Data Set Information
DATA_SET_NAME GO E PWS EDITED EARTH 2 WAVEFORM RECEIVER V1.0
DATA_SET_ID GO-E-PWS-2-EDR-E2WFRM-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during the second Earth encounter. These measurements are electric or magnetic waveforms obtained by rapidly sampling the potential at the input to the receiver from either the electric dipole antenna or the magnetic search coil antenna. The sample rates are 201,600 s^-1, 25,200 s^-1, or 3,150 s^-1 taken through bandpass filters of 80, 10, or 1 kHz, respectively. Each sample is a 4-bit measurement after an automatic gain control (AGC) amplifier designed to keep the signal amplitude in a range commensurate with the optimal analog-to-digital converter dynamic range with a time constant of about 500 msec. As such, the measurements are not absolutely calibrated, although it is possible to determine the approximate AGC gain from a digital performance parameter available every 2.667 seconds, assuming the signal amplitude does not vary appreciably over the 2.667 second interval. Alternately, the sweep frequency receiver (low rate) portion of the instrument can be used to determine the absolute amplitude of waves. In many cases, the waveform data are used without any calibration for the purposes of identifying characteristic frequencies of the plasma via resonances or cutoffs, observing discrete emissions such as chorus or whistlers, or looking at the detailed form of the waveforms. In general, the waveform samples are not continuous over long time periods due to the limited telemetry capability of the Galileo data system and limits on the bandwidth available to the PWS instrument. Instead, sequences of contiguous samples are collected for up to about 67 msec followed by a gap. The number of consecutive samples between gaps is determined by the telemetry format and the bandwidth (instrument mode). Details of the timing, number of consecutive samples in a series, and the effective duty cycle are described in the inst.cat, rowpfx.fmt, and edrhdr.fmt files included with the data set. The data are formatted in files covering no more than 1 RIM (60.667 s) each up to 91 data records, with a record containing 10 or 80 blocks of contiguous waveform samples. The data in any one file are from only a single combination of instrument mode (waveform) and telemetry format, however, the antenna can change within a file; this is noted in the record header information, but is only updated every 2.667 sec, hence, may not be accurate less than 2.667 seconds after a real antenna change. Since the instrument mode information is also updated only once per 2.667 seconds, the last data in a record (less than 2.667 seconds) may actually be in a different mode. The typical uses of the waveform data are to (1) display the waveform of plasma wave and other signals such as dust impacts, and (2) as highly detailed (in time and frequency) spectra through the use of Fourier transforms. To avoid artifacts, we suggest not transforming over the gaps but limiting the input to the Fourier transform to a single contiguous series of samples. Spectra from individual waverform series can be stacked in order to generate frequency-time dynamic spectrograms. During the time interval spanned by this data set, Galileo approached Earth from the local early morning sector, made a close approach to Earth by passing through the magnetosphere, plasmasphere, ionosphere, and finally exited the Earth system in the local late morning.
DATA_SET_RELEASE_DATE 1996-08-01T00:00:00.000Z
START_TIME 1992-11-24T03:12:01.580Z
STOP_TIME 1992-12-12T06:47:15.513Z
MISSION_NAME GALILEO
MISSION_START_DATE 1977-10-01T12:00:00.000Z
MISSION_STOP_DATE 2003-09-21T12:00:00.000Z
TARGET_NAME EARTH
TARGET_TYPE PLANET
INSTRUMENT_HOST_ID GO
INSTRUMENT_NAME RADIO AND PLASMA WAVE SCIENCE
PLASMA WAVE RECEIVER
INSTRUMENT_ID PWS
INSTRUMENT_TYPE PLASMA WAVE SPECTROMETER
NODE_NAME planetary plasma interactions
ARCHIVE_STATUS PRE PEER REVIEW
CONFIDENCE_LEVEL_NOTE This data set includes all available wideband waveform data within the interval of time covered. Original EDRs contained inaccuracies in the instrument status and Spacecraft Event Time (SCET). Each file contains a corrected SCET in the attached PDS label and binary EDR header, and corrected instrument status information in the record headers. The mag- netic spectra contain narrowband interference lines at 2.4 kHz and har- monics. Operation of the UVS grating stepper motor produces a series of narrowband interference lines in the magnetic spectra between about 100 Hz and 2 kHz. Missing data are indicated by zero.
CITATION_DESCRIPTION Kurth, W.S., GO-E-PWS-2-EDR-E2WFRM-V1.0, GO E PWS EDITED EARTH 2 WAVEFORM RECEIVER V1.0, NASA Planetary Data System, 1996.
ABSTRACT_TEXT This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during the second Earth encounter. These measurements are electric or magnetic waveforms obtained by rapidly sampling the potential at the input to the receiver from either the electric dipole antenna or the magnetic search coil antenna. The sample rates are 201,600 s^-1, 25,200 s^-1, or 3,150 s^-1 taken through bandpass filters of 80, 10, or 1 kHz, respectively.
PRODUCER_FULL_NAME DR. WILLIAM S. KURTH
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