Data Set Overview
  =================
    This data set consists of electric field waveform samples from
    the Voyager 2 Plasma Wave Subsystem waveform receiver obtained
    during the entire mission.  Data after 2006-03-07 will be added to the
    archive on subsequent volumes.  The data set encompasses all
    waveform observations obtained in the cruise mission phases
    before, between, and after the Jupiter, Saturn, Uranus, and
    Neptune encounter phases as well as those obtained during the
    four encounter phases.

    The Voyager 2 spacecraft travels from Earth to beyond 80 AU over
    the course of this data set.  To provide some guidance on when
    some key events occurred during the mission, the following table
    is provided.

    Date         Event
    1977-08-20   Launch
    1979-07-02   First inbound bow shock crossing at Jupiter
    1979-08-03   Last outbound bow shock crossing at Jupiter
    1981-08-24   First inbound bow shock crossing at Saturn
    1981-08-31   Last outbound bow shock crossing at Saturn
    1982-04-26   10 AU
    1983-08-30   Onset of first major LF heliospheric radio event
    1986-01-24   First inbound bow shock crossing at Uranus
    1986-01-29   Last outbound bow shock crossing at Uranus
    1986-05-26   20 AU
    1989-08-07   30 AU
    1989-08-24   First inbound bow shock crossing at Neptune
    1989-08-28   Last outbound bow shock crossing at Neptune
    1992-07-06   Onset of second major LF heliospheric radio event
    1993-05-08   40 AU
    1996-10-10   50 AU
    2000-01-27   60 AU
    2002-11-01   Onset of third major LF heliospheric radio event
    2003-04-21   70 AU
    2006-07-01   80 AU
    2009-09-03   90 AU
    2012-11-04   100 AU

  Data Sampling
  =============
    The waveform is sampled at 4-bit resolution through a bandpass
    filter with a passband of 40 Hz to 12 kHz.  1600 samples are
    collected in 55.56 msec (at a rate of 28,800 samples per second)
    followed by a 4.44-msec gap.  Each 60-msec interval constitutes
    a line of waveform samples.  The data set includes frames of
    waveform samples consisting of up to 800 lines, or 48 seconds,
    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.


  Data Processing
  ===============
    Because there is no direct method for calibrating these data and
    because the raw format of packed, 4-bit samples is
    space-efficient, these data are not processed for archiving.
    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 frequency-time
    spectrogram can be produced.


  Data
  ====
    The waveforms are collections of samples of the electric field
    measured by the dipole electric antenna at a rate of 28,800
    samples per second.  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.


  Ancillary Data
  ==============
    None


  Coordinates
  ===========
    The electric dipole antenna detects electric fields in a dipole
    pattern with peak sensitivity parallel to the spacecraft x-axis.
    However, no attempt has been made to correlate the measured
    field to any particular direction such as the local magnetic
    field or direction to a planet.  This is because the spacecraft
    remains in a 3-axis stabilized orientation almost continuously,
    and these data are not obtained during the infrequent
    calibration turns.  Furthermore, the automatic gain control
    feature would tend to counteract any orientation-dependent
    amplitude variations.

Overview
  ========
    The Spacecraft Event Time (SCET) originally included in
    Cxxxxxxx.DAT files is very often incorrect or missing (zero),
    especially through the Jupiter encounter.  It is important to
    use the SCET which is provided in the Cxxxxxxx.LBL file for the
    .DAT file your are using.  The SCET from the .LBL file is the
    best known time for the data, based on the use of the
    appropriate SPICE kernel.  The originally-provided data file
    includes no consistently present spacecraft identification.  The
    SPACECRAFT_ID in the .LBL file is the most reliable indicator of
    the host spacecraft.  Because the .LBL files are detached from
    the .DAT files, it is possible to lose the SCET and
    SPACECRAFT_ID information.  Therefore, an ASCII entry has been
    added to spare words in the .DAT file header at byte 249
    including SPACECRAFT_ID, spacecraft clock partition (rollover
    indicator), and SCET.  In both the PDS .LBL file and this ASCII
    SCET entry in the .DAT file header, the SCET refers to the time
    of the first sample of the 48-second frame, assuming all data
    are present.  For example, if the first 10 seconds of data is
    missing, the SCET provided in these two locations would be 10
    seconds earlier than that of the first data present in the
    frame.  Given this time, the line and sample number of a
    measurement provides an accurate time for the sample with the
    understanding that the time between the beginning of two
    adjacent lines is 60 milliseconds and the time between samples
    is 34.72 microseconds.

    This data set includes all available waveform receiver data
    obtained from launch through the end of 2006.


    Note that for data acquired during the Voyager 2 Jupiter
    Encounter mission phase, it is usually the case that the first
    16 samples (8 bytes) of waveform data per data line are invalid.
    Hence, it is strongly recommended that these bytes be skipped by
    any analysis software.

    Beginning on 1998-09-15, the telecom performance would no longer
    support playing data off the tape recorder at its lowest
    playback rate.  As a work-around, four data lines of every five
    are discarded during playback beginning with this date.  For
    various reasons, the one data line out of five which is returned
    to the ground are repeated 5 times in the *.DAT files.  The
    DATA_LINES parameter in the *.LBL file, therefore, counts only
    UNIQUE valid data lines; the maximum DATA_LINES after this date,
    then is 160.

    There has been no attempt to clean various interference signals
    from the data.  Most of these can normally be easily seen in
    frequency-time spectrograms as narrowband, 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 with the operation of the
    spacecraft gyros.  The spacecraft tape recorder results in a
    rather intense band in the frequency range of a few hundred
    Hertz.  There are few times when the data in this frequency
    range can be used.  However, there are times when the real
    signals in this frequency range can exceed the intensity of the
    interference sufficiently so that the frequency range near a few
    hundred Hz can be used.  Use of the spectrum analyzer data can
    be of use to determine when these time periods occur.  The
    stepper motor of the LECP instrument also interferes in the
    frequency range of a few hundred Hz, but for periods of a few
    seconds.  The LECP interference is very intense and captures the
    automatic gain control so that real signals, even where there is
    no interference, will appear to decrease in amplitude until the
    LECP interference fades in amplitude.  The PLS instrument
    periodically interferes at 400 Hz and odd harmonics because of a
    400-Hz square wave used to modulate a grid in the detector.  The
    PLS interference lasts for several seconds and ends abruptly.
    Telemetry errors result in a fairly graceful degradation of the
    waveform data.  Assuming the telemetry errors are randomly
    occurring bursts, they typically appear as an enhanced
    background level in the spectrum.  Since the bursts are short,
    their Fourier transform is a broadband spectrum.  When looking
    for relatively narrowband features or features with distinct
    frequency-time characteristics, the result of the bursts simply
    reduce the signal-to-noise in the spectrum.  One way of reducing
    the effect of burst telemetry errors is to pass the waveform
    data through a low-pass filter to despike it, prior to running
    the Fourier transform.  The waveform data is not subject to the
    negative effects of the failure in the Voyager 2 Flight Data
    System which reduces the sensitivity of the spectrum analyzer
    and affects the calibration above 1 kHz.  In fact, use of the
    1-12 kHz waveform data is an effective way of avoiding the
    problems with the spectrum analyzer data in this frequency
    range.

    Beginning on about May 20, 2001 the Voyager 2 wideband receiver
    began to display degraded operation and by September of 2002, the
    receiver showed virtually no response.  Attempts to playback
    wideband data from Voyager 2 have ceased.

  File Edits
  ==========
    Minor edits have been applied to the original EDR files in order
    to provide reliable spacecraft and time identification and to
    adjust for missing file header records.  Detailed format
    information is provided elsewhere, but briefly, an ASCII text
    string has been inserted starting at byte 249 of the first
    record of each file.  This string provides the most reliable
    spacecraft and time identification and is in the format:

      VOYAGER-n PWS  n/nnnnn.nn yyyy-mm-ddThh:mm:ss.sssZ\0\0

    In cases where the EDR file header record was missing, a pseudo
    header was created by duplicating the first available record of
    the file, inserting the ASCII text string starting at byte 249,
    and zero-filling the remaining bytes of the record.  Since these
    files are a possible source of confusion for anyone attempting
    to extract detailed engineering information from EDR headers,
    they are listed below.  The first element of the directory path
    is actually the volume name.

      VGPW_2001/DATA/P2/V2P2_001/C1848121.DAT
      VGPW_2001/DATA/P2/V2P2_002/C1871937.DAT
      VGPW_2001/DATA/P2/V2P2_056/C2044131.DAT
      VGPW_2001/DATA/P2/V2P2_059/C2047252.DAT
      VGPW_2001/DATA/P2/V2P2_060/C2047327.DAT
      VGPW_2001/DATA/P2/V2P2_060/C2047328.DAT
      VGPW_2001/DATA/P2/V2P2_060/C2047330.DAT
      VGPW_2001/DATA/P2/V2P2_066/C2053850.DAT
      VGPW_2001/DATA/P2/V2P2_066/C2053851.DAT
      VGPW_2001/DATA/P2/V2P2_083/C2056838.DAT
      VGPW_2001/DATA/P2/V2P2_084/C2056929.DAT
      VGPW_2001/DATA/P2/V2P2_094/C2058832.DAT
      VGPW_2001/DATA/P2/V2P2_122/C2072015.DAT
      VGPW_2001/DATA/P2/V2P2_126/C2082839.DAT
      VGPW_2001/DATA/P2/V2P2_135/C3168857.DAT
      VGPW_2001/DATA/P2/V2P2_145/C4798011.DAT


  Review
  ======
    This archival data set was examined by a peer review panel prior
    to its acceptance by the Planetary Data System (PDS).  The peer
    review was conducted in accordance with PDS procedures.

    Prior to creation of the final version of the archival data set,
    key elements of the archive were distributed for preliminary
    review.  These included electronic versions of example PDS
    labels, CATALOG files, and Software Interface Specifications.
    These materials were distributed to PDS personnel, the
    experiment investigator, and others, as appropriate.