Transcript Slide 1
The Sun, Earth’s Ionosphere, and VLF Radio waves Students Monitor Solar Disturbances to Earth’s Ionosphere – An Education Project for the International Heliophysical Year 2007 Interpreting SID Data The students receive their SID data as a signal strength value and a timestamp. The data are easily read by Excel and graphed. There is a characteristic sunrise and sunset shape to the graph, which can be used to test the monitor. Solar events showC5.9 up as spikes in the signal strength. M1.3 C4.5 Students compare their spikes to data from the GOES satellite to identify C3.8 flares. Occasionally, students will detect flares that the (human) GOES data interpreter has missed. Students can also track down the solar active region which generated the disturbance. Could they learn to predict flares and their effects? Deborah Scherrer [email protected] Ray Mitchell [email protected] Morris Cohen [email protected] Umran Inan [email protected] Philip Scherrer [email protected] Stanford University The International Heliophysical Year (IHY) 2007 Organizing Committee and the United Nations have designated our Space Weather Monitors as supported projects of the IHY, to be placed in each of the 191 nations of the world. Nighttime Daytime Selected VLF transmitters around the world Antenna Wires Primarily U.S. Navy stations for communicating with submarines One of the VLF broadcasting stations – Jim Creek, WA “NLK” 24.8KHz 200’ Towers Amplitude (Peak-to-Peak) for 24.8KHz Earth's ionosphere reacts strongly to the intense x-ray and ultraviolet radiation released by the Sun during a solar event. Students around the world can directly monitor and track these ionospheric disturbances by using a receiver to monitor the signal strength from distant VLF transmitters, and noting changes as the waves bounce off the ionosphere. Stanford's Solar Center, in conjunction with the Electrical Engineering Department’s Very Low Frequency group and local educators, have developed inexpensive ionospheric monitors that students can install and use at their local high schools. Students "buy in" to the project by building their own antenna, a simple structure costing about $10 and taking a couple hours to assemble. Data collection and analysis is handled by a local PC. Stanford will be providing a centralized data repository and chat site where students and researchers can exchange and discuss data. Radio Signal AWESOME -- The Research Quality Monitor Atmospheric Weather Educational System for Observation and Modeling of Effects Sudden Ionospheric Disturbance monitor •Preassembled and pretuned •Students build their own, simple antennas •Sample rate of 1 per 5 seconds; data handled and plotted by Excel •Changeable frequency boards tuned to particular VLF transmitters around the world •Easy to set up and use •Suitable for use in high school and community colleges •Low cost (~$150 per monitor) •Based on AAVSO original concept •Designed to capture ELF/VLF frequencies, roughly 30 MHz-50kHz •Dual use system -Daytime: monitor solar activity Nighttime: monitor atmospheric phenomena, e.g. lightning •Precision timing/phase accuracy •So sensitive that nearly any signal above the ambient Earth noise floor can be detected •Broadband; sample rate of 100KHz on each channel •Preassembled but students build their own antenna •Data appropriate for high school as well as solar and ionospheric researchers •Moderate cost (~$3100 per monitor) Motorola M12+ OnCore GPS And FPGA provide 1 pulse per second signal with 200 ns accuracy 10 bit, Analog to Digital Conversion DATAQ B-Field Antenna All frequencies Band-pass, Only 24.8KHz (Amplitude Modulation) Preamp = RS-232 M1.3 C3.8 Students Locate Source of Disturbance SID – The low-cost monitor Signal Strength C5.9 :Product: 20030802events.txt :Created: 2003 Aug 05 0302 UT :Date: 2003 08 02 # Prepared by the U.S. Dept. of Commerce, NOAA, Space Environment Center. # Please send comments and suggestions to [email protected] # # Missing data: //// # Updated every 30 minutes. # Edited Events for 2003 Aug 02 # #Event Begin Max End Obs Q Type Loc/Frq Particulars Reg# #------------------------------------------------------------------------------1910 + 1529 1537 1545 G12 5 XRA 1-8A B8.1 6.3E-04 0424 1910 1533 1534 1553 HOL 3 FLA S17E71 SF 0424 1920 1604 1609 1617 HOL 3 FLA S18E70 SF 0424 1930 1625 1650 1726 HOL 3 FLA S18E68 SF 0424 1930 + 1637 1642 1650 G12 5 XRA 1-8A C1.1 7.6E-04 0424 For more information, see solar-center.stanford.edu/SID 24.8KHz Filter C4.5 Because there are VLF transmitters scattered around the world, the monitors can be placed virtually anywhere there is access to power. Our goal is to place one AWESOME and up to five SID monitors in each of the 191 UN countries. Distance traveled over time Coax Students compare their data with that from the GOES satellite Two versions of the monitor exist – one low-cost (“SID”) and one research quality (“AWESOME”). 1 Cycle = 7.5 Miles (12 KM) Pre-Amp With AWESOME monitors, students also pick up other signals, including gamma ray bursts, lightning storms, and other nighttime phenomena. By talking with each other and checking other data, they attempt to determine what caused their unidentified signals. Computer DC voltage Level Sample every 5 Seconds B-Field, Magnetic Loop Orthogonal Pair 1.0 Ω, 1.0 mH Various sizes ok Cuts off at ~318 Hz Long Cable GPS Antenna Line Receiver Preamp impedance matched Paschal amplifier PowerOne Had15 power supply 3 cutoff modes Anti-aliasing filter Gain selectable GPS synchronization Calibration circuit Weatherproof Two channel: Narrowband & broadband Works with Matlab Computer Analog to Digital National Instruments 6034E Plugs into PCI slot PCMCIA laptop version available 200 kS/second, 16-bit 100 kHz sampling each LTC1562 channel 12th order lowpass Elliptical filter 47 kHz cutoff 100dB attenuation at 55 kHz 50 us relative delay Contacts: Morris Cohen [email protected] Ray Mitchell [email protected] Deborah Scherrer [email protected] List of Partners Stanford Solar Center Deborah Scherrer Hao Thai Sharad Khanal Scott Winegarden (now at UC Irvine) Stanford Solar Observatories Group Philip Scherrer Sarah Gregory Stanford EE Department Umran Inan Morris Cohen Justin Tan Cal State University East Bay Ray Mitchell, Chief Engineer Chabot Community College Shannon Lee (now at Cal State SF) Tim Dave San Lorenzo High School William Clark, Senior Engineer Richard Styner Castro Valley High School Sean Fotrell Kenny Oslund (now at CalTech) Concept: Paul Mortfield & AAVSO VERY LOW FREQUENCY (VLF) Radio Transmission Stations Note – VLF signals can be received all over the world, whether there is a station nearby or not. Station Station Frequency Site ID (kHz) U.S. Navy Cutler, ME NAA 24.0 Jim Creek, WA NLK 24.8 Lualualei, HI NPM 21.4 LaMoure, ND NML 25.2 Aquada, Puerto Rico NAU 40.8 Keflavik, Iceland NRK 37.5 Australia Harold E. Holt NWC 19.8 Federal Republic of Germany Rhauderfehn 18.5 Burlage DHO 23.4 France Rosnay HWU 15.1 St. Assie FTA 16.8 LeBlanc HWU 18.3 Iceland Keflavic TFK 37.5 Italy Tavolara ICV 20.27 Norway Noviken JXN 16.4 Russia Arkhanghelsk UGE 19.7 Batumi UVA 14.6 Kaliningrad UGKZ 30.3 Matotchkinchar UFQE 18.1 Vladivostok UIK 15.0 Turkey Bafa TBB 26.7 United Kingdom Anthorn GQD 19.0 Rugby GBR 16.0 London GYA 21.37 Radiated Power (kW) 1000 250 566 500 100 100 1000 500 400 23 43 45 150 input 100 input 100 input 100 input 100 input 500 45 120 Information courtesy of Bill Hopkins, Technical Representative for Pacific-Sierra Research Corp.