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.
Version:2.3.1
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.
| Role | Person | |
|---|---|---|
| 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)