DE1 PWI Digitized Wideband Archive Binary File Format
=====================================================

This file describes the format of the binary data files containing the
digitized analog wideband measurements made by the Plasma Wave Instrument
(PWI) on the Dynamics Explorer 1 (DE1) spacecraft.  Each file contains
all available data for one minute of time divided into records each
containing 10 milliseconds of sampled waveform.  Due to variations in
analog tape playback speed during digitization, difficulties in decoding
analog time code, poor quality or missing data, and various errors, these
records are of variable length even though the digitizing sampling rate
was held constant.  Also due to the same reasons, not all data in every
available minute could be recovered, so many files do not contain the
nominal 6000 records.

The data file names are patterned after the following template:

  DE1_bw_yyyy_ddd_hhmm_v.DAT

where
   bw   is either 01, 10, or 40 for the data bandwidth in kHz
   yyyy is the 4-digit year
   ddd  is the 3-digit day of year
   hh   is the hour of day
   mm   is the minute of hour
   v    is a version indicator beginning with 0

Multiple versions may exist due to data being available from multiple
ground stations with slightly different characteristics or due to
multiple digitizing passes yielding unresolved differences.

Each data file has a corresponding DE1_bw_yyyy_ddd_hhmm_v.LBL file which
contains ASCII text similar to a Planetary Data System label providing
important information beyond that contained in the data file itself and
also describing the data file binary format.  In particular note the
value of the SAMPLE_RATE item in the WAVEFORM_SERIES object, which is
the median value derived from all records in the data file.

There is only one record type, described below.  Note that all multi-byte
values are in most-significant-byte-first (MSB, big-endian) format.

Binary Record Format
====================

byte                                                                          
offset  description                                                           
------  ----------------------------------------------------------------
     0  REMAINING_ROW_BYTES:  2-byte MSB unsigned integer giving the
        number of bytes remaining in this record, or the offset to the
        next record.  The total record size is this value plus 2.

     2  MILLISECOND_OF_MINUTE:  2-byte MSB unsigned integer giving the
        millisecond of minute of the beginning of the 10-millisecond
        interval contained in this record.

     4  FLAG:  2-byte MSB unsigned integer indicating digitized (0) or
        interpolated (1) timecode.

     6  SAMPLES:  2-byte MSB unsigned integer giving the number of 1-byte
        waveform samples that follow.

     8  WAVEFORM_SERIES:  variable number of 1-byte unsigned integers
        ranging from 0 to 255.  The zero-voltage reading is ideally 127.5
        with 0 being the maximum of one polarity and 255 being the
        maximum of the opposite polarity.  There is no gain or other
        calibration information available, so only a relative power
        spectrum may be derived from these data.


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