in a room, specifically designed considering the environmental parameters suchas ambient temperature, mechanical shock and vibrations, magnetic and RFI shielding. Continuousmonitoring and remote logging of ambient room temperature, current requirement as well as othervital AHM parameters are being carried out using tools developed in-house. The software tools arealso developed to record the phase data between the GPS disciplined Rubidium oscillator and AHMto compare and understand the stability parameters.

To understand the long term characteristics and behavior of the AHM, collaborative effort is initiatedwith ISTRAC-ISRO. Through this collaboration, the GMRT timescale system is built with the help ofISRO timescale instrumentation setup. GMRT timescale system had the AHM unit, GPS disciplinedRudium oscillator and two free-running rubidium oscillators and common view GPS systems.

This presentation will explain the characteristic understood of the Maser Unit with the help of GMRTTimescale system giving the brief of present Phase noise, stability, drift characteristics of the AHMsystem. Also, the presentation will walk-through the future plan and collaboration with other Insti-tutes within India for the performance evaluation of AHM.

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Closed-loop control of Filter Wheel for 70 cm GROWTH tele-scopeAuthor(s): Aniruddh Herle1

Co-author(s): D.V.S Phanindra ; Kamath P. U ; Sagayanathan K ; Anupama G. C ; Varun Bhalerao ; SudhanshuBarway

1 Student


The GROWTH (Global Relay of Observatories Watching Transients Happen) – India telescope atHanle in Ladakh is India’s first effort towards a fully robotic telescope. It is also the first one dedi-cated for a rapid follow-up of transient events in the universe. Mounted in between the CCD cameraand the output port of the GROWTH telescope is a filter wheel which houses 6 filters whose centersare located on the same pitch circle. These filters are rotated into position in a specified sequence by

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a stepper motor coupled to the filter wheel shaft. A closed-loop control system has been designedto rotate the filter wheel and ensure that the correct filter is positioned before the camera in therequired sequence, in line with stringent performance requirements. This system is realized with a16-bit dsPIC33F microcontroller. The Quadrature Encoder Interface module is used to interface withan optical encoder attached to the filter wheel shaft. The Output compare module on the microcon-troller has been used to generate the pulses to the stepper motor driver which will be used to movethe stepper motor. The stepper motor rotation is ramped by varying the frequency of the pulsesfrom pre-defined maximum to minimum frequencies to reduce the inertial effects of the filter wheel.An algorithm has been designed to calculate the shortest distance between any two filters and rotatethe motor accordingly in either direction. As a marked improvement from the previous system, aninterrupt system has been designed to ensure that the encoder values and desired position matchwith a very high accuracy. The electronic components have been carefully chosen keeping in mindthe low temperatures of the observation floor of the telescope at Hanle. A GUI has been designedto allow the user to select the required filter, after which, the filter wheel is rotated to the positionwithin 6 arcseconds of the position in a maximum of 25 seconds.In this talk, I will present the key improvements made to the existing system and the methodsused.

113

Coffee/Tea

109

Coffee/Tea

83

Coffee/Tea Break

11

Concept Design of retractable dome for the proposed 2m classNational Large Solar TelescopeHari Mohan Varshney1 ; Govinda KV1 ; P.M.M. Kemkar1 ; Ravindra B1

1 Indian Institute of Astrophysics

CorrespondingAuthor(s): [email protected], [email protected], [email protected], [email protected]

ABSTRACTThe National Large Solar Telescope (NLST) is a proposed 2 m class telescope dedicated for makinghigh resolution solar observations. A suitable site has been identified at Merak village, near PangongTso Lake in Jammu & Kashmir state, India.It has been observed that installing a telescope near the lake produce good images during the daytime observations. At the same time the open dome conditions help to reduce the “dome seeingeffect”. The absence of dome around the telescope also ensures that no temperature gradient is cre-ated around the telescope and the cool breeze without any obstruction, helps to cool the telescopestructure and mirror.

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In this paper, we present a number of design concepts of retractable dome for NLST, their function-ality, time taken to open and close the dome, power requirement, weights etc.Keywords: Dome Concept Design, Retractable dome, National large Solar Telescope

13

Conceptual Design of PrimaryMirror Cover for the proposed 2mclass National Large Solar TelescopeAuthor(s): GOVINDA K V IIA, BENGALURUNone

Co-author(s): PMM KEMKAR IIA, BENGALURU ; Hari Mohan Varshney 1



The National Large Solar Telescope (NLST) is proposed to be built in India which will be one of themost powerful telescopes to study the Sun. It will have a 2m size primary mirror. The primary mirrorneeds a removable cover to carryout two important functions: first one is to protect primary mirrorfrom environmental conditions when the telescope is not in operation and second one is to preventdangerous concentrated solar radiation from primary mirror arriving directly to secondary mirroror any part of the telescope structure without passing through the heat rejecter when the telescopepoints to an unintended direction due to some malfunctioning of the drive control system.Few design concepts worked out for this primary mirror cover along with their drive mechanismsfor the 2m NLST are presented in this paper.Keywords: Primary Mirror Cover, National large Solar Telescope

58

ConfigurationDesign for a Prototype SegmentedMirrorTelescope

Author(s): Abhishek Goudar1

Co-author(s): GOVINDA K V IIA, BENGALURU ; PARIHAR PADMAKAR SINGH 2 ; PMM KEMKAR IIA, BEN-GALURU

1 engineer trainee2 IIA, BENGALURU


To cater the need of growing astronomical community of India, there is a proposal to realize a 10-12msize optical-NIR telescope, equipped with state of the art back-end instruments. With the currenttechnology, it is not possible to realize a monolithic primary mirror required for such a large tele-scope. This necessitates use of smaller mirror segments aligned to act like a single mirror. Since theSegmented Mirror Telescope (SMT) is yet to be realized in India, it is essential to realize a PrototypeSegmented Mirror Telescope (PSMT) of smaller size to understand the complexities of design, fabri-cation, assembly and testing of a SMT. This will help to reduce the cost, time and risk for realizingthe full size ( 10-12 m) SMT.With this in mind, design of a 7 Segment PSMT having hexagonal mirror segments of size 500mmeach and overall aperture of about 1.5 m, is initiated at IIA. After considering various aspects of aPSMT, a configuration is designed which is now undergoing fabrication. Some of the mechanicalaspects of the design of this PSMT are presented in this paper.

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24

DESIGNOFDRIVECIRCUIT FORPIEZOWALKERFORCONFIG-URABLE SLIT UNITPankaj Madhwani1

1 TIFR, Mumbai


We at TIFR, have initiated the development of a Multi-Object Infrared Spectrometer (MOIS) using aconfigurable multi-slit arrangement for a large aperture Indian optical/infrared telescope. In orderto retain flexibility, avoid design and operational issues involved in using focal plane masks for multi-object spectroscopy we present here the first design concepts for the Configurable Slit Unit (CSU)that will be used to place multiple slits at different positions on the sky. The CSU simultaneouslydisplaces bars across the FoV of the telescope to mask unwanted light so that a rectangular slit isformed at any desired position in the focal plane by positioning two opposing bars. The two oppositebars need to be independently controllable from either side so as to achieve any slit width opening asrequired during observation so that any slit width right from fully closed to fully open imaging fieldcan be achieved. For infrared observations the entire mechanism has to be operational at cryogenictemperatures. We are currently working on a preliminary design for the CSU based on piezo-walkersto achieve the linear movement of the slits. In this talk I will present an overview of the CSU andspecifically the microcontroller based drive circuit that we have designed to control the motion ofthe piezo-walkers accurate to 2.5 micron.

116

Departure from VBO and arrival to IIA Bangalore, Conferenceclosure

37

Design and Development of Telescope Cover Structure for 3.6mTelescope at ARIESTarun bangia1 ; Ashish Sahu2

1 ARIES2 IIT Ropar (Punjab)


The 3.6 m optical telescope of ARIES is installed at Devasthal site for astronomical observations.Need for additional protection of telescope apart from that provided by its dome was felt to avoidany minute water leaks from dome roof, accumulation of dust on the mirrors and also to minimizeeffect of humidity on telescope during rainy season. A telescope cover structure has been designed tocover the telescope inside its dome. It was designed as a permanent structure that will be integratedwith dome’s existing structure. Structure will allow movement of two 10 MT under slung cranesin dome as well as periodic health run of the telescope during rainy season. Prototype of telescopecover structure was prepared and its assembly was tested with dome structure. Components formanual version of the telescope cover structure were fabricated in-house, assembled with dome andtested successfully at site with plastic covers. Presently further work on up-gradation of telescopecover structure with retractable water proof and fire resistant fabric is under progress.

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17

Design and Development of stress relieving support system forTMT primary glass blanksAlikhan Basheer1 ; Sriram SNone ; Vineeth Valsan2 ; Mahesh P K 3 ; Anupama G C3 ; Viswanatha N3 ; Krishna MurthyT4

1 Indian Institute of Astrophysics, Bangalore2 Christ Uinversity3 Indian Institute of Astrophysics4 Indian Institute of Space Science and Technology


The Thirty Meter Telescope (TMT) adopts a recently developed technology known as Stressed Mir-ror Polishing (SMP) for the polishing of its 492 glass blanks. In this process, first the meniscus typespherical shape glass blanks are converted in to the conjugate of desired aspheric shape by the ap-plication of forces around the edges using warping arms. This is followed by spherical polishingin the stressed condition to obtain the required surface figure. The stress accumulated in the glassblank needs to be released before the metrology to measure the asphericity of the surface. Hence itis essential to remove the stress by keeping the glass blank in a free floating condition. To achievethis, the glass blanks need to be kept over a platform or a support system which will provide a zerogravity condition.As a part of this, we designed and simulated a passive support system which works using the whiffle-tree mechanism to produce a floating condition. This is achieved by sensing the reaction force at eachsupport point and nullifies the gravity effect by giving equal and opposite counter acting forces. Thisstress relieving support system which additionally gives optimized support for the glass blank andhelps to minimize the surface deformation due to its self weight sagging. This paper discusses aboutthe design and analysis of the support system and it also discusses about the sensitivity, toleranceon position and force and alignment sensitivity of the glass blank over the support system.

50

Design and development of mechanical systems of SUIT Payloadonboard Aditya L1.Akshay Kulkarni1 ; Aafaque KhanNone ; Anamparambu Ramaprakash2 ; Durgesh Tripathi2 ; Ravi Kesharwani2 ;Sreejith Padinhatteeri1 ; Avyarthana Ghosh2 ; Subhamoy ChatterjeeNone

1 Inter University Centre for Astronomy and Astrophysics2 Inter-University Centre for Astronomy and Astrophysics

CorrespondingAuthor(s): [email protected], [email protected], [email protected], [email protected], [email protected],[email protected], [email protected]

The Solar ultraviolet imaging telescope (SUIT) onboard Aditya L1 is an upcoming space telescope tostudy the Sun in near UV (200nm - 400nm) range and will be placed in a halo orbit around Sun-EarthL1 point. The mechanical systems design of SUIT involved considering crucial factors of structuralintegrity to withstand launch loads, meeting temperature specifications within the payload, light-weighting of components, assembly and alignment sequence to meet the optical requirements.The instrument can reach high temperatures due to exposure to 1450W/m2 solar intensity at L1,while the CCD imaging device will need to operate at a temperature of -55 degrees Celsius. Moreover,the payload components include moving mechanisms, optics, and electronics, which have specificvibration qualification values. Therefore, the design of the mechanical housing for these items needsto ensure that the thermal deformation is within allowed limits and the components will survivelaunch loads.In the presentation, we will be discussing the procedure to develop the mechanical design of theinstrument and the various techniques used to validate the design. We used the design software

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Solidworks and NX Nastran for the CAD modeling and FEM studies for designing these components.This included features such as grid structures, thin-walled structures, honeycomb panels, flexuresbased mounts, to meet the final optical, structural and thermal specifications. The presentation willinclude the methods and results of thermal distortion studies, vibration simulation studies, and abrief report on manufacturability, optomechanical assembly procedure of the instrument so as tomeet the design requirements.The overall impact of this study is that it can be an additional guideline for facilitating the mechanicalsystems design of space telescopes and will be useful in similar future projects.

4

Development of tools andmethods to characterize lownoise powersupplies for the purpose of Astronomical instrumentationAuthor(s): Anwesh Kumar Mishra1

Co-author(s): U.S. Kamath 2

1 Indian Institute of Astrophysics2 Indian Institute of Astrophysics


Reducing power supply noise is one of the essential steps in order to implement precision and reliableinstrumentation. However, commercial power supplies are usually insufficient for the purpose ofastronomical instrumentation. They usually lack noise characterization over a range of frequenciesand also over a range of applied load. In this regard, we have defined a method of estimating toler-able noise limits along with specific bandwidth and load limit requirements for various electroniccomponents. We have developed tools such as DC constant current loads and active RC filters totest and measure the noise performance of off-the-shelf power supply modules. Finally, We havefabricated a range of old and modern voltage regulator architectures and compared their measurednoise figures for the purpose of realizing a low noise (< 50 microVolt RMS) power supply. We willdiscuss the various methods of noise measurement using a modern digital oscilloscope and varioustechniques to reduce power supply noise.

22

Developmental status ofX-ray polarization sensitivemirrors.Panini SingamNone ; Sreekumar P.1 ; Shyama Narendranath K.C.2 ; Maheswer Nayak3 ; Paresh Chandra PradhanNone

1 ISRO2 URSC3 RRCAT


We have developed multilayer mirrors which can reflect X-rays are Brewster angle (~45o) and henceare sensitive to X-ray polarization. We have fabricated several W/B4C multilayer mirrors usingmagnetron sputtering technique with different parameters, optimizing the performance and sensi-tivity at soft X-ray region (photon energy < 1 keV). We have developed a conceptual design for abroad-band X-ray polarimeter using X-ray optics and multilayer mirrors. These mirrors have polar-ization sensitivity for soft X-rays. In order to improve the overall performance of the instrument,these mirrors are made transparent to hard X-rays by etching out the substrate. These type of mir-rors acts as polarimeters for soft X-rays while transmitters for hard X-rays simultaneously which hastremendous applications for astronomical X-ray polarimetry. I will present the design of an X-ray

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polarimeter instrument along with the developmental and test results of substrate etched W/B4Cmultilayer mirrors.

85

Dinner at ICNAPP

23

Dual polarized broadband dipole antenna feed with conical re-flector for uGMRTHANUMANTH RAO BANDARI1 ; s suresh kumar2

1 TATA INSTITUTE OF FUNDAMENTAL RESEARCH2 GMRT-NCRA-TIFR


Dual polarized broadband dipole antenna feed with conical reflector for uGMRT

Hanumanth Rao B, Suresh Kumar S

GMRT Observatory, NCRA-TIFR, Post Bag 3, Ganeshkhind, Pune 411007, Maharashtra, India

(hanuman, [email protected] )

The Giant Metrewave Radio Telescope (GMRT) is an international facility for Radio Astronomy, op-erational since 2002. It consists of 30 fully steerable prime focus feed parabolic antennas, each of 45m. diameter, spread over an area with an effective radius of nearly 15 km, and covering frequenciesin the range of 150 MHz to 1420 MHz. Though meant primarily as an aperture synthesis instrument,antenna arrays can be formed out of the 30 dishes, where separate sub-arrays can work on differentfrequency bands concurrently.

To meet the requirement of seamless frequency coverage from about 50 MHz to 1500 MHz, we havedesigned and developed wide-band feeds of an octave or more bandwidth, to efficiently cover thefollowing bands: 120-240 MHz (Band-2), 250-500 MHz (Band-3), 550-850 MHz (Band-4) and 1000-1500 MHz (Band-5).

This paper describes the broadband dipole antenna feed with conical reflector design for L-band(1000-1500 MHz). This feed has been designed and prototype model was implemented at GMRTobservatory. This future cone-dipole design for 900-1500 MHz, provides very good return loss per-formance (<-10 dB) and with uniform edgetaper ~ 12 dB throughout the band.

Dipole Design Concept: Any λ/2 dipole is resonant to particular frequency and narrow band innature. When the dipole is loaded with plates/sleeves either on the top or bottom of the dipole, itwill nullify the effect of Inductive reactance and improves the electrical bandwidth. λ/2 Dipoles forBand-2, -3, -4 & -5 have been designed and optimized the sleeve configuration to achieve requiredband width.

Cone Design Concept: Dipole and dipole with flat reflector will have asymmetric radiation pattern.If dipole arms are bent to achieve symmetry in radiation pattern, it will affect antenna impedanceand power handling capabilities. To solve the above mentioned, dipole has to keep in the standardform and the flat reflector has to be bent to improve the radiation pattern symmetry. For Band-3,-4 & -5, cone-angle has been adjusted to 70 deg to optimize spill over and illumination losses for 45meter dia. GMRT parabolic dish.

Successful completion and deployment of this wideband feed on all 30 antennas will make the GMRTa very sensitive and versatile instrument for a variety of new science in astronomy.

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References

[1] Swarup, G., Ananthakrishnan, S., Kapahi, V.K., Rao, A.P., Subramanya, C.R., and

Kulkarni,V.K., “The Giant Metre-wave Radio Telescope”, Current Science, Vol.60, No.2, 1991.

[2] Wong, J., King, H., “A Cavity-Backed Dipole Antenna with Wide-Bandwidth

Characteristics”, IEEE Trans. Antennas and Propagation, Vol. AP-21, No. 5, pp. 725-727, 1973.

44

Engineering challenges in realization of Visible Emission LineCoronagraph on-board Aditya L1Subramanya Nagabhushana1 ; Umesh Kamath1 ; S Kathiravan1 ; S Amit Kumar1 ; V Natarajan1 ; S Pawan Kumar1 ;Venkata Suresh Narra1 ; Shalabh Mishra1 ; Chavali Sumana1 ; Varun Kumar1 ; Bhavana Hegde1 ; Jagdev Singh1 ; BRaghavendra Prasad1

1 Indian Institute of Astrophysics, Bangalore

CorrespondingAuthor(s): [email protected], [email protected], [email protected], [email protected], [email protected],[email protected], [email protected], [email protected], [email protected], [email protected],[email protected], [email protected]

Engineering challenges in realization of Visible Emission Line Coronagraph on-board Aditya L1

Nagabhushana S, Kamath P U, , Kathiravan S, Amit Kumar, Natarajan V, Pawan Kumar S VenkataSuresh Narra, Shalabh Misahra,Chavali Sumana, Varun kumar, Bhavana Hegde, Jagdev Singh, Raghaven-dra Prasad B

Indian Institute of Astrophysics, Bangalore

Visible Emission Line Coronagraph (VELC) on board India’s first space solar mission Aditya-L1 isan internally occulted reflective coronagraph designed for solar coronal studies. VELC is capableperforming the observations in imaging, spectroscopic and spectro-polarimetric modes closer to thesolar limb (50arcsec). Super polished off-axis parabolic mirror is chosen as primary mirror (M1). Dueto the off-axis primary, the payload structure deviates from the cylindrical structure. VELC consistsof 21optical assemblies, 4 detectors and 4 baffles. The payload volume is 1.71m (L) x 1.07m (W) x0.540m (H). All the payload components should be aligned to tight tolerances (<20 arcsec) in orderto meet the performance requirements. Payload global stiffness has to be > 100 Hz to withstandthe launch loads. The in-orbit thermo-structural (check) stresses should be minimal such that thepayload performance is not compromised. Thermal gradient in the optical cavity is around 6˚C(22±3˚C), this gradient should not affect the inter separation between the optical elements. Theoptical components are spread out over the optical bench of size 1.6m x 1m and to keep the interfacestress to minimum, the flatness demanded is ~10 microns. The overall mass budget of the payload isabout ~172 kg. The results of the optical tolerance analysis calls for the CTE of the optical bench tobe < 8ppm.VELC includes three sCMOS (visible channels) and one InGaAs (IR channel) detector systems. Eachof the detectors has four packages consisting of Detector Head Assembly (DHA), Control and DataProcessing Electronics (CDPE), Power Supply Electronics (PSE) and Interface to BMU (CERT). Thesensor, Detector Proximity Electronics (DPE) and interface with payload thermal control systemconstitute the DHA. Considerable efforts are made in the selection of sensors (to meet the proposedscience goals), configuring electronics design and interface, mechanical interface, thermal interface,optimizing camera electronics, on-board data processing protocols, etc.All of these systems have to be integrated, tested and calibrated to achieve the designed systemperformance. Sub-system level tests and calibrations are being developed. Stringent contaminationcontrol protocols have been evolved and implemented to minimize the scatter due to particulate andmolecular contaminants. Sub-system level tests and payload integration will be carried out in class-10 clean facility. Vacuum calibration of VELC is critical and hence its final performance test willbe carried out in vacuum environment. Several system-level calibration protocols such as PSF/MTFmeasurements, spectroscopic, radiometric/photometric, polarization calibrations, etc. are planned

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and also being implemented.The science goals, overall instrumentation, criticalities and challenges faced in each domain will bepresented across various sessions by the concerned authors.

5

Evolution of GMRT Servo Computer with RTAI: Status and Up-datesThiyagarajan Beeman1 ; Shailendra Bagde1 ; Suresh Sabhapathy1 ; Bhal Chandra Joshi2

1 Giant Metrewave Radio Telescope - Tata Institute of Fundamental Research2 National Centre for Radio Astrophysics - Tata Institute of Fundamental Research


Now a days General Purpose GNU Linux Operating Systems employed in variety of applicationsfrom digital gadgets to avionics, flight navigation systems and nuclear power plant control applica-tions. Monolithic kernel architecture of Linux OS makes it not suitable for safety and time criticalapplications. In such cases, to convert the GPOS into strict timing constraints, several approacheswere followed in embedded system industry (ex: RTAI, RT-Patch and Xenomai etc). In this paperwe are going to present, one such technique which converts the General Purpose Linux OperatingSystem (GPOS) into Time critical system based on Real Time Application Interface (RTAI). In ad-dition with, we present minimal embedded system building techniques with Buildroot, and how itwas used to develop the complete RTAI patched RTOS with different Linux kernel releases and RTAIversions. Also we presented performance measures of RTAI and debugging tools which helped usto tune and implement the RTAI based embedded software for GMRT Servo application.

8

FE analysis for themechanical structure of Prototype SegmentedMirror TelescopeAuthor(s): SANDEEP D S1

Co-author(s): NAGABHUSHANA S 1 ; GOVINDA K V 1 ; KEMKAR PMM 1 ; PARIHAR PADMAKAR SINGH1

1 IIA, BENGALURU

Corresponding Author(s): [email protected], [email protected], [email protected], [email protected],[email protected]

Abstract:To keep in pace with the emerging trends in scientific research and cater to the need of growingIndian astronomical community, a need is strongly felt for realising an 8-10 meter size optical tele-scope in India. Construction of such a large optical telescope size is possible only when the primarymirror is made of large number of small mirror segments. In segmented mirror technology, smallermirror segments are aligned with respect to each other so that it acts like a single, monolithic largeaperture telescope.Before embarking on such a large and expensive segmented mirror telescope project, it is necessaryto understand the complexities of the segmented mirror technology by thoroughly working on thedesign, development, analysis, fabrication, realisation and laboratory experimentation by making afull-fledged prototype segmented mirror telescope (PSMT) of a smaller size. It is planned to realise a1.5m aperture PSMT at IIA, with 7 segments for this purpose. The design and analysis of this PSMTis in advanced stage.

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Detailed structural and thermal analysis has been carried out for different configurations of the tele-scope to evaluate the stresses, deformation, stiffness/natural frequencies, reaction forces and mo-ments due to gravity, wind load and temperature variations for static, dynamic and transient cases.Some details of these analysis are presented in this paper.

(Abstract sent for oral presentation at META 2019)

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FPGA-based Focal PlaneArrayBeamformerArchitectures for theExpanded GMRTKaushal Buch1 ; Ajith Kumar B.1 ; Bela Dixit1 ; Atul Ghalame1 ; Jayaram Chengalur1

1 GMRT, NCRA-TIFR


The Expanded GMRT (eGMRT) is a proposal to look at three expansions to theGMRT - increasing the field of view, increasing angular resolution andimproving the sensitivity to the extended radio emission. In this talk, wewould focus on increasing the field-of-view using Focal Plane Array (FPA)and the ongoing development of the FPGA-based prototype FPA beamformer. Aprototype is being developed to understand the challenges in buildingreal-time beamformer with multiple inputs and multiple beams. As part ofthis project, we have calculated the computational complexity ofimplementing FPA beamformer in real-time and the various tradeoffs at thearchitectural level. This tradeoff analysis helped in arriving at anoptimal number of inputs, spectral channels, and beams for Virtex-5 FPGA.In case of an FPA system, the computation of beamformer weights through thecorrelation operation is only needed at distinct time intervals. This ledto a further increase in the number of inputs for the same hardware setup,by separating the correlation and beamforming designs, and exploring FPGAreconfigurability. An alternate approach through a fully offlinecorrelation design using recorded raw voltages would also be described. Thecurrent version of the multi-element, multi-beam design of the narrowband(32 MHz bandwidth, 16-input, 4-beam) and wideband (300 MHz bandwidth)beamformers have been developed using the CASPER (Collaboration forAstronomy Signal Processing and Electronics Research) methodology. Therecent test results from the above- mentioned beamformer designs conductedin a free-space test range (at the GMRT site) would be described. As a steptowards migration to contemporary signal processing platforms and the finalprototype beamformer, we have started beamformer development using XilinxRFSoC (RF System-on-Chip).

19

Filter integrated Low Noise Amplifier to suppress out of band Ra-dio Frequency InferenceVILAS VILAS BHALERAONone ; SURESHKUMAR S1

1 NCRA-TIFR


Radio Telescope Operating at Low Frequency suffer from various commercial transmission outsidethe observing ban. Low Noise Amplifier being the first device to receive the Radio signals easily

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get saturated due to the out of band transmission and become impossible to carry out useful RadioAstronomical observation. In addition to saturation the out of band Interfering signals produce inband Intermodulation product. Placing a band pass filter after the LNA do not reduce these prod-ucts and prevent from saturation of LNA. Similarly placing the band pass filter before the LNA willdegrade the Receiver performance. The paper present a LNA design with Low Pass Filter integratedbetween the amplification stages of the LNA without degrading the Noise Figure of LNA. The LPFcuts off the out of band RFI and prevent early saturation of the LNA and reduce the intermodulationproduct in the band. The designed LNA for frequency 120-245 MHz have a gain of 35 dB and Noisetemperature of 40 K with a 80 dB rejection for the Interfering mobile signal.Reference:1. Swarup, G. et al., The Giant Metrewave Radio Telescope. Curr. Sci., 1991, 60, 95–105.2. Yashwant Gupta, et al., The upgraded GMRT: Opening new windows on the radio Universe. Curr.Sci., 113(4):707-714 • January 2017.

39

GMRT back-end system monitoring systemAtul Ganla1 ; Dnyandeo Nanaware2 ; Ajithkumar B2

1 NCRA- GMRT2 NCRA-GMRT


Giant Meterwave Radio Telescope (G.M.R.T) back-end system is installed in three differentlocations correlator room, new receiver room and Active Hydrogen Maser (A.H.M.) room thereare many critical electronics components whose electronics circuits are susceptible to variationsin environmental parameters such as temperature, humidity and supply voltage etc. Hence areal time 24/7 monitoring of these parameters along with warning alarm is essential themonitoring system developed also provides recording and plotting of the data on a web basedinterface.A.H.M. and the related time and frequency circuits are extremely critical in ensuring properoperation of G.M.R.T. system. The proper working of these circuits depends on stableenvironmental parameters. We have installed comprehensive monitoring scheme for theA.H.M. which can monitor temperature, relative room humidity, and mains supply voltagealong with monitoring of proper operations of air conditioners installed. For safety and securitywe have also included CCTV based monitoring for the room. The temperature is monitored atdifferent locations of the room.We have also developed web based application to monitor various internal parameters ofA.H.M. and give warning, plotting program is also developed to see the performance over time.An integrated health monitoring scheme of the back-end receiver is developed which monitorsthe parameters of the back-end electronics and power level of received signals at differentlocations.This poster presentation will describe the implementation of this monitoring scheme and plansfor future development

42

INSIST: A Proposed Wide-Field, UV-Optical, Imaging and Spec-troscopic Space TelescopeSriram Sripadmanaban1

1 Engineer E Optics


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Optical imaging has been the driving force of astrophysical research, historically driven by theground based telescopes, which still drives the ground based astronomy, with the recent surveyslike the SDSS, PANSTARRS as well as the upcoming LSST. IR and UV wavelengths obtained fromspace are complimentary to the ground facilities. With the upcoming JSWT to compliment the IRwavelength range in the near future, a deep photometric survey in the complementary UV range islacking for the international astronomical community. India reached a major milestone in the areaof space astronomy with the successful launch and post launch operations of its first space obser-vatory, ASTROSAT and has achieved in securing a firm foot print for Indian in the internationalastronomy scene. The success of this space observatory and the lessons learned has motivated toenlarge the footprint of Indian space astronomy in the international scene.The high resolution optical/UV images have so far been provided by the Hubble Space telescope(HST) since 1990s. The high spatial resolution imaging of the HST is limited to very small fields. Asthe mission is approaching the end of its life time, it is unlikely to be available for a very long period.As the 2030s will produce deep sky images in the optical and IR regions, a similar coverage in theUltraviolet are not addressed by any of the planned mission. This is where India with its capacity tolaunch and operate space observatories, can fill the gap. The UVIT was a capability demonstrationand it is important to take this strength to create the next generation UV-¬optical observatory classspace telescope in the next decade, to fill the gap in the international scene.In order to fill the gap in the UV space astronomy, Indian astronomical community has submitted aproposal, Indian Spectroscopy and Imaging Space Telescope (INSIST), to ISRO. INSIST is an obser-vatory class mission aims to do imaging with high spatial resolution (0.2”) covers 0.25square degreeFOV with the sensitivity of 28th magnitude in the UV for an exposure of 1ksec and a multi objectspectroscopy feasibility with a spectral resolution of R~2000 in UV. During the design phase, variousoptical configurations have been considered and the merits and demerits of each design has beenstudied. Optical design and design challenges of INSIST will be discussed in details here.

14

INVESTIGATING SINGLE PHOTON INTERACTION PRODUCEDBY TYPE II SPDCSUBHRO DAS SUBHRO DAS1

1 IIT (BHU) VARANASI


INTRODUCTION-

SPDC is a nonlinear instant optical process that converts one photon of higher energy (namely, apump photon), into a pair of photons (namely, a signal photon, and an idler photon) of lower energy,in accordance with the law of conservation of energy and law of conservation of momentum. It isan important process in quantum optics, for the generation of entangled photon pairs, and of singlephotons.

METHOD OF PHOTON INTERACTION EXPERIMENT-

The main goal of photon interaction experiment is to collide two photons at specific point in spaceand time exploring the particle nature of light and to reveal new information about the very nature ofphotons. The goal of photon collision is accomplished using β barium borate crystal which producesa pair of entangled photons using spontaneous parametric down-conversion (SPDC) process whichare to be collided.

INFERENCES OF THE EXPERIMENT-

The main inference that can be drawn from the results of the experiment is to explain how the photons can be split into more fundamental particles (possibly dark photons).

This interaction between the photons collision will help us to know and clarify our understanding of photon and our universe. It will also give us a clue as to how our universe might meet its ultimate fate.

CALCULATION OF COLLISION POINT-

x=a cos θ, y=l_1+b sin θ (for one of the ellipse)x=c cos ∅, y= -l _2+ d sin ∅ (for second ellipse)

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∅= sin ^(-1) [(da/bc)± √(( da/bc) ^2-4[ {l _1+l_2+b^2- (bc/a) ^2}/ (bc/a) ^2 ] )]

θ = c/a cos[ sin ^(-1) [(da/bc)± √(( da/bc) ^2-4[ {l _1+l_2+b^2- (bc/a) ^2}/ (bc/a) ^2 ] )]] ]

REFERENCES-

1) Effect of high dimensional entanglement of Laguerre - Gaussian modes in parametric down conversion in journal of optical society of America B (April 2009) by Yoko Miyamoto (University of Tokyo), Schigeki Takeuchi (University of Kyoto).

2) Constraining the photon lifetime in physical review letters ( July 2013) by Julian Heeck (Max Planck institute of nuclear physics).

3) The mass of the photon (compilation of 130 research papers), by Liang-Cheng Tu1, Jun Luo and George T Gillies.

63

Invited Talks

“Square Kilometre Array”-Y. Gupta, Director,NCRA

34

Low cost - 21cm observation on Sun from Kodaikanal Solar Ob-servatoryManickavasagam G1

1 SBM college of Engg and Technology, Dindigul


Traditionally 1420 MHz line emission is used to study the Doppler Spectrum of the 21-cm hyper fineline of interstellar atomic hydrogen.This radiation comes from the transition between the two levelsof the hydrogen 1s ground state, slightly split by the interaction between the electron spin and thenuclear spin. We have modified the old dish antenna and the receiver system to study the radiationfrom Sun at 21 cm at Kodaikanal. The result is compared with the available online resources tocompute the thermal emission from Sun (Quiet Sun) at this wavelength. The radio instrumentationand interesting results will be presented.

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Low cost Characterisation of Sun and Nadir Sensors for AttitudeControl of Nano SatellitesASIR NESA DASS N 1

1 IIST


Nanosatellites based experiments are having an exponential growth in recent times. These satellitesuse miniaturised components that consumes less power. Attitude control of Nanosatellites dependsupon various sensors such as sun sensor, nadir sensor, inertial measurement unit and others. Allthese sensors need to be qualified/characterised before the actual flight. Academic institutions and

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small companies don’t have access to equipment that are dedicated for precise testing of these sen-sors.This paper discusses about two different low cost testing methodologies of sun and nadir sensors inthe laboratory requirement. These sensors are based CMOS camera technology that takes the imageof the sun and earth to estimate the satellite attitude. First method uses direct sun as the light sourcewith readings obtained for different azimuth and elevation. Second method uses xenon-arc lamp ina laminar flow chamber that closely resembles the sun spectrum. Third method uses multi-spectrumlight source for the testing.A separate setup was made for the nadir sensor testing in which an aerobics ball with light sourcefrom behind placed inside a dark chamber was used to simulate earth. Camera images of the aerobicball (earth simulator) were taken from the sensor for different positions and attitude was estimated.The experimental setup, comparisons, pros and cons for each of the methods are discussed in de-tail.

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Lunch Break

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Lunch Break

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Lunch Break

16

Mirror Segment Error Budget Development for 10 meter classTelescope; NLOT/MSE

Janani VaradhachariNone ; Sriram SNone ; Gajendra PandeyNone ; Anupama G.C.None ; Kei SzetoNone ; Eric WilliamsNone


The proposed India’s National Large Optical Telescope and the Mauna Kea Spectroscopic Explorerare optically designed to have nearly identical hyperbolic primary of 60 segments of size 1.44m, de-livering a circumscribed 11.25 meter aperture. In order to get the best image quality, all the segmentsin the primary mirror need to be aligned in the telescope for a monolithic profile. Any deviationfrom the monolithic profile would degrade the Image Quality(IQ).The possible error contributions from M1 which could cause the image degradation are categorizedinto seven major groups: (i) Segment Residual Figure Error (SRFE), (ii) Segment Thermal Distortion(STD), (iii) Segment Support Print Through (SSPT), (iv) Segment Drift Errors (SDE), (v) SegmentIn-plane Displacement (SIPD), (vi) Segment Out-of-plane Displacement (SOPD) and (vii) SegmentDynamic Displacement Residuals (SDDR).The primary error components in each of the above mentioned group is represented as the lowerorder Zernike term (4th order) except the 1g gravity effect where the higher order Zernike terms aresignificant. Most of the lower order surface deformation on each of the segment will be corrected bywarping harness in the segment support system but eventually introduces high frequency residuals.In order to achieve the M1 system-level top-down IQ allocation, we have developed M1 shape error

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budget which includes lower and higher order surface deformation. The Image quality is character-ized by the 80% Encircled Energy (EE80) in error budget. Details about the technique used for thedevelopment of the mirror segment error budget and the sensitivity of each lower order term andgravity effects on M1 for telescope Zenith angle 0 and 30 degree for on-axis as well off-axis fieldswill be discussed here.

51

Monopole antenna for detecting the signal during Cosmic Dawnto Epoch of Reionization – Current statusAuthor(s): Raghunathan Agaram1

Co-author(s): Girish B.S. 1 ; Jishnu Nambissan T 1 ; Mayuri Sathyanarayana Rao 1 ; Ravi Subramanian 1 ; SaurabhSingh 2 ; Somashekar R 1 ; Srivani K.S. 1 ; Udaya Shankar 1

1 Raman Research Institute2 Raman Research institute

CorrespondingAuthor(s): [email protected], [email protected], [email protected], [email protected], [email protected],[email protected], [email protected], [email protected]

Cosmic Dawn to Epoch of reioniztion is a period which began in the history of universe, with theformation of stars for the first time and ended in transforming completely the neutral state of hydro-gen to ionized state. Thermal history of the universe during this era is currently poorly understood.The 21cm line of neutral hydrogen is considered as a power tool to probe this era to gain better un-derstanding of it. Its intensity variation as a function of time is predicted to carry information aboutvarious physical processes responsible for either heating or ionizing the intergalactic medium. Thissignal could be detected by measuring the spectral distortion imprinted by the signal in the spec-trum of the cosmic microwave background radiation over the frequency range of 50-200 MHz. Themagnitude of these distortions is orders of magnitude weaker than the Galactic and Extragalacticforegrounds and hence measuring them in the presence of foregrounds is challenging.Several factors of an antenna used for the detection often mask the desired signal. They eithermake the antenna insensitive to the signal or produce undesired features in its spectral responsewhich would mimic the signal under detection. Reflection efficiency, radiation efficiency and spec-tral smoothness in impedance characteristics and radiation patterns are the three primary factorswhich predominantly govern the detection process. It is desired to have reflection efficiency betterthan 10%, radiation efficiency more than 50% and spectral smoothness at a few parts in a million over1:4 band of 50-200 MHz. It is difficult to achieve these simultaneously over a large bandwidth be-cause of their complex dependencies on i) physical dimensions of the antenna and ii) media aroundit. In this talk, I present the recent progress made by us in the antenna design, experiences in sim-ulation and prototyping and the measurement results. Our work continues towards constructing abroadband antenna with all the desired features at metre wavelengths.

7

Non-spherical representation of optical surfaces - an advancedstudyTOTAN CHAND1



In general a majority of optical system used conventional spherical surfaces as it is easy to makeand characterize. Though advantages of using non-conventional surfaces such as aspheric, freeform

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are being well known since primitive era of geometric optics. The recent progress in high precisionengineering technology continuously demanding these surfaces in order to meet stringent opticaldesign requirements. However the right choice of representation of these surfaces is not easy andsometimes may lead to fabrication and metrology criticality which directly push the cost of the optics.In this document different type of non-conventional surface representation with their advantagesand disadvantages is being covered.

45

Opto-mechanical design and analysis of Cubesat basedNUVSpec-trographBinukumar Nair1 ; Bharat Chandra1 ; Shanti Prabha1



A NUV (1800-3000 Å) spectrograph has been designed to investigate the diffuse nebulae and otherextended sources. The spectrograph has been designed to fit into a 6U form factor (350 × 240 × 150mm) Cubesat and will be launched into a low-earth orbit (LEO). Optical design, optimization, andtolerancing have been completed. Designs of mounting elements are in progress; stringent volumeconsiderations restrict the optomechanical design of various subsystems. In this work, we presentsome of the work we have done in modeling the sub-assemblies and system-level assembly of theCubesat. We have adopted an analysis methodology in such a way that we design each componentand model by applying Finite Element Analysis using Ansys® software. Find the resulting deforma-tions, validate the model and incorporate the corrections and improve it. The cycle will continueuntil we have a model with optimal performance. Once the subsystem level analysis is completedwe will re-initiate the same model for complete system-level assemblies to improve and validatethe design. Our aim is to arrive at an optomechanical model of the system such that it is reason-ably lightweight and does not affect the optical performance of the spectrograph both in terms ofmechanical integrity and thermal performance.

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Plenary Session, ”L&T’s contribution to Mega Science Projects”-Ravi Kataria, Head Business Development & Marketing, Missiles& Aerospace Business, Larsen & Toubro Limited.

“L&T’s contribution to Mega Science Projects”-Ravi Kataria, Head Business Development & Market-ing, Missiles & Aerospace Business, Larsen & Toubro Limited.

101

Poster Presentation & Coffee/Tea Break

89


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18

Power andHeatManagement ofNewEraElectronic Systems (GMRT)

Author(s): Irappa Halagali1

Co-author(s): Ajith Kumar B. 2 ; Yashwant Gupta 2

1 GMRT, NCRA-TIFR2 NCRA - TIFR


Modern Engineering Trends in Astronomy – 2019Sunday 15 September 2019 - Tuesday 17 September 2019, Bengaluru

Authors : Mr. Irappa M. Halagali, [email protected] , Mr. Ajith Kumar B. , [email protected], andProf. Yashwant Gupta, [email protected]

Abstract for Poster :

“Heat and Power Management of new era Electronic Systems”

With the developments in Electronics device technology and software based modern design tools, signal processing systems are becoming compact and powerful. These developments alongwith the advent of high speed computers and software based signal processing, the per cubic feet power consumption and heat generation in modern signal processing systems has thrown up new challenges to designers. Dissipating the generated heat, needs special efforts and planning to continue to use the systems with their maximum capacity. Accomodating multiple systems in a small room makes it necessary to use the specially designed electronic cabinets with suitable arrangements for signal, power distribution while allowing free flow of cold air to take away the generated heat within the units.

During the development of the upgraded GMRT Backend systems, we also faced the task of sup-porting continued observations using the legacy backend systems and develop and install the newsystems without affecting the old receivers. It is also challenging to meet the electric power re-quirements of these systems in safe, secure and disciplined way. In the GMRT receivers sytem, thelegacy 32MHz bandwidth digital backend and the new 400 Mhz digital backend consume about 15KWatts of power each generating a heat of 4,30,000 calories/minute. We have modified the stan-dard 19” racks to make them suitable for handling this heat generated within the racks. We havedeveloped a cost effective solution to provide a cool air supply through the circuits and maintain thetemperature.

Here we present the details of the system developed, analysis and test results. As part of this activityan automatic calculator is also developed to calculate the heat genetated in calories/minute and theamount of cooling needed to maintain the temperature.

40

Prototype for raw voltage recording in the backend system of theupgraded GMRT

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Shelton GnanarajNone ; Mekhala Muley1 ; Suda Harshavardhan Reddy2 ; Sandeep Chaudhari3 ; Ajithkumar B4 ;Yashwant Gupta5

1 GMRT-NCRA-TIFR2 GMRT - NCRA - TIFR3 GMRT-NCRA,TIFR4 NCRA-GMRT5 NCRA - TIFR

CorrespondingAuthor(s): [email protected], [email protected], [email protected], [email protected],[email protected], [email protected]

Abstract for META2019

Poster Title : Prototype for raw voltage recording in the backend system of the upgraded GMRT

Author list : Shelton Gnanaraj, Mekhala Muley, Harshavardhan Reddy Suda, Sandeep Chaudhari,Sanjay Kudale, Irappa Halagalli, B. Ajith Kumar, Yashwant Gupta.

The GMRT Wideband Backend (GWB) combines the Baseband signals of all antennas and gives out the visibilities in each of the baselines. The Baseband signals are digitized and coarse correction of geometric and astronomical delays is performed before converting the time domain

continuous samples into frequency domain. In the frequency domain, the fine delays are compen-sated by proportionate phase rotation and the signals in each baseline are multiplied and then accu-mulated. The resulting visibility spectrum is stored for offline processing. The hardware of the GWBconsists of FPGAs, CPUs and GPUs. This hardware has been frozen as per the observatory require-ments. Due to hardware limitations the digitized data needs to be accumulated before storing themon the Hard Disk Drives and cannot be processed directly in real time. The raw voltages if recordedwill give astronomers the flexibility to analyze the data using their own algorithm/software. Thiswill also lead to the development of new observatory modes which require raw voltages for dataanalysis.The final aim of this project is to record the raw voltages from the antenna which is sampled atNyquist rate on the Hard drives installed on a computer. The writing speed of the disks is the majorbottleneck in the data recording. Hence as a precursor to the raw voltage recording project it is es-sential to find the maximum speed at which the data can be written on the Hard drives of a computerand enhance the data recording speed if needed. In addition to the writing speed of the Hard drivesa huge volume of the data has to be recorded on the drives.As a prototype of the raw voltage system a RAID0 of the hard drives is done on a server to over-come the problems of speed and volume limitations of Hard Disk Drives. RAID0 is a technologythat is used to increase the performance and/or quantity of data storage. The abbreviation standsfor Redundant Array of Inexpensive Disks. A RAID system consists of two or more drives workingin parallel.Upcoming technologies such as the NVMe SSDs are also being explored which increase the writingspeed upto 35 times as that of the standard Hard drives.The poster presentation explains the setup of the prototype system and shows the test results of thesystem. It explains the methodology used to show that all the packets coming from the network tothe node is written on the hard disk drive without any data loss. Upcoming technologies in the fieldof data storage are also discussed in the poster.


RASCAL (ReflectorAntenna SensitivityCalculator) SoftwareAuthor(s): Sougata Chatterjee1

Co-author(s): s suresh kumar 1

1 GMRT-NCRA-TIFR


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G/Tsys defines the sensitivity of a radio telescope and is an important figure of merit. It is importantto know the overall antenna efficiency and system noise temperature of the telescope in order tocalculate the G/Tsys. In order to calculate the G/Tsys for uGMRT bands, a Software was developedin-house at GMRT-NCRA, named as RASCAL (Reflective Antenna Sensitivity CALculator).This paper presents the G/Tsys calculation of any single-dish radio telescope (Prime Focus feed/Cassegrain Feed) using it is a software and can be used for any other Reflector antenna. Some basicinputs like primary Dish dimensions (F/D, Dish diameters, angle of quadruped, feed house area, etc),Radiation pattern of the feed, LNA noise temperature and receiver losses are required to computeantenna overall efficiency, system noise temperature and finally G/Tsys and secondary Radiationpattern of single dish. The program was also used to calculate the G/Tsys of other radio telescopesin order to cross verify the results and the results were found to match closely.


RF over fibre optic backplane for phased array antennasSanjeet Kumar Rai1 ; Sureshkumar S.1 ; Pravin Raybole1

1 NCRA TIFR


RFoF technology enables a path for low loss signal transmission over longer distances, carry hugebandwidth of data, and is also immune to electrical noise. The paper discusses the technology, design,and methods for implementing it for phased array antennas application. The RFoF backplane isvery much compact and suitable for phased array antennas, these replace the need for bulky RFcables, which is capable of carrying the output of the only single element. MPO (multi-fiber push-on) developed to provide multi-fiber connectivity in one connector to support higher bandwidth andhigher density applications. The purpose of the project is to design RF over fiber-optic backplanefor the focal plane array, it consists of 144 Vivaldi antenna elements with frontend electronics (LNA)behind it. The low cost, high dynamic range signal transport system is designed and implementedwith multi-fiber push on technology. The laser transmitter section is directly connected to the RFoutput of elements, so this is made very lighter in weight keeping the overall weight of feed to beminimum, making it suitable to be mounted over the prime focus of dish antenna. The designedsystem supports the frequency range from 500 to 2000 MHz and has an optical budget of 8 dB whichwill support an additional distance of 32 km at 1310 nm wavelength.

25

Radio Frequency Interference and itsmitigation at upgradedGMRT

Sureshkumar S1

1 NCRA-TIFR Pune


Giant Meterwave Radio Telescope (GMRT) is an array telescope of 30 antennas each of 45 meter in di-ameter located at Khodad, Pune. The upgraded GMRT have a seamless coverage over the frequencyband ( 120 MHz – 1450 MHz ) with high dynamic radio receivers. The Radio frequency interfer-ence to a radio telescope is a permanent threat and needs continuous monitoring and mitigation toprotect the operation of radio telescope. Intentional transmissions like mobile communication, TVtransmission, wireless service, Air traffic control signals, FM radio stations, satellite services andun-intentional radio interference from power lines, CATV, Industries, Wind power generating sta-tions, computers, computer network components, UPS, SMPS, AC units, Lights etc. are the common

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sources of radio interference to a Radio Telescope. This paper presents RFI monitoring, characteriza-tion of various types of RFI, RFI shielding solutions and various other mitigation techniques adoptedat upgraded GMRT for the control of radio frequency interference and maintain a RFI free ambience.References:1. Swarup, G. et al., The Giant Metrewave Radio Telescope. Curr. Sci., 1991, 60, 95–105. 2.2. Yashwant Gupta, et al., The upgraded GMRT: Opening new windows on the radio Universe. Curr.Sci., 113(4):707-714 · January 2017.3. Pravin Ashok Raybole and S.Sureshkumar, “ External sources of RFI at the GMRT: Methods forcontrol and coexistence with commercial users” in Proceedings of Science 2010,4. Pravin Ashok Raybole, S.Sureshkumar, SantajiKatore and SanjeetRai,“Real time prediction, detec-tion and co-existing with satellite interference at GMRT” RFI2016, Socorro, New Mexico.5. S.Sureshkumar, Pravin Ashok Raybole, Sanjeet Rai and Ankur,” RFI characterisation and mitiga-tion at upgraded” IEEE Xplore

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Radio telescope observationplanningusingmachine learning tech-niquesShashank S Bhat1 ; Prabu T2

1 PES University2 Raman Research Institute


Low frequency radio telescope observations suffer from time varying interference from the neigh-borhood. We plan to extract radio spectrum features through a statistical analysis and develop ma-chine learning techniques to make predictions about available good-band regions for an observationschedule. We consider routine monitoring of signals across a broadband and use noise characteristicanalysis to classify and rank the frequency bands. The results will be stored in a database and oncea sufficient data set is available, we will explore possibilities of feeding the data through a layers ofdimensional analysis and clustering algorithms to classify and predict the probability of a selectedband being a good choice for a radio astronomy observation that is scheduled in a near future. This isan on going work, and we will present the details and current status of this work in a poster.

12

Recent and Future development of Far Infra-Red (FIR) Balloonborne experiment.Pradeep Sandimani1

1 TIFR


T100 is a TIFR 100 cm balloon borne telescope which is used for the FIR observation with the JapaneseFabry Perot Spectrometer (FPS) as a focal plane instrument. FPS is tuned to the [CII] line at ~158micron to study Galactic star forming regions. T100 along with FPS is being flown regularly fromTIFR Balloon Facility, Hyderabad. The FPS consists of two Fabry Perot Interferometer, one withmovable plates to scan the wavelength and the other with fixed plates which acts as an order sorter.FPS is operated in two primary modes as chopped and unchopped modes. In the chopped mode,secondary mirror of the T100 telescope wobbles at the 10 Hz in two different positions such thatin one position, telescope is focused on the region of interest and in the other position, telescope ispointed to the blank sky. This helps us to subtract the background emission and to get meaningfulresults. In the unchopped mode, background subtraction is done separately without wobbling the

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secondary mirror. Telemetry and Tele-command systems are currently in the process of upgradation,as the existing hardware is quite old and needs modifications. We designed and developed a micro-controller based encoders which can be interfaced with the windows OS. We developed a softwarein LabVIEW to receive the telemetry data over the Ethernet (as UDP packets) and plot them asper our requirements. We have also developed an onboard telemetry data storage module usingthe single board computer which is under test. We have also developed an offline telemetry dataanalysis software in the LabVIEW which operates in the file I/O mode. This helps us to understandthe telemetry data using a standalone computer or laptop, without using the bulky data playbacksystem at the balloon facility at Hyderabad. The present single pixel FPS focal plane instrument isplanned to be upgraded to 5x5 FPS array, which would improve resolution of image from 90” to 40“.This would need change in the Telemetry data rate, frame formats, command rate and commandformat, data analysis software etc. These changes will be done on both the onboard and groundbased systems.

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Reducing effects of cross talk in a Radio Telescope using WalshmodulationPrakash Hande1 ; Sweta Gupta1 ; Abhijeet Dhende1

1 GMRT-NCRA,TIFR

Corresponding Author(s): [email protected], [email protected], [email protected],[email protected]

Authors: Shri. Sandeep Chaudhari, Shri. Prakash Hande, Mrs. Sweta Gupta, Shri. Navnath Shinde,Shri. Abhijeet Dhende, Shri. S. Harshavardhan Reddy, Shri. Ajay Vishwakarma, Shri. Ajith Kumar,Prof. Yashwant Gupta

The signal flow chain of a typical radio telescope receiver consists of various sub-systems viz. feeds,front-end electronics, signal conditioning circuits, signal transportation to central station, basebandconversion circuits, and digital back-end receivers. There are strong possibilities of spurious cou-pling of signals from one to the other signal chains at various locations. Since a radio telescope is avery sensitive instrument, such cross talk can seriously affect its usefulness and capabilities. A suit-able method for reducing the effect of such cross talk is Walsh modulation and demodulation scheme.The suggested scheme utilizes phase modulation of the received signals using ortho-normal patternsat the front-end receiver of the antenna, and demodulating them just before combining the signalsfrom antennas in the digital back-end. It is very important to match and align the modulating anddemodulating patterns, else this can lead to loss of coherence of the desired signal. This poster de-scribes the scheme proposed for the upgraded GMRT receivers that are currently under installation.We also present the tests carried out and the results obtained.

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Registration opens and breakfast

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Sky Watch Array Network (SWAN) : Wide-band Receiver Instru-mentation development and Current StatusRaghavendra Rao K.B1 ; Srivani K S1 ; Kamini P.A.1 ; Sandhya1 ; Arasi Sathyamurthy1 ; Nagaraja H N1 ; Avinash A.Deshpande1

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The Indian SWAN (Sky Watch Array Network) initiative aims to significantly enhance Indian ob-serving capabilities in radio, and importantly, also to sustainably build & nurture future genera-tions of talented radio astronomers in India to take up the challenges and lead in exciting researchin astronomy. The SWAN focus is to design, develop and use a wide-band interferometric arrayof antenna across different parts of India to facilitate and conduct deep searches & studies of fastand slow transient radio radiation from astronomical sources, also enabling high angular resolution(VLBI) imaging of discrete galactic & extragalactic sources at low radio frequencies. It also facili-tates hands-on experience to a large number of undergraduate/postgraduate students through theirdirect & active participation, starting from the design stage to competitive research using the arraynetwork. The proposed competitive network, with nominally 1000 sq. m array area at each locationand operation spanning a decade in frequency (50-500 MHz), is being developed in three phases. Asa proof-of-concept/demonstrator setup, a 7-station narrow-band system, using small tiles (based onMWA design) and receiver hardware from RRI-GBT Multiband system, is successfully configuredand tested in array mode. In addition to the above, a broad-band receiver system capable of simulta-neously catering to eight input signals (each of width 175 MHz) is being developed to operate in thefrequency range 50MHz – 400MHz, having low noise amplifiers with FM band rejection, high-gainamplifier modules, a set of band shaping microstrip based filters, as well as a high-speed ADC andVirtex-6 FPGA based digital back-end receiver. The evaluation of this system in the laboratory is inprogress.

In this talk, we discuss the technical aspects related to the design, development, and the laboratorytest results obtained from the broad-band RF receiver system.

6

Study of Alignment Sensitivity of TMTPrimaryMirror Segmentson ImageQualityVarun Prakash P1 ; Vineeth Valsan2 ; Annie Rose1 ; Athul kurian 1

1 Christ University2 Christ Uinversity

CorrespondingAuthor(s): [email protected], [email protected], [email protected],[email protected]

TMT is a ground-based optical/infrared telescope. The telescope utilizes a Ritchey-Chrétien opticaldesign with 30-meter hyperboloid f/1 primary mirror. As it is difficult to make a monolithic mirrorof such dimension the primary mirror is subdivided into 492 hexagonal segments each having a di-ameter of 1.44 meter from edge to edge. The primary mirror is having 6-fold symmetry and hencethey are divided into 6 sectors. Each mirror segment is supported by segment support assembly con-sisting of 3 actuator and 12 capacitive edge sensor which controls the relative segment position. Anymisalignment of these segments from their mean position causes a deviation from near diffractionlimited performance. The algorithms for aligning and phasing these segments is similar to that ofKeck primary mirror algorithms with few modifications. Keck is a 10-meter class telescopes with 36hexagonal segments with 492 segments TMT algorithm has to process large amounts of data. An at-tempt was done in the present work to simulate the sample of TMT model using Python and therebydetermining the PSSN (Normalized Point Source Sensitivity) for different segment perturbation, fur-ther clustering these values for creating a database for better error analysis using neural networkalgorithm.

10

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Study of performance of segment support assembly forNLOT/MSEprimary mirror segmentsAuthor(s): SANDEEP D S1

Co-author(s): NAGABHUSHANA S 1 ; SRIRAM S 1

1 IIA, BENGALURU


Abstract:To keep in pace with the emerging trends in scientific research and cater to the need of growingIndian astronomical community, a need is strongly felt for realising an 8-10 meter class optical tele-scope in India. Construction of such a large size optical telescope is possible only when the primarymirror is made of large number of small mirror segments. In segmented mirror technology, smallermirror segments are aligned with respect to each other to match with the ROC so that it acts like asingle, monolithic large aperture telescope.Before embarking on such a large and expensive segmented mirror telescope project, we tried themechanical design adaptability of already existing similar class telescope’s segment support assem-bly (SSA) whose primary mirror segments size remains same but of varying ROC. Finite elementanalysis is carried out for the primary mirror segments of similar size but of varying ROC supportedwith identical SSA with similar loading and boundary conditions to compare the structural and ther-mal analysis results to verify the deviation in results among them and to check whether the sameexisting SSA could be used to support NLOT/MSE primary mirror array with minimal design modi-fications and tweaking the actuator mechanism.Detailed structural and thermal analysis has been carried out for the primary mirror segments arraysupported with SSA at various levels to evaluate the stresses, deformation, stiffness/natural frequen-cies, reaction forces and moments due to gravity, wind load and temperature variations for static,dynamic and transient cases. Some details of these analysis are presented in this paper.(Abstract sent for oral presentation at META 2019)

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TELESCOPE AUTOMATION AND CONTROLMUKESH JAISWAR1 ; HEENA ASLAM2

1 ENGINEER C, ARIES,Nainital2 ZHCET,ALIGARH MUSLIM UNIVERSITY…………(ARIES INTERN)


1.04M aperture optical telescope named as Sampurnanand has been installed as the one of the mainobserving facility in optical domain at, Aryabhatta Research Institute of Observational SciencesManora Peak, Nainital. The 104-cm, f/13 telescope produce a field of around 45 arcmin with correc-tor at the cassegrain end. the total research output of the 104cm Sampurnanand Telescope reachesnearly 364 scientific publications in different refereed journals and 45 PhD Thesis. The telescope iscovered by a spherical dome with a slit opening for observation. The dome and the telescope arerotated and moved accordingly in order to take observations. This paper presents the work on thecontrol system and movement control of the telescope using PIC18F4431 microcontroller of 8051family along with Gurley Models A19 Absolute Rotary Encoder which had resolution up to 18 bitand gave an SSI output.The code was compiled and run using ICD-3 debugger and MPLABX IDE v5.25 and xc8 compiler.A pair of SPDT relay’s was used to change the direction of a DC motor.Theraw data as acquiredfrom the data acquisition software is transfered to the another PC meant for archiving the 40-inchdata. Transfer is done through ftp or windows PC sharing facility. It’s faster and more accuratethan any resolver-based system. This paper presents the use of mentioned electronic componentsto control Sampurnanand Optical Telescope, ARIES, Nainital.

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Testing a Multi-element, Multi-beam, FPA Beamformer in Free-space Test RangeBela Dixit1 ; Kaushal Buch1 ; Ajith Kumar B.1 ; Rahul Aragade1 ; Sudhir Phakatkar1 ; Jayaram Chengalur1

1 GMRT, NCRA-TIFR


The Expanded GMRT (eGMRT) is a proposal to look at three expansions to theGMRT - increasing the field of view, increasing angular resolution andimproving the sensitivity to the extended radio emission. In this talk, wewould focus on the testing of multi-element, multi-beam beamformer usingthe144-element Focal Plane Array (FPA) procured from ASTRON.The preliminary tests for the beamformer are being carried out with FPA asanaperture array. A free-space test range, meeting the far-fieldrequirements atL-band, has been developed at the GMRT site. The narrow beamwidthtransmittingantenna (a 3m diameter parabolic dish and a cross-dipole feed at theprime-focus) required for beampattern measurement and beamsteeringexperiments was fabricated at NCRA. Beamsteering measurements have beencarried out by radiating continuous wave and broadband noise in this testrange. Tests have also been carried out to observe navigational satellitesin the L-band with the transmitting antenna used for “phasing” the array.The test methodology, details of the experiments and the results would bedescribed. The test results from the beamsteering experiments show a closematch with the theoretically expected outcome. The entire process oftesting from setup to data acquisition and analysis is automated to allowfor a speedy understanding of the data and efficient debugging.Currently, we are working to test multiple beams in the field-of-view (FoV)by applying optimal beamforming weights.


The 3.6 m DOT electronics: Maintenance and future upgradationstrategiesAuthor(s): Kumar T. S.1

Co-author(s): Shobhit Yadava 1 ; Brijesh Kumar 1 ; Wahab Uddin 1

1 ARIES


We describe here the electronics aspects of the 3.6 m Devasthal Optical Telescope (DOT) and discussthe strategic approach adopted by the ARIES electronics engineering team for maintaining and up-grading the telescope. The construction of the 3.6 m DOT was completed at the AMOS Factory inBelgium in the year 2012 and the telescope was partially disassembled into its sub-systems and trans-ported to ARIES Devasthal site and reassembled and commissioned in 2016. The critical electronicparts of the telescope consist of both the customized systems like local realtime control computersrunning customized software for controlling the active optics enabled primary and secondary mirrorsupport systems, wavefront sensor, azimuth and altitude motors and the standard industrial compo-nents like Delta Tau motion controllers, B&R programmable logic controllers, Kollmorgen and LTI

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drives, Kollmorgen motors and Heidenhain and Renishaw encoders. The control components areprogrammed and interfaced to implement suitable control law to deliver the stringent performances.Owing to large size of the telescope the control components are distributed over different realtimenetwork. Additionally, these components require constant monitoring, preventive and scheduledmaintenance and upgradation for their smooth and reliable functioning.

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The Infrared Astronomy Group (IR group) of TIFR, Milind Naik

Milind Naik1

1 TIFR


The Infrared Astronomy Group (IR group) of TIFR has been developing near-infrared (NIR) instru-ments for ground based Indian telescopes, far-infrared instruments for TIFR 100-cm balloon bornetelescope and has recently developed space platforms via IRSIS & other projects. Thistalk will present an overview of NIR astronomical cameras developed by the IR group which havebeen commissioned / used at various observatoriesin India (e.g. IGO, IUCAA,Pune; MIRO, PRL, Mt Abu; HCT, IIA, Hanle, Ladakh and DOT, ARIES,Devasthal, Uttarakhand). TANSPECOptical-NIR spectrograph is recently (April 2019) installed and commissioned at DOT 3.6 meter tele-scope. TIRSPEC NIR imager and spectrometer was commissioned at 2 meter HCT, Hanle in 2014andis currently being used for science observations. TIRCAM2 NIR imager has been used at MIRO,IGO and is currently installed at the side port of DOT 3.6 meter telescope. Talk will also cover abriefoverview of the IRSIS related work.

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Title: Reliability Study of GMRT Analog Backend Receiver Sys-temSudhir Phakatkar 1

1 GMRT Khodad


Abstract: Reliability means the probability of the system to perform a required function withoutfailure under stated conditions for a stated period of time. Reliability study is essential for electronicsystems. Hence, this study is applicable to a radio telescope receiver. Giant Metrewave Radio Tele-scope’s (GMRT) receiver system consists front end (FE), antenna base receiver (ABR), baseband (BB)and Digital. Also, systems peripheral to the receiver systems are servo, feed positioning, teleme-try systems. All these systems are design-wise identical across 30 antennas. ABR and BB systemsinclude local as well as master oscillator systems. These systems have control and monitoring elec-tronics as well. Several types of units i.e. amplifier, oscillator, filter, mixer, switch, attenuation,power supplies form an interconnection. Such multiple active-passive devices and components areconnected through RF cables and connectors. Hence the receiver system assembly becomes diverseand complex and hence understanding its reliability becomes crucial.

GMRT, as part of its day-to-day operation, is keeping a record of functional performance of all sys-tems through a callsheet database. Using the data from the same, reliability performance is studied

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of old (32MHz) and new (400 MHz) Analog back end systems. Studying mean time between fail-ures over a certain duration and plotting performance with respect to time, prediction of qualityperformance is done for GMRT Analog back end receiver systems.

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Towards an Optimal Real-time Broadband RFI Filter for the Up-graded GMRTKaushal Buch1 ; Ruta Kale1 ; Mekhala Muley1 ; Sanjay Kudale1 ; Ajith Kumar B.1

1 GMRT,NCRA-TIFR

Corresponding Author(s): [email protected], [email protected], [email protected], [email protected], [email protected]

Broadband Radio Frequency Interference (RFI) is one of the main reasons for corruption of astronom-ical data observed using the Upgraded GMRT (uGMRT) at frequencies below 700 MHz. A real-timeRFI excision system, operating on Nyquist-sampled digital time-series per antenna and polarization,has been implemented as part of the GMRT Wideband Backend (GWB). The system, implemented onFPGA, computes robust standard deviation and detection threshold using Median-of-MAD (MoM) es-timator. The RFI samples are replaced by digital noise samples. We describe the techniques for simul-taneous acquisition of data with and without the filter for the interferometer and beamformer modesof uGMRT and present results from the tests. We show the effect of filtering on the signal-to-noiseratio, cross-correlation function and closure phase for the interferometric data. The system-levelaspects and the tests carried out to fine-tune the filtering parameters would be described.

To understand the filtering performance on imaging, we carried out test observations on calibratorradio sources and extended sources from June 2018 to August 2019. Typically 1 − 5% of the samples(at 2.5ns time resolution) are found to be affected by broadband RFI filter during monsoon when thebroadband RFI is stronger. Our offline data processing pipeline used for imaging utilizes the Com-mon Astronomy Software Applications (CASA) software tasks customized for use with the uGMRTdata. The spatial cross-correlation spectrum (visibilities) at short baselines show significant improve-ment in the form of the reduced standard deviation on the visibilities by factors of two or more andconsequently improved image fidelity. We have also quantified the decorrelation introduced in thedata due to the digital noise replacement. We are currently testing a strategy for optimizing the filterbased on the engineering and imaging test results. The online RFI filtering system is planned to bereleased for the users of the uGMRT.

84

Ultra-PrecisionEngineering-Enablinghuman’s fundamental questto decode the COSMOS - Sendhil Raja S. Ph.D., RRCAT

114

Visit to JCBT,40” & 30” Telescopes

110

Visit to VBO (Starting Point: IIA, Koramangala)

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112

Visit to VBT (90”)

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Welcoming Remarks -Director, IIA, Bengaluru

Welcome Remarks -Director, IIA, Bengaluru

81

“Accelerated Tile Processor”- Prabu T, RRI

91

“Adaptive Optics Program at IIA”- Dr.Sridharan Rengaswamy,IIA,Bengaluru

107

“An overview of Analog Receiver System for Detection of GlobalEoR Signal” - Somashekar R, RRI

100

“Antenna and RF”-Abdipour

94

“Conceptual Design of Primary Mirror Cover for the proposed2m classNational Large Solar Telescope”- Mr. Govinda K.V. IIA,Bengaluru

77

“Design and Development of Telescope Cover Structure for 3.6mTelescope at ARIES”– Dr.Tarun Bangia, ARIES

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76

“Design and Development of stress relieving support system forTMT primary glass blanks”-Mr. Alikhan Basheer, IIA, Bengaluru

75

“Design and development ofmechanical systems of SUIT Payloadonboard Aditya-L1”-Mr. Akshay Kulkarni, IUCAA

103

“Design of Drive Circuit for piezo walker for configurable slitunit”- Mr Pankaj Madhwani, TIFR, Mumbai

105

“Developmental status of X-ray polarization sensitive mirrors”-Mr Panini Singam, IIA, Bengaluru

102

“Dual polarized broadband dipole antenna feed with conical re-flector for uGMRT”-Mr Hanumanth Rao Bandari, TIFR

73

“Engineering challenges in realization of Visible Emission LineCoronagraphon-boardAditya-L1”-Mr. SubramanyaNagabhushanaIIA,Bengaluru

104

“Evolution ofGMRTServoComputerwithRTAI: Status andUpdates”-Mr.ThiyagarajanBeeman,Mr.ShailendraBagde, GMRT,TIFR.

93

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“FE analysis for themechanical structure of Prototype SegmentedMirror Telescope”- MrSandeep D.S.IIA, Bengaluru

92

“FE analysis for themechanical structure of Prototype SegmentedMirror Telescope”- MrSandeep D.S.IIA, Bengaluru

90

“INSIST: A Proposed Wide-Field, UV-Optical, Imaging and Spec-troscopicSpace Telescope”-Mr.Sriram Sripadmanaban, IIA, Ben-galuru

64

“India and SquareKilometreArray”-Y.Gupta, CentreDirector,NCRA

“Square Kilometre Array”-Y. Gupta, Centre Director,NCRA

66

“India’s contribution to TMT hardware”-N Viswanatha, FormerGD, ISRO & Consultant TMT Project, IIA, Bengaluru

71

“Lowcost - 21cmobservation on Sun fromKodaikanal SolarObservatory”-Mr. Manickavasagam G (SBM college of Engg. and Technology,Dindigul)

69

“Low cost Characterisation of Sun and Nadir Sensors for AttitudeControl of Nano Satellites”- Mr. Asir Nesa Dass N, IIST

108

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“Non-spherical representation of optical surfaces - an advancedstudy”- Mr Totan Chand, IIA, Bengaluru

99

“RASCAL (Reflector Antenna Sensitivity Calculator) Software”-Mr. Sougata Chatterjee,GMRT-NCRA-TIFR

98

“RFoverfibre optic backplane for phased array antennas”-Mr.SanjeetKumar Rai ,NCRA TIFR

79

“Radio Frequency Interference and itsmitigation at upgradedGMRT”-Mr.Sureshkumar S. , NCRA-TIFR Pune

21

“Single Antenna Receiver Design for Radio Astronomy”Sweta Gupta1 ; Mekhala Muley1 ; Sandeep Chaudhari1 ; Irappa Halagali1 ; Abhijeet Dhende1

1 GMRT-NCRA-TIFR

CorrespondingAuthor(s): [email protected], [email protected], [email protected], [email protected],[email protected]

Authors: Shri. Sandeep Chaudhari, Mrs. Mekhala Muley, Mrs. Sweta Gupta, Shri. Irappa Halagali,Shri. Navnath Shinde, Shri. Abhijeet Dhende, Shri. Ajith Kumar, Prof. Bhalchandra Joshi, Prof.Jayaram Chengalur, Prof. Yashwant GuptaThe single dish telescope is a basic building element of radio astronomy that can be used for tryingnew concepts like FPA (Focal Plane Array), Pulsar & VLBI experiments and by enthusiastic studentsto get hands on experience. The single dish telescope receiver chain consists of various sub-systemsviz. feeds, front-end electronics, signal transportation system, analog back-end system (signal con-ditioning circuits, down conversion circuits) and digital back-end. The front-end system may differin frequency of operation viz. L-band, X-band, S-band. The back-end system consists of analog back-end and digital back-end. The analog back-end is a dual polarization system with frequency downconversion, bandwidth selection and gain adjustment features. The digital back-end system is usedas a spectrometer and for pulsar & VLBI observations. Remote radio quiet zone is chosen for an-tenna site and unlike in array of telescopes operation of all antennas can simultaneously controlled& monitored from center station, single dish telescope control is at antenna site. Hence reliability isimportant due to remote location and manpower availability.The single dish receiver system can be used on full time basis in existing antennas viz. 15m NCRAcampus and possibly with unused/experimental communication dish in various organizations. Thesystem can be a piggy back on partially used antennas. We are in search of and in talk with someorganizations to revamp their telescope back-end. The receiver setup can be used by any universitiesin their campus all over country and will be in public domain for encouraging it’s use.The receiver systems for 15m dish at NCRA operates at L-band and going with other telescopes willgive access to extended frequency range and will be useful to get experience to build back-ends for

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them. The 15m dish receiver system has real time spectrometer and 10Gbe raw voltage recordingfacility for offline analysis. Various features and modes of back-end system and test results will beillustrated in the poster presentation.

70

“Sky Watch Array Network (SWAN): Wide-band Receiver Instru-mentation development and Current Status”- Mr. RaghavendraRao K.B, RRI

86

“Software for the Thirty Meter Telescope”- Prof. Annapurni Sub-ramaniyam, IIA, Bengaluru

96

“Telescope Control Software and Communication server for 30inch Telescope, VBO - an Overview / Software aspects of 2.4 Mmirror coating plant, VBO”- V Arumugam,Engineer-E,IIA, Ben-galuru

80

“Testing aMulti-element,Multi-beam, FPABeamformer in FreespaceTest Range”- Ms Bela Dixit, GMRT, NCRA-TIFR

97

“The 3.6mDOT electronics: Maintenance and future upgradationstrategies”- Dr Kumar T. S. ARIES

88

“VELCpayload onADITYA-L1” –Prof.B.R.Prasad, PIVELCADITYAL1,IIA, Bengaluru

87

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“VELCpayload onADITYA-L1” –Prof.B.R.Prasad, PIVELCADITYAL1,IIA, Bengaluru

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