Stream IDs explained

GCF data from digitisers are identified by the combination of System ID and Stream ID. The “System ID” identifies the digitiser from which the data originate and each stream from a given digitiser is then identified by its “Stream ID”. Each Stream ID is composed of two parts, the “Serial Number” and a two-character suffix to identify which data are contained in the stream. These terms are explained in the following sections.

System ID

The System ID is factory-set to contain the sales order or works order number. It can be re-programmed to contain any combination of upper-case letters (A-Z) and digits (0-9), usually up to a maximum of five characters in length. It cannot begin with the character 0. The ranges of permissible IDs is determined by the digitiser type as shown in the table below:

You can re-programme the System ID by:

• using Scream (see section 7.1 of the Scream manual);
• using an EAMEnhanced Acquisition Module - see the data acquisition page for details. or NAMNetwork Acquisition Module - see the data acquisition page for details. (see section 8.1.1.1 of the EAM manual); or
• from the command line of the digitiser (see SET-ID in section 4.3 of the DM24 manual).

The System ID is typically set to a code identifying the project or network in which the digitiser is deployed.

Serial Number

The Serial Number is factory-set to contain the serial number of the digitiser or, in the case of digital instruments, the serial number of the instrument. It can be re-programmed to contain almost any combination of upper-case letters (A-Z) and digits (0-9), up to a maximum of four characters in length.

Due to the encoding method used, Serial numbers must be alphabetically less than ZIK0 – see the GCF quick reference for details.

You can re-program the Serial Number by:

• using Scream (see section 7.1 of the Scream manual);
• using an EAM or NAM (see section 8.1.1.1 of the EAM manual); or
• from the command line of the digitiser (see SET-ID in section 4.3 of the DM24 manual).

The Serial Number is typically set to a code identifying the location or node of the network in which the digitiser is deployed.

Data source suffix

The Stream ID ends in a two-character suffix which identifies the data source. The possible values are given in the table below.

Notes

1. The letters Z, N and E (which identify the three main inputs and are used throughout this table) can be replaced by any three consecutive letters of your choice: see section 7.2 of the Scream manual for details.

2. Digitisers with a SENSOR B input can either use the stream suffices in this section (the default) or be programmed with a second serial number for the second instrument, in which case they will use the same suffices as the SENSOR A instrument. You can programme a second serial number

   • using Scream (see section 7.1 of the Scream manual);
   • using an EAM or NAM (see section 8.1.1.1 of the EAM manual); or
   • from the command line of the digitiser (see SERIAL2 in section 3 of the DM24 manual).

3. Strong motion data and low-latency, causal-filtered streams are described in section 8.1.1.4 of the EAM manual.

GCF Examples

Here are some examples of typical stream IDs with their constituent parts decoded:

• SITE2-PIT0Z2 :
  • SITE2 → System ID
  • PIT0 → Serial number
  • Z2 → SENSOR A, main output, vertical component, second tap
  
  
• SITE2-PIT0M9 :
  • SITE2 → System ID
  • PIT0 → Serial number
  • M9 → SENSOR A, mass position output, North/South component
  
  
• SITE2-PIT000 :
  • SITE2 → System ID
  • PIT0 → Serial number
  • 00 → Status stream
  
  
• SITE2-PIT0E5 :
  • SITE2 → System ID
  • PIT0 → Serial number
  • E5 → SENSOR B, main output, East/West component, third tap
  
  
• SITE2-PIT0NN :
  • SITE2 → System ID
  • PIT0 → Serial number
  • NN → SENSOR B, triggered output, North/South component, fourth tap
  
  

SEED Output

SEED data from EAMs, NAMs and Scream are named using SCNL (Station, Channel, Network, Location) notation. When automatic stream-name mapping (GCF to SCNL) is used:

• the Serial Number is used as the Station name;
• the Channel name is created from a type prefix (HH for main outputs and MM for mass position outputs) and the component identifier (Z, N or E for Vertical, North/South and East/West, respectively); and
• the first two characters of the System ID are used as the Network name;
• the Location name is the tap number (0-7) or multiplexed-input identifier (8-F), with a leading zero (“0“).

The Channel name for both the status stream and the InfoBlock stream is SOH. The Location name for the status stream is 00 and, for the InfoBlock stream, 0B.

Note that the Platinum firmware on EAMs and NAMs allows you to completely or partially over-ride the automatic name mapping, so you can use any SCNL names that you wish. The examples below use automatically mapped names.

SEED Examples

• PIT0.HHZ.SI.01 :
  • PIT0 → Station name (from the Serial number)
  • HHZ → High-gain seismometer, main output, vertical component
  • SI → System ID (From the first two characters of “SITE2″: a poor choice of system ID if automatic name-mapping is used! A better choice would have been S2, as in the examples below)
  • 01 → SENSOR A, first tap
  
  
• PIT0.SOH.S2.00 :
  • PIT0 → Station name, from the Serial number
  • SOH → status stream or meta-data
  • S2 → System ID (From the first two characters of the System ID)
  • 00 → status stream
  
  
• PIT0.MME.S2.0A :
  • PIT0 → Station name, from the Serial number
  • MME → Mass position, East/West component
  • S2 → System ID (From the first two characters of the System ID)
  • 0A → Multiplexed input A (E/W mass position)