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CSEM Receiver Time Series

Data files for the Controlled-Source Electromagnetic System (CSEM) Receiver are described here.

Oceans 2.0 API filterdataProductCode=CSEME

Revision History

  1. 20110803: MAT data product released
  2. 20110302: Binary .raw data files released

Formats

This data is available in binary .raw and .mat formats. A new file is created for each numbered experiment that is downloaded from the CSEM Receiver. The filename is appended with the experiment start time and the experiment number (e.g., UOT_CSEM_20110315T212751Z-20110303T025924_11.raw, where 11 is the experiment number). If the date and time limits of your search criteria are mid-experiment, the full experiment is still returned.

Content descriptions and example files are provided below.

RAW Binary file

The format of these binary files is described by the BinaryDataFormat.pdf document listed within the CSEM Receiver documentation.

Oceans 2.0 API filter: extension=raw

Example: UOT_CSEM_20110315T212751Z-20110303T025924_11.raw

MAT

MAT files (v7) can be opened using MathWorks MATLAB 7.0 or later. The file contains four structures: meta, adcp, config, and units.

meta: structure containing the following metadata fields.

  • deviceID: A unique identifier to represent the instrument within the NEPTUNE Canada observatory.
  • creationDate:Date and time (using ISO8601 format) that the data product was produced. This is a valuable indicator for comparing to other revisions of the same data product.
  • deviceHeading: Obtained at time of deployment.
  • siteName: Name corresponding to its latitude, longitude, depth position.
  • deviceName: A name given to the instrument.
  • deviceCode: A unique string for the instrument which is used to generate data product filenames.
  • locationName: The node of the NEPTUNE Canada observatory. Each location contains many sites.
  • samplingPeriod: Sampling rate of the instrument in seconds.
  • depth: Obtained at time of deployment.
  • lat: Obtained at time of deployment.
  • lon: Obtained at time of deployment.

data:

  • namesRX: vector of receiver designations
  • time: matrix (numRX X nSamples), timestamp in datenum format for each receiver
  • tCount: vector of internal timing counter values used as a diagnostic of the program
  • voltage: matrix (numRX X nSamples) of voltage readings for each receiver
  • errorCount: vector containing number of erroneous voltage readings per receiver

config:

  • numRX: number of receivers
  • gainTX: corrects for voltage divider in front of RC circuit
  • gainRX: corrects for voltage divider in front of RXs circuits
  • gain: vector of receiver programmable amplifier setting
  • sampleRate: vector of receiver sample rates
  • ADC_Registers: matrix (numRX X nRegisters) of status registers. For details of the status registers, refer to p. 30 of the Analog-to-Digital Converter Specification (ads1256.pdf )

units: structure containing unit of measure for fields in structures above. For instance, units.voltage='V'.

Oceans 2.0 API filter: extension=mat

Example: UOT_CSEM_20110603T015123Z-20110602T210530Z_02.mat

Discussion

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  1. Recently, I've been noticing that the experiment date and number are from 2008. Based on reading the code, it looks like the experiment operator has to input the experiment date and number when they connect to the instrument to collect data or they have to make sure they aren't retransmitting old data. Regardless of the cause, this can cause some issues - potential confusion with other experiments for one. Other issues include: the metadata may be erroneous, and most importantly, time base of the time stamps in the mat file (data.time). I've changed the code to attempt to rescue the meta data, but please be wary of the data.time as there's not much we can do to fix those time stamps. The file naming convention, as noted above, is UOT_CSEM_TimeOfRetrieval-ExperimentStartDate_ExpNumber[.mat/.raw]. The time of retrieval is when the CSEM was told to transfer its data to Neptune. This usually occurs immediately after an experiment. If the time of retrieval and experiment start date are quite different this is best indication that this erroneous experiment date problem has occurred. I've changed the code to add a comment to the meta data and issues warnings to the UI and server logs when this occurs.