Data Set Information
DATA_SET_NAME VG2 URA PWS RAW EXPERIMENT WAVEFORM 60MS V1.0
DATA_SET_ID VG2-U-PWS-1-EDR-WFRM-60MS-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION This data set consists ofelectric field waveform samples from the Voyager 2 Plasma WaveReceiver waveform receiver obtained during the Uranus encounter.The waveforms are collections of 4-bit samples of the electricfield measured by the dipole electric antenna at a rate of 28,800samples per second. 1600 samples are collected in 55.56 msecfollowed by a 4.44-msec gap. Each 60-msec interval constitutes aline of waveform samples. The data set includes about 271 frames ofwaveform samples consisting of up to 800 lines, each. Thetelemetry format for the waveform data is identical to that forimages, hence the use of line and frame as constructs in describingthe form of the data. The waveform is sampled through a bandpassfilter with a passband of 40 Hz to 12 kHz. The 4-bit samplesprovide sixteen digital values of the electric field with alinear amplitude scale, but the amplitude scale is arbitrarybecause of the automatic gain control used in the waveformreceiver. The instantaneous dynamic range afforded by the 4bit samples is about 23 db, but the automatic gain control allowsthe dominant signal in the passband to be set at the optimumlevel to fit within the instantaneous dynamic range. With the gaincontrol, the overall dynamic range of the waveform receiveris about 100 db. The automatic gain control gain setting is notreturned to the ground, hence, there is no absolute calibrationfor the data. However, by comparing the waveform spectrum derivedby Fourier transforming the waveform to the spectrum provided bythe spectrum analyzer data, an absolute calibration may beobtained in most cases. The data may be plotted in raw form toshow the actual waveform; this is useful for studying events suchas dust impacts on the spacecraft. But the normal method ofanalyzing the waveform data is by Fourier transforming the samplesfrom each line to arrive at an amplitude versus frequency spectrum.By stacking the spectra side-by-side in time order, a frequency-time spectrogram can be produced.Additional information about this dataset and the instrument whichproduced it can be found elsewhere in this catalog. An overview ofthe data in this data set can be found in Gurnett et al. [1986] anda complete instrument description can be found in Scarf and Gurnett[1977]. SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = 0.000034722 MINIMUM_SAMPLING_PARAMETER = N/A MAXIMUM_SAMPLING_PARAMETER = N/A SAMPLING_PARAMETER_INTERVAL = 0.000034722 MINIMUM_AVAILABLE_SAMPLING_INT = 0.000034722 SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = PLASMA WAVE WAVEFORM NOISE_LEVEL = 0.000005 DATA_SET_PARAMETER_UNIT = VOLT/METER (Data not absolutely calibrated)
DATA_SET_RELEASE_DATE 1993-02-01T00:00:00.000Z
START_TIME 1985-11-08T07:04:08.649Z
STOP_TIME 1986-02-22T08:41:34.186Z
MISSION_NAME VOYAGER
MISSION_START_DATE 1972-07-01T12:00:00.000Z
MISSION_STOP_DATE N/A (ongoing)
TARGET_NAME URANUS
TARGET_TYPE PLANET
INSTRUMENT_HOST_ID VG2
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 ARCHIVED
CONFIDENCE_LEVEL_NOTE This data set includes all available waveform receiver dataobtained during the Uranus encounter. There has been no attemptto clean various interference signals from the data. Most of thesecan normally be easily seen in frequency-time spectrograms asnarrowband, fixed-frequency tones. The most common include narrow-band tones at 2.4 and 4.8 kHz which are power supply harmonics.There is sometimes a tone near 1.7 kHz which is associated withthe operation of the spacecraft gyros. The spacecraft taperecorder results in a rather intense band in the frequency rangeof a few hundred Hz. There are few times when the data in thisfrequency range can be used. However, there are times when thereal signals in this frequency range can exceed the intensity ofthe interference sufficiently so that the frequency range neara few hundred Hz can be used. Use of the spectrum analyzer datacan be of use to determine when these time periods occur. Thestepper motor of the LECP instrument also interferes in thefrequency range of a few hundred Hz, but for periods of a fewseconds.The LECP interference is very intense and captures the automaticgain control so that real signals, even where there is nointerference, will appear to decrease in amplitude until the LECPinterference fades in amplitude. The PLS instrument periodicallyinterferes at 400 Hz and odd harmonics because of a 400-Hz squarewave used to modulate a grid in the detector. The PLS interferencelasts for several seconds and ends abruptly. Telemetry errorsresult in a fairly graceful degradation of the waveform data.Assuming the telemetry errors are randomly occurring bursts, theytypically appear as an enhanced background level in the spectrum.Since the bursts are short, their Fourier transform is a broadbandspectrum. When looking for relatively narrowband features orfeatures with distinct frequency-time characteristics, the resultof the bursts simply reduce the signal-to-noise in the spectrum.One way of reducing the effect of burst telemetry errors is to passthe waveform data through a low-pass filter to despike it, prior torunning the Fourier transform. The waveform data is not subjectto the negative effects of the failure in the Voyager 2 FlightData System which reduces the sensitivity of the spectrum analyzerand affects the calibration above 1 kHz. In fact, use of the 1 -12 kHz waveform data is an effective way of avoiding the problemswith the spectrum analyzer data in this frequency range.
CITATION_DESCRIPTION Kurth, W.S., VG2-U-PWS-1-EDR-WFRM-60MS-V1.0, VG2 URA PWS RAW EXPERIMENT WAVEFORM 60MS V1.0, NASA Planetary Data System, 1993.
ABSTRACT_TEXT This data set consists ofelectric field waveform samples from the Voyager 2 Plasma WaveReceiver waveform receiver obtained during the Uranus encounter.The waveforms are collections of 4-bit samples of the electricfield measured by the dipole electric antenna at a rate of 28,800samples per second. 1600 samples are collected in 55.56 msecfollowed by a 4.44-msec gap. Each 60-msec interval constitutes aline of waveform samples. The data set includes about 271 frames ofwaveform samples consisting of up to 800 lines, each. Thetelemetry format for the waveform data is identical to that forimages, hence the use of line and frame as constructs in describingthe form of the data. The waveform is sampled through a bandpassfilter with a passband of 40 Hz to 12 kHz. The 4-bit samplesprovide sixteen digital values of the electric field with alinear amplitude scale, but the amplitude scale is arbitrarybecause of the automatic gain control used in the waveformreceiver. The instantaneous dynamic range afforded by the 4bit samples is about 23 db, but the automatic gain control allowsthe dominant signal in the passband to be set at the optimumlevel to fit within the instantaneous dynamic range. With the gaincontrol, the overall dynamic range of the waveform receiveris about 100 db.
PRODUCER_FULL_NAME DR. WILLIAM S. KURTH
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