PDS_VERSION_ID          = PDS3
RECORD_TYPE             = STREAM
OBJECT                  = TEXT
  PUBLICATION_DATE        = 2006-11-07
  NOTE                    = "
    DATATIPS.TXT provides quick-start help for anyone wanting to write
    software to make use of the raw Voyager PWS waveform data on this
    volume."
END_OBJECT              = TEXT
END

========================================================================
DATA FILE OVERVIEW
========================================================================

The binary files containing the raw Voyager PWS electric field waveform
samples are found under directories named

  DATA/Pn/V112nn

where Pn indicates a spacecraft clock (SCLK) partition number and
V112nn ranges from V11201 to V11235.  The data files are named

  Cmmmmmnn.DAT

where mmmmm is the SCLK modulo 65536 (16-bit) counter and nn is the SCLK
modulo 60 counter.  The modulo 60 counter changes once every 48 seconds
and each data file contains all of the available waveform samples
obtained during one of these 48 second intervals.  A SCLK sub-interval
called a line count ranges from 1 through 800 during this time and
corresponds to each of the possible 800 data records within a file.
Each file record is 1024 bytes in length and the first record is a
header record which contains various engineering parameters, but no
waveform data.  Details about each file can be found in detached PDS
labels named with corresponding SCLK values

  Cmmmmmnn.LBL

The common description of the file header fields and record header
fields can be found in each directory in files named

  WFENGHDR.FMT and WFROWPFX.FMT

These files along with information in the CATALOG and DOCUMENT
directories provide full details.

========================================================================
DATA PROCESSING OVERVIEW
========================================================================

There are generally two ways to use these data:

  1.  Plot, list, or listen to the time-domain electric field samples.

  2.  Plot or list the frequency-domain power spectra resulting from
      processing the electric field samples through an FFT.

Although advanced analysis details are beyond the scope of this
document, the most important first steps of extracting individual
samples and associating them with time are addressed.

The following facts are essential in using these data:

  1.  The electric field waveform samples are 4-bit values
      (range 0 - 15).

  2.  The amplitudes are modified by an AGC, so there is a varying
      amplitude scale.

  3.  There is no direct way to calibrate the samples to scientific
      units.

  4.  The sample rate is 28,800 samples per second.

  5.  The detector utilizes a bandpass of 40 Hz to 12 kHz.

  6.  Each line (record) contains 1600 continuous samples with a time
      gap equivalent to 128 missing samples before the next available
      line.

The most important details needed to extract the waveform samples are:

  1.  Reliable information about an individual file can be found in an
      ASCII label beginning at byte 249 in the first record (where the
      first byte is byte 1).  The format is:
      "VOYAGER-n PWS  n/nnnnn.nn yyyy-mm-ddThh:mm:ss.sssZ"

  2.  The time offset of the beginning of a set of waveform samples
      (relative to the time in the ASCII label above) should be
      calculated from the SCLK line count, which is a 2-byte MSB integer
      beginning at byte 23 of data records.  This offset is simply:
      0.06 seconds * ( line - 1 ).

  3.  The 800 bytes holding 1600 4-bit waveform samples begins at byte
      221 of each data record.

See the EXTRAS/SOFTWARE directory on this volume for annotated code
illustrating how to extract the waveform samples.