1 RFI Measurements at the Argentine Institute of RadioastronomyDetection and measurement of RFI in radio astronomy Yebes Observatory (IGN, Spain) June 8-9, 2017
2 Outline IAR, Brief introductionEquipment & measurements for RFI-SKA campaign, 2005 Equipment & measurements for RFI-TIGO campaign, 2012 RFI equipment & measurements, IAR development, 2013 RFI data processing and study.
3 Instituto Argentino de Radioastronomía (IAR)Brief introduction to IAR Instituto Argentino de Radioastronomía (IAR) Consejo Nacional de Investigaciones Científicas y Técnicas (CCT La Plata - CONICET) - Director: Dr. E. Marcelo ARNAL -Commitment for creation agreement: 30/10/1962 Primary Objective Scientific research on frequency bands corresponding to hydrogen. -First Observation: 24/3/1966 -Creation agreement : 10/12/1969 (CICPBA, CONICET, UBA, UNLP) -12/11/85 -> Depends only on CONICET. Latitude : -34° 51' 57".35 Longitude : 58° 08' 25".04
4 Brief introduction to IARCurrent Instrumentation As a new development we are updating the Front-End and Back-End for PULSAR observations With the aim to continuous Monitoring of known Pulsars, as a collaboration to the NanoGrav Project.
5 “LLAMA (Long Latin American Millimeter Array )”Brief introduction to IAR New Sub/millimeter Instrumentation Development Integration of the LLAMA Cryostat at NOVA, Kapteyn Astronomical Institute at the University of Groningen, with Band 5 (167GHz) & Band 9 (602GHz) “LLAMA (Long Latin American Millimeter Array )”
6 Brief introduction to IARTechnological Facilities Electronics Laboratory Anechoic Chamber Infrared Characterization Laboratory Electronics Assembly Laboratory Open Field Antenna Measurement 6
7 Brief introduction to IARTechnological Developments Satellite Instruments Radiometers RF Design MWR, Microwave Radiometer 23&36GHz Digital Design Antenna Design Pad, Data Acquisition computers NIRST, New Infra Red Sensor Technology
8 RFI-SKA campaign, 2004 First Experience on Long Period RFI Measurements for the SKA-Site Characterization. Located on “Pampa del Leoncito” in San Juan, from February 2005 to March 2006. RFI Measurements : LNA’s from 100Mhz to 22GHz. Single Pol Antennas with mechanical Pol change. Automated acquisition for 24/7 measurements. RFI Measurements Results: Poor site for SKA-low and SKA-mid band (.07-3GHz). Excellent Site for SKA-High bands (3 GHz or higher to GHz) Still an Excellent Site on High bands for Future Instruments
9 Transportable Integrated Geodetic ObservatoryRFI-TIGO campaign, 2012 TIGO, as part of the geodetic VLBI network, owns a 6mts antenna with a cryogenic receiver working in two bands: S ( GHz) & X ( GHz) For their RFI concern on the new location near the IAR, a two stages of RFI measurements where conducted: Stage 1: one month survey with IAR-RFI Equipment. Stage 2: one month survey with BKG-RFI Equipment. Transportable Integrated Geodetic Observatory Concepción - Chile Dr. Hayo Hase Director of TIGO
10 RFI-TIGO campaign, 2012 Stage 1Developed for SKA site finding in Argentina in 2005, quickly reconditioned in 2012 for TIGO Stage I: RFI Equipment Design & Test April June 1st Start Campaign By June 11 (one week of delay) Stage 1 Dual ridge horn antenna Frequency range: GHz. polarization change mechanically. 359° spatial coverage 5° resolution. Antenna box 3 LNA from Miteq, GHz (!) relays for 50 ohm reference load used for periodic Calibration. HP9583E Spectrum Analyzer Tsys: ~700°K Data logging: Custom software for automated measurements. overall gain: 75dB at 2 GHz incl. ~8dbi at 2 GHz antenna directivity
11 RFI-TIGO campaign, 2012 Stage 2-a Stage 2-bCombination of RFI-monitoring systems BKG Wettzell and IAR La Plata Rohde&Schwarz-Antenna HL024A1 Frequency range: 1-18 GHz, input signal: horizontal + vertical polarization Antenna box 1 LNA for each polarization relais for noise cal injection noise cal diode NC346B Receiver Box power combiner for both polarizations amplifier Rohde&Schwarz SA FSL18 Tsys: ~300°K Data logging: Notebook PC One week of measurements Measurement 30kHz resolution bandwidth 2-14 GHz range divided in 1GHz bands each 1GHz band requires 2.5s sweeptime (12 bands = 30s) 8 directions (N, NE, E, SE, S, SW, W, NW) + 1 Cal. = 15min => 96 azimuth scans/day => 768 images/day After 30 days of measurement ( ): => images of the spectrum analyzer recorded Manual pointing most dense RFI data set known to the IVS overall gain: 70dB at 2 GHz incl. ~7dbi antenna 1 image = 9600 amplitude data points spaced by 1.25 MHz. => 209 million data points.
12 RFI-TIGO campaign, 2012 Stage 1 - IAR
13 RFI-TIGO campaign, 2012 Stage 2 - BKG TIGO VLBI FREQUENCY BANDS
14 RFI-TIGO campaign, 2012 Stage 2 - BKG
15 IAR New Development, 2014 RF-BOX RF-TLMY PDUWith the need to expand frequency and obtain a better S/N ratio. NEW Dual ridge horn antenna EST-Lindgren 3117 frequency range: GHz. HPW – (E-Plane) Antenna box New 2 LNA from Miteq, GHz! relais for 50 ohm reference load used for periodic Cal. NEW Spectrum Analyzer Agilent N9344C better DANL (display average noise level) of spectrum analyzer. NEW Antenna Rotor Improved mechanics. polarization change mechanically. 359° spatial coverage 5° resolution. Data logging: PC (or SBC) with custom software for automated measurements. RF-BOX RF-TLMY PDU System Gain: 70dB~60 dB. ~3-10dBi from Antenna.
16 IAR New Development, 2014 16 Software DescriptionControls the PDU unit, RF-Ctrl Unit and Rotor Unit Configure and reads the Spectrum Analyzer Web page for monitoring system status Measurements configuration from external file Run's on Linux PC or Linux SBC (like BeagleBone) BeagleBone SBC present a Smaller size then PC (CreditCard Format). More sensitive to loss of power (OS stored in uSD). #Configuration Sample File ………………………… # End of File 16
17 IAR New Development, 2014 System Block Diagram 17x2 LNA ~38dB Gain NF~2.5dB RF Switch Noise Source NoiseWave ENR23dB + 20dBAT Voltage & LNA Temperature measurements. RF-Switch & Noise Source Control. RS-232 Communication. Estimated 17
18 IAR New Development, 2014 Custom Antenna Rotor Custom Design Robust.Small Size – (..Almost Lightweight..). Simple Installation. Easy to disassemble for repair / verification. Spatial Coverage 355° in Azimuth with ~5° resolution. 0° to 90° for Mechanical Polarization change. Remote Control Serial Interface Position measurement with magnetometer & Potentiometer. RF signal thru RF rotary Joint
19 RFI data processing and studyOff-Line Process Math's with Octave Scripts Analysis thru direction of measurement. Peaks above noise floor. Percentage thru time of measurement. References: SSSM System Design Considerations (R.P. Millenaar – Astron) SKA site Spectrum Monitoring (Boonstra / Millenaar – SKA) 1-14GHz TIGO RFI Monitoring System (Gancio / Larrarte – IAR)
20 RFI data processing and studyRadio Astronomy uses frequency spectra to study astronomical phenomena. The signals under study are: Very Low Power – Noise Like – Bandwidth dependent. According to the phenomena different frequencies and bandwidth are used, e.g.: IAR TIGO & SKA When RF Interference appears…. Mask the phenomena under study. Saturates low noise amplifiers affecting linearity, possible damage to receiver. As a result: Loss of Sensitivity. Loss of astronomical data. Loss of observation Time. “Mediciones de contraste, Radiometro Antena I, M.Salibe, D.Perilli, J.J.Larrarte.”
21 RFI data processing and studyRFI Identification for Radio observatories: Local Interference Self Generated RFI, Computer, Networks, Power Lines, etc. External Interference Radio Links, Cell Phone Masts, TV, FM, Radar, etc. Study of Interference Power Spectra – Frequency – Bandwidth – Modulation. Duration over days: Continue – Random. Work with the Communications Agencies of Governments. Spectrum Allocation, Radio Quiet zones. IAR was present at the WRC-15
22 Thanks for your attention!Some Links of interest… Instituto Argentino de Radioastronomía – RFI Monitor System web page (English) Online Data 22