Serial Numbers for six-channel digitisers

Overview

Güralp DM24 digitisers are available in three-channel and six-channel versions. (Both actually have an additional full-specification input channel so you may also see them referred to as four-channel and seven-channel units.)

A six-channel DM24 can be configured to appear either as a single six-channel system, with a single System ID and Serial Number (used to identify the streams), or as two virtual three-channel digitisers, sharing a single System ID but with two separate, distinct Serial Numbers. The only differences between the two modes are the names of the resulting output streams.

This document explains how to configure each of the modes and how to switch between them.

Stream naming

GCF output streams are identified by Stream IDs, which are composed from four elements:

  • The System ID, which is user-programmable;
  • The Serial Number, which is user-programmable;
  • The Component ID, which identifies the component (Vertical, North/South, East/West) from which the stream originates; and
  • The Tap Number, which relates to the sample rate and the decimation tree (the way in which the initial high sample rate is reduced by successive division to the wanted output rates).

These are combined as shown below:

Stream ID structure

For more information about Stream IDs, including some of the more unusual variants, please see the document Stream IDs explained.

Single serial-number mode

In single serial-number mode, the first attached triaxial sensor (SENSOR A) gets allocated even tap numbers and the second attached triaxial sensor (SENSOR B) gets allocated odd tap numbers.

The first (fastest) tap outputs, therefore, have Stream IDs ending in Z0, N0 and E0 for SENSOR A and Stream IDs ending in Z1, N1 and E1 for SENSOR B. Similarly, the second (next fastest) tap outputs have Stream IDs ending in Z2, N2 and E2 for SENSOR A and Stream IDs ending in Z3, N3 and E3 for SENSOR B.

To select single serial-number mode, right-click on the digitiser’s icon in Scream! and select Terminal from the context menu. When the terminal window opens, enter the following commands, providing the desired System ID and Serial Number when prompted:

  • The RESETLABELS command clears dual serial-number mode, if set. It also clears any customised Component IDs, which are not described in this document.
  • The SET-ID command prompts for new values for the System Identifier (System ID) and Serial Number:
    • The system identifier that you supply should contain between one and five alphanumeric (0-9, A-Z) characters. Alphabetic characters should be entered in upper-case.
    • The serial number that you supply must contain exactly six alphanumeric (0-9, A-Z) characters and should end with two zeroes ('00'). Alphabetic characters should be entered in upper-case. The first four characters are used when generating Stream IDs. The final two characters are used for customised Component IDs, which are not described in this document (but you can see here for details). If you wish to use an ID which is shorter than four characters, pad it with leading zero ('0') characters.
    The system responds by printing the new system identifier and serial number, the sensor type and the “ok” prompt (which is now derived from the new serial number). If the sensor type has not been set, the word NOTSET is printed in its place.
  • The RE-BOOT command re-starts the system using the newly set IDs. It first asks for confirmation: key Y in response.

A typical session looks like this (where “SYS0” is the old System ID, “DM24” is the new System ID and “C902” is the new Serial Number):

ok_SYS0
RESETLABELS
ok_SYS0
SET-ID
System Identifier ? {ALPHA} DM24
Serial # ? (SYS000) C90200
DM24 C90200 CMG-3T ok_C902
RE-BOOT
Confirm with 'y' ? Y

Dual serial-number mode

In dual serial-number mode, the two sensors share a System ID but each has its own, distinct serial number. All tap identifiers are even.

The first (fastest) tap outputs, therefore, have Stream IDs ending in Z0, N0 and E0 for both SENSOR and SENSOR B. Similarly, the second (next fastest) tap outputs have Stream IDs ending in Z2, N2 and E2 for both SENSOR and SENSOR B.

This arrangement allows stream identifiers such as:

  • SITE1-VEL0Z0
  • SITE1-VEL0N0
  • SITE1-VEL0E0
  • SITE1-ACC0Z0
  • SITE1-ACC0N0
  • SITE1-ACC0E0

to be produced simultaneously from a single digitiser, which can be used to create more easily-recogniseable stream IDs.

To select dual serial-number mode, right-click on the digitiser’s icon in Scream! and select Terminal from the context menu. When the terminal window opens, enter the following commands

  • The SET-ID command prompts for new values for the System Identifier (System ID) and the Serial Number for the first sensor (SENSOR A):
    • The system identifier that you supply should contain between one and five alphanumeric (0-9, A-Z) characters. Alphabetic characters should be entered in upper-case.
    • The serial number that you supply must contain exactly six alphanumeric (0-9, A-Z) characters and should end with two zeroes ('00'). Alphabetic characters should be entered in upper-case. The first four characters are used when generating Stream IDs. The final two characters are used for customised Component IDs, which are not described in this document (but you can see here for details). If you wish to use an ID which is shorter than four characters, pad it with leading zero ('0') characters.
    The system responds by printing the new system identifier and serial number, the sensor type and the “ok” prompt (which is now derived from the new serial number). If the sensor type has not been set, the word NOTSET is printed in its place.
  • The SERIAL2 command prompts for the second Serial Number. The serial number that you supply must contain exactly four or exactly six alphanumeric (0-9, A-Z) characters. If you enter six characters, the final two should be zeroes ('00'), as described above.
  • The RE-BOOT command re-starts the system using the newly set IDs. It first asks for confirmation: key Y in response.

A typical session looks like this (where “SITE1” is the new System ID and “VEL0” and “ACC0” are the new Serial Numbers):

ok_C902
SET-ID
System Identifier ? {ALPHA} SITE1
Serial # ? (C90200) VEL000
SITE1 VEL000 CMG-3T ok_VEL0
SERIAL2
Secondary Serial # {0} ? 6 characters : ACC000
ok_VEL0
RE-BOOT
Confirm with 'y' ? Y

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