PDS_VERSION_ID     = PDS3
RECORD_TYPE        = STREAM
OBJECT             = TEXT
  PUBLICATION_DATE = 2016-05-16
  NOTE             = "VPDS_EVENT_XYZAMP_FORMAT document
                      in the Viking Lander 2 seismology experiment archive."
END_OBJECT         = TEXT
END

VPDS EVENT XYZAMP FORMAT

The data file VPDS_EVENT_XAMP.CSV is the full raw X-axis Event mode envelope
(amplitude) record of the Viking Seismometer data. In Event mode, readings were
compressed in the instrument itself by recording the number of positive- going
zero crossings in a 1.01s interval, and recording an envelope value generated by
digital filtering.
 
The file was generated by parsing the raw ('VUSA') files, and where the High
mode flag was detected and valid data found with the standard 51-point length,
the X-axis envelope readings are extracted and placed into a single record (one
line) in this file. The record number in the first column is that in the
summary/index file (EVENT_WIND_SUMMARY.TAB) allowing location of the original
raw record, and relation to the closest meteorological data.

Column 2 is the reconstructed lander time (Local Mean Solar Time) in decimal
Sols, starting from Sol 0 (landing). LMST is calculated from the Sol, hour,
minute and second of the start of the record from the VUSA file (itself
reconstructed from the lander clock), noting that one mean solar day on Mars is
88775.24 seconds. The subsequent 4 columns are the the Sol, hour, minute and
second of the start of the record.

The subsequent 4 columns are the reconstructed Sol, hour, minute and second 
of the start of the record.

The following 51 columns are the X-axis envelope values (7 bit unsigned
integers). The record is 51.5s long. The corresponding Y- and Z- axis envelopes
are found in the VPDS_EVENT_YAMP.CSV and VPDS_EVENT_ZAMP.CSV files. The number
of positive zero crossings are found in VPDS_EVENT_XFREQ.CSV,
VPDS_EVENT_YFREQ.CSV, and VPDS_EVENT_ZFREQ.CSV.

Original VUSA files are archived at JAXA.

The data files were generated by R. Lorenz on 3/16/2016 and may be cited by
'R. D. Lorenz, Y. Nakamura, J. Murphy, Viking Seismometer Data Restoration and
Meteorological Application, VL2-M-SEIS-5-RDR-V1.0, Planetary Data System, 
2016'. This work was supported by the NASA Mars Data Analysis Program (MDAP) 
Grant, Viking Lander Meteorology and Seismology, NNX12AJ47G.

Column  1
An ordinal number indicating the record in the present file.

Column 2
The time in decimal sols on which the data were acquired.

Column 3
The sol number of the mission on which the data were acquired.

Column 4 
The hour of acquisition start.

Column 5
The minute of acquisition start.

Column 6
The second of acquisition start. Note that High rate data are acquired at 
20.2 Hz, thus the 83-sample record corresponds to about 4 seconds.

Column 7 
The first X-axis envelope reading.

Column 8
The second X-axis envelope reading.

...

Column 55
The 51st X-axis envelope reading.


This description was generated by R. Lorenz on 3/18/2016.