README.TXT describes the contents of this volume. CLUSTER WBD LEVEL1 Data Distribution ============================================================================ INTRODUCTION ============================================================================ This volume contains the Cluster Wideband Receiver (WBD) time series data. Except for a limited amount of burst mode (BM-2) data, this data set is derived entirely from real time telemetry (normal science mode TDA-8) received by the Deep Space Network (DSN) stations and forwarded to Iowa for processing. These burst mode and real time raw data are the only sources of Cluster WBD data. The files in this data set are called LEVEL1 files (referring to the LEVEL1 processing that the raw data have undergone: When the data files are received from DSN, the WBD team at Iowa checks these raw data files for problems, determines the time tags associated with each data record [see TIMETAGS.TXT], unpacks all status parameters, and writes the LEVEL1 files). LEVEL1 files have the following naming convention: yymmddtt.ivs where: yy = last 2 digits of the year mm = Month dd = Day of month tt = The files are divided into ten minute periods and tt is the ten minute period in HEXADECIMAL. Example: tt = 20 (hex) = 32 (base 10) 32*10 minutes = 320 minutes of day 320/60 = 5.33333 Hours. 0.33333*60 = 20 minutes The start time of the file will be 05:20:00. The file will contain data with 05:20 <= time < 05:30. Or going the other way, Want to find the file containing s/c 4 data at 13:47:00 on 23 Nov. 2003 (13*60 + 47)/10 = 82.7 minutes (base 10) Truncate to integer, 82 (base 10), and convert to hex, 52 (hex) The file will be 03112352.8C4 (assuming a version 'C' file). i = Instrument number (6-9) v = Version number (Should be B for burst mode data or C-Z for DSN data. Later letters = more recent versions, with version A files already being obsolete.) s = Spacecraft number (1-4) For version 'C' files, the resulting extensions are: S/c 1 = 9C1, s/c 2 = 6C2, s/c 3 = 7C3, s/c 4 = 8C4. These files are found under the directory [DATA] which is subdivided into directories by date and spacecraft. The DVD volume naming convention, except for Burst Mode, is as follows: WBD_yyyymmdd_dd_v, where: yyyy = Year mm = Month first dd = Day of month of first day of data contained on this DVD last dd = Day of month of last day of data contained on this DVD v = version of the DVD (A-Z) (Note, these versions are independent of those contained in the file names described above.) For Burst Mode, the DVD volume naming convention is as follows: WBD_yyyymmdd_dd_v_BURST, where: yyyy = Year mm = Month first dd = Day of month of first day of data contained on this DVD last dd = Day of month of last day of data contained on this DVD v = version of the DVD (A-Z) (Note, these versions are independent of those contained in the file names described above.) ============================================================================ IMPORTANT INFORMATION ABOUT THIS VOLUME ============================================================================ This volume contains Cluster WBD time series data. All users are encouraged to verify the correctness of the data (by contacting any member of the WBD science team--see the CONTACTS section at the end of this document) prior to submitting any publication or other work based on these data. Users are encouraged to acknowledge the Principal Investigator of the data used in analysis in all publications. All data files are recorded in the [DATA] branch of the root directory, which is further divided into subdirectories by date and spacecraft number. The format of the WBD data files on this DVD is described in the text file WBFORMAT.TXT. ============================================================================ TIME STAMPS AND RELATIONSHIP TO OTHER CLUSTER DATA SETS ============================================================================ The WBD time of measurement time stamps known as UT_OBT are derived using the On Board Time (OBT) counter and the ESA-supplied time calibration files (see TIMETAGS.TXT). These derived times stamps should correlate with the time stamps provided to the other Cluster instruments by ESOC (European Space Operations Centre). The WBD UT_OBT time stamps are found in bytes 1232-1247, byte 1275 and byte 94 of the LEVEL1 record (see WBFORMAT.TXT). There are also alternative time stamps available in the LEVEL1 files. These time stamps are derived using DSN's Earth Received Time as a basis, as opposed to the On Board Time counter. These alternative time stamps are referred to as UT_GRT, and can be found in bytes 1224-1231 of the LEVEL1 file (see WBFORMAT.TXT). Please see the TIMETAGS.TXT file for details on these alternative times, and for indications of when it might be appropriate to use them. ============================================================================ MULTIPLE SPACECRAFT OPERATIONS ============================================================================ For any given interval, simultaneous WBD data may be available for one to four spacecraft. There are certain operations however, designated as Multiple Spacecraft Operations (MSOs), when special procedures were used at DSN while taking three- or four-spacecraft data. For a 10-minute period, all of the DSN antennas involved in the operation would track and receive data only from a single spacecraft. These calibration (CAL) data can be used, under certain circumstances, to further increase the accuracy of the UT_GRT time stamps by analyzing time stamp differences for any one data frame between any two antennas. These difference should be nearly repeatable over time because they are associated with the delay of the signal from the reception antennas to the individual telemetry recording stations. Applying these differences to the appropriate antennas when tracking other Cluster spacecraft thus provides greater relative timing accuracy across the Cluster spacecraft as opposed to absolute time stamp accuracy. The data for these MSO CAL runs are in separate directories on the DVD (see DVD CONTENTS AND STRUCTURE section below). Please contact the PI for a suggested software routine to carry out the timing analysis of the MSO CAL data. ============================================================================ SPACECRAFT NAMING CONVENTIONS ============================================================================ Note that the WBD instrument number that is in one of the status bytes (byte 1271 of LEVEL1 file--see WBFORMAT.TXT) has a value ranging from 4 to 7 and therefore must be mapped to the ESA spacecraft numbering system using the following table. |- WBD ID'S -| Instr. Instr. DSN | S/C Old Name Color Style Symbol Status # # | Id Name Value | 4 6 185 | 2 FM6 Salsa Red _ _ Plus or Diamond 5 7 194 | 3 FM7 Samba Green . . asterisk or Circle 6 8 196 | 4 FM8 Tango Magenta _... Star or Triangle 7 9 183 | 1 FM5 Rumba Black ____ Cross or Square ^ | ^ |<-- WBD Values | |<-- ESA Values ============================================================================ FILE FORMATS ============================================================================ The data files on this DVD are in binary format (1-, 2-, and 4-byte unsigned integers) and contain no floating point values. Multi-byte items are "most significant byte first" or "big endian". The only fields to which this applies will be the multi-byte fields, most of which hold time values. See WBFORMAT.TXT, which gives a detailed description of the format of the data files. Burst mode data from ESA processing have been placed into the same LEVEL1 format as the DSN data. There are some differences, primarily in that the burst mode records do not have any of the Ground Received time fields or any of the DSN-specific elements contained within the Standard Formatted Data Unit (SFDU) header area of the data record. (For details see the format document, WBFORMAT.TXT.) Most files other than the LEVEL1 files on this DVD are ASCII text whose lines are terminated by a carriage return and line feed. ============================================================================ ERRATA ============================================================================ The file ERRATA.TXT contains a list of deficiencies or caveats associated with this and previous DVD's, as known at the time this DVD was produced. For data interpretation issues, please see the Cluster Interpretation Issues web page, available at: http://www-pw.physics.uiowa.edu/cluster/interpretation_issues/ and also at the Cluster Active Archive (http://caa.estec.esa.int/caa/). Please check these files before contacting the PI about data problems or interpretation issues. ============================================================================ SOFTWARE ============================================================================ There is a set of example software routines that read the LEVEL1 files contained on this DVD. The code should be compatible with most common architectures supporting an ANSI standard C compiler. There are also routines to correct known problems found in the data (see ERRATA.TXT) and routines to calibrate the electric and magnetic field wave data in the time domain for each instrument. The current set of programs can be found in the directory [SOFTWARE] under subdirectories [EXAMPLES], [CLU2_FIX], and [CAL]. Updates, corrections, and additions to this software may be found online at http://www-pw.physics.uiowa.edu/cluster/dvd/SOFTWARE/ ============================================================================ DVD CONTENTS AND STRUCTURE ============================================================================ Below is a tree diagram of this DVD, followed by a description of the directory function and key files in each directory. [THIS VOLUME] | |- README.TXT This file. | |- [DATA] Contains all data in the subdirectories. | | | |- [yyyy_mm_dd] for each day for which data are available, | | | where yyyy is the year, mm is the month, and dd is | | | the day of month. | | | | | |- [CLUSTERn] for the appropriate spacecraft (n = 1, 2, 3, 4). | | | | | | | |- yymmddtt.ivs These are the level 1 data files, one | | | | for each available 10-minute interval. The file | | | | naming convention is described above. | | | | | | | |- [CAL] Contains ground time calibration files | | | | (period = 10 minutes). This directory will | | | | only be present when there is a | | | | multi-spacecraft operation (MSO). | | | | | | | |- [DSS_n1] Calibration files for first station. | | | |- [DSS_n2] Calibration files for second station. | | | |- [DSS_n3] Calibration files for third station. | | | |- [DSS_n4] Calibration files for fourth station. | |- ERRATA.TXT Contains a list of known problems | with WBD data found on this DVD. | |- INSTDESC.TXT A description of the WBD instrument in | ASCII text format. | |- MD5CRLF.TXT Lists all files on this disk along with their MD5 | checksum. This version is formatted with ASCII | cr/lf line termination for Microsoft platforms. | Use "md5sum -c MD5CRLF.TXT" to verify each file. | See http://www.gnu.org/software/coreutils/ | |- MD5LF.TXT Lists all files on this disk along with their MD5 | checksum. This version is formatted with ASCII | lf line termination for UNIX platforms. | Use "md5sum -c MD5LF.TXT" to verify each file. | |- [SOFTWARE] Contains example software. Individual files for | | these directories are not described here. | | | |- [CAL] Contains C source code to calibrate the | | data in the time domain. | | | |- [CLU2_FIX] Contains C source code to fix a known | | problem with Cluster 2 data. | | | |- [EXAMPLES] Contains example programs for reading LEVEL1 data | files, including sample input and output files. | |- TIMETAGS.TXT A description of the time stamps contained in the | WBD level 1 data files. | |- WBFORMAT.TXT Contains the description of the format of the LEVEL1 data files found on this volume. ============================================================================ DRIVER AND HARDWARE INFORMATION ============================================================================ This disk has been formatted according to a combination of ISO 9660 level 2, Rock Ridge (UNIX), Joliet (Microsoft), and UDF standards. It has been recorded on DVD-R media and should be readable on all major computing platforms hosting DVD readers. ============================================================================ UPDATES ============================================================================ Non-critical updates to this file and other general text documents provided on this volume may be found online at: http://www-pw.physics.uiowa.edu/cluster/dvd/ Be sure to check the current ERRATA.TXT file for errors reported for this particular volume. If the errors are sufficient to warrant the release of a new version of this volume (corrected level 1 data, for example), then a note will be made in the current online ERRATA.TXT. ============================================================================ CONTACTS ============================================================================ Principal Investigator: Jolene S. Pickett (Since Jan. 1, 2006) Tel. 319-335-1897 pickett@uiowa.edu Former Principal Investigator: Professor Donald A. Gurnett (Up to Jan. 1, 2006) Tel. 319-335-1967 donald-gurnett@uiowa.edu Cluster Systems Administrator: Larry Granroth Tel. 319-335-2536 larry-granroth@uiowa.edu WBD Science Team: http://www-pw.physics.uiowa.edu/cluster/directory.html ============================================================================ ============================================================================