Data Set Overview
  =================
    This data set consists of electric field spectrum analyzer data from
    the Voyager 1 Plasma Wave Subsystem obtained during the entire
    mission.  Data after 2019-12-30 will be added to the archive on subsequent
    volumes.  The data set encompasses all spectrum analyzer
    observations obtained in the cruise mission phases before, between,
    and after the Jupiter and Saturn encounter phases as well as those
    obtained during the two encounter phases.

    The Voyager 1 spacecraft travels from Earth to beyond 90 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
    1977-09-05   Launch
    1979-02-28   First inbound bow shock crossing at Jupiter
    1979-03-22   Last outbound bow shock crossing at Jupiter
    1980-11-11   First inbound bow shock crossing at Saturn
    1980-11-16   Last outbound bow shock crossing at Saturn
    1981-02-20   10 AU
    1983-08-30   Onset of first major LF heliospheric radio event
    1984-06-19   20 AU
    1987-04-08   30 AU
    1990-01-09   40 AU
    1992-07-06   Onset of second major LF heliospheric radio event
    1992-10-10   50 AU
    1995-07-14   60 AU
    1998-04-18   70 AU
    2001-01-25   80 AU
    2002-11-01   Onset of third major LF heliospheric radio event
    2003-11-05   90 AU
    2004-12-16   Termination shock crossing
    2006-08-16   100 AU
    2009-05-31   110 AU
    2012-03-16   120 AU
    2012-10-23   First interstellar plasma oscillation event
                    (only see in wideband data)
    2013-04-09   Second interstellar plasma oscillation event
    2014-05-13   Third interstellar plasma oscillation event
    2015-01-01   130 AU
    2015-09-05   Fourth interstellar plasma oscillation event

  Data Sampling
  =============
    This data set consists of average and peak wave electric field
    intensities accumulated over 1-hour intervals from the Voyager 1
    Plasma Wave Receiver spectrum analyzer obtained during the entire
    mission.  For each 1-hour time interval squares of the calibrated
    electric field measurements obtained during each hour-long interval
    in each of the 16 spectrum analyzer channels are summed and then
    divided by the number of measurements.  The square root of the
    resulting value is obtained and stored as the average electric field
    strength for the respective channel.  During the same hour-long
    interval, the maximum electric field strength acquired in each of
    the 16 channels is also recorded and stored as the peak electric
    field strength for the respective channel.  Hence, for each hour, an
    average and peak electric field spectrum from 10 Hz to 56.2 kHz is
    obtained.  The 16 spectrum analyzer channels have center frequencies
    that range from 10 Hertz to 56.2 kiloHertz and are logarithmically
    spaced in frequency, four channels per decade.  The time associated
    with each peak and average spectrum is the time of the beginning of
    the averaging interval.  Given variations in the sweep rate of the
    instrument (from a minimum of 4 seconds/sweep to a maximum of 96
    seconds/sweep) the maximum number of samples in an hour-long
    interval can range from 900 to 38.  Data gaps within the interval
    can further reduce the number of samples.

    During data gaps where complete spectra are missing, no entries
    exist in the file, that is, the gaps are not zero-filled or tagged
    in any other way.


  Data Processing
  ===============
    The spectrum analyzer data are a continuous (where data are
    available) low resolution data set which provides wave intensity as
    a function of frequency (16 log-spaced channels) and time (one
    spectrum per time intervals ranging from 4 seconds to 96 seconds in
    the full-resolution data set, depending on telemetry mode.) This
    data set includes one-hour average and peak values for each channel.
    The data are typically plotted as amplitude vs. time for one or more
    of the channels in a strip-chart like display, or can be displayed
    as a frequency-time spectrogram using a gray- or color-bar to
    indicate amplitude.  With only sixteen channels, it is usually best
    to stretch the frequency axis by interpolating from one frequency
    channel to the next either linearly or with a spline fit.  One must
    be aware if the frequency axis is stretched that more resolution may
    be implied than is really present.

    The measurements provided in the average and peak electric field
    spectra included in this data set are in units of electric field
    (volts/meter).

    Spectral density units may be obtained by dividing the square of the
    electric field value by the nominal frequency bandwidth of the
    corresponding spectrum analyzer channel.

      specdens = (efield(ichan))**2 / bandwidth(ichan)

    Finally, power flux may be obtained by dividing the spectral density
    by the impedance of free space in ohms:

      pwrflux = (efield(ichan))**2 / bandwidth(ichan) / 376.73

    The center frequencies and bandwidths of each PWS spectrum analyzer
    channel for each Voyager spacecraft are given below:

      VOYAGER 1 PWS SPECTRUM ANALYZER
      Voyager-1
      Channel    Center Frequency      Bandwidth
          1          10.0  Hz           2.99 Hz
          2          17.8  Hz           3.77 Hz
          3          31.1  Hz           7.50 Hz
          4          56.2  Hz          10.06 Hz
          5         100.   Hz          13.3  Hz
          6         178.   Hz          29.8  Hz
          7         311.   Hz          59.5  Hz
          8         562.   Hz         106.   Hz
          9           1.00 kHz        133.   Hz
         10           1.78 kHz        211.   Hz
         11           3.11 kHz        298.   Hz
         12           5.62 kHz        421.   Hz
         13          10.0  kHz        943.   Hz
         14          17.8  kHz       2110    Hz
         15          31.1  kHz       4210    Hz
         16          56.2  kHz       5950    Hz

    In an attempt to remove many of the noise spikes caused by telemetry
    bit errors, raw data numbers are compared to the maximum thresholds
    given in:

       DATA/HOUR1/FILTER.CSV

    If a value for any channel is above the given maximum threshold for
    that channel then the value is eliminated from the average.  Near
    planetary encounters raw values were not subject to elimiation when
    exceeding maximum threshold values.  This is represented by using the
    maximum possible 8-bit value, 255 as the cutoff.  Threshold filter
    values may be changed in the future.
    Additional information about this data set and the instrument
    which produced it can be found elsewhere in this catalog.  A
    complete instrument description can be found in
    [SCARF&GURNETT1977].


  Data
  ====
    The average and peak spectrum analyzer data are a continuous
    (where data are available) low resolution data set which provides
    wave intensity as a function of frequency (16 log-spaced channels)
    and time (one spectrum per hour).  Each sample is a floating point
    electric field strength in units of volts/meter.


  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 usually
    remains in a 3-axis stabilized orientation almost continuously.
    Furthermore, even during the rare times when the spacecraft is
    turned, the hour-long averages in this data set would almost
    completely mask any modulation caused by the rotating dipole
    antenna pattern.

Overview
  ========
    This data set includes all available spectrum analyzer data acquired
    during the Voyager 1 mission to date.  The data set near planetary
    encounters has been cleaned prior to averaging for periodic noise
    spikes due to a stepper motor operating on the LECP and a modulated
    grid within the PLS.  Other spikes of noise below 1 kiloHertz due to
    the operation of attitude control thrusters have not been removed.
    Telemetry errors appear in the full resolution data set as
    randomly-occurring spikes over the entire frequency range.  No
    attempt has been made to remove such spikes because of the
    difficulty of differentiating between them and valid data, i.e. real
    bursts of wave activity.  The spikes, therefore, can adversely
    affect the averaged values.  The 17.8-Hz channel is sometimes
    contaminated by interference from the PRA instrument, depending on
    that instrument's mode.  This interference is at a relatively
    constant level.

  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.