rfi analysis and instrumentation viva 2010

8/9/2019 RFI Analysis and Instrumentation VIVA 2010

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OBJECTIVEOBJECTIVETo identify and quantify the RFI in INSTUNTo identify and quantify the RFI in INSTUN

RFI survey data help to locate the radioRFI survey data help to locate the radiotelescope UMRT IItelescope UMRT II

Importance to study RFI to make sure bckgrndImportance to study RFI to make sure bckgrndnoise are low coz cosmic ray radio wavesnoise are low coz cosmic ray radio waves

extremely weakextremely weak

To study the spectra cyber and the correlator for To study the spectra cyber and the correlator for interferometeryinterferometery ± ±superheterodyne receiver superheterodyne receiver conceptconcept



The pioneer of radio astronomyThe pioneer of radio astronomy ± ± Karl JanskyKarl Jansky

1 Jy1 Jy || 1010 --2626 W/mW/m 22HzHz 11

± ± The jansky is a measure of The jansky is a measure of spectral power spectral power flux density flux density² ² the amount of RF energy per the amount of RF energy per unit time per unit area per unit bandwidthunit time per unit area per unit bandwidth



RFI is undesired radio signal that interferes thatRFI is undesired radio signal that interferes thatcause extraneous signal or noise.cause extraneous signal or noise.Importance to study the RFI migitation .Importance to study the RFI migitation .

Conductivity

Radiation



Radio Frequency InterferenceRadio Frequency Interference

widebandwidebandnarrowbandnarrowband

Why taking 24hours reading?Why taking 24hours reading?Why 1420MHz in hydrogen line?Why 1420MHz in hydrogen line?

Hydrogen clouds at 1420.405 MHz, using a2.3m dish antenna,will be able to resolve multiple clouds.



RFI setupRFI setup

Discone antenna

1420MHz LNA

Spectrum

analyzer Computer totransfer data

BELDEN 9913

In general, the HIGHER theIn general, the HIGHER thefrequency/number of waves, thefrequency/number of waves, theGREATER the energy of the radiation.GREATER the energy of the radiation.

In other words, the shorter the wave,In other words, the shorter the wave,the higher the energy.the higher the energy.



R F I P rofile by us ing omnidirec tional antenna v sdis c one antenna(INS TUN)

200 400 600 800 1000 1200 1400 1600 1800 2000

F requency (MHz)

D i s c o n e

Antenna

O m n i

Antenna



RFI PROFILE FOR 0RFI PROFILE FOR 0- -2800MHz at INSTUN2800MHz at INSTUN

Perak FM(97.50 MHz)325.48 V

Government Use(392.50MHz)288.40 V

FM radiobroadcasting(945.00MHz)405.249 V

Mobile satellites

service(1520.00 MHz)166.73 V

Radio Navigationsatellites

(1595.00MHz)301.12 V

Government Use(1892.50MHz)

284.13 V

Fixed Mobileradiolocation

(2467.50MHz)160.43 V



F requency(MHz)

RFI

Level(dBm)

RFI

Level(µV)

Source(s) Comment(s)

A 97.50 -56.7494 325.4826 F ixed MobileBroadcasting

Perak F M

B 392.50 -57.8 288.4032 Mobile Exclusive for Malaysian

Governmentuse

C 945.00 -54.8456 405.2493 MobileSatellite,Broadcasting

F M radiobroadcasting

D 1520.00 -62.5594 166.7354 Mobile Satellite Service(Space To Earth)

E 1595.00 -57.425 301.1272 AeronauticalRadionavigation,

Radionavigation Satellite

Possibleneighbouring

radionavigationsatellite

F 1892.50 -57.9294 284.137 F ixed Mobile Transmission fromaircraft station,

MalaysianGovernment

use

G 2467.50 -62.8939 160.4374 F ixed MobileRadiolocation



INSTUN SurroundingINSTUN Surrounding



RFI PROFILE FOR 0RFI PROFILE FOR 0- -2800MHz at LNO2800MHz at LNO

Mobile phone(930.0MHz)5.134 V

Broadcasting(950.0MHz)11.918 V

Aeronauticalnavigation

(1012.5MHz)2.795 V

GSM DIGI(1860.0MHz)

3.738 VMobile Satellite

(1520.0MHz)2.667 V



F requency(MHz)

RFI Level(dBm)

R FI Level(µV)

Source(s) Comment(s)

A 930.0 -92.791 5.134 Mobile,Broadcasting,Radiolocation

Mobile phoneCelcom,Maxis,Digi (890-935MHz)

B 950.0 -85.476 11.918 Mobile,Broadcasting,Radiolocation

C 1012.5 -98.073 2.795 AeronauticalRadionavigation

D 1520.0 -98.480 2.667 Mobile, MobileSatellite (Spaceto Earth)

E 1860.0 -95.547 3.738 Mobile Mobile-GSM Digi(1855-1872.5MHz)



Langkawi SurroundingLangkawi Surrounding



RFI profile from 0MHz to 2800MHz at UM

0

50

100

150

200

250

300

350

400

450

0 500 1000 1500 2000 2500

Frequency(MHz)

S i g n a l s t r e n g

t h d B ( W

. m - 2 . H z - 1 )



Pu r Pa r as RFI di INSTUN dan Unive r siti Malaya

0

50

100

150

200

250

300

350

400

450

0 500 1000 1500 2000 2500 3000

UM

INSTUN



Why Use Radio Telescopes?Why Use Radio Telescopes?

Why use radio telescope?

Can be doneat day and

night.



The Receiver The Receiver

The Spectra Cyber The Spectra Cyber ± ± Radio Continuum and Spectral LineRadio Continuum and Spectral Line

Receeiver Receeiver

Superheterodyne receiver conceptSuperheterodyne receiver concept--measure spectral power densitymeasure spectral power density



Small Radio TelescopeSmall Radio Telescope

Using the small radioUsing the small radiotelescope, continuumtelescope, continuum

measurements weremeasurements weretaken in the defaulttaken in the defaultfrequency of 1420frequency of 1420MHz.MHz.

A 25 A 25--point grid scanpoint grid scanwas used to obtain thewas used to obtain theraster map.raster map.



Images of the SunImages of the Sun

Raster map imaged by the small radio telescopeSOHO Extreme Ultraviolet image takenJuly 24, 2006



COMPARISONCOMPARISONSINGLE DISH & INTERFEROMETRYSINGLE DISH & INTERFEROMETRY

SRT (single dish)SRT (single dish) SRT (interferometer)SRT (interferometer)

High RFIHigh RFIHigh SensitivityHigh Sensitivity

Low costLow costDo not need large area exceptDo not need large area exceptfor large single radio telescopefor large single radio telescopeData obtained doesn¶t requiredData obtained doesn¶t requiredcorrelationcorrelation

Better RFI due to different RFIBetter RFI due to different RFIeach placeeach place

Higher sensitivityHigher sensitivityHigh costHigh costNeed large distance to locate theNeed large distance to locate thedishesdishesVery fine angular resolutionVery fine angular resolutionMore stable to gain variationMore stable to gain variationHigh resolution imageHigh resolution imageHave narrower beamHave narrower beam



Conclusion & DiscussionConclusion & DiscussionINSTUN average RFI level isINSTUN average RFI level is - -94.312 (94.312 ( 0.999) dBm0.999) dBmis near to compared Langkawi RFI level isis near to compared Langkawi RFI level is--100.352 (100.352 ( 0.036) dBm0.036) dBm

INSTUN have better facility and near to UMINSTUN have better facility and near to UM

The UMRT 2 can be located at INSTUNThe UMRT 2 can be located at INSTUN

The data of spectrum analyzing are lessThe data of spectrum analyzing are lesssensitive due to the older version of spectrumsensitive due to the older version of spectrumanalyzer.analyzer.



Future workFuture work

To join Very Long Baseline Interferometer To join Very Long Baseline Interferometer for South East Asia Astronomy Networkfor South East Asia Astronomy Network

To have first Radio Quiet Zone in MalaysiaTo have first Radio Quiet Zone in Malaysia

Cited : http://astronomyonline.org/Stars/BlackHole.asp

Sgr A using VLBI technique



ReferenceReference

rfi analysis and instrumentation viva 2010

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