Guralp Systems Limited

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Introduction Installing the CMG-DM24 Using the DM24 Using Scream! Command line interface Inside the DM24  Güralp Compressed Format Connector pinouts Digitizer specifications Revision history

Digitizer specifications

Seismic channels

Number

4 – 8

 

Format

32 bit

 

Inputs

Differential with transient protection; ±10 V input range

 

Input impedance

1 MΩ, 10 nF

 

Common mode rejection ratio

110 dB at 10 Hz

Mux channels

Number

8

 

Format

24 bit

 

Inputs

Single ended; ±10 V input range

GPS

Unit

External GPS (CMG­GPS2)

 

Power

supplied through GPS connector

 

Time format

NMEA

 

Max. cable length

50 m

Sensor control

Functions available

Lock, unlock and centre sensor (active low CMOS); enable calibration

Sensor calibration

Types

Sine and square wave; adjustable amplitude and frequency

Digital signal processing

Type

Texas TMS320CV33

 

Hardware sampling rate

2 KHz

 

Sample output rates

6 cascaded rates, each 2, 4, or 5 times lower than the previous rate (even integers only)

 

Anti-aliasing filters

2 pole

 

Low-pass filters

FIR

 

Out-of-band rejection

140 dB

 

In-band ripple

–140 dB

 

Trigger modes

STA/LTA, threshold, external trigger

Digitizer performance

Output format

32 bit

 

Noise-free resolution (NPR)

22.5 bits at 20 samples/s; 21.5 bits at 100 samples/s

 

Absolute accuracy

0.5% standard (0.1% optional)

 

Type

5th-order, single-bit, low‑pass noise shaper

 

Analogue transducer outputs

3-C signals

Clock

Oscillator

8 × 10–7 standard (5 × 10–8 oven-controlled optional)

 

External receiver interface

GPS RS232 and PPS

 

External receiver synchronisation

<50 µs

Internal thermometer

Accuracy

±0.33 °C (30 °C)

±0.5 °C (10..50 °C)

±1.0 °C (–10..75 °C)

Linearity

±0.5 °C

Resolution

0.0625 °C

Power

Supply

+10 to +24 V DC

 

Current at 12 V DC

~0.12 A

Previous Next

Introduction Installing the CMG-DM24 Using the DM24 Using Scream! Command line interface Inside the DM24  Güralp Compressed Format Connector pinouts Digitizer specifications Revision history