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., and M. Golkowski, 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.
Version:2.3.2
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., and M. Golkowski, 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.
| Role | Person | StartDate | StopDate | Note | |
|---|---|---|---|---|---|
| 1. | ArchiveSpecialist | spase://SMWG/Person/Morris.Cohen |
Sampling rate of the data, usually 100 kHz or 1 MHz.
the center frequency of the VLF transmitter (for narrowband data)