AUSAC Meeting 9-10 March 2009
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.
AUSAC Meeting 9-10 March 2009
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)
AUSAC Meeting 9-10 March 2009
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)
AUSAC Meeting 9-10 March 2009
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
AUSAC Meeting 9-10 March 2009
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!!)
AUSAC Meeting 9-10 March 2009
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)
AUSAC Meeting 9-10 March 2009
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
AUSAC Meeting 9-10 March 2009
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
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