%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ % $Id: Data.tex,v 1.3 2007/10/05 22:33:48 swift Exp $ %~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ % RCS Log: % % $Log: Data.tex,v $ % Revision 1.3 2007/10/05 22:33:48 swift % Change telemetry retry interval and add definitions of bit-masks for status words. % % Revision 1.2 2006/11/24 23:58:15 swift % Updated format descriptions to account for changes in Sbe41cp firmware. % % Revision 1.1 2006/11/03 19:08:57 swift % Added user manual to CVS control. % % Revision 1.2 2006/07/10 22:24:49 swift % Modifications to bring the manual up to date with % changes to the SeaBird CTD firmware (v1.1c). % % Revision 1.1 2006/04/11 15:32:32 swift % Initial revision % %~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ \section{Telemetered data.} \label{sec:TelemeteredData} Iridium floats telemeter two kinds of data for each profile cycle and these data are transferred as separate files: message files and log files. Message files contain hydrographic data and follow a naming convention \emph{FloatId}.\emph{ProfileId}.msg where \emph{FloatId} is the 4-digit serial number of the float controller and \emph{ProfileId} is the 3-digit profile counter. Log files contain detailed engineering data with time-stamped diagnostics of float operations. Examples of message files and log files from actual floats can be found in Appendixes~\ref{sec:IridiumMsgSample} and \ref{sec:IridiumLogSample}. It will be helpful to refer to these examples as you read this section. \subsection{Format specification for APF9i firmware.} This section summarizes the format specification for hydrographic data telemetered by Iridium floats. The ``official'' format specification can be found in the ``src'' directory of your distribution. Any discrepancy between \textbf{src/FormatNotes} and the information in this manual should be resolved in favor of the former. Iridium message files end with a ".msg" extension. Each iridium message file consists of blocks of similar data presented in the order that they were collected during the profile cycle. This firmware revision includes five blocks of data: \begin{enumerate} \item Park-phase PT samples: These are hourly low-power PT samples collected during the park phase of the profile cycle. \item Low resolution PTS samples: The deep parts of the profile can be represented using low-resolution spot samples collected at predetermined pressures. Low resolution spot sampling in the deep water was implemented as an energy savings measure. \item High resolution PTS samples: The shallower parts of the profile can be represented with high resolution (ie., 2 decibar) bin-averaged PTS samples. In continuous profiling mode, the CTD samples at 1Hz and stores the data for later binning and averaging. \item GPS fixes: After the profile is executed and the float reaches the surface, the location of the profile is determined via GPS. \item Biographical and engineering data: Various kinds of biographical and engineering data are collected at various times during the profile cycle. \end{enumerate} Usually, only one telemetry cycle is required to upload the data to the remote host computer. However, sometimes the iridium connection is broken or the quality of the connection is so poor that the float will abort the telemetry attempt, wait a few minutes, and then try again. Data blocks 4 and 5 will be repeated for each telemetry cycle of a given profile. A description of the format for each of these blocks of data follows. A sample Iridium-message file is available in Appendix~\ref{sec:IridiumMsgSample}. \subsubsection{Format for park-phase PT samples.} \label{sec:PtSample} Hourly low-power PT samples are collected during the park phase of the profile cycle. The park phase is also when active ballasting is done. Each sample includes the date and time of the sample, the unix epoch (ie., the number of seconds since 00:00:00 on Jan 1, 1970), the mission time (ie., the number of seconds since the start of the current profile cycle), the pressure (decibars), and the temperature ($^\circ$C). For example: \begin{verbatim} |------- date -----| UnixEpoch MTime P T ParkPt: Jul 03 2006 18:37:34 1151951854 14414 988.18 7.4971 ParkPt: Jul 03 2006 19:37:31 1151955451 18011 992.15 7.3613 ParkPt: Jul 03 2006 20:37:31 1151959051 21611 998.23 7.3428 ParkPt: Jul 03 2006 21:37:31 1151962651 25211 1000.38 7.2806 ParkPt: Jul 03 2006 22:37:31 1151966251 28811 1003.01 7.2844 \end{verbatim} \subsubsection{Format for low resolution PTS samples.} \label{sec:LowResPtsSample} The SBE41CP that is used on iridium floats has features that enable subsampling of the water column (similar to the SBE41) as well as the ability to bin-average a continuous sampling of the water column. For subsampled data, the values of pressure, temperature, and salinity are not encoded but are given in conventional units (decibars, $^\circ$C, PSU). For example: \begin{verbatim} $ Discrete samples: 6 $ p t s 1002.59 3.912 34.4573 (Park Sample) 1000.11 3.929 34.4547 947.36 4.035 34.4454 897.56 4.163 34.4303 847.54 4.344 34.4104 798.09 4.478 34.3934 \end{verbatim} \subsubsection{Format for high resolution PTS samples.} \label{sec:HiResPtsSample} For conintuously sampled data, 2-decibar bins are used for bin-averaging. These data are encoded as three 16-bit integers (PTS) and then an 8-bit integer that represents the number of samples in the bin: \begin{verbatim} # Nov 05 2006 23:38:59 Sbe41cpSerNo[1520] NSample[11134] NBin[495] 00000000000000[2] 002B5CE0885115 003C5CE188511F 00505CE088511E 00645CE088511D 00785CDF88521C 008C5CDF88521B 00A05CDF88511A 00B45CDC88511A 00C85CAD885A1A 00DC5C8D886418 00F05C88886919 01045C88886A19 01185C74887618 012C5C4E88BB15 [snippage...] 2684144D874814 2698145C874D14 \end{verbatim} The first 4-bytes of the encoded sample represents the pressure in centibars. The second 4-bytes represents the temperature in millidegrees. The third 4-bytes represent the salinity in parts per million. The final 2-bytes represent the number of samples collected in the 2dbar pressure bin. For example, the encoding: 2698145C874D14 represents a bin with (0x14=) 20 samples where the mean pressure was (0x2698=) 988.0dbars, the mean temperature was (0x0EDE=) 3.806C, and the mean salinity was (0x86A0=) 34.464PSU. The PTS values were encoded as 16-bit hex integers according to the C-source code found in Appendix~\ref{sec:EncodeCSource}. Integers in square brackets '[]' indicate replicates of the same encoded line. For example, a line that looks like: 00000000000000[2] indicates that there were 2 adjacent lines with the same encoding....all zeros in this case. \subsubsection{Format for GPS fixes.} Each telemetry cycle begins with the float attempting to acquire a GPS fix. The fix includes the amount of time required to acquire the fix, the longitude and latitude (degrees), the date and time of the fix, and the number of satellites used to determine the fix. For example: \begin{verbatim} # GPS fix obtained in 98 seconds. # lon lat mm/dd/yyyy hhmmss nsat Fix: -152.945 22.544 09/01/2005 104710 8 \end{verbatim} Positive values of longitude, latitude represent east, north hemispheres, respectively. Negative values of longitude, latitude represent west, south hemispheres, respectively. The date is given in month-day-year format and the time is given in hours-minutes-seconds format. If no fix was acquired then the following note is entered into the iridium message: \begin{verbatim} # Attempt to get GPS fix failed after 600 seconds. \end{verbatim} \subsubsection{Format for biographical and engineering data.} These data have the format, "key"="value", as shown in the following examples: \begin{verbatim} ActiveBallastAdjustments=5 AirBladderPressure=119 AirPumpAmps=91 AirPumpVolts=192 BuoyancyPumpOnTime=1539 \end{verbatim} Interpretation of these data requires detailed knowledge of firmware implementations and is generally beyond the scope of this manual. However, there are two 16-bit status-words (status, Sbe41cpStatus) whose asserted bits indicate special conditions as described below The definition of each bit mask for the 16-bit ``status'' word are given in the table below: \label{StatusBitMasks} \begin{verbatim} DeepPrf 0x0001 The current profile is a deep profile. ShallowWaterTrap 0x0002 Shallow water trap detected Obs25Min 0x0004 Sample time-out (25 min) expired. PistonFullExt 0x0008 Piston fully extended before surface-detection algorithm terminated. AscentTimeOut 0x0010 Ascent time-out expired. DownLoadCfg 0x0020 The mission.cfg file has not been downloaded yet. BadSeqPnt 0x0100 Invalid sequence point detected. Sbe41cpPFail 0x0200 Sbe41cp(P) exception. Sbe41cpPtFail 0x0400 Sbe41cp(PT) exception. Sbe41cpPtsFail 0x0800 Sbe41cp(PTS) exception. Sbe41cpPUnreliable 0x1000 Sbe41cp(P) unreliable. AirSysLimit 0x2000 Pneumatic inflation limits imposed; excessive energy consumption. WatchDogAlarm 0x4000 Wake-up by watchdog alarm. PrfIdOverflow 0x8000 The 8-bit profile counter overflowed. \end{verbatim} The definition of each bit mask for the 16-bit ``Sbe41cpStatus'' word (Pneumonic:~SBE41) are given in the table below: \label{SbeStatusBitMasks} \begin{verbatim} Sbe41cpPedanticExceptn 0x0001 An exception was detected while parsing the p-only pedantic regex. Sbe41cpPedanticFail 0x0002 The SBE41 response to p-only measurement failed the pedantic regex. Sbe41cpRegexFail 0x0004 The SBE41 response to p-only measurement failed the nonpedantic regex. Sbe41cpNullArg 0x0008 NULL argument detected during p-only measurement. Sbe41cpRegExceptn 0x0010 An exception was detected while parsing the p-only nonpedantic regex. Sbe41cpNoResponse 0x0020 No response detected from SBE41 for p-only request. 0x0040 Not used yet. 0x0080 Not used yet. Sbe41cpPedanticExceptn 0x0100 An exception was detected while parsing the pts pedantic regex. Sbe41cpPedanticFail 0x0200 The SBE41 response to pts measurement failed the pedantic regex. Sbe41cpRegexFail 0x0400 The SBE41 response to pts measurement failed the nonpedantic regex. Sbe41cpNullArg 0x0800 NULL argument detected during pts measurement. Sbe41cpRegExceptn 0x1000 An exception was detected while parsing the pts nonpedantic regex. Sbe41cpNoResponse 0x2000 No response detected from SBE41 for pts request. 0x4000 Not used yet. 0x8000 Not used yet. \end{verbatim} \subsection{Engineering log files.} The engineering log files contain time-stamped entries of what the float was doing at any given time. Every nook and cranny of the float firmware has self-monitoring features built in that are a synthesis of self-adaptive and user-controlled behaviors. The self-adaptive nature stems from the fact that if the float firmware detects problems or difficulties then engineering log entries are automatically generated as an aid to on-shore diagnostics. The user-controlled nature stems from the fact that the user can remotely adjust the verbosity of the engineering logs using the 2-way \textbf{Verbosity} command. Refer to Section~\ref{sec:RemoteControl} for information about 2-way (ie., remote) float configuration. \section{Processed data.} \label{sec:ProcessedData} Decoding and processing the message files from this \iridium\ implementation is relatively easy because the data are ASCII and mostly self-describing. Only the high resolution hydrographic data are encoded although some of the engineering data must be processed through calibration equations. Appendix~\ref{sec:EncodeCSource} contains the C source code used to encode the high resolution data and Appendix~\ref{sec:IridiumProcDataSample} contains an example profile after decoding and processing has been applied. %%% Local Variables: %%% mode: latex %%% TeX-master: "IridiumApex" %%% End: