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Getting housekeeping data using MIT tools


MIT tools can be used to decommutate telemetry data, both real-time and SSR dumps. This memo describes how to extract engineering and DEA housekeeping information.

Available Processed Data

If the data of interest was dumped more than a few hours ago, it is likely in the archive. ACISpy may be a more efficient method of examining the data and producing plots.

Running MIT Tools on a Data Dump File

You can use MIT tools to extract both the engineering and DEA housekeeping values from SSR dump files and real-time files. The engineering data is what appears on the ACIS R/T web pages and the DEA housekeeping on the PMON web pages.

These instructions have been adapted from Peter Ford's ACIS Quick-Look Processing Guide, Section 13 on troubleshooting.

  1. Log onto colossus-v as acisdude. The GOT data files are at the OCC and cannot be accessed from the HEAD LAN.

  2. To get the MIT tools in your path:
    source /home/acisdude/setup_psci
    WARNING! This changes your acisdude setup in ways that may make other tasks not work correctly. Always start new tasks in a clean environment!
    This sets up useful shortcuts such as $SSR_DIR and $RT_DIR, which point to the directories for SSR and real-time dump data.
    This also puts the "man" pages for the MIT tools in your path, for further reading.

  3. Move to a working directory.
    cd /home/acisdude/ceg_test
    Remember that the acisdude directory on colossus-v is not infinitely large. Come back and clean up unnecessary files later.

  4. Find and copy the data dump file to your working directory. SSR dump files are in the directory /dsops/critical/GOT/input or $SSR_DIR. The file names include the start and end times of the data in the file. For example:
    ls $SSR_DIR
    ...
    2016_082_0348_082_1117_Dump_EM_86985.gz
    covers day 82, from 03:48Z to 11:17Z. Find the files that cover the time period of interest and copy into your working directory.

    You can also run the same procedure on the real-time telemetry files. These files are in the directory /dsops/critical/GOT/RT_raw or $RT_DIR and are named:
    ls $RT_DIR
    raw_telem_yyyy-mm-dd_HH:MM:SS
    The date and time are when the file was first written to. These files only include data during DSN contacts, so have very sparse time coverage. Once the dump data appears, it is usually prefered over the real-time data.

  5. Now run the tool getnrt, which reads the telemetry data and extract ACIS packets, and pkt2dea or pkt2eng, which convert the housekeeping channels to ASCII.

    getnrt -O 2016_082_0348_082_1117_Dump_EM_86985.gz | pkt2dea -s > acis-dea.txt

    or

    getnrt -O 2016_082_0348_082_1117_Dump_EM_86985.gz | pkt2eng -s > acis-eng.txt

    It doesn't matter if the telemetry data file is gzipped or not. The tools will refuse to overwrite files, so make sure to pick a new name or delete the old file, if running more than once.

    The output consists of a header line followed by one line per engineering or DEA housekeeping packet in the input packet file. The data fields are comma separated by default. Non-numeric data fields are enclosed in double quotes. The header contains the ASCII mnemonics for the data fields, separated by the delimiter.

    The time is always formatted as year, day-of-year, and seconds-of-the-day.

    Each tool has optional flags, which may be of use. A few of them are listed below. Consult the man pages for the full list.

    • getnrt: There are multiple ways to extract timing information. If you don't trust the time values in the output, try something else. See the flags -G, -M, -O, or -t in the man file.
    • pkt2dea and pkt2eng: The -s flag skips the first data packet, since it's often incomplete. Recommended!
    • pkt2dea and pkt2eng: The year is assumed to be the current calendar year. If not, use the -y flag: pkt2dea -s -y 2012.
    • pkt2dea and pkt2eng: By default the field delimiter is a comma. Use the -d flag to change the delimiter to something else, such a single space: pkt2dea -s -d ' '
    • pkt2dea and pkt2eng: Want to know all the possible mnemonics in the housekeeping data? Use pkt2dea -N all by itself (without the pipe from getnrt or the redirect to the output file.)
    • pkt2dea and pkt2eng: By default all housekeeping channels are included in the output file, but you can be more selective. Select particular housekeeping channels with the -p flag. The -T flag includes the fields "YEAR", "DOY", and "SEC". The -H flag includes the time fields, plus some others including the "OBSID".
      pkt2dea -s -H -p FPTEMP_11,FEP0_ACTEL
    • pkt2eng: By default, the PSMC serial digital channels are reported as a pair of 32-bit hexadecimal fields ("XPSMCA" and "XPSMCB"). The -l flag (lower-case L) expands these into 64 individual channels or you can include one or more of the 1-bit mnemonics in the -p argument list. pkt2eng -s -H -p 1DPPSAX,1DAHTAON The 1-bit mnemonics can most easily be found on the ACIS real-time web pages.

  6. The output can then be read into a spreadsheet program, or any other plotting program.

Last updated: 26 Apr 2016 by C. Grant