Blacknest BDS Meta Data Definitions

Date 2010-06-04
Version 1.2.4

Note that this is a "work in progress" document and is being continually updated.

Introduction

This document describes all the Meta data used in the BDS system.
There are two groups of Meta Data used in the BDS system.

Data File MetaData

In order to simplify and generalise data file metadata information, the Bds Data File API provides meta data information in the form of a set of named values implemented as a String dictionary. This allows arbitrary information to be stored. In order to generalise and simplify usage a set of standard parameters are defined. These are:

Item Name Description
startTime The start time of the following data.
endTime The end time if a file format (not in streamed data)
array The Array the data is from if only from a single array
description General description
channels.number The number of channels
channels.synchronous A boolean defining if the channels are synchronously sampled
channel1.startTime The start time
channel1.endTime The end time
channel1.network The network the data is from
channel1.station The station the data is from
channel1.channel The channels identifier name
channel1.source The data source, "Master" is the normal.
channel1.type The channels type (BHZ etc)
channel1.auxId The auxillary or location ID.
channel1.numSamples The total number of samples if known, 0 otherwise
channel1.sampleRate The channels sample rate
channel1.sampleFormat The sample format Int16, Int32, Float32 etc
channel1.format The file format. BDS, BDRS, GCF etc
channel1.formatOriginal The original data format this file was created from

Networks

The network is the sesmic organisations name. This is limied to two characters in SEED files. A list of valid network names is given in the following list: http://www.iris.washington.edu/stations/networks.txt

Station Names

The station names used in the BDS system should match the IDC standards: USG85 and IMS01. This states:

Seismic station and site names shall be registered with the International Seismic Centre (ISC) or the
National Earthquake Information Center (NEIC) of the U.S. Geological Survey. Seismic station and site
names shall conform to standards given in [USG85]. For example, station names shall be three to five
characters in length, and therefore the station field will never be completely filled. No counterpart
registry exists for hydroacoustic and infrasonic station or site names, but station and site name formats
shall conform to IMS station naming conventions [IMS01].

In addition to the standard names there are some specific Blacknest names to handle particular data channels. These are:

Channel Types

The channel types and channel auxId used in the BDS system should match the IDC standards FDSN) [IRI93] and IMS01 for the Channel Name. Note that the BDS uses a channel name that is the channel type and channel auxId combined with a "_" character. If there is no auxId, the "_" character is omitted.

The channel name is the three-character string that labels the bandwidth, gain, and orientation of the
sensor. Channel names for seismic stations shall conform to the standards of the Federation of Digital Seismograph Networks (FDSN) [IRI93]. Channel names that are not defined by the FDSN shall conform to IMS channel naming conventions [IMS01].  The location field is provided in anticipation of the need to distinguish between two or more sensors at one site with the same channel name. Although a location identifier is included in the SEED format [IRI93], no convention has been defined for location naming.