l Guralp Cmg-dm24s3dcm

The Gralp CMG-DM24S3DCM is a combined digitizer and network

communications unit which provides a convenient and expandable way

of connecting an analogue

instrument to your network.

Inside the robust, waterproof casing

are housed a standard DM24

digitizer and a DCM data

communications module, connected

by an internal serial interface.

The DM24S3 is a high-quality

digitizer with full 24-bit resolution

and 3 primary data channels,

designed for data quality and

durability, whilst the DCM is a stable

and robust Linux-powered unit with

on-board storage and networking

facilities.

Key features

- Under 2 W total power consumption

- 4 low-noise 24-bit channels (3 primary, 1 auxiliary)

- STA/LTA, level and external trigger

- 4 concurrent output sample rates (continuous or triggered)

- Fourth channel for user signals and calibration

- Multi-user Linux operating system with full network support

- Remote configuration with on-board Web server

- On-board, hot-swappable USB hard disk (40 Gb +)

- Full remote control of digitizer parameters

- Remote sensor locking, unlocking and centring

- Conversion to multiple data formats

6- and 12-channel versions

(with 7 and 14 ADCs each)

are also available.

CMG-DM24S3DCMDigitizer and Communications Module

Distributed by:

Gralp Systems Limited, 3 Midas House,

Calleva Park, Aldermaston RG7 8EA, U.K.

tel. +44 118 981 9056 : fax +44 118 981 9943

: email [email protected]://www.guralp.com/

Analogue sensor

SENSOR A

Analogue sensor

SENSOR A

Analogue sensor

SENSOR A

Additional storage

12 V DC

via DATA OUT

USB (optional)

Serial or modem link

12 V DC

DATA OUT

12 V DC

via DATA OUT

PORT A or B

Local TCP/IP network

Digitizer

Applications

Autonomous data storage

The DM24S3DCM uses a standard

USB hard drive, replaceable in the

field with 100% data surety.. Self-

contained, low power installations

can have over 40 Gb of storage

space, ideal for long-term

experiments in remote locations.

Long-range telemetry

The DM24S3DCM can digitize

signals from an analogue instrument

and transmit the data directly over a

serial modem or VSAT link.

Alternatively, PPP and SLIP

capabilities allow you to use a

modem link as an extension of your

local network.

Fully networked installations

The DM24S3DCM runs a fully

configurable and scriptable Linux

operating system.

In addition to the on-board digitizer,

its two digital inputs allow it to

collate data from additional digital

instruments.

All received data can be saved to

the hard disk and transmitted to a

data centre as normal.



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DAS-D24-0008-B : Page 2 of 11



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Digitizer features

The Gralp CMG-DM24 is a high-quality 3-channel digitizer

with full 24-bit resolution, designed for data quality and

durability.

The component housed inside the DM24S3DCM is a full-

featured DM24 unit with direct output to the DCM

component.

Features

- 4 low noise 24-bit channels (3 primary, 1 auxiliary)

- 12-channel digitizer options available

- Auxiliary channel for user signals and calibration

- Multiple concurrent data rates up to 1000 samples/s

- 8 environmental channels with 20-bit resolution

(3 mass position, 5 user)

- Optional further 8 environmental channels

- Low power 32-bit DSP and ARM processor

- System power consumption < 1 W (for 4 channels

recording at 100 samples/s)

- STA/LTA, ratio, external and software triggering

- Up to 4 triggered or continuous streams output

simultaneously on each channel

- Event selection and download over data port

- Full control of Gralp broadband sensors

including remote lock, unlock and centre

- Calibration using step, sinusoid or broadband noise signals

- Remotely configurable through the DCM component over

the Web or using Scream!

- UTC timestamped data using low power GPS

DAS-D24-0008-B : Page 3 of 11



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The CMG-DM24 uses the latest in 24-bit

ADC technology, giving true 24-bit

performance with ultra-low power

consumption.

Multiple concurrent sample rates are

available, from 1000 samples/s down to 1

sample/s, using combinations of

decimation filters. Decimation factors of

10, 8, 5, 4 and 2 are supported.

The DSP chipset and digitizer design give

the DM24 a first-class noise profile. Input-

terminated noise tests demonstrate that

the performance of the DM24 at 40

samples/s exceeds 22.5 bits, giving it a

maximum potential dynamic range over

137 dB. The noise floor is further reduced

to over 24 bits at slower sample rates.

Low noise variant

A variant design of the CMG-DM24 is

available which uses enhanced signal

processing techniques to reduce

digitizer noise still further.

At 40 samples/s the input-terminated

noise performance of the low-noise

unit exceeds 23 bits, for a maximum

potential dynamic range over 141 dB.

The performance below 10 samples/s

exceeds 24 bits. To take advantage of

this resolution, the output word length

is increased to 32 bits.

This exceptional noise performance is

achieved by drawing extra power to

process the input signal.

Digitizer performance

DAS-D24-0008-B : Page 4 of 11



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Inside the DM24

The ARM RISC processor

inside the DM24 component

uses the latest in low-power

logic technology to run a real-

time multi-tasking operating

system using under 650 mW

of power.

The DM24 can output up to 4

concurrent data streams per

instrument at sample rates

from 1000 to 1 sample/s.

A dedicated 20-bit DAC is

responsible for generating cali-

bration signals and injecting

them into any or all of the

seismometer components. The

clean calibration signal is also

digitized on the fourth channel.

The 20-bit DAC can generate

step or sinusoidal signals and

PRBS noise, allowing both

time- and frequency-domain

calibration.

Data is output direct to the on-

board DCM for storage and

transmission. If desired, users

can connect to the digitizer

console to retrieve data from

Flash storage, configure or

control attached instruments.

All data, including additional channels, triggered data, and text

status information, is transmitted in tagged streams in GCF

format. This efficient format is also used by Gralp SAM, CRM,

and DCM units, as well as Scream! software. The specification of

GCF format is freely distributed from our Web site.

DAS-D24-0008-B : Page 5 of 11

Digital filterDSP

RS232 interface

8 x

analo

gue

inputs

. .

.

Dig

ital I/O

channels

Dif

fere

nti

al analo

gue inputs

ZN

-SE-W

GP

S

Data

16 1 Mb

program Flash

16 .5 Mb

system Flash

X

20-bit DAC

Digital I/O

8-way

buffered

multiplexer

Pre-

amplifier

24-bit ADC

24-bit ADC

24-bit ADC

24-bit ADC

16-bit ADC

32-bit ARM

microprocessor

SPI

Precision timer

UARTS

64 8192 Mb

data Flash

Signal generator

GPS synchronizer

Cal

The DCM component provides a low-

power, flexible data hub suitable for all

seismic installations, from autonomous

stations to large arrays.

Using a full Linux operating system, the

DCM is a stable and robust unit which

can be deployed long-term with

confidence.

As a stand-alone unit, the DCM is rugged

enough to withstand the harshest

environments, using a specially-designed

hard disk caddy and secure, durable

connectors throughout.

Features

- < 0.7 W power consumption

- Stable and robust for total autonomy

- Multi-user Linux operating system

- Ethernet or wireless LAN

- Full TCP/IP support with PPP

- Optional on-board PCMCIA modem

- Remote configuration with on-board Web server

- Remote access with secure shell

- Digitizer console access and scripting

- Flash and USB mass storage as standard

- Optional support for other USB devices (e.g. cameras)

- On-board, hot-swappable USB hard disk (40 Gb +)

- Optional USB network emulation

- Simultaneous recording in GCF, CSS3.0 (flat file), sac,

MiniSEED and full SEED

- Supports Scream!, DSS, CD1.0 and CD1.1 protocols

- Pass-through digitizer access from Scream!

- CRM/SAM compatible serial interface



tel. +44 118 981 9056 : fax +44 118 981 9943


DCM features

DAS-D24-0008-B : Page 6 of 11

Web server interface



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DAS-D24-0008-B : Page 7 of 11

The DCM component provides a secure Web server, giving authorized users

access to its configuration options.

Remote administrators can monitor incoming data streams in real time using

a simple Java applet.

The DCM offers full control of its network settings. It is fully compatible with

Gralp Systems Scream! software, and can gather data from Scream! servers

or run its own Scream! server as required. CD1.0/1, DSS and SeedLink

protocols are also supported.




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DAS-D24-0008-B : Page 8 of 11

The DCM can take GCF data from multiple sources and record it to disk in any of

GCF, miniSEED, full SEED, sac, and CSS3.0 (flat file) formats. Multiple

simultaneous recording formats are supported.

Through the DCM component, administrators can configure or control the

on-board digitizer, or other connected digitizers, from anywhere on the

network. If the DCM is running a Scream! server, you can configure it to

allow control of attached digitizers direct from Scream!.

In addition, users of the Linux shell can connect directly to the digitizer and

issue commands.




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DAS-D24-0008-B : Page 9 of 11

The DCM has a variety of configuration options for its serial interfaces, including

extensive modem and PPP support. Without rebooting, you can configure any

serial port to input or output GCF data, communicate with modems, or provide

access to the Linux shell.

Files held in the on-board Flash memory, or on disk, can be downloaded

from the DCM Web page with a single click.

Channels

Input voltage range (surface)

Input impedance (surface)

Inputs (borehole and integrated)

Environmental channels

Environmental channel range

ADC converter type

Output format

Dynamic range

Absolute accuracy

Common-mode rejection

DSP sampling rate

Output rates available

Highest output capability

Decimation filters

Anti-alias filters

Low pass filters

Out-of-band rejection

In-band ripple

DSP trigger modes

Timing source precision

Optional precision RTC

Calibration signal generator

Flash storage

Sensor control commands

Optional smart sensor interface

Operating temperature

Power supply

Current at 12 V DC

4 @ 24 bits (3 primary, 1 auxiliary)

10 V (20 V optional) differential

1 M / 10 nF

matched to sensor

8 @ 4 samples/s, 16-bit resolution

10 V single-ended

5th-order single-bit low pass -

24-bit (32-bit low-noise option)

137dB (141dB) @ 40 samples/s

0.5% (0.1 %)

120 dB @ 10 Hz

32 kHz

1000 .. 1 samples/s

3 1000 + 1 500 samples/s

2, 4, 5, 24, 25

3-pole

FIR (other options available)

140 dB

140 dB

STA/LTA, level, external, software

-7

8 10-8

1.7 10 (30 mW power cost)

Amplitude/frequency adjustable

sine wave, step or broadband noise

64+ Mb

Remote lock, unlock, centre2

SSI I C/1-wire interface

40 to +60 C

12 36 V DC

Module: 77 mA = 0.92 W

GPS: 35 mA = 0.42 W



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Digitizer component specifications

DAS-D24-0008-B : Page 10 of 11



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Operating system

Communication technologies

supported

Internet technologies

supported

Direct disk recording formats

Seismic network protocols

Form factors

Port types

Flash memory

Onboard disk type

Disk capacity

Filing system

External disks

Operating temperature

Power consumption (average, 3

100 samples/s at 20 C)

Ultra low power variant of

Familiar Linux

RS232, RS422, PCMCIA modem

Ethernet (10BaseT / 100BaseT)

Wireless LAN (802.11b)

TCP/IP

PPP/SLIP

HTTP, HTTPS server and client

Other Linux-supported protocols

on request

Firewall and routing capabilities

CSS3.0 (flat file), sac, GCF

miniSEED, SEED

Scream! (Antelope/Earthworm)

Optional CD1.0/1.1

Stand-alone (3 or 7 ports),

rack-mounted (10 ports),

sensor-integrated, borehole

Data in/out, modem, console

(user-configurable)

128 Mb +

Gralp USB & Firewire

40 Gb +

Hot-swappable, journalling,

Windows FAT32 compatible

Unlimited USB mass storage

40 to +60 C with

managed disk heating

0.55 W recording to Flash

0.65 W transmitting to network

DAS-D24-0008-B : Page 11 of 11

DCM component specifications

l Guralp Cmg-dm24s3dcm

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