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RFI in the alpha band pass Murray Lewis

RFI in the alpha band pass Murray Lewis. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R. Senior Research Associate Radio Astronomy Group. Propose to cover. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R.

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RFI in the alpha band pass Murray Lewis

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  1. RFI in the alpha band pass Murray Lewis N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R Senior Research Associate Radio Astronomy Group

  2. Propose to cover N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R FCC frequency allocations in spectral region GPS Galileo PR Radars in band RFI Mitigation possibilities radar blankers! nine level sampling! algorithms! cross correlation between feeds Reinforcement of AO anti-RFI activity!

  3. The frequency range covered by alfa is from 1225 to 1525 MHz N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R

  4. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R

  5. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R

  6. GPS L1, L2, L5 N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R L5 L2 L1 General coverage -158 dBW Spot Beam -138 dBW Alfa 1225 - 1525

  7. GPS N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R L1 & L2 -157 dBW for C/A -160 dBW for Y L5 -154 dBW ≈24 MHz, full time occupancy This is 6 dB stronger than present L1 & L2 L5 spfd ~-205 dBW/m^2/Hz 1164-1188 MHz ~-197 dBW/m^2/Hz in center 5 - 8 satellites always available Also, of concern, GPS L3 circa 1381 MHz

  8. Galileo -- full set due 2008 N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R E5A_E5B 1164-1215 MHz (WRC2000) E6 1260-1300 MHz (WRC2000) E2,L1,E1 1559-1591 MHz Use of C_band under consideration To have 30 satellites, in 3 planes, inclination 56 deg 14 hr orbits, radius 23,616 km Power 50 W amplifiers peak power 120 W

  9. Galileo N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R On orbit validation 2001-5 2/4 satellites Deployment 2006-7 26-28 sats Commercial Ops. 2008 Concern is their presence at 1260-1300 MHz

  10. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R Details of Common/Unusual RFI Available on AO Web Page

  11. Hilltop Monitor 1200-1450 MHz N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R

  12. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R Examples Blanking San Juan Airport Radars? (1330 & 1350 ) BUT in the Surroundings of 1400-1427 MHz band (i) US has proposed a satellite feeder-link system Uplink 1390-2 MHz, downlink 1430-2 MHz (ii) L3 (GPS) at 1381 MHz (iii) Timing explorer in Space Lab was at 1427 MHz

  13. Fractional occupation of 0.1 MHz bins N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R

  14. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R Changeability -- Old systems GO Roosveldt Roads closure Tethered Aerostat ~1260 MHz gone -- New systems arrive UWB! -- Sporadic Incursions daily rfi complaints varied in nature and cause some known, such as GPS L3 activity some site-generated - AO work

  15. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R Countermeasures! -consider radar blanking at least for the airport radars 1330-1350 MHz perhaps for others too!! -Sampling sufficiently nine-level sampling for the correlator 12 bits or more for the digitizer -Algorithm developments pipeline excision cross-correlation between pixels robust statistics applied to the signals (eg http://www.iucaf.org/sschool/peterf/fridmanpaper4.pdf)

  16. N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R

  17. 400 0 0 500 1000 1500 2000 RATAN-500 1116+28 20 0 0 500 1000 1500 2000

  18. Arecibo anti-RFI activity N A T I O N A L A S T R O N O M Y A N D I O N O S P H E R E C E N T E R overwehelming importance of L_band to alfa Should you use the radar blankers? How bothersome is the residual 1350 MHz birdie? Should you be using 9-level sampling? Algorithm development

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