| DATA_SET_DESCRIPTION |
This data set includes wideband waveform measurements from the
Galileo plasma wave receiver obtained during Jupiter orbital
operations. These data were obtained during selected observation
periods near perijove, satellite encounters and other select times.
These measurements are electric waveforms obtained by rapidly
sampling the potential at the input to the receiver from the
electric dipole antenna. The sample rates are 201,600/s, 25,200/s,
or 3,150/s 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 waveform series can be stacked in order to generate
frequency-time dynamic spectrograms.
This data set is highly discontinuous in time. Because of the severe
limitations in the downlink capability of the Galileo spacecraft,
LPW rate data were recorded only for targeted observations. Most
of these data were acquired near the Galilean moons, although
selected observations were made in various locations around the
magnetosphere. Table 1 below provides a listing of the start and
stop times of the recorded data segments. Even within these time.
intervals, the data are discontinuous. Data are acquired by using
both the electric field and magnetic field antennas. The PDS labels
provided contain information about which antenna was used to
to generate the data in each file. All 10 kHz observations were
recorded in the LPW tape format with the instrument configured
into the PWH5 data format.
----------------------------------------------------------
TABLE 1
----------------------------------------------------------
Start Telemetry PWS
Orb Obs-ID* Date Time Range mode format
----------------------------------------------------------
J00 IO 1995/12/07 15:30 - 17:24 LPW PWH5
J00 PJOV 1995/12/07 23:25 - 23:57 LPW PWH5
G01 GAN 1996/06/27 06:10 - 06:48 LPW PWH5
G01 PSX 1996/06/30 02:01 - 02:48 LPW PWH5
G02 GAN 1996/09/06 18:36 - 19:28 LPW PWH5
G07 GAN 1997/04/05 06:45 - 07:40 LPW PWH5
G08 QRS 1997/05/06 13:00 - 15:09 LPW PWH5
G0* GAN 1997/05/07 15:36 - 16:22 LPW PWH5
C09 CALL 1997/06/25 13:25 - 14:11 LPW PWH5
C09 TAR 1997/06/28 13:57 - 14:43 LPW PWH5
C10 CALL 1997/09/16 23:49 - 00:49 LPW PWH5
E11 EUR 1997-11-06 20:19 - 22:50 LPW PWH5
E14 EUR 1998-03-29 13:05 - 14:01 LPW PWH5
E15 EUR 1998-05-31 20:42 - 21:43 LPW PWH5
E18 PSX 1998-12-10 19:36 - 00:23 LPW PWH5
E19 EUR 1999-02-01 01:49 - 02:39 LPW PWH5
C20 PJOV 1999-05-03 15:59 - 18:01 LPW PWH5
C22 PJOV 1999-08-12 08:16 - 13:06 LPW PWH5
C23 PJOV 1999-09-15 02:10 - 02:14 LPW PWH5
I24 IO 1999-10-11 03:42 - 06:41 LPW PWH5
I25 TOR 1999-11-26 21:06 - 05:45 LPW PWH5
E26 EUR 2000-01-03 17:29 - 18:30 LPW PWH5
I27 IO 2000-02-22 11:10 - 14:25 LPW PWH5
G28 GAN 2000-05-20 09:40 - 10:43 LPW PWH5
G29 GAN 2000-12-28 07:54 - 08:55 LPW PWH5
C30 CALL 2001-05-25 11:09 - 11:45 LPW PWH5
I32 TOR 2001-10-15 15:30 - 17:26 LPW PWH5
I32 IO 2001-10-16 21:53 - 01:53 LPW PWH5
* The ID element is derived from the SEF identifier for the
recorded observation. The recording identifiers translate to:
IO, GAN, EUR, CALL - satellites
PSX - plasma sheet crossing
TAR - trans-auroral region
QRS - quarter rotation survey
DSK - dusk side of orbit C9
DAWN - dawn side of orbit C9
APJ - apojove
TOR - Io torus
EQX - magnetic equator crossing
PJOV - perijove
RAMP - outer torus
These designations were defined by the sequence team.
|
| CITATION_DESCRIPTION |
Gurnett, D.A., Kurth, W.S., Granroth, L.J.,
GO JUPITER PWS EDITED EDR 10KHZ WAVEFORM RECEIVER V1.0,
GO-J-PWS-2-EDR-WAVEFORM-10KHZ-V1.0, NASA Planetary Data System, 1997
|
| ABSTRACT_TEXT |
This data set includes wideband waveform measurements from the
Galileo plasma wave receiver obtained during Jupiter orbital
operations. These data were obtained during selected observation
periods near perijove, satellite encounters and other select times.
These measurements are electric waveforms obtained by rapidly
sampling the potential at the input to the receiver from the
electric dipole antenna. The sample rates are 201,600/s, 25,200/s,
or 3,150/s taken through bandpass filters of 80, 10, or 1 kHz,
respectively.
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