RFI & Spectrum Management

AUSAC Meeting 9-10 March 2009

RFI & Spectrum Management

Murray Lewis


Cooperative Agreement with NSF

Charge #5

Maintain a vigilant awareness of the radio frequency environment of the Observatory through a program of RFI monitoring, and take all appropriate steps to mitigate to the extent possible the impact of such signals on the Observational mission of NAIC.


unwanted man-made radio signals in data == RFI

the radio spectrum is coveted by many users• Commercial sector• Government• Military• Scientific users

radio spectrum must be shared and managed

active users may contaminate adjacent spectrum with spurious and unnecessary emission thus causing RFI

Radio Frequency Interference (RFI)


Sources of RFIRFI Source Regulatory Body

Site Inadvertent Arecibo StaffPR Radar, Military FCC, PRSUGGlobal Satellite, Aircraft FCC, NTIA, CORF, ITU• NAIC acts on RFI matters through an internal committee:

Spectrum Management and RFI Group (SMARG)

• Meets monthly, Minutes on the internal web

• Attended by Site Director, Head Astronomy Dept., & Yervant Terzian

• Spectrum Management at Arecibo -- ~1.5 FTE• Rey Velez (0.4 FTE), Murray Lewis (~.4 FTE), Phil + others (~.7 FTE)


SPECTRUM MANAGEMENT


HILLTOP MONITOR 1 - 10 GHz data available from AO Web


Output Hilltop Monitor

daily average 30/10/2002


Hilltop Monitor 1200-1450 MHz


Fractional Occupation of 0.1 MHz bins


Site-Generated RFI

We are often our own worst enemy == eternal need for vigilance

Vet all new equipment before it is installed • tertiary reflector controls• telescope tie-down electronics• cell-phone detectors

Monitor installed equipment for RFI• deterioration of shielding due to oxidation of seals• wear & tear on equipment seals• installation of improvements to RFI shielding, etc


RECENT

Hill top monitor overhauled and reinstalled

430 MHz transmitter and amateurs: event day for amateurs

Space shuttle coordination

Coordination with GPS, Iridium, GlobalStar, Puntas Salinas Coming

License application for 3rd HF frequency

Coordination negotiation about 5 GHz birdies (Neptuno!!)


Puerto Rican IssuesFederal regulations apply to Puerto Rico

• PRCZ was set up on September 26th, 1997• allows the Observatory to comment on license requests made

to the FCC (Federal Communication Commission)

PR Spectrum Users Group (PRSUG)• provides a forum for making contacts with island spectrum

managers• provides notice of new developments• eases coordination - eg with Punta Salinas

Current island issues• TARS MoU to be revised • X-band (CASA) weather radars expected (9.41 GHz)


Global ConcernsFCC, NTIA == US Domestic Regulators

CORF == National Academy of Science’s Committee on Radio Frequencies

International Telegraphic Union ( ITU )• ITU regulations provide for the protected RAS bands• allocate particular pieces of spectrum to particular classes of users• provide guidelines for interpreting spurious & out of band emissions• provide guidelines for interpreting “harmful levels” of emission• band-sharing coordination, etc • provisions for radio astronomy from space == need for foresightIUCAF: unfettered voice of radio astronomers at the ITU

obtained an MoU with Russians re GLONASS

rallying point in dealing with Iridium satellite incursion


CURRENT

GPS 1381 MHz use -- coordination (US domestic issue)

GPS administration offered to code a software mitigation solution for much of their L3 signal

Lou Nigra (Wisconsin pre-doc) engaged to provide the Arecibo end of this project (test data, receiver calibration/linearity, and implementation) with help of Electronics Dept. engineers.

Method based on Ellingson et al, APJS 135, 87 (2001)

Analog-digital transition: #54 will go off the air, site visit

RFI & Spectrum Management

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Transcript of RFI & Spectrum Management