2.3.1 spase://GBO/NumericalData/AWESOME/VLF/PT0.02S AWESOME receiver system narrowband VLF data https://doi.org/10.48322/6t7b-s324 2020-09-28T21:24:52Z Most of the data is collected on two air-core loop antennas, oriented orthogonal, to collect the two horizontal components of the magnetic field. The north-south, or N/S antenna is sensitive mostly to waves arriving from the north of from the south direction, meaning it picks up the magnetic field component in the east-west direction. The other antenna is the east-west antenna, which is the opposite. Narrowband data are the amplitudes and phase of specific frequencies, usually corresponding to VLF transmitters that are used for communications and navigation. Sampling rate is usually either 1 Hz or 50 Hz. They are also useful as a diagnostic of the ionosphere. Most of these transmitters use minimum shift keying (MSK) modulation, and the recording software extracts the amplitude, and the phase is calculated by demodulating the MSK demodulation. Details of the demodulation algorithm and examples of its application can be found in Gross, N.C.; Cohen, M.B.; Said, R.K.; Golkowski, M, "Polarization of Narrowband VLF Transmitter Signals as Ionospheric Diagnostic", JGR, 2018, 901-917. https://doi.org/10.1002/2017JA024907 Narrowband files available in the WALDO archive are in 24-hour blocks, so the start time of all files is 00:00:00 UT, and the end time is 24:00:00 UT. Even if only a small amount amount of data was recorded on a given day, the file on WALDO will contain 24-hours worth of samples. This is done to make the analysis easier, since all files have the same start time. The raw original data actually starts a new set of files whenever the computer or software reboots, but the archivists made the effort of stitching them together. Where data were not actually recorded, the value will be “NaN” or not a number. DATA USAGE POLICY The data in the WALDO database have been collected by Stanford University, the Georgia Institute of Technology, and the University of Colorado Denver. Funding has been provided by the United States government under various basic science research grants over many years. To maximize the benefit of those investments, WALDO data are released without restriction, and can be freely analyzed or published. The curators of WALDO are Morris Cohen (Georgia Tech) and Mark Golkowski (CU-Denver). We request that the following acknowledgement be added in any publication using data from WALDO "VLF data are provided by the WALDO database (http://waldo.world), operated jointly by the Georgia Institute of Technology, and the University of Colorado Denver, using data collected from those institutions as well as Stanford University, and has been supported by various US government grants from the NSF, NASA, and the Department of Defense." If extensive amounts of WALDO data are used in a publication, the curators request, but do not require, to be contacted to discuss the possibility of joint authorship, with the WALDO curators providing help analyzing and interpreting the large dataset. Morris B. Cohen, Umran S. Inan, Mark A. Golkowski 2020-01-01T00:00:00Z Worldwide Archive of Low frequency Data and Observations (WALDO) spase://SMWG/Person/Morris.Cohen ArchiveSpecialist Worldwide Archive of Low-Frequency Data and Observations (WALDO) http://waldo.world spase://SMWG/Repository/WALDO Worldwide Archive of Low-Frequency Data and Observations (WALDO) Narrowband Data http://waldo.world/narrowband-data/ MATLAB_4 VLF data are provided by the WALDO database (http://waldo.world), operated jointly by the Georgia Institute of Technology, and the University of Colorado Denver, using data collected from those institutions as well as Stanford University, and has been supported by various US government grants from the NSF, NASA, and the Department of Defense. spase://SMWG/Instrument/AWESOME/VLF Waves.Passive 2005-04-28T00:00:00 -P3Y Different stations have different start/stop dates P1D Earth.NearSurface Earth.NearSurface.Ionosphere start_year Temporal start_month Temporal start_day Temporal start_hour Temporal start_minute Temporal start_second Temporal latitude Positional longitude Positional altitude Positional Fs Sampling rate of the data, usually 100 kHz or 1 MHz. PT0.000001S PT0.00001S Other gps_quality DataQuality adc_channel_number Other adc_sn Other adc_type Other antenna_bearings Orientation antenna_description InstrumentMode cal_factor Other computer_sn Other gps_sn Other hardware_description InstrumentMode is_broadband InstrumentMode station_description Other station_name Other VERSION Other is_amp Other is_msk Other Fc the center frequency of the VLF transmitter (for narrowband data) Other call_sign Other filter_taps Other data Electromagnetic ACMagneticField RadioFrequency 0.3 50 kHz