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

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 Propose to cover 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!

The frequency range covered by alpha 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

GPS L1, L2, L5 L5 L2L1 General coverage -158 dBW Spot Beam -138 dBW Alpha

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 GPS L1 & L dBW for C/A -160 dBW for Y L dBW ≈24 MHz, full time occupancy This is 6dB stronger than present L1 & L2 L5 spfd ~-205 dBW/m^2/Hz MHz ~-197 dBW/m^2/Hz in center satellites always available Also, of concern, GPS L3 circa 1381 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 Galileo -- full set due 2008 E5A_E5B MHz (WRC2000) E MHz (WRC2000) E2,L1,E MHz Use of C_band under consideration To have 30 satellites, in 3 planes, inclination 56 deg 14 hr orbits, radius km Power 50 W amplifiers peak power 120 W

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 Galileo On orbit validation /4 satellites Deployment sats Commercial Ops Concern is their presence at 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 Details of Common/Unusual RFI Available on AO Web Page

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 Hilltop Monitor 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 Blanking San Juan Airport Radars? Examples Surroundings of MHz band US has proposed a satellite system Uplink circa 1400, downlink circa 1427 MHz Timing explorer in Space Lab was at 1427 MHz L3 (GPS) at 1381 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 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

RATAN

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 importance of L_band to alpha Do you want radar blankers How bothersome is the 1350 MHz birdie? Should you be using 9-level sampling? Algorithm development