1. K. Liewer ANITA-Irvine CA 11/24/02 Anthropogenic Background K. Liewer

2. K. Liewer - 1 ANITA-Irvine CA 11/24/02 Introduction Man-made (anthropogenic) radio frequency signals may reduce the efficiency of instrument or disable it completely two types of RFI –CW –pulses CW signals interfere mainly by raising the system temperature causing either : –higher threshold and lower sensitivity –higher trigger rate and increased deadtime Pulsed signals may interfere in three ways –a pulse may mimic neutrino signals causing data reduction/analysis problems this is unlikely as few emitters have the right properties –pulses that trigger the system reduce the live time –high rate pulses could increase the system temperature

3. K. Liewer - 2 ANITA-Irvine CA 11/24/02 Know ground radiators National Telecommunications and Information Agency (NTIA ) lists 5 transmitters in our frequency range which are visible to us –4 in range from 400 to 411 MHz power 10 W or less low gain antennas –one at 962 MHz (TACAN) (may go to 1.2 GHz) mobile, 400 W, 3 dB gain antenna, 900 RPM beam rotation rate The Government Master File (GMF) lists ~150 sources –many in the 10-25 W range –TACAN (McMurdo, 3 kW, 962-1024 MHz) –approach radar (McMurdo, 2.7-2.9 GHz, 1.4 Mw peak power) Auroral radar exists at 3 sites (Halley, Sanae IV, Syowa) –3-20 MHz (adjustable)

4. K. Liewer - 3 ANITA-Irvine CA 11/24/02 Station contacts For normal orbits the balloon latitude lies between 73º and 82 º S The field of view radius is 6.157 º at the nominal float altitude 34 station will fall within the field of view if the balloon remains within the normal latitude range –9 more stations, nearly all on the peninsula, are within a few degrees of cutoff –neither count includes temporary sites

5. K. Liewer - 4 ANITA-Irvine CA 11/24/02 Orbit map with known research sites Nominal orbit (78º S) Contact area for normal range of orbit latitudes Instantaneous filed of view

6. K. Liewer - 5 ANITA-Irvine CA 11/24/02 Station contacts

7. K. Liewer - 6 ANITA-Irvine CA 11/24/02 Station contacts

8. K. Liewer - 7 ANITA-Irvine CA 11/24/02 Satellite interference Main impact would be from pulsed signals –SAR Only 4 satellites (3 flying, 1 proposed) have SAR operating frequencies are ~5.3 GHz –altimetry Two satellites pass over the Antarctic operating frequencies are 13.5 GHz beams are ANITA in beam for < 1 minute

9. K. Liewer - 8 ANITA-Irvine CA 11/24/02 Effect of transmitter in beam horizon