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VG2 NEP PWS RAW EXPERIMENT WAVEFORM 60MS V1.0 (PDS)

NSSDCA ID: PSFP-00591

Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1989-06-06 to 1989-09-27

Description

This description was generated automatically using input from the Planetary Data System.

Data Set Overview ================= This data set consists of electric field waveform samples from the Voyager 2 Plasma Wave Receiver waveform receiver obtained during the Neptune encounter. The waveforms are collections of 4-bit samples of the electric field measured by the dipole electric antenna at a rate of 28,800 samples per second. 1600 samples are collected in 55.56 msec followed by a 4.44-msec gap. Each 60-msec interval constitutes a line of waveform samples. The data set includes about 271 frames of waveform samples consisting of up to 800 lines, each. The telemetry format for the waveform data is identical to that for images, hence the use of line and frame as constructs in describing the form of the data. The waveform is sampled through a bandpass filter with a passband of 40 Hz to 12 kHz. The 4-bit samples provide sixteen digital values of the electric field with a linear amplitude scale, but the amplitude scale is arbitrary because of the automatic gain control used in the waveform receiver. The instantaneous dynamic range afforded by the 4 bit samples is about 23 db, but the automatic gain control allows the dominant signal in the passband to be set at the optimum level to fit within the instantaneous dynamic range. With the gain control, the overall dynamic range of the waveform receiver is about 100 db. The automatic gain control gain setting is not returned to the ground, hence, there is no absolute calibration for the data. However, by comparing the waveform spectrum derived by Fourier transforming the waveform to the spectrum provided by the spectrum analyzer data, an absolute calibration may be obtained in most cases. The data may be plotted in raw form to show the actual waveform; this is useful for studying events such as dust impacts on the spacecraft. But the normal method of analyzing the waveform data is by Fourier transforming the samples from each line to arrive at an amplitude versus frequency spectrum. By stacking the spectra side-by-side in time order, a frequencytime spectrogram can be produced. Additional information about this dataset and the instrument which produced it can be found elsewhere in this catalog. An overview of the data in this data set can be found in Gurnett et al. [1989] and a complete instrument description can be found in Scarf and Gurnett [1977]. Parameters ========== Derived Parameters -----------------Sampling Parameter Name : time Sampling Parameter Resolution : 0.000034722 seconds Minimum Sampling Parameter : n/a Maximum Sampling Parameter : n/a Sampling Parameter Interval : 0.000034722 seconds Minimum Available Sampling Interval : 0.000034722 seconds Data Set Parameter Name : plasma wave waveform Noise Level : 0.000005 Data Set Parameter Unit : volt/meter (Data not absolutely calibrated) Plasma wave waveform: A plasma wave waveform is a time series of measurements of the electric or magnetic field component of the wave spectrum taken through a broadband filter. The temporal sample rate is normally such that samples are made at more than twice the analysis filter bandwidth. A typical waveform will consist of the order of 1000 contiguous samples of between 4 and 12 bits each. For a 10-kHz analysis bandwidth, the sample rate would normally be approximately 25 kHz or 25,000 samples/second. Once received, the waveforms are typically Fourier transformed in order to provide an amplitude versus frequency spectrum across the analysis bandwidth. The sample rate, then, is required to be at least a factor of two greater than the filter bandwidth in order to avoid aliasing in the transformed spectrum. The spectra can be stacked side-by-side in time to build a frequency-time spectrogram (that is, amplitude as a function of time and frequency) in order to identify the temporal and spectral variations in the wave spectrum. Alternately, the untransformed time series can be used to study the details of the waveform. This has been useful for measuring small-scale structures in the plasma and for identifying the signature of micron-sized dust impact on the spacecraft. Measured Parameters ------------------Electric field component: A measured parameter equaling the electric field strength (e.g. in milli-volts per meter) along a particular axis direction. Wave magnetic field intensity: A measured parameter equaling the magnetic field strength in a specific frequency passband (in MKS unit: volts/meter) measured in a single sensor or antenna. Wave electric field intensity: A measured parameter equaling the electric field strength in a specific frequency passband (in MKS unit: volts/meter) measured in a single sensor or antenna. Processing ========== The data files in this data set were created using the 'CDREF' software. CDREF ----Node ID : IMAGING Software Release Date : 1990-04-07 Cognizant Full Name : MR. JASON J. HYON CDREF is primarily a data format translation routine which is used to convert Voyager PWS EDR tape files to CD-ROM files. CDREF is written in FORTRAN and is not available for public use. The EDR, or Engineering Data Records, are produced at Multi-mission Image Processing Laboratory at JPL as the uncalibrated, full-resolution PWS spectrum analyzer data set. The CD files contain uncalibrated, full-resolution PWS data with minimal ancillary data in a simplified format which may be used in CDROM production.

These data are available on-line from the Planetary Data System (PDS) at:

https://pds-ppi.igpp.ucla.edu/data/VG2-N-PWS-1-EDR-WFRM-60MS-V1.0/

Alternate Names

  • VG2-N-PWS-1-EDR-WFRM-60MS-V1.0

Discipline

  • Planetary Science: Fields and Particles

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II

 

Personnel

NameRoleOriginal AffiliationE-mail
Prof. Donald A. GurnettData ProviderUniversity of Iowa
Dr. William S. KurthGeneral ContactUniversity of Iowawsk@space.physics.uiowa.edu
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